Ethanol fuel needs more energy to make than it provides when burnt
Ethanol, produced from corn and mixed with diesel to produce a fuel for vehicles, takes more energy go make than it yields when combusted, according to a US scientist.
Cornell University professor David Pimentel, formerly chair for a US Department of Energy panel that investigated the energetics, economics and environmental aspects of ethanol production, has revealed that one acre of corn yields approximately 328 gallons of ethanol, but that growing and harvesting the corn uses 1,000 gallons of fossil fuel, costing $347. In order to produce fuel from the crop, as many as three distillation steps are needed to separate 8% of ethanol from 92% water in the crop.
“About 70% more energy is required to produce ethanol than the energy that actually is in ethanol,” said Pimentel. What’s more, whilst ethanol from corn costs $1.74 per gallon to produce, a gallon of gasoline is only 95 cents. “That helps explain why fossil fuels – not ethanol – are used to produce ethanol,” he said. “The growers and processors can’t afford to burn ethanol to make ethanol. US drivers couldn’t afford it, either, if it weren’t for government subsidies to artificially lower the price,” – of which there is currently $1 billion being spent across the US, he adds.
Ethanol from corn can’t even be considered a truly renewable resource, says Pimentel. “Corn production in the US erodes soil about 12 times faster than the soil can be reformed, and irrigating corn mines groundwater 25% faster than the natural recharge rate of groundwater.”
“Abusing our precious croplands to grow corn for an energy-inefficient process that yields low-grade automobile fuel amounts to unsustainable, subsidised food burning,” he said.
Pimentel’s findings will be published in September this year in the forthcoming Encyclopaedia of Physical Sciences and Technology.