Representative Jim Sensenbrenner (R-WI) sent a letter July 19 to the Environmental Protection Agency saying that the agency is required to reduce requirements for petroleum refiners and importers to blend cellulosic biofuels into gasoline if a sufficient amount of the biofuel is unavailable. Petroleum refiners and importers are being penalized for their failure to purchase a fuel that is not available in the quantities required by the agency under the Energy Independence and Security Act of 2007. Congressmen Sensenbrenner asked the agency to respond by August 17.