Brian,

Thanks for the interesting, but disappointing, data on the limit to biodiesel's ability to substitute for fossil fuels. As you point out, there is a limit to the rate at which biomass can be generated. I would not have imagined that there might not be enough land available to grow an ample supply. I guess I am not experienced enough in thinking globally.

See how you like this for a global idea. How about increasing the rate at which plants are able to grow by photosynthesis, say by increasing the amount of CO2 in the air and the average temperature of the climate? Warmer oceans might make for more rain, which presumably would help, too.

If you don't care for that, how about creating energy from turkey droppings? Here's the intro to a just-published article on the subject (more at http://story.news.yahoo.com/news?tmpl=story <http://story.news.yahoo.com/news?tmpl=story&ncid=753&e=1&u=/nm/20041215/sc_nm/energy_environment_turkeys_dc> &ncid=753&e=1&u=/nm/20041215/sc_nm/energy_environment_turkeys_dc):

Turkey leftovers will take on a whole new use after a Minnesota company finishes construction of a power plant fired by the birds' droppings. It may not be the total answer to relieving the United States' addiction to foreign oil, but the plant will burn 90 percent turkey dung and create clean power for 55,000 homes.

I wonder how many power plants and how many turkeys would be needed to meet the world's demand for energy.

Gordon Davy
Baltimore, MD
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