Not so green

Willie D. Jones reports on research (preliminary, apparently not yet published) by the Virginia Water Resources Research Center that compares various energy sources and means of power generation in their efficiency of water consumption. That certain high-tech darlings of alternative energy, like ethanol, are relative water hogs is less surprising than the wide spread of computed values, spanning four orders of magnitude. While natural gas requires only 38 liters of water per 1000 kilowatt-hours generated, biodiesel was measured at 180.9 to 969 kiloliters of water per 1000 kW-h. On the generation side, the range is from 260 l/kW-h for hydroelectricity to 31000 to 74900 l/kW-h.