By Armond Cohen | November 26, 2007

CONTRARY to recent pronouncements on Beacon Hill, the biodiesel mandate proposed by Governor Deval Patrick and State House leaders will not help efforts to slow global warming. Instead, their bill - which contains a pair of measures that would require automotive diesel and some home heating oil to contain a minimum percentage of biodiesel by 2010 - is likely to make things worse.

Massachusetts' leaders are not the only ones who have been misled into believing that the biodiesel being produced today can help reduce the amount of greenhouse gas emitted from our cars, homes, and businesses. Politicians around the country, especially those running for president, are repeating the dangerously oversimplified story they've been told by biofuel promoters. Biodiesel is usually made by processing oils extracted from virgin crops like soybeans and palm fruit, so proponents like to point out that the carbon dioxide emitted when biodiesel is burned in an engine or a furnace is the same carbon dioxide that was absorbed by the plants that were used to make the fuel. As such, the story goes, biofuels are "carbon-neutral."

The reality of the situation is quite different, unfortunately. At the bill's rollout, US Representative William Delahunt pointed out that Massachusetts has 500,000 acres of farmland and, in what was probably meant to be a rhetorical question, asked, "Why not grow energy crops there?" The reason, in the simplest terms, is that we can't eat biodiesel.

Whenever an acre of farmland is converted from food production to fuel production, we can either forgo the food that used to be produced there (leading to higher food prices and food shortages) or we can make up the difference by cultivating previously unfarmed land somewhere else. The choice is clear, but all too often the new farmland is carved from forests, wetlands, and grasslands that are doing much more in their natural state to reduce greenhouse gas levels than policies like the Massachusetts biodiesel mandate could hope to achieve.

The unavoidable lesson from places currently promoting biodiesel is that replacing forests and wetlands with energy crop farms is bad for our climate. Soybeans grown to produce biodiesel in Brazil are displacing conventional food crops from the most arable regions of the country. The food farmers, in turn, are displacing ranchers, who are creating new grazing lands by slashing-and-burning large sections of the Amazon. The enormous climate benefit that the forest provided by absorbing and storing atmospheric carbon is forfeited.

Likewise, the demand for bio-oils created by the European Union's biofuel policy (a mandate that resembles the governor's bill) is contributing to the wholesale conversion of Indonesian and Malaysian forests into palm oil plantations. So much carbon dioxide is released into the atmosphere when these forests are cleared that Indonesia recently jumped from 21st to third on the list of countries with the highest national greenhouse gas emissions. Because the destruction of Indonesian forests and the resulting emissions are due in part to Europe's biofuel policy, analysts have calculated that the biodiesel sold in Europe is as much as eight times worse than petroleum-based fuels when it comes to net greenhouse gas emissions.

Language in the governor's bill that requires the biodiesel to be produced "sustainably" is of little help, even if it's interpreted broadly enough to account for emissions from land conversion. Researchers are developing models that can project how food and energy markets will react to biodiesel mandates, but these tools will not be ready for some time. By proceeding without that knowledge, Massachusetts is repeating the mistake Europe made. The result is likely to be the same, as well: food production will be outsourced at the expense of forests, wetlands, and, ultimately, our climate.

State officials learned of these risks earlier this year, but decided to plunge ahead anyway. It's not too late to change course, though. If Massachusetts wants to enact a biofuels policy that won't increase greenhouse gas emissions, we can take several concrete steps. First, we can ask academic institutions to help develop the necessary analytic tools for assessing the true climate impact of policies that expand biofuel usage. Second, we can support research into biofuels made from municipal waste, algae, and other feedstocks that won't compete with food crops for farmland. And finally, we can - and must - abandon the proposed biodiesel mandate.

Armond Cohen is executive director of the Boston-based Clean Air Task Force