Experts: Biodiesel May Not Be So Green

Biodiesel made from vegetable oil seems to have good green credentials.

Several musicians fill their tour buses with it, and environmental entrepreneurs brew it themselves from recycled kitchen grease.

However, expectations that this renewable fuel will deliver significant reductions in greenhouse gases may be too high.
“The general belief is that biodiesel offers a huge benefit from a global warming standpoint,” said Russell Heinen, vice president of SRI Consulting, which last month released a biofuel report for the chemical industry. “We found that it’s not necessarily that great.”

Biodiesel and other biofuels such as ethanol release carbon dioxide when burned, but part of this is offset by the carbon dioxide absorbed by the biofuel crop.

However, Eric Johnson, the report’s author and editor of the journal Environmental Impact Assessment Review, found the environmental benefits of biofuels depend on what crops are planted and how the land might be used otherwise.

Surprisingly, European farmers currently growing rapeseed for biodiesel could reduce their carbon footprint by more than half if they planted trees and let regular diesel be burned instead.

This is partly because commonly used fertilizers emit nitrous oxide, a greenhouse gas that has nearly 300 times more warming effect than carbon dioxide, which tends to get all the attention.

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