Solar is quite plentiful
All estimates I've seen indicate that the earth receives more surface incident solar energy in one hour than the entire world consumes in fossil fuels per year. If you work out the numbers, and conservatively assume photovoltaic efficiency of 10% (satellites use 28% efficient cells, and 40% efficient cells have been developed in labs), then placing solar cells over just 7% of the continental US would completely replace the *world's* demand for fossil fuels.
Nuclear power plants on average only output 1GW. The world consumption of fossil fuels is currently equivalent to 13TW. To replace fossil fuels with nuclear would require us to build one nuclear plant per day for the next 30 years.
I agree with previous posters that biodiesel as a fossil fuel replacement is a sham. It is indeed carbon-neutral, but it's a very inefficient way to harness the sun.