Considerations for factoring biomass into clean energy

Monday, July 5, 2010

WHEN YOU think of next-generation energy technologies, burning wood pellets probably isn't the first thing that comes to mind. But buried in energy proposals across Capitol Hill are policies that promote doing just that.

Many lawmakers want the government to require utilities to derive a certain percentage of their electricity from clean sources. And one of the sources that would probably qualify is so-called renewable biomass -- everything from forest debris to algae, which can be burned in some power plants. Sure, the logic goes, you produce carbon emissions when you burn this material. But when the stuff grows back, it takes carbon out of the atmosphere, too.

That logic works well if harvesting biomass results in additional net plant growth, or if you're collecting discarded forest debris that would otherwise degrade and release its carbon into the atmosphere anyway. Chopping down and burning forest that gobbles up and stores lots of carbon, on the other hand, could easily do more harm than good.

This should be a simple problem to address: Require that qualifying biomass have low net emissions across the course of harvesting, burning and regrowth. But there are political obstacles to this, not least the farm bloc in Congress, which prefers a different regulatory scheme and also doesn't want certain land-use changes to factor into such "life cycle" emissions calculations, a critical part of accounting for biomass's carbon cost.

In a recent letter to Congress, 90 scientists pointed out that biomass's accounting problems only get worse from there. Climate legislation and international treaties, for example, don't count emissions from the burning of biomass, treating it as though it produced none at all. "Improper accounting," they say, could lead to massive clearing of the world's forests. And some argue that this effect is already visible as plants open in the South to produce wood pellets for burning in European power plants, which can receive carbon credits under similar policies.

Even if you don't share the scientists' degree of alarm, it's hard to disagree with the resulting policy conclusions. Any biomass that qualifies as "renewable" or "clean" should significantly reduce emissions relative to natural gas. That calculation must honestly account for land-use changes attributable to the harvesting of biomass. And any net emissions that result should be counted as such under any carbon cap.

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