As part of efforts to dampen high gasoline prices, the Biden administration is temporarily allowing gas stations to sell a special fuel blend called E15, containing 15% ethanol, year-round. Under the Clean Air Act, E15 cannot be sold in summer because it evaporates more readily in warm weather and can worsen air pollution. Aaron Smith, professor of agricultural economics at the University of California, Davis, explains how E15 differs from the E10 that is blended into most gasoline sold nationwide, and the general environmental impacts of corn-based ethanol.
