An international study has produced a sobering perspective on so-called "inexhaustible" energy resources -- hydrogen fusion and solar power. Promising as their long-term potential may be, their probable contribution over the next 50 years seems strictly limited. The world half a century from now will still have to rely on a mix of energy sources, including shale oil, coal, and nuclear power.
Promoters of fusion, and especially of solar energy, may be quick to cirticize this prognosis. Nevertheless, the study's reasoning is worth considering, for it views these energy sources with a tough-minded perspective.
The study, conducted at the International Institute for Applied Systems Analysis (IIASA), an East-West think tank near Vienna, took seven years. Some 140 scientists from 20 countries worked on it, under the direction of Wolf Hafele of West Germany.
Recognition of time constraints on introducing new energy sources on a significant global scale underlies IIASA's conclusions. It takes decades to build up the capital equipment to exploit an energy source effectively.
Because of this and because no one yet knows even when it will begin to be commercially feasible, IIASA gave fusion brief mention. Its practicality is too nebulous to be factored into serious energy supply planning now.
On the other hand, solar power -- including energy from the winds sea --time frame. It too has enormous potential and might eventually form the basis for a sustainable global energy supply. Yet its growth demands enormous capital investment, which cannot be made quickly.
Pointing out that much of hte best area for large-scale solar energy production lies in North Africa and the Middle East, the study notes: "A crucial dimension of exploiting the solar potential is therefore the development of both the technical and institutional infrastructures for transporting solar-generated electricity and fuels from the sun-rich regions to those that are sun-poor." This could take decades.
It adds: "For orientation, a program designed to build up over the next 100 years [a solar energy capacity to meet world needs] . . . could require each year an amount of concrete roughly equal to that produced worldwide in 1975." Likewise, using wood and other biomass to supply, say, a sixth of that energy need "would correspond to managing . . . more than twice the land area devoted to agriculture worldwide in 1975."
Thus, while solar energy, and perhaps eventually fusin, will become increasingly important, it will take many decades for them to have a major global impact. The study sees no way around this fact of earthly life. Meanwhile, the world needs to maintain a viable mix of energy sources while building the capacity to move to a sustainable energy base.