I've just had a nice email back from David Pimentel. He likes the blog and pointed out that you need legumes not manure for organic agriculture to work.
Once again I should have
listened to my granddad. He came from market gardening stock and he explained to me that it was important to put a crop of beans or peas in different parts of the garden and move crops around. I think clover's pretty good too for fixing nitrogen in the soil but not much good if you're growing vegetables.
Anyway, back to Professor Pimentel: He kindly sent me a couple of papers, which I'll attempt to get through before the Christmas break, and an editorial from BioScience, November 2006 (56(11):875) Green Plants, Fossil Fuels and Now Biofuels, which he co wrote with Tad Patzek of University of California-Berkeley.
To quote directly from BioScience
The environmental impacts of corn ethanol are enormous. They include severe soil erosion, heavy use of nitrogen fertilizer and pesticides, an a significant contribution to global warming. In addition, each gallon of ethanol requires 1700 gallons of water (mostly to grow the corn) and produces six to 12 gallons of organic effluent.
Nitrogen fertilizer is typically made by displacing the carbon and a hydrogen atom from natural gas in the Haber-Bosch process... the carbon's got to go somewhere and since the other reactant is air (a mixture of nitrogen, oxygen and a few other bits) its going to be carbon dioxide.
The professors continue:
Growing crops to provide fuel squanders resources; better options to reduce our dependence on oil are available. Energy conservation and development of renewable energy sources such as solar cells and solar-based methanol synthesis should be given priority.
This is the opposite end of the spectrum to people like Scott Miller, who's work I like and whom respect very much.
In a recent comment on this blog, he said:
James Woolsey says that biofuels (ethanol and biodiesel) and plug-in hybrids represent the quickest solution to fossil fuel addiction. So lets develop both. You can read about his latest speech at the Santa Monica Alt Car Expo on my site.
He adds:
Our focus should be on deploying commercial-scale versions of solutions like the above [biofuels] so we can solve the problem.
But this conflict in opinion is a good thing. We need to debate the relative merits and disadvantages of the different fuel options we have for the future, because, as sure as eggs are eggs, we can't go on like we are. Personally, I'd like to see more talk of energy conservation.
Would you buy a smaller, less featured car on environmental grounds, or would it take some sort of incentive? Please let me know what you think.