thomas malloy wrote:
keep coming back to our being able to run the country on the biodiesel produced on 61,000 square miles of algae ponds in the deserts.
I recall that ~10,000 square miles of solar thermal generators could supply all of the energy in the U.S., not just liquid fuel. I will bet this would not only take up much less space, it would also be far cheaper.
The reason this takes less space is not complicated. Plant photosynthesis year-round in North America converts roughly 0.1% of the solar energy into chemical fuel, whereas solar thermal generators are 20 to 30% efficient. In other words, it works 200 times better. That is why all biomass schemes are inferior to direct use of sunlight or wind. In addition, wind has a huge advantage over sunlight: it is narrowly concentrated in some areas and not others, like water flowing through a river. The overall total energy produced by wind is the same as the total energy from sunlight, which is no coincidence, as Deffeyes pointed out.
Wind has another obvious advantage: it is mechanical energy that converts easily and efficiently into electricity. The only thing better is falling water, which is why water power was the first major source of industrial energy on land. Wind power was by far the oldest and most potent source of energy at sea, of course.
- Jed
