Getting Water From Where Water IS

We buy a bottle of water in the city, where clean water comes out in its taps.
You know, back in 1965, if someone said to the average person, 'You know in
thirty years you are going to buy water in plastic bottles and pay more for
that water than for gasoline?' Everybody would look at you
like you're completely out of your mind.
Paul Watson

Aspects of the topic include sources of fresh water and their implications, with relevance that ranges from local to global. This essay considers mainly potential sources of bulk supply of fresh or brackish water.

The summary at the end lists the most promising options.

However: to anticipate a common misconception arising from hasty reading of what I present here, first please note and bear in mind, out of context:

In this essay I nowhere recommend towing of icebergs,
nor anything like towing of icebergs.

Now: this essay is self-contained, but parts of it are based on earlier work. The texts are too long to include, but they are accessible at the links I provide here.

The first of the earlier two postings discusses the extraction of fresh water from seasonally frigid regions — for any interested reader, its URL is:

https://fullduplexjonrichfield.blogspot.com/2018/03/water-on-rocks.html

That essay deals with the most important aspects of the proposals in this current essay; in particular the fact that nature does more renewable salination than humanity ever is likely to do unaided.

It deals with broader aspects than this proposal does, but it also supplements a lot of the material that I present here, including why not to tow icebergs, plus options for what to do instead of towing icebergs. The proposals here demand development and investment, but they lend themselves to several forms of prototyping, culminating in a gross freshwater industry on a scale that could in principle provide any amount of fresh water that humans on the planet really need, whether for human consumption, agriculture, or industry.

Other considerations include the fact that different approaches apply to different needs. A source of water that in most places or circumstances would be trivial, uneconomic, or pernicious, might be life-giving elsewhere. For such reasons I discuss various options in this essay. It is not that one solution simply is better than another: the reality is that one cannot shirk the identification of the needs and the applicability of the options for meeting those needs.

The other online essay mentions how to get effectively clean water from massive sources of electric power, but realistically, that technology is too far in the future for much discussion here. The URL is:

https://fullduplexjonrichfield.blogspot.com/2011/01/stop-mucking-with-geothermal.html

For several reasons this current essay does not deal with any single theme of desalination, but of all that I do deal with, the strongest proposal, in that it would have the most decisive effect on the global dearth of fresh water, is the one I reprise in the section: Summary of Major Salient Points

Meanwhile:

Many sources of fresh water are of value in particular circumstances
Such sources demand various approaches and accordingly require evaluation in their respective contexts: solutions that could be useful in some circumstances, could not pay their way in others. Smaller-scale measures, individually, unattractive, need not be dismissed offhand: some could combine to meet particular needs: in arid places it might be useful to combine grey water treatment with harvesting mist from onshore winds, where neither would be viable alone, nor in affluent regions. Though I respect their value, this essay deals with larger scale initiatives.
The most valuable large-scale technology that I discuss, demands correspondingly large scales of development and investment — accordingly, there are time-related and context-related factors: urgent needs may require compromises of scale and cost.
I propose such initiatives without apology: global needs demand large-scale initiatives: by way of illustration consider such infrastructures as optic cabling and microwave communication — within my own professional career they were laboratory speculations that grew into facilities so ubiquitous that few of the users even realise what they are, how they work, how they had to be developed, or how affects their lives daily.
And yet, their establishment required many billions of dollars of annual investment world wide during the last five decades or so. What I propose here demands heavy investment over perhaps a decade or two, but I see it as investment at a monetary profit, apart from yielding more fresh water than we need, plus contributions to ameliorating the global warming problem.

The main themes of this essay are to:

Get fresh water from where the most fresh water is to be found.
Get nearly fresh water from where there is brackish, grey, or polluted water or runoff in forms that are worth processing.
Increase availability of water as a benefit supplementary to other projects dealing with renewables, especially in arid areas where fresh water could be most valuable.
In consequence spare poorly renewable or limited water resources, such as lakes, dams, and ground water.
Explore associated economics, challenges, and opportunities of water processing, of water infrastructure, and of energy production: such factors can increase the scope for production of fresh water.
Explore potential for redirection of precipitation.

At first sight aspects of some schemes might seem unpractical — for instance: marketing and delivering water on massive scales over long distances — but human geography is changing, and promises to change a more drastically in coming decades.

However, technology on the scale I propose here does not emerge with one bound: I propose no band-aid solution, but development of an industry on a scale to rank with any massive enterprise in history. Practical proposals for how to approach a revolution cannot predict details, any more than Daimler could have predicted traffic lights. That inability did not reduce the significance of his invention; nor should the immaturity of the proposals in this essay disqualify them.

At all events, trade in water bids fair to rival trade in oil fairly soon.

Perhaps when people find that they must pay for it, they will treat water with more respect, and value it more highly.

However, I do not hold out much hope for that.

Which Water Sources Will Be Most Rewarding?

When a distinguished but elderly scientist states that something is possible,
he is almost certainly right.
When he states that something is impossible,
he is very probably wrong.
Arthur C. Clarke's first law

Begin with the minor, least promising sources. That does not imply that they may be dismissed, but they should be put into proper perspective before passing onto the main theme in the next section.

Brack and Brine

Perfection is the enemy of good.
(Established aphorism)

Simple production of fresh water should be the obvious objective, but sea water is our largest source of water and for most purposes is too salty to be worth processing. Artificial desalination of sea water is technically possible and is valuable for certain applications, but for some of the most desperate large-scale needs it is unaffordable in effort, investment, or delivery. However, reverse osmosis and some other means of utilisation do become more attractive in dealing with lower concentrations of impurities than the salt in seawater.

Seawater typically contains salt at concentrations of about 3% to 4%; there are various ways to desalinate water at higher concentrations, but in terms of money, maintenance, and energy, desalination works best and most cheaply on water of lower salinity, and the lower the concentrations of impurities the better.

Furthermore, desalination of seawater produces a brine of still higher concentration, and to dispose of large quantities of strong brine harmlessly is more difficult than it seems: simply dumping strong brine back into the sea is not in all circumstances acceptable.

Also in particular, I cannot think of any circumstances in which dumping brine into groundwater would be acceptable, unless perhaps if the groundwater were already a still stronger brine.

In short, while artificial desalination of seawater becomes increasingly attractive as the technology improves, it still has major costs and limitations and should be avoided whenever more rewarding sources are available. Accordingly in this essay I largely ignore most options for desalination of seawater, though in the latter part of the essay I accept that in some applications there are rewarding options, and it especially may be rewarding in dealing with low concentrations of impurities.

Considerations in dealing with desalination of say, brack water that has a concentration of about 1% salt, while discarding brine containing 3% salt is a good deal cheaper and less harmful than starting with a seawater at a salinity above 3%. What is more, such a process would sacrifice only one third of the water as brine. Even starting with water at an input concentration of 2% would yield about one parts of fresh water to two parts at 3% salt.

Brine at a concentration of about 3% is similar to seawater anyway, so dumping it at open sea presents no pollution problem. If the unprocessed brack water is at a still weaker, but still unacceptable, concentration, say 0.35% salt, then only 10% of the input would be discarded at a concentration of 3.5%, which causes no harm if dumped into the sea.

Just which levels would be suitable for processing, retaining or discarding, would depend on local conditions, infrastructure, economics, regulations, and similar considerations, but the principles remain unchanged, and existing technology is adequate to deal profitably with weak brack water.

This might seem trivial, but it becomes important in the context of some resources that I discuss hereinafter.

Grey- and Black Water

Where there's muck, there's brass.
North Country proverb

Some principles similar to those that apply to brack, apply also to grey- and black water. Once sludge has been removed, say by bioremediation, centrifuging, or filtration, such water usually contains low concentrations of soluble substances, well under 3%, which implies that reverse osmosis can produce clean, potable water, discarding concentrated waste, whether that waste is salt or not.

Much of such waste from black water may in itself be useful to recycle for its content of valuable minerals or organic matter that is good for recycling or fertiliser. Its relatively low volume compared to the extracted fresh water, implies that it either can be dumped safely at sea, or into agricultural land or wetlands, possibly constructed specially for the purpose. In such media suitable organisms can perform the necessary immobilisation and biodegradation of troublesome materials. I am open to discussion of examples on request.

Details of that aspect however, I do not discuss here. There is nothing novel in this; I mention it only for perspective and because there is increasing scope for attention paid to processing waste water. Notice too, that the reverse osmosis I mention here is not the typical domestic equipment, which is not nearly efficient enough to take seriously; I refer to modern industrial equipment, which is altogether more powerful and sophisticated.

The remaining question is: which other sources of water are prospects for processing?

Discussion of some options follows in relevant contexts:

Politics of Liquid Water from Low-salinity Seas and Estuaries

Seawater ranges in salinity from less than 2% in some places, such as parts of the Caspian and the Baltic, to over 4% in say, parts of the Red Sea. Some of the variation is seasonal, and at times estuary water may be nearly fresh. Damming such places is not everywhere acceptable, but desalination of water from brack regions, to charge water towers, or even just tanks, could be of value.

Some brack water might be fit for special purposes, say for pumping into places in desperate need, such as from the Caspian into the Aral sea, but I mainly consider cases where we contemplate production of irrigation water or even potable water, relying on processes such as reverse osmosis or freezing.

As I have pointed out: contaminated or brack water containing say, 1% of solutes or less, could be seen as desirable input for desalination: it might be acceptable for some livestock, but industrially such salinity demands processing. In cold regions freezing might work, or in hot regions, solar distillation.

I discuss various aspects of such natural desalination in later sections of this essay, but in regions such as the Baltic and some major estuaries that freeze seasonally, many of which already are harvested for ice, the industry could be expanded to supply water as well as ice. It is not yet a prospect for commercially viable water export, but as the demand for potable water increases, it would be quite promising in some regions.

The commercial basis of such an industry would vary according to needs and agreements. A country with access to say, the North-Eastern Baltic sea, could supply foreign countries with cubic kilometres of potable water annually, maybe by tanker-loads, such as has been done on a small scale in regions such as Namibia, where for many decades fresh water from the Western Cape has been imported by ship to serve restaurants whose clientele do not like beverages made with brack water. That is a trivial example on a trivial scale, but it illustrates one commercially viable option.

Alternatively, for really large scale export, pipelines might be more practical.

Those would have to be huge pipelines, and client countries commonly would be distant, in regions with large populations and arid climates, say the middle East, or American Pacific-coastal regions. Commercial and political frictions would demand skilled negotiation and diplomacy — otherwise termed haggling — but there is no reason to expect such nuisances to be insurmountable.

In principle such problems need be no worse than those associated with existing gas or oil pipelines.

In short, none of the suggested solutions for obtaining input or dumping waste should be in any way more challenging than existing conventions. Nor should negotiations for rights of way or claims of boundaries of territorial waters be unusually challenging.

Whether the water in anything like its raw form, is to be pumped for processing at the consumers’ end, or processed into usable potable water before dispatch, would be open to negotiation: a technologically immature client country might not be ready to invest immediately in desalination infrastructure. Conversely, having once invested in the necessary infrastructure, an exporting country would not wish to forego profitable use of the equipment by exporting brack water at lower prices than potable water.

Furthermore, partially desalinated non-potable water for industrial purposes or for irrigation, could be a profitable export on a large enough scale, with the client deciding whether or when to complete the desalination according to requirements.

Again, the client country might be able to pay for their desalination costs by retailing some of their output to neighbours in turn.

But balancing such preferences are details, and in no way unfamiliar in international commercial relations.

Those examples were for illustration only. The Baltic is a particularly dramatic example, though also a particularly complex one, both technically and politically: its salinity varies drastically, not only seasonally and with variation in currents, but with depth.

But the Baltic could be seen as an extreme example of estuarine water. Similar principles apply at all the major estuaries wherever the capacity of a river is not overwhelmed by upstream demand. This is not always so — consider the once imposing Colorado river: who can tell for how long it still could be called a river at all in its lower reaches? As things already are, upstream demand for Colorado river water is so great that its stream is hardly better than endorrhoeic.

Circumstances similar to the Baltic apply to other estuarine sites. The Amazon and Congo could supply water for many other countries along their respective Atlantic coastlines. Some estuaries opening into the Indo-Pacific ocean might also offer water fit for purification and export.

It might seem implausible that even a large river's water would dilute seawater for kilometres out to sea, but firstly, fresh river water is less dense than seawater, so it floats on top to a surprising degree. In fact, even a rainstorm may form a pool of fresh, or at least less brack, water on the sea surface: such pools are vitally important for sea snakes that cannot survive by drinking undiluted seawater.

At first sight the idea of marketing water on such a scale over such distances might not seem practical, but human geography has changed drastically in recent decades, and keeps changing.

Trade in water, whether crude or refined, bids fair to rival trade in oil fairly soon.

And rivers commonly run through properties and countries where there is conflict over who is entitled to what share of the water, or entitled to pollute it, or to control floods, or similar practical questions.

As a case in point, the river Nile, that Egypt traditionally regarded as its own, seems likely to be consumed more or less completely by upstream countries, notably Ethiopia and Sudan, that already are drafting treaties to fend off armed conflict over Nile water and dams new or under construction. Even if the consumption of Nile water upstream of Egypt is not complete before long, it very likely will be sufficient to prevent seasonal floods and the delivery of fertile silt.

Faith in the long-term stability of such situations would be unrealistic. The roles of rivers once taken for granted, are changing; and the rivers change with them.

Water economics, politics, and engineering must progress if disasters are to be averted; political and economic adjustments will demand advances in technology and engineering, and comprehension of the needs of riparian regions.

The idea of free water being a natural right never was better than a delusion, and it now is emerging as a gross delusion. Many communities will have to abandon reliance on traditional sources of fresh water, in favour of buying or processing water supplies in future.

Water Vapour: Steering the Rain

Most people miss Opportunity because it is dressed in overalls
and looks like work.
Thomas A. Edison

Weather control is not yet at the stage where we can propose it in detail: as far as I can tell rain-making has nowhere yet delivered water in significant quantities, but I suspect that strategies for dealing with anthropogenic global warming might change the perspectives.

Global warming, whether anthropogenic or not, is increasingly taken for granted, though generally so naïvely that planners and public are unable to make use of the concept in either planning or reaction: there is more to it than hot weather and melting poles. One aspect that matters here, is that hotter climate favours an increase in the water content of the atmosphere. This has many implications, but the one of greatest relevance here, is that the more water the atmosphere contains, the better the prospect for precipitating and exploiting it.

I do not much discuss promotion of precipitation in this essay, simply because it would at best be too speculative. However, most of our fresh water comes ultimately from or via water vapour in the atmosphere, so we should pay serious attention both to extraction and replenishment of humidity.

Cloud seeding I reject, as being too expensive, too poorly controllable, and too uncertain. Still, it seems to me that there are two approaches that suggest promise:

extracting fresh water from confined vapour; and
promoting precipitation of fresh water from unconfined air.

I discuss both in subsequent sections.

In all these options, the most attractive source of power for generating humidity that I can think of is solar irradiation, though waste heat from cities and industries could be useful in some situations. Probably the two would best be used in combination, with assistance of computer modelling.

Both options would be most productive in combination with the processing of polar sources, as discussed hereinafter.

Confined air humidity generation and extraction

On arid plains, especially where one might have photovoltaic farms, most of the actual solar energy goes to waste as heat.

Heating of photovoltaic components causes loss of efficiency, so there is in any case an incentive to develop a suitable cooling technology fed by seawater or other sources of non-potable water.

If the design of the water cooling is such as to pass the cooling water under glass that is so sloped that condensate drips into collection gutters, then it should be possible to harvest worthwhile volumes of water from photovoltaic installations that commonly cover several square kilometres of land.

The technology is not obscure: it is an industrial‑strength variation on solar stills.

This is an example of a technology that is unlikely to make any impression on the global problem of desalination; however, it could be valuable specifically in arid areas, simultaneously for collecting potable water and for supporting the water needs for hydroponic farming combined with electric power generation.

Warm, saturated waste air from such plant could be used for supplementing the need for power to assist the melting of imported polar ice, as described elsewhere in this essay. The hot, moisture-saturated, air could be bled off to the melting ice, on which it not only provided its share of melting power, but would shed most of its moisture onto the ice in the process, while constructively contributing its latent heat of evaporation.

Whether or not this would be combined with photovoltaic power, is a matter of detail. Any remaining cool air would be of value in its own right, such as for air conditioning or industrial cooling.

Open air humidity generation and rain extraction

Anything that increases the warmth and humidity in columns of air may be expected to shed the moisture as rain into watersheds where it might be desirable. Such effects are common in nature. Warm, moist air is buoyant, and its convection may be effective in steering air columns in desirable directions, or in encouraging precipitation, such as happens when wind blows up a mountain range, or when a cold front moves in beneath warm air in nature.

Wildfires and firestorms are not under consideration here, but the ways in which they sometimes affect local weather are illustrative.

Local heating by the sun would be the only widely viable source of energy.
Sea water commonly would be the main viable source of clean water vapour.

Most of the solar energy on the planet is shed on the surface of open ocean, in a form that, for one thing, is a major driving force in the generation of open-ocean storms under names such as “hurricane”, “typhoon” and more.

Essentially, the longer that the thinnest possible layer of surface water can be warmed, together with the layer of air above it, the greater the prospect of a violent cyclone: the air’s density is decreased by its higher temperature and by its growing content of light molecules of H₂O among air molecules of nearly twice the molecular mass.

It is like holding down a balloon that is inflating: the longer it inflates, the more violently it shoots upwards when released. If vertical convection starts early enough to let the local warm air escape without recruiting distant warm air and water vapour in a positive feedback loop, nothing more drastic results than a mild vortex, perhaps local cloud, and possibly rain. The better the symmetry of the heated layer, the greater the area in which low-lying warm air can accumulate to supply the development of a vortex until convection finally increases drastically, and the more violent the resulting cyclone.

It should be possible in principle to limit the frequency and intensity of tropical storms by breaking the symmetry of their accumulation of hot air early and in many distributed spots, thereby frustrating the development of harmful storms. One way to do this could be by starting the upward convection early and in many places. This could be done by using solar energy to start vigorous updraughts in multiple local areas perhaps a few kilometres across and a few kilometres apart.

A multitude of small storms may be harmless where a single large storm would be disastrous: ten tropical storms would be less costly than a single category-three hurricane; they even could be profitable in terms of precipitation.

Now, hurricane prevention is not the point of this essay, but that principle might well be an incidental benefit of rain engineering. If we could increase surface water heating in multiple, suitably distributed patches of sea surface where onshore prevailing winds blow over relatively arid land, or even agricultural land, that could increase precipitation in such regions. It also might deflect local wind patterns, potentially shifting the location of associated precipitation. In principle it should be a more controllable, effective, and reliable means of weather control than cloud seeding for rain.

The effect might well apply even in regions where hurricanes are vanishingly unusual. Wherever such warm-water patches start updraughts near where a cyclone would be brewing, they seem likely to bleed the main mass of its accumulation of energy, but still would cause the accumulation of moisture in the rising air, and accordingly should promote rain where it passes over land.

Apart from over open ocean, similar principles apply to open plains over land in tornado belts, except that the warm earth is not likely to add much moisture to the updraughts. However, if the air is in the first place sufficiently humid, then the rising currents still might well trigger thunderstorms with rain.

Well then, how is one to achieve local warming of the air in comparison to the surrounding regions, breaking the symmetry before a disastrously large vortex can develop?

There are several options, such as darkening checkerboard patterns of earth. There is nothing obscure about this: for over 100 years glider pilots have taken advantage of updraughts over dark patches of ground. By darkening patches at suitable intervals, one could bleed off the warm, moist air in the form of multiple lesser vortices such as dust devils, instead of relatively few tornados.

Whether such darkening would be of practical value in preventing the formation or severity of tornadoes, I cannot say, though it seems possible. However, large patches of such dark surfaces adjacent to open water, such as desert soil near to the sea, could be expected to convect moist air inwards over land, and raise it till it cools and sheds the moisture on land as rain.

As for how to darken the earth, I suggest two possibilities: either spray the area with a non-toxic suspension of carbon black in a weak solution of an adhesive such as molasses, or scatter black-stained pellets of fertiliser. Either material could be sprayed on either crop or fallow land, or on open ground in general, whether agricultural land or not. The darkening material could be designed to last for just a season or so, so that the effect could be modified in the light of needs or experience.

The dark patches could be alternated with light patches sprayed with lime or gypsum, thereby reducing global warming as well as increasing convection.

At sea on the other hand, it is less obvious how to achieve the darkening effect.
I propose experiments along two lines.

The first is to prepare buoyant pellets of black gel of a material that will not decay rapidly, but will not last in the water beyond a season or so. At a guess the pellet size could be one to five cm in diameter. I think that suitable materials might be a dry froth of density 0.5, resembling polystyrene foam pellets, but consisting of blackened cellulose, cellulose derivatives, hemicellulose, amylose, papier-mâché, or other biodegradable material that might not be very nutritious, but will be harmless if eaten by fish, turtles or whales, and will decay within a season or so if not attacked. A mass of such pellets sufficient to cover a desired area, could be mixed into a syrupy froth to keep them together while it flattens out over the water surface, could be dropped where desired by aircraft or surface craft.

Such a discontinuous froth would not interfere seriously with sea life in the way that a continuous sheet might.

There has been some excitement over the possibility of increasing carbon fixation over open ocean by spraying the sea surface with nutrient bottleneck elements such as iron or phosphorus. It seems likely that including traces of such compound in the floating pellets might be beneficial. But however attractive the idea, the effectiveness of including nutrients in the approach is speculative.

The entire idea is not to be confused with geoengineering.

The most obvious alternative to passive floating pellets would be larger balls that could be black on one side and white on the other. They might contain mechanisms to turn one side or the other upward, either robotically, or by microwaved instructions. To avoid risks to shipping or marine life, they would not be tethered to each other, but could contain magnets that could be oriented so as to attract or repel each other to maintain or disperse the dark or light patch. They could be porous so as to wick water to the black upper surface and evaporate it as plentifully as possible.

In very calm regions one might manage the desired effect by spraying a dark powder, froth, or buoyant fluid for shorter-term effects. Unlike the pellets, the effect of such a spray would be more transient because turbulence and diffusion would disperse them more rapidly.

One way or another, the intended effect of such pigments in the superficial water should be to trap the solar energy into a thin surface layer, thereby increasing evaporation and humidity and the buoyancy of the air. It would differ from the effect of darkening soil surfaces in that the location of the darkened surfaces would be less stable, so that the management of the effects would be more of a challenge in complexity.

I cannot be more specific at this point, because all those options will need research to assess their scope, relative merits, and the effectiveness of alternative designs, but the principles offer scope to steer local climates to mitigate harm from storms and — in particular in the context of this project — droughts.

Making Blessings of Afflictions

A genius is a man who takes the lemons that Fate hands him
and starts a lemonade-stand with them.
Elbert Hubbard

Floods as Tragedies and as Wasted Benefits

To these from birth is Belief forbidden; from these till death is Relief afar.
They are concerned with matters hidden - under the earthline their altars are
The secret fountains to follow up, waters withdrawn to restore to the mouth,
And gather the floods as in a cup, and pour them again at a city's drouth.
Kipling The Sons of Martha

An age-old affliction of humanity is flooding. And yet, it should be, and often was, a benefit. Certainly that is how the Egyptians along the Nile saw it for millennia. In fact, a large proportion of damaging floods are caused by human activity — often activity intended to obviate nuisance flooding, but leading instead either to drought or to disastrous flooding.

The source of flooding commonly is either waste water from activities such as disposal of water from deep mining, or disasters when dams burst, or when catchments release more water than river banks can hold back.

The irony is two-fold or worse: such flooding tends to be combined with flood control and with drought disasters. The combinations are associated with, for example, the loss of vegetation or glaciers along mountain streams. Fens get destroyed by farming and climatic warming causes the shrinkage of ice and snow. The result is that high ground cannot hold water, and releases precipitation rapidly, causing damage or disaster, and keeping nothing for irrigation later in the season. Simplistic flood control by clearing, cementing and straightening stream beds tends to cause adverse consequences of more floods and erosion downstream and more droughts both upstream and downstream.

Basically the problem is not to let the water (freshwater at that!) get away more quickly, but to retard its escape both upstream and downstream. Enable it to soak into the soil, conserving soil water, and store it wherever there are spots for dams along minor streams, even seasonal brooks that pass through culverts. Such dams could be dug to compensate for lost ice and snow and to encourage beavers or other organisms that favour the retention of water. They would make at most trivial difference to downstream flow, and to input into big dams, with the only effective reduction being the flow during rainstorms. The idea is to turn the whole region into a sponge that does not release water until it is saturated, and then releases it grudgingly, not as a flood.

If relevant upstream structures can retain valuable silt, preferably for retrieval for agriculture or building, they should thereby extend the useful lives of dams downstream, because every bucket of silt, that had harmfully been eroded out of valuable arable land, will displace a bucket of usable water that will soak away into unusable mud, or simply flow down to sea.

That sort of reduction could make a drastic difference to increasingly frequent disastrous flooding, if only it were applied to all tributaries, and the effect were amplified by universal contour furrows and similar engineering, then the abrupt flooding by direct runoff would be buffered, and the loss of fresh water in damaging floods would diminish. In some regions it almost could be abolished.

Details would have to be explored by regional engineering authorities, but as global warming strikes ever harder, with heavier rainstorms and increased drought with decreased groundwater, the need to conserve and modulate the flux of fresh water can only grow.

At the rate at which mountain glaciers are retreating, destroying options for mountain agriculture, such agricultural engineering needs urgent attention.

There is one cheerful aspect to this matter: every drop averted from flooding or erosion is another drop added to the credit side of the drought ledger.

Man Grow Mangroves

Mahomet made the people believe that he would call an hill to him,
and from the top of it offer up his prayers, for the observers of his law.
The people assembled; Mahomet called the hill to come to him,
again and again; and when the hill stood still, he was never a whit abashed,
but said, If the hill will not come to Mahomet, Mahomet will go to the hill.
Francis Bacon

For every major estuary world-wide, there are dozens of creek and brook mouths, whose water goes uselessly into the sea. Often the water, such as sewage or agricultural waste, is too small in quantity or too poor in condition to justify artificial processing. Then if the topography and local climate lend themselves to the scheme, it could be more productively dedicated to lowering local salinity and enriching local biodiversity; to this end it may be worth obstructing the passage of water to the open sea by the construction of barrier islands, tied islands, salt marshes, or simple breakwaters that moderate the rapid dispersal of the runoff. The structures could be planted with sea grasses, mangroves, or similar salt tolerant species supporting self-sustaining populations.

Though that would not yield fresh water directly, it would put potentially useful fresh water to work without continuous investment.

Solid Water to Rival the Great Rivers

The only way of discovering the limits of the possible
is to venture a little way past them into the impossible.
Arthur C. Clarke's second law

Many an idea originally seen as impossible, unprofitable, or stupid, has turned out to be, first possible, then obvious, then profitable, then routine. Nearly every genuine advance encounters greater difficulties than expected, but then becomes vital as new needs or profits emerge. The idea of exploiting the planet's largest resources of fresh water, namely our great ice sheets, has variously been bruited and mocked for perhaps a century, but it is increasingly obviously unavoidable.

However, the simplistic view of the value of the fixed ice is irrelevant: fixed ice stores are not always accessible, and even if they were, they would not be as renewable as we wish: like water mining, mining the great ice sheets would be unsustainable. What we really should be planning for should be utilisation of the annually renewed fresh ice resources; apart from other attractions, those commonly are more accessible.

Like it or lump it, we will be doing that, on a scale that even proponents hardly imagine as yet. But it will come. People will make and lose fortunes, people will die trying it, and people will make livings from it as routinely as anyone now uses cellphones — and cellphones did not even exist half a lifetime ago.

Ice harvesting markets started in the early 19^th century during the tail end of the little ice age, and at its height it amounted to several millions of tonnes per year within the United States alone. Exports of ice from Northern countries to India and affluent countries in general, probably exceeded domestic United States consumption. Ice harvesting as a trade was killed, not by lack of demand, but by expanding refrigeration technology, although to this day local ice delivery for various purposes remains more significant than most people realise.

I mention the ice trade, not so much in the context of water delivery, as to point out that in principle ice marketing is nothing absurd. The market for winter ice succumbed to refrigeration in an age when water in most affluent regions was so cheap as to be barely worth metering; and that market never did die completely. In real terms the cost of ice as water and as stored energy is changing, and in destitute societies in arid regions the need for coolth and water is increasingly desperate.

And the rest of us too, already might be living in the last days of piping domestic water: piped domestic water soon might seem as ridiculous an idea as the idea of piping domestic petrol already would seem to us. It is worth remembering that just a century ago, many hotels considered it worth advertising "running water in every room". The following comic postcard seems to date from the 1940s.

Currently, piped water losses are among our greatest losses of potable water.

The rest of this document deals with what it would take to re-establish ice harvesting; but for delivery of fresh water rather than as a vehicle for low temperatures.

So far most ideas for exploiting sub-polar ice have been unpractical: the trend is to talk about towing icebergs: which would be futile, expensive, and dangerous. Many solutions are obvious, but what is less obvious is that the technology itself is difficult, and that the scale of the operations is necessarily enormous: few people can grasp it; and such a huge scale necessarily alters the very nature of the enterprise.

And another thing is that implementing sub-polar ice harvesting will demand drastic changes of perception about what values to place on anything as banal as having fresh water on tap.

Scale and its Consequences

A large system, produced by expanding the dimensions of a smaller system,
does not behave like the smaller system.
John Gall

Icebergs generally are masses of freshwater ice calved off from glaciers or other masses of ice on land. Most of the discussion in this document deals with sea ice instead, but the distinction is not in every context relevant.

Variables in water consumption, client city size, and the size of floating ice masses are so great that I can offer nothing better than guesses at relevant figures, but typical sizes for icebergs are in the range of 0.25 million tonnes to 2.5 million tonnes mass. The frequency of bergs towards the high end of that range is much lower than for small masses, but suppose that we could transport a million-tonne iceberg to a typical city: that would be equivalent to delivering an ice cube measuring a hundred metres on each edge. Something like a city block of ice. So much water might ease the need for a while.

And yet, such a cube is only about a day's consumption for a large city. Even small cities consume water at unbelievable rates. You would have to deliver your ice cubes at a great rate. Granted, my assumptions are simplistic: each city has all sorts of strategies according to needs and local competence, but the fact remains that the long-term volume of water consumption in the first world is beyond the imagination of Joe Average.

And that sheer volume is not the main point: the killer is the infrastructure.

If one could magically park million-tonne icebergs alongside a major port city, unprepared, they would be useless: nothing better than wastefully-melting nuisances rather than assets. Water must go through storage, treatment, and delivery systems to be of use to a city. How to get a mass of ice into water piping reticulation is beyond most people's imagination. In practice it gets worse: for instance there is the question of the nature of the water, its impurities, and the needs and options necessary for its treatment.

The challenges that kill simplistic ideas for mass importation of water are: the required volumes are massive; and water must be supplied in usable form to a prepared and adequate infrastructure for storage, treatment, and delivery.

As for the global need for fresh water, I guesstimate it to be of the order of some four teratonnes annually, which is not far from the average annual flow of the Amazon river. How relevant that is, I cannot say, because it includes more than just city requirements, but it certainly dwarfs most conceptions of what might be necessary — or possible.

Givens, Options, and their Consequences

Excuses will always be there for you.
Opportunity won’t.
Anonymous

First, consider quantity and, more importantly, accessibility. In polar or sub-polar regions in all relevant ages, there has been more frozen desalinated water than we could use.

Certainly there is growing concern about the reduction of polar or subpolar ice cover. This is justified by the drastic recession of sea ice and glacier ice as global warming increases: in particular the reduction of Arctic sea ice is downright alarming for more reasons than most alarmists themselves realise.

The obvious objection is that to harvest receding ice cover is insane, but objectors fail to understand the situation: the reason for seasonal recession of sea ice is that it is melting faster in summer than it used to. That is distinct from the more serious, but different, problem of receding glaciers and fixed ice in general; it is not is even the same as the recession of the permanent ice floe sea cover. However, for as long as Earth maintains an axis of rotation tilted at an angle of more than 20 degrees towards the ecliptic, we can rely on winter temperatures sufficiently low, and remaining low for sufficiently long, to assure regional production of more fresh ice than we can use: ice in the form of nilas and heavier drift ice. There also is brackish ice in the form of frazil and similar textures, though that is less valuable.

Such ice is the first to melt in summer, so not only does it do no harm to harvest sea ice canopy before it melts back into the water, but clearing the ice from the sea surface favours the solution of atmospheric CO₂ in the surface water. Furthermore, removing freshwater ice leaves brine-enriched water on the surface: brine-rich water is denser, and tends to sink, taking dissolved CO₂ with it.

As I discuss in the essays that I supply the links to, the younger the sea ice, the likelier it is to contain salt: however we also could use brack water profitably as input for desalination, and even very new ice generally contains less than 1% of salt, which is an attractive prospect for desalination.

For the foreseeable future there should be plenty of seasonal drift ice on the Southern Ocean, but even in the North in current trends in the Arctic, new sea ice largely melts long before it becomes solid and thick enough to be useful for seals or bears. The logical way to meet our needs for fresh water from the Arctic is to encourage freezing as far we can in early winter, collect as much sea ice as we can in late winter to early spring, and drain off as much salinity as we can before it melts.

Shipping polar fresh water

New systems mean new problems.
John Gall

Yet again, remember the mind-numbing scale of the volumes of water we would want to deliver and store. No significant scheme to make a dent in global water demand could get anywhere without dealing with that aspect of the problem. It lies at the heart of all the approaches presented in this essay.

Partly for that that reason it makes no sense to specify design details from scratch, let alone equip a fully fledged industry in the first year. There will have to be several stages of prototyping, because nothing so big can emerge in acceptable form without costly experiment and exploration. I suggest that, instead of starting with purpose-built shipping, it might be more reasonable to begin with a few old bulk carriers ready for retirement and scrapping. They could be modified for pilot applications, to harvest and carry early loads of thousands or hundreds of thousands of tonnes of ice or water. The main point would be to develop techniques for loading, shipping, processing, and delivery.

The ice will not harvest itself and climb aboard the ship: there also must be a job lot of smaller vessels to deal with development of various aspects of securing the product and loading it. And that ignores the offloading at the other end.

Considering that the conditions they would be working in would be sub-polar winter and spring, weather and related factors would in themselves demand development of experience necessary for dealing with the practicalities. The Southern Ocean in particular is nightmarish year round.

All the same, as we gain experience with ice harvesting and with designing delivery and mooring structures, we would need to consider design concepts for the vessels for the long-term future. In the light of early experience we then would need to develop and scale those ideas in subsequent generations.

The largest supertankers so far have been designed to carry about half a million tonnes of deadweight (cargo). I propose that polar water carriers eventually should be designed to carry twice to ten times as much or more, and on a different basis.

Barges and Pods

However, that is a guess: there is more to ship design than simply that "bigger is better"; studies will be necessary to determine economies and diseconomies of scale; and practicalities of handling and infrastructure. One problem with such a system for the future is that both loading and unloading of million-tonne blocks of harvested ice would be a protracted process: it would be prohibitively expensive to commit an entire giant ship to lying idle during months of unloading. Such a ship would amount to a costly giant barge.

Other considerations include: bigger vessels may improve rates for ice delivery; but will take longer to harvest the ice and start the delivery. During that delay the equipment and the already-loaded part of the harvest will lie idle. And worse: at the end of the journey, the larger the load, the longer the offloading will take.

Accordingly, I propose two general schemes, without prejudice. The two have much in common: once the experimental small bulk carriers are retired, I favour having larger vessels with little or no self-propulsion — ocean-going tugs should provide all their propulsion and generate nearly all the power necessary for handling the harvested ice.

While the storage barges are active in harvesting and on the delivery voyage, they might be supplied with minimal facilities in attachable units: "pods", that house the necessary loading equipment, plus the crew in some luxury. But once moored at the port of delivery, the command pod would be detached and shipped back to the polar regions for the next delivery voyage, along with any empty barges awaiting dispatch. At each end of each delivery voyage, the empty barges themselves, minus propulsion tugs and command pods, would join the parked harvesting or delivery queues. Depending on their design and circumstances, a queued barge might literally be physically connected to the end of a chain of predecessors, awaiting its turn while the following barge is connected to its stern.

As will appear, barges in either kind of queue would amount to storage tanks for water or crushed ice, and their simplified construction would minimise the idle capital while they remained inactive. However, they also could be profitably occupied, either freezing more ice while loading, or melting ice at the delivery point. Freezing might largely take the form of blowing ambient frigid air over or through loaded wet ice.

As for the barges, I am of the opinion that they might be either of two general types: tankers or dracones.

Dracone barges

Personally I prefer the idea of the dracone to the tanker barge. I propose a cylinder of polymeric material with a sinusoidally varying diameter more or less like a vast caterpillar, so that the vessel could accommodate considerable variation in tensile and compressive distortion. I call that the eruciform architecture. As for the choice of material for constructing the dracone, I leave that to the polymer engineers, but offhand I favour polyethylene terephthalate, with a wall thickness of say, 1 cm.

Purely as a guess, the mean diameter of a full-sized dracone might be some 40 metres, its circumference about 125 metres, and its length about 1 km. Its unloaded mass would be about 1250 tonnes and its capacity about 1000000 tonnes deadweight. The longitudinal tensile strength of such an unreinforced eruciform structure should be something like 25000 tonnes, though I cannot guess what safety factor would be appropriate; that sort of thing would be subject to the nature of the handling of the equipment in practice.

An eruciform dracone very likely would be provided with external longitudinal cables or ribs for extra longitudinal strength and stability, especially for towing several dracones in tandem. Dracones generally have built-in fending capability, so the decision whether to tow them in parallel or in tandem would be a decision for the tugmasters.

Alternatively, the wall thickness could be increased for greater strength: a few thousand tonnes mass for a vessel of such a huge capacity is trivial at worst. However, the cables could be designed for concertina-like contraction of the eruciform cylinder, so that the cylinder's length when empty could be a fraction of its length when full.

The external cables could be valuable when a tug tows an empty dracone, or even a string of empty dracones. Even more importantly they also could be a vital in packing a dracone with ice: the first ice packed into a contracted dracone would be deepest in, and the cable would be relaxed to permit progressive expansion as the segments are filled with crushed ice.

That eruciform architecture is a very conservative design, and far more creative structures might be considered: for example, instead of a circular cross section with an area of 100 square metres, the dracone could have an elliptical cross section of the same area, but half the draft and nearly twice the tensile strength for the same deadweight. It would suffer less wind resistance though it would require nearly twice as much polyester. As is the case with a cylindrical dracone, such an elliptical eruciform cross section could also accommodate the contraction of a dracone under tension on the cables.

There is no simple limit to the possible variations. However, the engineering options are not simple choices: given the turbulent seas in which they would operate, any such a long, thin shape might be prone to damage. An oblate spheroid, shaped like a fat discus, might be less prone to damage than a cylinder filled with ice, and would require somewhat less material for the same volume of cargo. Such a shape would not lend itself to eruciform contraction: however, it could very likely be easier to fill with ice or water from the top down.

However, practical engineering choices, such as choice of structural material, internal baffles, and external appendages to assist contraction and propulsion when being towed, must be left to the engineers, as must the means of loading the barge.

Advantages of a polyester dracone as compared to a metal barge, include safety, relatively low cost, low toxic or ecological impact, long working life with practically no maintenance, no painting, no corrosion, indifference to UV and Teredo, and complete recyclability of the material when the craft gets scrapped, either at the end of its useful life, or after gross damage. Such dracones, with any load they contain, would be practically unsinkable. It also could be parked in arrays with little fear of problems from collision against neighbouring barges. Also, as compared to a steel vessel, a dracone of any realistic shape and structure would be easier to fabricate largely automatically, using 3-D printing techniques to apply raw feedstock of polyethylene terephthalate or similarly suitable thermoplastic.

Thermosets probably would require mending and maintenance and be unfit to recycle.

Metal Barges

As an alternative, we could use metal barges. Such a barge might resemble a super-tanker — it even might be constructed from a retired tanker — or it could be constructed from scratch to be more nearly cylindrical. Later designs would presumably be larger, eventually double-sized. Like the polymer dracone barges, they would largely be unpowered unless they were provided with command pods for manoeuvring, pumping, and crew accommodation.

Metal barges certainly would be internally partitioned for various reasons, such as trimming the vessel, strengthening its structure, and avoiding sloshing, but unlike oil or ore carriers, they need not be double-hulled. Their shape need not be the familiar rectangular cross-section of bulk carriers, but might be cylindrical or prolate-spheroidal to save their mass and cost, and optimise their strength.

Steel barges would be denser than water, so they would sink if badly damaged. However, their cargoes would be buoyant in seawater, so if metal barges were suitably partitioned, they could remain afloat unless disastrously breached.

Respective Merits of Barges

Such a barge, whether metal or polymer, variously might be manned or unmanned. If manned, the crew pod could be detachable so that it need not remain inactive with a single laden vessel while the cargo of the is being processed at the client port, or otherwise out of action. Depending on their design, barges might or might not be connected in strings or in parallel for towing, and they would be used for storage as well as transport. If intended to store ice rather than water, they might be insulated.

All the same, independently of such considerations, they ideally should be very, very large, much like currently familiar supertankers that have their own power supply, equipment, and crew accommodation, only giant ice barges probably should be even larger. Maybe millions of tonnes deadweight rather than hundreds of thousands of tonnes.

Possibly such a barge, if of metal instead of polymer, would be easier to tow at a higher speed than the eruciform dracones, though I suspect that suitably designed flaps on the outside of the polymer dracones, resembling the non-return valves in the large veins in mammals, might have beneficial effects in propelling the vessel forwards when there is a heavy swell.

Still, metal barges would be several times as expensive to build and maintain than the polyester dracones, more prone to damage, and more dangerous and expensive to scrap and recycle at the end of their life-cycle. Probably they also would have a shorter life cycle. Another factor is the cost of parking a vessel for months while it is being loaded or waiting its turn to be unloaded. Parking a special-function multi-million-tonne barge or dracone plus its load, should demand a lot less overhead expense than parking a fully functional, smaller vessel of metal.

The front and rear structures of the barges, especially the polymer barges, should be standard and designed to connect either to other barges of the same design, or to command pods. Preferably barges also should be able to dock side-by-side with each other as well in rectangular arrays; queuing up in lines of indefinite length could aggravate navigational hazards, and increase vulnerability to storms, as compared to rectangular arrays of barges that should be effective in damping swells and similar circumstances.

Probably the empty command pods should be able to link head to tail as well, to permit efficient transport by the tugs on the way out with empties.

Those tugs should be continuously active except when under maintenance; I suspect that, given the nature of their function, it would be profitable if they could be nuclear powered.

Furthermore, there is no clear limit to how large a polymer barge can be made. Even if the cargo chooses to split under the assault of storm turbulence, a suitably designed vessel could survive considerable distortion without serious harm. A metal vessel on the other hand cannot safely exceed a certain size limit: excessively large storm swells or rogue waves could be expected to break the back of excessively large tankers. And building effectively unbreakable giant metal hulls would be unrealistically expensive.

Besides, large metal vessels might be unsuited to relevant zones and seasons, such as the Southern Ocean in winter — sub-polar seas are notoriously prone to turbulence and storms. This is an important consideration for vessels that would be at their most active during sub-polar winter and spring. Simply braving the Southern Ocean at all at such a time might seem a rash enterprise, but there is no reason to believe it to be unpractical, given suitable design of vessels.

In contrast, polymer dracones loaded to float low in the water should be immune to most storm conditions; they simply could conform to the swells and stresses, and even to collisions.

The advantages of each option would depend on the nature of the collection mechanism. For example, parking a million-tonne ship or barge anywhere near an iceberg or ice cliff, or even among aggressive sea ice floes, might be suicidal. It should prove more practical to collect the ice or water with fleets of small foraging and loading vessels that capture and process the material before passing it on to the transport vessels.

Regular monitoring of ice locations and water and weather conditions by satellite and possibly by drones would be of great importance to all aspects of ice harvesting, whether in the Arctic or Antarctic.

Ice Types and Harvesting Strategies

When Grandmamma fell off the boat,
And couldn't swim (and wouldn't float),
Matilda just stood by and smiled.
I almost could have slapped the child.
Harry Graham

Not all sub-polar ice is the same. In this topic the main categories from our point of view are firstly drift ice, which ranges from perhaps 10 cm thick up to say three hundred centimetres thick. More particularly, we might be interested in pack ice, that is to say drift ice that covers a good three quarters of the local sea surface. Such sheets could be harvested more efficiently by scavenging craft or ice nibblers, than chasing after individual flakes. In the colder regions such ice should be renewed annually wherever the water surface is exposed. Young sea ice, one or two years old, being saltier, generally would be less valuable than three-year-old ice, but it still is much less salty than seawater.

The extremely thick floating ice would be the most valuable, because it is older — and old ice generally is practically non-saline. However, ice that is more than one metre thick may be difficult to break and handle. Preferably we would look for sheets a metre or so thick. Sheets of such ice could be collected by fleets of harvester vessels. Mature drift ice of manageable thickness could in fact be so precious that prospecting for it by satellite should be rewarding as well as convenient and cheap. Because old ice is so much more valuable than young, it probably would be worth maintaining continual dynamic satellite surveillance of young ice fields as well as mature fields, possibly for years. We then could harvest the ice after it had ripened, thickened, and shed most of its brine, rather than while it still is salty.

The design of the drift ice harvesters could be based on modifications of ice-breaker principles: unlike the traditional icebreaker, that breaks through floating ice by riding up on it till it falls through under its own weight, an ice harvester might invert the process by sliding beneath the crust and raising the ice in strips a few tens of metres wide and stacking them on board till the load reached capacity. It then could return the booty to the mother ship or the dispatching facility for loading into the barges or dracones.

It might however be premature to abandon the prospecting for sheets of old ice too thick for conventional icebreakers: say three metres thick or even more. It probably is feasible to design vessels with appendages that smash thick ice for collection, and carve sheets into strips that can be loaded as units. The field is wide open for new functions and designs.

Having delivered a load, a harvester would return to its floe nibbling; it very likely could continue profitably accumulating loadable patches of sea ice for a long time while awaiting the arrival of the loading pods.

One cannot always expect ice to break neatly and obligingly according to our desires, so other, cheaper utility shuttle vessels could scavenge free-floating blocks small enough to fish out of the water, in lumps massing a few tonnes or tens of tonnes at a bite. The machinery for loading such lumps into the barges or dracones might exploit such lumps particularly valuable: they could be crushed into slurry as filler of gaps between large masses in the holds, and preventing irregular masses of ice from damaging the walls of the barges. At temperatures well below freezing, such ice gravel would rapidly cement neighbouring masses together, preventing tumbling and sloshing hazards.

Harvesting such well-formed sheets of ice should be relatively safe and profitable, as compared to dealing with icebergs and large, irregular ice floes. A fairly small sheet, say a hundred kilometres square and with a mean thickness of about one metre, could yield about ten billion tonnes of relatively pure ice in manageable form. To be sure, such a mass would take some thousands of ships or barges to collect it all and deliver it to the client countries and cities. The clients in turn would need facilities to handle the imports, but the facilities need not be any more demanding than damming and treating the water of major rivers. It also would be a good deal less costly and less ecologically harmful than damming, especially if the water were collected and delivered in the form of ice that at local temperatures could be used as a power source.

There always is scope for more design, so I do not go into detail here and now, but for example, polar storms at sea can be very severe, especially in the Southern Ocean, so it might turn out to be worth designing some of the ice harvesting and management craft as submarines, preferably nuclear submarines. Whether they did most of their work on the surface or not, they could ride out the worst storms in deep water, when submerged a few tens of metres.

Global warming seems to be affecting glacial ice on Greenland and Antarctica as well as sea ice, and glacier ice tends to be temptingly fresh. But at present glacier ice is less relevant to the proposals that I describe here: for one thing, harvesting glacier ice raises issues of conservation. Iceberg that can be carved into loadable chunks certainly will be added to ice harvests after they are calved into the sea. But before we consider them, we should master the techniques for harvesting drift ice.

Manufacturing Polar Fresh Water

A wise man will make more opportunities than he finds.
Francis Bacon

Cold Comfort Creation

The primary objective is to deliver water to the thirsty clients: for them to receive it exactly when required and pump it to where it is required is the obvious option. However, the entire operation is costly in energy, infrastructure, and human resources; the source is largely seasonal; the volumes necessarily are huge; and every material saving and gain is in the enlightened interest of all parties.

Polar ice is in many ways valuable, but Nature does not present it ready for consumption. The most plentiful and accessible forms of drift ice tend to contain more salt than we would like, though not nearly as much as seawater does. Even if we cannot get pure water, sufficient reduction in salt content is of value; we might well ship brackish water to willing clients who could process it further according to their needs. Practically any water to be delivered to end users needs to be processed first anyway, even if you pump it out of an unpolluted river. The decision of when to stop polishing your product may be critical: you do no favours to a client by delivering water pure enough for an analytical reagent when the need is for potable water, or delivering potable water when the application is irrigation. And each pass in purification hugely increases costs and delays. And sometimes the need for acceptable water today is greater than the need for water of high purity after the client is dead or bankrupt for lack of any water at all.

We might have better uses for large quantities of brackish water than dumping it at sea.

On the other hand, brack water, say 0.1% to 1% salt, compared to seawater's 3% to 4% or so, also could be processed at the site of collection in subpolar regions, by freezing it in a polar winter instead of shipping it to be desalinated on delivery; that could work better than freezing seawater, and produce ice much less salty than frozen seawater. Brackwater can freeze to produce a clean, solid surface layer of ice: nilas, rather than the salty frazil that tends to form on seawater.

To begin with, seawater is rarely still, so a lot of things that seem simple to the landsman, become terribly complicated in real life at sea. For instance, the turbulence causes mixing of surface waters, and mixing makes it difficult to discard the salt. So finding ways to keep water still can be very valuable.

Imagine a giant tabular ice sheet near Antarctica, whether landfast, moored, or floating, but not yet about to fragment or proceed rapidly north. Imagine that we had excavated a large, deep quarry into it. That hollow might be excavated by adding traces of carbon black or organic pigments such as chlorophyll or other porphyrins to promote solar-powered melting during summer. We then would have pumped the fresh water into our tankers for freezing during the following winter before shipping it to the client ports.

During summer we could dump our harvest of marginally brack water into that hollow, where it would melt high quality, low salinity ice from the underlying sheet, increasing the volume of brack water while decreasing its salinity. The surface of the water in the hollow would be relatively still, without any swell compared to the turbulence of the open sea, and the water in the hollow is already not very brack.

Come winter, the surface would freeze more rapidly than seawater, and unlike fresh sea ice, the new surface ice would be of high purity. It could be skimmed and loaded for dispatch as soon as weather permits.

Such preprocessing should be easier than collecting clean ice from a restless sea surface. For one thing, to freeze seawater on open sea is neither as fast nor as easy as it sounds, because water that contains about as much salt as seawater does, does not expand as much as fresh water does when it approaches its freezing point, so it does not float as well, and it takes longer to freeze over deep water; and it tends to sink a few times before it freezes.

Once the ice harvesting industry has matured, there should be large numbers of dracones or barges continuously available, but not yet fully loaded. Or, if loaded, their water might be brack. If they contain much ice, the swell of subpolar seas should continuously massage the brack water out of them so that it drains downwards, leaving fresher ice above. This is much like what happens in nature on the sea surface. One could take advantage of this principle to refine harvested young sea ice by principles similar to those that expel salt from sea ice as it matures.

Another approach, and perhaps the most practical, would be to freeze seawater or brack water in dracones. Our dracones should be large enough and cheap enough for us to prepare an empty dracone in early sub-polar winter, half-fill it with cold sea water that is beginning to freeze, and use mechanical wind power to blow ambient air over it through the ullage, at temperatures between say —10C and —40C.

In a single dracone, as the nilas ice accumulates, skim it and pack it into the deep end of that dracone or perhaps pass it on to another dracone, and continuously drain brine and admit more freezing sea water. After long enough the packed dracone is full enough to drain and ship off. (By that I do not mean 100% full, because dracones work best with an ullage of some 10% to 20%.)

If filling the transport dracone takes more than one season, no problem! All the more time for any brine to drain to the bottom, from which it can be pumped out. If ice of lower salinity is required, the procedure can be repeated, using a series of dracones of successively reduced salinity.

Note that the brine ejected during this process will not be a problem: it can be expelled at a mild excess salinity and it will in any case be saturated with CO₂ and O₂ at the lowest temperature and highest density that will send it down into the depths. In such circumstances in turbulent water of great depth it cannot do any harm; and in fact it resembles the natural formation of sea ice that largely goes to waste. The sinking of weak brine from surface freezing is a huge seasonal process in sub-polar seas.

As nearly as practicable, the ideal is to freeze the cargo of a delivery dracone solid before starting the delivery leg of a voyage.

Assembly Line Ice Production: Ice and Economics

So much for freezing water in the dracone as a means of producing marketable brack water: but the foregoing does not exhaust the potential benefit of that principle. Suppose we take a string of some practical number of special-function desalination dracones. Their upper surfaces could be made of transparent greenhouse polymer, possibly with black undersurfaces, and with a flattened elliptical cross section rather than cylindrical. Probably they would be permanently moored next to each other in deep, frigid subpolar waters. Their ullage when loaded would be large, say 40% or so. They might be ballasted with keel frames to prevent capsizing, and to correct their attitude if some accident did none the less overturn them.

In the subpolar autumn the dracone at the input end of the string takes in seawater ready to freeze. Such seawater might contain about 3.5% of soluble salts. When ambient temperatures drop below freezing, use wind power to blow ambient cold air through the ullage of the dracones and start freezing the intaken water. As the ice freezes on the water in each dracone, rakes pass that surface ice forward into the next dracone in line. These dracones are equipped to monitor their salinity automatically, and keep taking in water at their input ends to replace the ice that they had passed on. But any brine left from their freezing, they pass back to their input dracone to maintain their own salinity at not much higher than that of the input water.

In this way the brine keeps getting passed back till it is ejected below the rear dracone, while ice, plus any water of acceptably low salinity, keeps passing forward until it melts by solar heating when the sun returns. At the output end of each dracone, the partly desalinated ice or water is passed on to the next dracone in line. At the input end of any drone, any water that is undesirably saline gets passed back into the input dracone: in each dracone but the tail-end, it will after all be less saline than raw seawater, so it should not be wasted.

We might expect ice coming out of the seawater in the input dracone to contain less than 1% of salt. When summer comes and melts the ice in the dracone "greenhouses", each dracone retains water of its assigned salinity, and ejects into the sea, any water of greater salinity than that of ambient seawater. Any water of lower salinity than a dracone's assigned concentration range, it passes on to the next dracone, and anything more saline, but less saline than seawater, gets passed back to the previous dracone.

This may seem very tedious, but such a string of dracones should never be longer than a line of four. Each dracone after the input dracone should desalinate the water more efficiently than the previous freezing step. After three seasons at most, the line should be full, and ready to charge transport drones every year with potable water and negligible costs, if any, in fuel or human intervention. There is no relevant limit to how many such strings of dracones could be established to load transport dracones at a suitable site.

Ice output from the second dracone is likely to be at a salinity of less than 0.01%, which is good enough for potable water, but if it turns out that there is an attractive market for water of still lower salinity, ice at the next level can be retained and melted in a third dracone, to freeze during the following winter. By that time the salinity would be vanishingly low. And in general, the output of the complex of freezing/thawing dracones could carry on indefinitely.

This could be the basis of a massive freezing desalination plant. The design of such equipment is a matter of engineering, so I do not discuss it here. Such technology is achievable, but must be developed in the light of experience.

When conditions are favourable it would be better to employ ambient cold to freeze, process, and reprocess, water on board while loading in the subpolar winter instead of shipping liquid water to the client ports. The more usably pure ice that can be delivered ready for final processing on land, the greater the profit and the safer the voyage: liquid cargoes can slosh dangerously.

In effect, subpolar conditions could be used in various ways to accomplish direct desalination by freezing. Desalination by freezing was attempted in the mid-twentieth century, but it never was energetically profitable, and uses large amounts of fuel — however, freezing should be profitable in subpolar winter conditions on scales of millions of tonnes. Furthermore, in the past, the value of fresh water was too low for such processes to be economically attractive, or for importation of sustainably desalinated subpolar fresh water.

To date, we have in my opinion been ignoring the world's cheapest large-scale desalination process short of evaporation of ocean surfaces to form clouds — and cloud water is not efficiently controllable or recoverable.

Ironically, if we were to import ice to thirsty countries, the value of ice as a heat sink might resurrect desalination of sea water as a viable technology. And ice or cold water can yield added water by condensing humidity from the air, as I mention elsewhere. We might not get two-for-the-price-of-one, but one-and-a-half for the price of one still can be an attractive prospect.

The speculative aspects of these schemes reflect the scale and the variety of their potential, rather than the unpracticality of the suggestions. The technology will reward the engineers who develop it, not scoffers who rage at their own inability to conceive the opportunities.

Given such measures on as large a scale as outlined here, one might consider some sidelines. One of them might be to combine bulk ice-and-water importation with block transport. Two versions seem promising. One would be completely literal ice trays in a suitable barge of a size tiny compared to the drogues, but still tens of thousands of tonnes deadweight. To match commercial unofficial de facto standards, each block could measure about 1 metreX50cmX25cm: roughly 1/8 tonne mass. They could be loaded into roughly standard shipping containers with suitable frames, at about 20 tonnes per load, implying about 160 blocks per load.

One way of producing the blocks would be to have the empty ice trays in place in the open containers in open air in late summer. Fill them with water of the appropriate grade from the desalination dracones. They would be frozen solid long before winter was over. They then could be sealed for shipping. A 10000‑tonne deadweight vessel should be able to transport some 200‑400 such containers at a load, with 50000 to 60000 blocks.

If it were decided to make such ice blocks a major line, of similar value to the desalinated water itself, far larger vessels would be possible. One could design dracones with the necessary frames and moulds built in. Ambient winter air would be blown through the cargo space to freeze the top layers of the cells. The brine could be discarded onto the bilge, which would be routinely pumped out by the attached crew pod. Such a dracone might have larger structural mass than the simple dracones, and a far smaller deadweight capacity, say 100000 rather than 1000000 tonnes, but on the other hand, it would not be dependent on sea ice, could be unloaded rapidly, and might make several round trips per season.

If it were decided that the ice-block water need not be potable, then the brack first-freeze from seawater might suffice: design the trays such that when filled with seawater they freeze top down to the required thickness, with the brine beneath. Then they eject the brine, and deliver the block of nearly pure water to the loading line, and accept the next charge of seawater. In a subpolar winter such a device should be able to produce a good 20 blocks per dish.

There are so many options that it is hard not to multiply proposals. The actual choices would depend on research and analysis of the economics.

Unloading Polar Fresh Water

It is their care in all the ages to take the buffet and cushion the shock.
It is their care that the gear engages; it is their care that the switches lock.
It is their care that the wheels run truly; it is their care to embark and entrain,
Tally, transport, and deliver duly the Sons of Mary by land and main.
Kipling: The Sons of Martha

The obvious way to collect water would seem to be to go to where the ice is, load some up, melt it, and take it home. However, I propose that although there might be some merit to piping subpolar liquid water from the North to where it would be welcome to clients further south, it makes sense to ship ice instead.

In the Southern Ocean on the other hand, it hardly makes sense to ship water at all if ice is equally easy.

Even if your collected harvest is at first melted at the time of loading, and cold is available, take advantage of the cold to freeze as much as is practical before dispatching the load. In fact, where practical, chill warm ice that is close to melting, to make it as much colder as may be, and keep it cold till you moor your barge at the delivery terminal.

There are several advantages to shipping ice rather than water, but delivery of either ice or water has its own attractions and each presents its own problems and rewards. Water is easy to pump aboard in loading the harvest, and easy to pump ashore in delivering the water. Water also is compact, either in itself or if we use it to fill the gaps between ice blocks in storage vessels' holds.

But water in bulk also needs special precautions to handle at sea: sloshing can be deadly to a large vessel, although less so to a dracone. Also, water cannot be stacked like solid ice blocks. And its capacity for storing cold is small, compared to the latent heat of melting of ice. In various industries concentrated cold can be as valuable as concentrated heat. That is why we who remain ashore spend money on freezers, heat pumps, air conditioning and the like.

So importing cold can be a profitable sideline.

It could in fact pay for the importation of the water.

Massive ice delivered to warm regions with suitable infrastructure, could be valuable, for instance in cooling and drying air; and in melting, the ice could condense water from warm, humid air. Latent heat of condensing vapour could melt more than its own weight from the masses of imported ice. The cold also could be used in heat pumps to freeze seawater or brack water to produce ice from which to collect pure water.

Furthermore, at the delivery end, seawater warmed by solar power or heat pumps or waste heat from power stations, foundries, or other industrial installations, could be used to humidify air that then could melt the ice. Jets of such humid air could carve mass ice into usable blocks, while yielding a profit in condensed water; block ice is of value in its own right whether one needs the water or not. Air that had been cooled and dried by the ice in such ways could be used for air conditioning, much as one can use waste heat from power stations for combined heat-and-power schemes.

Ice delivered in masses in barges rather than in loadable blocks such as might be delivered from containers, would be hard to unload from ships, so it would be a liability that took months. This would be a good reason for using low-value dracone barges or even the more expensive metal barges for transport. Such ice-laden vessels would serve as storage buffers while the load thawed and got pumped ashore, or delivered as blocks.

Some of the free water on the barges could be expected to be brack; on the trip and while waiting in the offloading queue, brack ice would tend to melt and drain to the bottom. In the offloading process, the first water could be bled off for desalination or other less salt-critical purposes (livestock watering, for example). The salinity of the offtake should of course be monitored throughout the melting process: ice generally includes brack patches. But such monitoring and treatment is routine in water processing anyway.

In contrast to the residue from desalination of seawater, the volume of brine from desalination of brackish water should be too small to be worth attention, so there would be advantages to desalinating brack water to no higher salinity than the local seawater could accept without special treatment.

Conservative desalination would remove the problem of disposal, because brine at a concentration similar to local seawater, could be dumped into the sea without precautions. The problem of brine disposal after desalination has turned out to be a serious concern in practice.

Salt water from brine is likely to contain nutrients that would favour the growth of photosynthetic organisms that consume atmospheric carbon dioxide, so its presence in local water would be beneficial. It also might find a market in the preparation of salt-lick blocks for livestock.

The economics of managing such processes could become quite sophisticated.

Meanwhile, as the loaded barges await unloading, the tugs and crew pods could have returned polewards, taking previously emptied vessels and container barges with them. They might fetch several full loads on successive journeys by the time their previous load had been discharged, so a team of tugs could serve a larger team of crew pods, and their crew pods serve a still larger flock of barges.

Polar Ice as Fuel

As a method of sending a missile to the higher, and even to the highest parts of the earth's atmospheric envelope, Professor Goddard's rocket is a practicable and therefore promising device.
It is when one considers the multiple-charge rocket as a traveler to the moon
that one begins to doubt ... for after the rocket quits our air
and really starts on its journey, its flight would be neither accelerated nor maintained
by the explosion of the charges it then might have left.
Professor Goddard, with his "chair" in Clark College and countenancing of the
Smithsonian Institution, does not know the relation of action to re-action,
and of the need to have something better than a vacuum against which to react ...
Of course he only seems to lack the knowledge ladled out daily in high schools.
-New York Times Editorial, 1920

One major concern in all such harvesting and transport initiatives is energy. There is no room to argue against the value of ice delivered in usable form to places where it is wanted; but if we have to go thousands of kilometres to fetch it and spend months on the trips both ways, then questions of cost and fuel are worrying.

Costly water amounts to no water, except perhaps on a spacecraft.

And the most important cost in this connection is energy. It is not a cost we can dodge; arguably the most implacable constraints in our world are those of thermodynamics.

So one thing is certain: we can't get our water free of cost.

The question is how far we can reduce the cost, and at that cost, can we turn a net profit? We want fresh water or ice, not as an expensive luxury, but a profitable staple. We must present major dams in temperate zones, and irresponsible parasitic consumption of river water, look like economic and ecological suicide.

And there is more to the equation than is obvious at first sight. Apart from our primary objective, subsidiary items can make the difference between failure and a handsome success.

Meaning profit.

We certainly cannot beat the laws of thermodynamics, but we might examine the fine print for options to exploit for profit.

One point is that what matters in exploiting energy is not how much energy we have, but the exergy, which depends rather on the difference in energy levels between one part of the system and another.

Let us call the high energy level the heat source, and the low energy level the heat sink. For example, a flame at a temperature of say 1000 degrees in a chamber at a temperature of 200 degrees notionally performs no better as a source of power than a flame at 800 degrees in a chamber at zero degrees. In both cases the heat source is 800 degrees hotter than the heat sink. For more coherent detail consult the essay at https://en.wikipedia.org/wiki/Exergy together with its links.

So one can improve the energy efficiency of a system just as much by reducing the temperature of the sink, as by increasing the temperature of the source. In fact, where feasible, decreasing the temperature of the sink achieves greater efficiency than by raising the temperature of the source. To see why, read the essay at https://en.wikipedia.org/wiki/Carnot_cycle.

Now, for most of this essay we regard the problem of importing ice as implying a need to melt it at the reception installation. And that is reasonable; there is not much we can use the water for before melting it. And although it does take huge amounts of fuel to drag billions of tonnes of ice through megametres of ocean, it also takes even more energy to melt billions of tonnes of ice.

And yet, a million tonnes of ice at a few degrees below freezing point, used constructively as a heat sink, offers the equivalent of something like 334 joules per gram, which works out at 334 billion kilojoules for a million tonnes, ignoring the scope for a few billion extra kilojoules to bring the melted ice to ambient temperatures. Those 334 billion kilojoules are roughly equivalent to the energy output of 30000 tonnes of coal or similar fuel.

And that exergy comes with no ash, no air pollution, no greenhouse gases, no wasted fossil fuels or other chemical feedstocks.

That also depends on the form in which we use the energy, but the choice of the form is a question of engineering, not a matter for us to pursue here. In this document I do remark on the value of exposing the ice to air, which condenses any water vapour, adding clean water to our yield from melting the ice, and at the same time producing cold, clean air, valuable in industrial applications, such as air conditioning.

But those too, are details.

The point remains, that we can exploit more exergy in melting masses of ice, than it takes to ship ice from the points of collection to the point of consumption. One could argue in favour of doing it all for the energy yield alone. Then the water we deliver would be a mere bonus.

But what does matter, is the relevance to the engineering strategy. If we melt the ice and ship the water, we thereby reduce the profit in imported exergy by a factor of several hundred.

We have an incentive to import our water in the form of ice, in low-cost passive vessels such as barges or dracones that can be parked for months at the point of collection or delivery, with as little melting and as much freezing as we can until we wish to extract the water and apply the exergy to achieve desirable objectives.

A temperature difference of say twenty- to thirty degrees centigrade might not seem very exciting to a power engineer, given that each degree of difference offers only about four joules per gram, but the latent heat of melting of the ice amounts to nearly eighty times as much, so that a shipping a million tonnes of ice to a hot climate begins to make things look a lot more attractive than shipping huge quantities of fuel pole-wards to melt it at the point of harvesting the ice.

Remember too, that the way one uses energy makes a big difference.

Energy is energy, no matter what you do to it, but exploiting the exergy by combining negative and positive differences between the source and the sink, can be the main reward. One could use the cold to produce cold dry air that would have taken a great deal of fuel to produce by refrigeration, but would take effectively no fuel when using warm, moist air to melt the ice. Then the fuel saved from melting could go to driving the collection of ice from the sea.

We cannot argue against the value of ice delivered to where it is wanted; but to go thousands of kilometres, taking months both ways, raises the cost.

And for our purposes costly water amounts to no water.

And the most important cost in this connection is not a cost we can dodge: thermodynamics. So one thing is certain: we never can get water free of cost.

But we may be able to pay that cost from exergy that the climate continuously accumulates, and that we currently are wasting.

It depends on the form in which we use that exergy, but that is a question of engineering: not a matter for us to pursue here. I do mention elsewhere the value of exposing the ice to air, which, in condensing humidity, adds clean water to our yield from melting the ice, incidentally producing large volumes of cold, clean air, which is valuable in various industrial applications, such as air conditioning.

The important point remains, that it is possible to extract more energy from the melting of the ice, than it takes to ship ice from the points of collection to the point of consumption. One almost is tempted to argue in favour of doing it all for the energy yield alone. Any water we then can extract at the point of consumption would be a bonus.

But one thing that does matter, is how such factors influence our engineering strategy. As I already have pointed out, one strategy is to melt the ice and ship the water, but we thereby would reduce the profit in imported exergy by a factor of several hundred.

Polar Ice for Scrubbing the Atmosphere

Don't find fault, find a remedy; anybody can complain.
Henry Ford

It seems likely that, given winter temperatures of well below -20C near the Antarctic coast, it should be practical to exploit that cold as a source of power in collecting, loading, and transporting fresh water. We already have contemplated using the cold air to produce ice in various roles, but really, that seems to be a narrow view of important opportunities.

Understand that, though the ambient temperatures near the Antarctic coast are not nearly low enough to liquefy gases such as O₂, N₂, or even CO_2, they are low enough to reduce the costs of liquefying, storing, and working with, such gases. Furthermore, Antarctica and the Southern Ocean around it, are a source of significant renewable solar and wind power — wind at all seasons, and solar photovoltaic power for nearly half the year, including a lot of midnight sun during high summer. The Southern Ocean is one of the windiest places on the planet, and with some of the strongest winds; wind turbines would need special designs to survive and function, but could well be worth it for powering the preparation and packing of harvested ice.

We obviously could exploit such resources to get fresh water and some power too, and they entail opportunities as well. If it were to support a large industry of clean power accumulation, that southern resource could be enormously valuable once the scale of operation grew large enough: we could exploit it without importing expensive, polluting, non-renewable fossil fuels.

Various renewable power units could be used at all seasons for accumulating cold compressed gases and possibly even for separating some of them. In particular, they could be used for condensing CO₂ as a liquid under pressure at winter temperatures, and for cooling air or even O₂, and N₂ if desired, for storage either as gases under pressure or as liquids in cryogenic storage.

"What on Earth for?" I hear the engineers cry! Understandably, because there is not much market for such products so far down south, and though compressed gases are valuable in industrial countries, it would be out of the question to produce them for commercial export thousands of kilometres to the north.

Yes, but compressed or condensed gas can be used for driving engines. In fact it is rather a good medium for storing power for such functions. And it is a very good medium for storing cold, because one need not store one's cold at such low temperatures; extremely low temperatures are harder to maintain than moderately low temperatures — and as the comfortably cold gas expands and the pressure drops, it accordingly cools further. The thermodynamics present tempting opportunities for sophisticated designers.

The following proposals are not to be taken seriously for early phases of development, but within a few decades of experience and expansion, they could become downright attractive, both commercially and ecologically. As an analogous example, not too many years ago, wind and solar power did not look at all promising, but already both are goring many of the sacred cows of the traditional power industries.

Such cold could be welcome as an aid to stripping greenhouse gases such as CO₂ and H₂O from the atmosphere directly, either for industrial use as a by-product, or simply for disposal wherever it might be suitable. That objective is not of direct interest to this project, but collecting CO₂ from the atmosphere might render the subpolar freshwater extraction industry carbon-neutral or even carbon-negative.

More directly, condensed or compressed atmospheric gases could be used on site or loaded onto transport vessels as fuel to be consumed at warmer latitudes. O₂or oxygen-enriched air might be used in combustion engines as a means of supercharging, but I prefer the idea of using the gases as they are, to drive the ships' turbines without using fossil fuels at all. For that we do not want the gases to be cold; in fact it would be good to heat them up, and the hotter the better. Reducing the pressure on the gases as they are used for propulsion could require the harvesting of heat from the environment; delivery pipes exposed to the air, or even to sea water at temperatures above freezing, could freeze any liquid water in the ice cargo or condense atmospheric water to add to the payload on the way home. In doing so, the waste heat would warm the gas to drive the vessel.

In this discussion it would be premature to propose details of how to manage the thermodynamics of allocating energies and materials most profitably; for one thing, such processes would only be worthwhile on a very large scale, after a lot of smaller-scale development had matured. But the scope for establishing a clean industry of global importance should not be ignored. Again, we should reflect on the explosive growth of the wind and solar power technology and industry in recent years, when just a few decades ago they looked derisory.

And condensing CO2 for disposal as we prefer, as an added benefit of desalinating seawater, seems to be an attractive prospect. Sinking millions of tonnes of blocks of dry ice where the sea is more than two kilometres deep would be a good mitigation of greenhouse gas, more than paying for our fuel costs and making the entire project carbon-negative.

Another beneficial effect of collecting sea ice from polar and subpolar seas, is that global warming seems to be increasing the accumulation of fresh, or at least less saline, surface water in those regions. That in turn bids fair to interfere harmfully with thermohaline circulation. The effect of ice harvesting, even on a large scale, should be trivial, but such as it would be, it would at least be in a favourable direction. The reduced salinity would also tend to favour the quality and quantity of ice available for harvest from such waters.

In sum, such environmental effects as we could expect from such ice harvesting would generally be favourable rather than otherwise.

Summary of Major Salient Points

First I tell ’em what I am going to tell ’em; then — then well, I tell ’em;
then I tell ’em what I’ve told ’em
Anonymous preacher

There are too many aspects and scales of the topic to enumerate in this essay, even too many mentioned in the foregoing text to summarise here; and some require too much research for immediate consideration.

Accordingly I propose the following points as demanding no more than industrial commitment for undertaking the rapid largest-scale development and implementation:

a) Second only to precipitation, the indefinitely sustainable, uncommitted and accessible resources of fresh water on the planet are on the subpolar seas. (Truly polar seas occur only in the North, but the distinction is largely academic.) And there is not a lot we can do about precipitation; although I do mention some items in this essay, they are speculative.

b) In contrast, the investment, technology, and infrastructure for harvesting, generating, and constructively utilising ice, all need commitment and development, but there are no fundamental obstacles to commercially viable production of high quality potable and industrial water on massive scales from those sources. Do not confuse the proposals in this summary, with small-scale local initiatives to deal with local needs, nor with towing of icebergs, which I reject as being counterfunctional.

c) Political and diplomatic difficulties arising from the harvesting of ice from international sub-polar waters are minor in comparison to those of exploitation of fishing or mining resources: I propose immediate initiation of responsible ice farming.

d) The geophysical and engineering considerations are manageable and tend, if anything, towards improvement of the status of albedo, sea acidification, all greenhouse gas levels, persistent pollutants such as microplastics, and of sundry toxic substances that get concentrated into waste brines.

e) The biological effects are manageable and likely to improve situations of current concern in subpolar regions and deep water.

f) Depending on the details, side products might emerge profitably from waste brines. Examples include compounds of bromine, calcium, lithium, magnesium, and potassium. Some that are not commercially viable in themselves, may prove valuable for sequestering and neutralising CO2 incidentally to the processing of the water. They could at least contribute to rendering the industry carbon-negative.

g) The major sources of fresh water discussed are subpolar sea ice, and seasonal freezing of impounded seawater, though the essay does briefly consider other sources such as fixed ice, atmospheric humidity and brack water sources in seasonally freezing regions.

h) The sea ice in question is mainly seasonal sea ice plus young ice: say nilas about 5cm thick, up to sheet ice perhaps 1 metre thick. Satellite monitoring of the most favourable harvesting areas would be continuous and invaluable.

i) As I point out in the document, seasonal subpolar freezing amounts to the second greatest desalination process on the planet, but largely free, currently largely wasted, sustainable, and carbon negative.

j) The most valuable and effective vessels for accumulating ice would be polymer dracones of capacities that are unprecedented, but technologically unchallenging. Their details are open to design, experience, and debate; but one reasonable class of configuration would be for the dracones to be towed by specialist tugs, managed and packed by specialist detachable pods that accommodate personnel and processing. The crews and pods also would deal with preliminary refinement and freezing of the load.

k) Such dracones also could be parked as storage vessels during loading at sea, and for unloading and preliminary processing at the client port. When not required for activity during a dracone's current status, the tugs, pods, and any other servicing equipment, having parked the dracone, would leave it and service other dracones. The material mass of a dracone of developed size might be of the order of 1000 tonnes, and of relatively small capital cost, but with a capacity of the order of 1000000 tonnes of deadweight. Loading and unloading accordingly could be protracted, with plenty of time for such a dracone to support considerable preliminary refinement of the cargo, and for a given team of service craft to serve multiple dracones in parallel. There are options for how best to use them. For example:

1. Dracones could be served by specialist harvesting craft that gather suitable sea ice or fixed ice, and load the cargoes; or:

2. Dracones could be designed, either to load seawater and freeze it by application of ambient wind and cold, discarding the brine on the spot, or served by strings of smaller dracones that perform the freezing or re-freezing function, then load the clean ice or water into the transport dracone.

l) Depending on the market, ice could be frozen in block form, to produce fresh industrial or potable water, either from brack water or even seawater; either in containers or in dracones with internal structures adapted for the purpose. That would not be a problem, seeing that polymer dracones would almost certainly be constructed by 3-D printing. Such a project would at first be secondary, but it is not clear that it never would grow indefinitely.

Water as Ice Cubes

In dealing with a complex range of subjects it is difficult to balance aspects in terms of relative importance. It occurs to me that I had overlooked a topic with enormous transformation potential for both first-world and third-world economies and individuals, though not necessarily in just the same way.

It is natural to overlook small-scale domestic consumption in considering the impact of any large-scale change to social infrastructure, and I find that in the main essay I had neglected to discuss the natural role of subpolar ice in the home. It deserves far deeper consideration: apart from the bulk transport of masses of ice, I did present the concept of a barge, possibly in the form of a dracone, in which subpolar desalination could produce blocks of fresh ice in million-tonne quantities.

There is nothing obscure about the principle; the engineering challenges are interesting but not discouraging.

I suggest producing fairly standard commercial blocks of fresh ice measuring about 100cmX50cmX25cm: i.e. the mass each block being about 0.125 tonne.

The following schematic picture suggests the principle of how a mould might be designed to freeze such blocks as I discuss below, by exploiting the subpolar winter winds for cooling. The seawater would be frozen from the top down, and the right thickness to fill the mould could be attained several successive times per season.

How?

A suitable vessel could produce and deliver such blocks prefrozen in cargoes of 10000 tonnes to 1000000 tonnes deadweight, with the blocks loaded in frames in containers that facilitate their loading and unloading with speed and efficiency.

I do however suggest that a better scheme would be to do the freezing and moulding in commercial cargo containers, either situated on stable fixed-ice sheets, or on land. It also could be done on the decks of a raft or ship, but I wish to avoid sloshing in rough weather. Containers could be kept busy practically throughout the freezing conditions of every year. Once laden with ice blocks in fixed frames, and with very little internally wasted space, the containers could be loaded onto container carrier ships or barges as they become available.

Stationary freezers on land or on fixed ice shelves have the advantages of over seagoing freezers, that they would be more stable in stormy or turbulent seas, and that they could actively continue freezing ice blocks for as long as the weather remains cold enough and the wind chill sufficient. They then need not waste freezing time while shipping cargoes. At any time that there are no vessels available for shipping, freezing could continue, accumulating loaded containers as long as empties are waiting.

On such a basis, block ice freezing could rival the output of bulk freezing volumes, or of harvesting ready-frozen sea ice.

The vessels employed for transporting the containers could be special versions of ordinary bulk container carriers, or in effect they could be dracones containing frames to accommodate containers practically underwater.

This might seem perversely unrealistic, but the potential advantages of the dracone concept in the storms and turbulence of the polar seas deserve consideration and perhaps deserve exploration and experiment as well.

If it proves practical to prospect for sea ice of good quality and close to 25 cm thick, there is no reason not to cut it into 50cmX100cm blocks for harvesting and marketing as such, but I suspect that to plan on that basis would be unrealistic: ice of that thickness might well be too salty or too poorly shaped to be rewarding for domestic purposes.

Anyway, I propose instead, that where winters are cold enough, and windspeeds are high, it should be practical to freeze motionless seawater top-down to a depth of 25cm a few times a season in moulds, removing completed blocks, and producing successive blocks in the same dish as changes of nearly freezing water pass through at a controlled rate. Accordingly, if we design suitable freezing moulds to accept clean seawater to freeze from the surface down without significant turbulence, leaving the bottoms insulated while the tops form a solid crust 25cm thick, then we can store the resulting blocks and dump the brine before starting on the next block in the same season.

As for how to do the freezing, seasonal subpolar winds could be directed through the open containers, with or without the assistance of channelling or of fans, whether wind-powered or not. Given the vicious winds prevalent over the Southern Ocean, one could probably extract sufficient mechanical wind power for automatic control devices, from turbines resembling traditional farm windmills: they are cheap, durable, simple, and can be designed to shut down automatically if the wind becomes too strong, and back on if it moderates.

Farm windmills

When an ice block in a mould reaches the correct mass, it should be moved, preferably automatically, to a vacant spiked frame in a dense shelf array in the container, to prevent it from shifting, either during storage or transport. When the array is full, it can be moved into the container.

As long as the temperature inside the container is warmer than the ambient air, wind should continue to be directed through. Afterwards the container would be sealed ready for despatch.

The growth of ice on seawater is a complex process, so it will take experiment to see how well seawater that is not subjected to open-sea turbulence can support the growth of ice with less than say 0.3% Total Soluble Solids. Even with a product of adequate purity, there still would be scope to optimise yield, quality, and handling procedures, but there is little room for doubt that we could determine such things in laboratory cold rooms without having to visit the fixed ice of the Ross shelf to iron out basic problems.

For example, instead of concentrating fixed batches of seawater to brine, it could be better to continue passing new sea water of low concentration through the brine chamber, keeping it diluted until the thickness of ice is right. Rapid freezing or strong brine commonly spoil the product quality.

At the delivery end, the frames containing those standard ice blocks could be wheeled out of the containers for warehousing or retail delivery.

Why?

Given the impending global shortages of power and fresh water, we need to consider not only the industrial mass use of water and ice, but also what the implications are for domestic use.

If, instead of relying only on piped water and cabled electricity, we could provide marketable blocks of ice as casually as we now provide petroleum gas cylinders for domestic use, the effects on water conservation and power consumption, even in a first-world country, could be startling.

First-world clients

Consider: ice blocks, the colder the better, would for each 8 blocks; slightly more if they can condense ambient humidity. For that yield of water to be worth while in any way other than convenience and consumption, would demand changes in domestic infrastructure: domestic ice chests in the past generally let the meltwater drain away as a nuisance, but that would be too wasteful to support this approach to domestic freshwater supplies.

As I see it, one would need domestic freshwater tanks feeding meltwater into familiar patterns of plumbing, plus appropriate filtration or osmotic purification depending on the details. There would necessarily be a need for new types of consumer durables, or modifications to old models.

But that is no novelty. We have seen such changes of varying degrees of abruption before, most particularly in increasing frequency during the past two centuries. Someone rightly pointed out that there was more difference between the modes of living of Queen Victoria at her coronation and her death, than between her coronation and the life of Solomon.

In our day, just looking at a modern movie like "Dating and New York" (2021) and comparing it with say, "The Secret Life of Walter Mitty" (1947): the two are hardly mutually comprehensible, even though they are barely a lifetime apart. Nowadays you hardly see landline wall phones or public post boxes, let alone iceboxes.

So let's not make too much of the impossibility of changing infrastructures. Governments have on occasion offered incentives for changing to gas stoves or solar power, and similarly changing to ice-block-friendly consumer durables would not only take large bites out of our water and power economic problems, but also stimulate various economies, such as of consumer durables manufacture, design and marketing.

As for water, the ice-block model not only would cut losses of water from faulty reticulation and domestic wastage of water and power, all of them concepts that Jack and Jill Average simply do not understand, but would focus family attention on water costs. Those alone would be major factors: leaks and waste in the home and in reticulation account for a major slice of societal water consumption. Use of waste water in anything from gardening to car washing and harmless low-sodium detergents would improve.

Next, we need not go back to naïve iceboxes such as were standard a century and a half ago; every icebox hereafter would have a different role in the house. Summer air conditioning is likely to be a growing need as anthropogenic global warming intensifies, and air conditioning would melt ice instead of using electricity both to cool air and reduce humidity. The heat output coils would melt ice and decrease the electricity consumption. The refrigerator too, would rely partly on direct cooling, ice-box style, plus also increasing the efficiency of the heat output coils.

Other uses would arise that currently do not occur to me, but all the applications that benefit from melting ice would collect their water for human consumption, feeding it to reverse osmosis or other forms of purification where desirable.

Private water consumption and energy consumption in first world countries would progressively reduce considerably for as long as the market increases, and that adds up to a huge saving when we translate it to savings for 300 million United States citizens, plus I couldn't guess how many other first-worlders.

Water intended for livestock need not be of the same purity; most livestock would be quite happy with a 0.5% salinity, especially if it were from seawater, which would contain nutrient ions such as Mg, Ca, I, etc, instead of just sodium chloride.

Less affluent client countries

Note that the impact on the lives of the poor in countries with problems of drought and heat could be enormous as well, at least if the supply of ice blocks is subsidised.

This is not the same as the benefits of the new economics and engineering in affluent countries: it concerns survival and socially criminal infliction of drudgery on the global poor, for whom the daily supply of water is nearly a day's walk away, and appallingly insanitary. Apart from sheer thirst, the scope for epidemics such as cholera, typhoid, giardiasis, and simple poisoning from soil water, such as excessive levels of arsenic and fluorides, would practically vanish in regions where such blocks could become the major source of water.

And the destructive mining of ground water could stopped, or at least slowed down drastically.

The very idea of such an unprofitable distribution of water must seem not merely impracticable, but hardly sane; but I suggest that for many affluent countries, the mere reduction of the influx of economic refugees would make it worthwhile to subsidise such charity. In fact, apart from charity, the mere political potential deserves consideration; China has been making enormous capital with analogous goodwill economic and health initiatives, and it is time for the EU, US, UAR etc to re-evaluate the nature, scope, and intent of their relations with needy countries.

It is cheaper than a water war, faster; and easier on the conscience.

And such a scheme is all sustainable without pollution: it converts the accumulated cold or energy debt, of melting the ice, into fuel savings and trapped CO₂. It favours global cooling and maintenance of thermohaline circulation. Its energy saving aspects could well compensate for more than the fuel consumed in transporting the ice; especially if some of the ships are nuclear powered.

And if not, then what?

ABREAST
He who aims
to keep abreast
is for ever
second best.
Piet Hein

Affluent and economically influential countries had better reflect that the potential opportunities offered by subpolar ice in particular, are not to be pulled out of a hat. They demand skills, technology, goodwill, and more; advantages of which cannot easily be overtaken after the opposition has stolen a march.

Not only the technology, not only the skills and infrastructure, but the very potential for bickering about international rights to sea ice, are best established in anticipation: not after the fact.

It already is late in the day for some authorities to wake up to their responsibilities in grasping national opportunities.

Remember:

If anyone is going to put you out of business,
better make sure it will be yourself.

Full Duplex

Sunday, August 10, 2025

Water From Where Water IS