In response to Bob Bates' letter, "The Solution," I need take issue on a few points. With regard to the sustainability of current solar cell technology, I assume the consumption being referred to is the energy cost of manufacturing vs. the output energy of the cells and is not referring to a cell's efficiency (which is mostly irrelevant since the sun is an unlimited source of power). Solar cells do not decay with use or time so their total output power is determined only by how long they are in service whereas the energy cost is a fixed amount. In other words, they can be sustainable if they are used for a long enough time.
More striking in Bob's letter, however, is his blatant omission of alternate technologies available for converting sunlight into electricity. Solar Tres in Spain is one of dozens of examples of a successful and fully sustainable method of converting sunlight into electricity without the use of solar cells.
Finally electricity can be used to run bulldozers, elevators, etc. and is limited only by funding and innovation. To put this into perspective, the main engines on the space shuttle are powered indirectly by electricity. These engines operate exclusively by the ignition of hydrogen and oxygen, both of which are manufactured by electrolysis, i.e. electricity, from water. Converting electricity into more convenient forms of liquid fuel is probably in the minds of many scientists as I write this. Surely if the shuttle can be powered by electricity, the sky is the limit.