Bioenergy Business: A bipartisan group of US Senators has introduced a bill to lower tariffs on imported ethanol, a proposal that US ethanol supporters have fiercely resisted in the past. The proposal is designed to ensure parity between the ethanol blending subsidy and two tariffs on imported ethanol, by requiring US President Barack Obama to lower the tariffs by at least $0.11/gallon ($0.03/litre) within 30 days of enactment. The 2008 Farm Bill lowered the ethanol blender subsidy from …