each unit of energy put into growing maize ethanol produces 1.34 units of output, but only by counting the energy of dried distillers’ grain, a by-product of the production process that can go into cattle feed. Without that, the gain was just 9 per cent. Other studies, though, came to less positive conclusions, including one estimate that there was a 29 per cent loss of energy in the process. Drilling for and refining oil, by contrast, gets you a 600 per cent energy return or more on your energy used.
