Biofuels can, in principle, provide a renewable source of energy and, by displacing fossil fuels, reduce greenhouse gas (GHG) emissions to the atmosphere. However, the biofuels production process itself consumes energy and emits greenhouse gases. To identify what the real savings are in terms of energy and GHG emissions, a careful evaluation of the entire ‘field-to-tank’ process is needed. In 1995, CONCAWE published a report (02/95) on alternative fuels, based on an extensive literature review. A new report to be published in due course updates the earlier report, including results from recent studies on the two main biofuels under consideration in Europe—ethanol from either wheat or sugar beet and rapeseed methyl ester (RME).