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Are wood pellets renewable?

Paul Kando

Europe has long used them to keep buildings warm, but using wood pellets in power plants is new, encouraged by “renewable energy” subsidies. Yet power plant boilers release 15 to 20 percent more carbon dioxide when they burn wood than when they burn coal — not counting the loss of a forest’s ability to absorb carbon dioxide after it is cut down, or pollution from drying and transporting wood. Wood burning in Europe displaced 620 million barrels of oil last year — in power plants and space heating. That’s almost half of Europe’s “renewable energy”. Meanwhile, to feed the growing appetite for wood, U.S. forests are being cut down, pelletized and shipped abroad.

Wood Pellets
photo credit: D-Kuru/Wikimedia Commons

EU energy policy assumes that carbon pollution released directly by burning fuel made from trees doesn’t matter because it will be re-absorbed by trees that grow to replace them. It treats electricity generated by burning wood as “carbon neutral” energy — just like solar and wind power. Climate science rejects this assumption because it ignores the decades it takes replacement forests to grow to be as big as the ones chopped down for energy — or that they may not re-grow at all. The loss of a tree’s ability to absorb carbon dioxide after it is cut down is also ignored.

Scientists calculate that, to mitigate climate change, it is better to just let trees grow. A forest renews, but only over a long time horizon. Landscape models — simulating the amounts of fossil fuel use avoided using trees as fuel; atmospheric climate pollution; and pollution forests absorb from the air — show that it takes centuries before older natural forests cut for wood energy provide net climate benefits, compared with leaving them to grow. Even plantation forests take decades to centuries. Wood must be burned for its energy, releasing climate-changing carbon dioxide. In contrast, wind turbines, solar panels and hydropower collect energy from the environment.

The EU’s expanding use of pellets in power plants harms the climate, but burning wood for energy isn’t always harmful. It may be better to burn wood in a power plant than have it burn in a field as logging waste. The same carbon enters the atmosphere, but using the wood for electricity can reduce fossil fuel use. Planting a forest on abandoned farmland — to eventually cut it down and burn it for energy every few decades — helps the climate overall, because carbon dioxide is absorbed by trees in a formerly barren landscape before it is released to the atmosphere. None of this happens in existing forests where whole trees are cut down.

To sum up, since energy demand is distributed and local, sustainable energy generation should be as well. Wood has a beneficial role if everyone relies on sustainably managed local supply. Exporting wood pellets made of whole trees (or any combustible fuel) for profit the world over is not sustainable. But we may export — over wires — solar and wind generated excess electricity to our hearts’ content.