Ethanol is not an alternative to petroleum-based fuel to reduce air pollution. It is a grow-it-at-home alternative to foreign-source petroleum-based fuel. It takes only 2 years to build an ethanol-extraction plant but 10 years to build a petroleum-extraction plant. Right now, as long as ethanol doesn’t increase air pollution, I’ll take it.

Lin Daniel
Chatsworth, Calif.

I wonder if Mark Jacobson included in his model comparing the air-quality effects of burning ethanol versus gasoline the decrease in automobile gas mileage with ethanol. I regularly track my mileage and routinely suffer a loss of 2 to 3 miles per gallon during the winter months when Albuquerque-area gas stations switch to an ethanol mix. Even if the polluting effects of both fuels were the same, increased efficiency would favor gasoline.

Jackie Ericksen
Placitas, N.M.

The article seems to have overlooked that ethanol, from plants, contains carbon directly removed from the atmosphere.

John Bodenschatz
San Francisco, Calif.