Not all biomass fuels are as Green as they first appear

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Not all biomass fuels are as Green as they first appear

Postby TheVat on December 4th, 2019, 1:50 pm ... ps-protest

In the last few years, though, new buyers for that wood have appeared. These "pellet mills" take the wood, crush it, and press it into little pellets made for burning. They've been expanding rapidly across the southeastern United States, and they're provoking heated debate over what deserves to be called "renewable fuel."

This industry relies on government subsidies, based on the idea that wood pellets are a tool in the fight against climate change. Some European governments are offering financial incentives to burn these pellets instead of, say coal. As a result, about seven million tons of wood pellets were shipped to Europe in 2018 as fuel for power plants, and these exports are growing....

Burning wood, also called biomass, releases lots of carbon dioxide, the greenhouse gas. Supporters of biomass as an energy source, though, argue that it's a renewable resource. As the forests grow back, they'll recapture that carbon dioxide from the air and store it in their branches and roots. As a result, the EU considers it "renewable," just like wind or solar energy...

Colette goes through his own accounting of the greenhouse emissions that resulted. First, before they were cut, those big trees were capturing tons of carbon dioxide from the air every year. That "carbon sequestration" ended when the trees were cut, and won't return to its previous level for many years.

Second, much of the carbon that had previously been stored in this forest was released as the wood pellets were burned and as tree roots decompose. In fact, Colette says, the soil here is still probably releasing carbon four years after the forest was cleared.

But you won't see any of this in the official calculations of greenhouse emissions. "None of it's ever been counted ... either in the U.S. or in Europe," he says. That because this land is still considered a forest, and because the trees eventually will grow back, recapturing the lost carbon — even though that could take a century.

Another point, which the article doesn't go into, is that considerable quantities of fossil fuel are burned in order for a tree pellet to get from North Carolina to a furnace in Germany. If you read the whole article, it does give a sense of how "renewable" equations sometimes leave out important terms....and can encourage private landowners to sell off portions of their woodlots for some quick cash. And sell off newer woodlots before they have reached their potential for carbon sequestration.
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