Solar energy is often pictured an the ultimate solution for our energy worriesBut caution seems indicated, as Catton explained in "Overshoot":
4. "Harnessing" the sun
The ultimate fall-back position of the modem Cargoist was the expectation that new technology would eventually "enable us to use solar energy." This view overlooked the ways in which man was already heavily dependent upon solar energy.
In more ways than one, solar energy supported the agriculture that had enabled Homo sapiens to irrupt from a few million inhabitants of the earth in pre-Neolithic times to some five hundred times as many only 400 human generations later. Solar energy supported agriculture not only through photosynthesis; it also supplied the energy for evaporation which was "pumping" each day some 68.6 trillion gallons (= 260 cubic kilometers) of water from the surfaces of land and sea up into the atmosphere, whence it could rain down upon the world's farms, forests, and hydroelectric watersheds.
If only 1/10 of 1 percent of the solar energy that reached the earth's surface was captured by plants and fixed in organic molecules, this did not mean the other 99.9 percent was a "vast untapped reservoir" awaiting man's exploitation. It could be exceedingly dangerous for mankind to try using even an additional 0.1 percent; the difference between an untapped 99.9 percent and an untapped 99.8 percent might seem trivial, but it would be an imposition upon the energy system of the ecosphere comparable to that already being made by the entire standing crop of organisms of all kinds.
The Cal Tech geochemistry professor Harrison Brown suggested back in 1954 that, a century hence, a world population of seven billion people could conceivably be living at an "American" level of energy use, and might be deriving one-fourth of that energy from solar devices. Rather simple calculations will show, however, that this would entail diverting to human use an amount of solar energy roughly three times as great as the entire quantity of energy used by the world's population in the year Brown made the suggestion. To put this in perspective, consider the fact that the total human use of energy is already equivalent to more than 10 percent of the total net organic production by the en tire biosphere. To sl1pply future humans with three times that much from solar devices means doing something to the largely unknown natural pattern of energy flow on a scale that is not infinitesimal after all. Homo colossus would be swinging almost as much weight as a third of the whole biosphere! The potentially disruptive effects upon the balanced processes of nature have to constitute an enormous risk. (Overshoot, p. 191-192, University of Illinois Press, 1980)
Not all cornucopian1 takeover proposals envisage taking over land. Homo colossus2 even proposes to take over enlarged fractions of sunshine upon which the life of this planet depends. To Cargoists3, solutions of energy shortage problems seem feasible partly because there is so much unexploited sunlight falling on every square meter of the earth's surface. Cargoist minds suppose that all we need to do is take over for human use (by various devices) solar energy that is now "going to waste". Proposals of this sort have been offered both by proponents of perpetual economic expansion, and by opponents of other more conventional but objectionable energy schemes, such as coal "development" or nuclear power plant construction.