Biofuels
As David Rotman states in his article on biofuels, the conversion of biomass to liquid fuel is energy intensive--just like the conversion of coal or any other solid fuel to liquid fuel ("The Price of Biofuels," January/­February 2008). That implies that the quantity of liquid fuel from biomass and the carbon dioxide released in the production process strongly depend upon the energy source used in the conversion process.

Each year, the United States could produce about 1.3 billion tons of renewable biomass for use as fuel. Burning it would release about as much energy as burning 10 million barrels of diesel fuel per day. If converted to ethanol, the biomass would have the energy value of about five million barrels of diesel fuel per day. The remainder of the energy would be used by the biomass-to-­liquids conversion plant. If a nuclear reactor or other energy source provides the energy for the ­biomass-­to-­liquids plants, the equivalent of over 12 million barrels of diesel fuel can be produced per day. If our goal is to end oil imports and avoid greenhouse-gas releases, we must combine biomass and nuclear energy to maximize biofuels production.
Charles Forsberg
Corporate fellow,
Oak Ridge National Laboratory
Oak Ridge, TN