and still more astonishing that so little knowledge
can give us so much power.
· Even where rock is effectively solid, it is elastic to a degree that can show dramatically in the curvature of masonry pillars under stress for example. (See the brilliant book by J. E. Gordon: "Structures, or Why Things Don't Fall Down".) The combined effects often are of great importance. For example, where rock is placed under stress by overlying ice or other overburden, it sinks, eventually to isostatic levels. When such overburden is removed the rock then slowly rebounds. Finland for example still is rebounding from its most recent period of glaciation. Conversely, where underground fluids thrust up under pressure, they cause the rocks above them to bulge. Usually this is hardly perceptible, but sometimes they bulge dramatically before they burst out as volcanic eruptions. Such bulges are among the most significant intimations of immanent eruptions.
· The plasticity of hot rock has important implications for deep engineering techniques that depend on the displacement of rock by pressure. If one digs down to thoroughly plastic or marginally molten rock, one can apply hydraulic pressure to form a bubble or a fracture, depending on the nature, pressure, and temperature of the rock. Even rock that one would hardly imagine to be capable of distortion can deform plastically under such conditions. For example, if surrounded by sufficient pressure, apparently solid marble can be deformed amazingly without cracking, almost like putty.
The implications will be familiar to anyone with experience of glass blowing.
Think of the effects of altering the costs or availability of either.
High-temperature electrolysis for production of hydrogen also is efficient, and would have the advantage of producing oxygen as well.
Another emergent consideration might result from the contact between magma and solvents such as superheated water or molten salts. Even under far milder conditions than those in power bubbles, such as in existing geothermal power schemes, we inadvertently extract troublesome minerals that currently we need to dispose of as wastes. In power bubbles however, we might find that the solvent extraction of live magma would yield large quantities of precious or at least valuable elements that are painfully rare on the surface or in the shallower parts of the crust.
Temptingly possible candidates might include rare earths, cobalt, iridium, platinum and other elements desperately in short supply for industrial purposes. If we strike it rich in some of our power bubbles, their waste streams might play a rewarding role in the economy of the power generation process. They might for example more than pay for all the waste processing. Gross concentrations of the elements would not be necessary; some of them would be attractive to extract from easily processed wastes even at concentrations of a few parts per million.
After all, to establish a power bubble would require far more than running a drill string from a surface ship, down a Mohole, to the mantle.
In short, whoever establishes a workable technology for deep-sea power bubbles will have the world by the tail.
There is one main point on which everyone agrees although they think they differ, namely that the end of organic fossil fuel supplies is urgently at hand. Some speak of decades, some of centuries, but no rational person speaks even of millennia, let alone significantly long periods. Bear in mind that in speaking of the survival of our "civilisation", centuries hardly count. They hardly count even in the history of a country worthy of its name or people.
Some characteristically technically illiterate economists seem to think that because the stone age did not end with the supply of stones, that we need not worry about the energy age ending with the supply of energy. If we do not prepare for the transition, that is just how it might end. The energy age simply might end with the supply of accessible energy. The foolish virgins among nations that have failed to establish a future for their peoples will have doomed themselves and pauperised their populations by not having prepared alternative power sources for their future economies. And power bubbles or some rival bootstrapping source of geothermal heat are the most promising successors to fossil organic fuels.
One constant in our history and prehistory that has varied only in its scale, variety, and inefficiency, has been our dependence on energy. Until economists explain how to transcend the laws of thermodynamics, their only option is to point out alternative sources of energy, or more likely, hope that some stupid technologist somewhere will point out a new source from which they could make money. Discussion of at least one source is the theme of this essay.
Even the limited supply of fossil organic fuels is not the whole story. New sources of energy had better not rely on fuels that are too oxygen consuming. We are consuming oxygen at a rate that should scare anyone spitless who takes our planetary budget seriously. After all, where did the oxygen came from in the first place, and how fast?
So, anyone who for example relies on a long-term hydrogen budget that does not produce as much oxygen as hydrogen, is leading us down the mortuary path. With due and generous respect for the cap and trade bandwagon, we could multiply our CO2 budget by a factor of ten with no clear risk of harm, but if we consumed just a few percent of our free oxygen, the consequences would be disastrous, in fact murderous. In comparison global warming would be trivial in consequences and trivial to control. Recent palaeontological evidence suggests that since the Cambrian period, the oxygen level has never dropped nearly as far as some had supposed. Even if it turned out that the recent evidence were wrong, it does not follow that we would comfortably survive such a change. We already see intimations that to increase the rate of photosynthesis is not nearly as simple as people had imagined.
The fashionable current concern about nuclear power is the hysteria about the nearly irrelevant problem of nuclear "waste disposal". I shall not go into that matter, except to remark that I never have seen any such “waste disposal” that did not amount to criminal waste of irreplaceable resources. The only rival to such criminality has been irresponsibly incompetent waste accumulation such as by the US and no doubt certain other major nuclear powers, where politicians and management were only interested in their pockets and short term careers.
Nuclear energy has important roles, for example for heavy-duty transport fuel and transportable generators. It also will have valuable functions in space, if only for expeditions far from the sun. On Earth it also has important functions in isotope manipulations and so on. However, fission power almost certainly will have a shorter fuel supply and less versatile output than power bubbles.
Fusion power currently seems likely to be even less versatile than fission and it is not clear how much harmful waste it will produce. Apart from some recent and sophisticated proposals, most claims that fusion power will be clean are exaggerated or ill-informed. There also is the question of whether it ever will be practical at all, and if so on what scale, in which form, and using which fuels. Though the technology deserves attention it is too early to rely on its success as a general purpose source of power.
Temperatures for melting the way down might be higher, perhaps more like 2000C, but those would be contained at the workface. Perfectly practical alloys could survive such temperatures, and many ceramics could resist them indefinitely. During the process of melting the way down, powerful oxidising and reducing agents would be used, but afterwards the operating environment would be chemically bland. This greatly increases the range of candidate materials for the working structures. In reducing or neutral atmospheres many carbides would work well at very high temperatures. I could list several pure or composite materials with promising characteristics, but it is a safe bet that whatever we guessed at present, the engineers on the job would prefer their own alternatives for reasons of strength, chemical resistance, flexibility, cost, availability, and so on.
In sum, I meant it when I said "stop mucking with geothermal"; it is past time to stop mucking about, and get down to serious business.