In Europe, wood is classified as a renewable, carbon-neutral energy. But that claim doesn’t hold up, according to a new report published last week by the London-based think tank Chatham House. The sustainability of woody biomass as fuel is exaggerated, the report says, resulting in negative effects on the global climate and forest ecosystems.
The burning of woody biomass—often in the form of lightweight pellets of wood pulp—at power plants to produce electricity and heat has increased in recent years, and most of the demand comes from the European Union. That’s because, according to E.U. policies, burning wood emits zero carbon. As such, it’s a vehicle to meet E.U. goals to reduce carbon emissions by 20 percent and source 20 percent of its energy from renewables by the year 2020. However, recent studies have shown that wood pellets are not all that renewable or sustainable. T. Edward Nickens reported on the change in scientific understanding in a 2014 Audubon feature:
According to E.U. policy, wood pellets are considered a carbon-neutral fuel source, based on the principle that regenerating forests will eventually recapture the carbon released when the trees were cut. But a growing chorus of scientists and conservationists points to new research showing that harvesting, transporting, and burning trees for large-scale energy production actually produces a “carbon debt” that isn’t repaid for 35 to 50 years—an eon in the rapidly shrinking timeline of climate change.
The new report summarizes recent evidence and concludes that wood pellets (or biomass) are far from carbon neutral. Wood itself releases more carbon than coal for the same amount of energy produced, for one. Additionally, the most common production for woody biomass—the harvesting of full trees that are then created into pellets shipped worldwide—is not considered in government analyses, and as a result the costs of tree harvest and transport are ignored. Most analyses assume the pellets are made from timber scraps and waste.
Crucially, the report takes on the main thrust of the argument in support of wood pellets: that they are a carbon-neutral fuel because, even as they are burned, other trees are growing to re-absorb the carbon elsewhere. The author of the report, Chatham House Energy Fellow Duncan Brack, does not mince words:
These arguments are not credible. They ignore what happens to the wood after it is harvested (emissions will be different if the wood is burnt or made into products) and the carbon sequestration forgone from harvesting the trees that if left unharvested would have continued to grow and absorb carbon. The evidence suggests that this is true even for mature trees, which absorb carbon at a faster rate than young trees. Furthermore, even if the forest is replanted, soil carbon losses during harvesting may delay a forest’s return to its status as a carbon sink for 10–20 years.
Beyond climate change, the production of wood pellets has real effects on forests and wildlife—and far closer to home than Europe. Wood pellets plants are being developed throughout the southeastern United States, and experts already worry about the health of the forests. Two years ago, Nickens wrote:
Much of the timber used to make pellets comes from the South’s bottomland hardwood forests—brooding groves of cypress, tupelo gums, sweetgums, oaks, and poplars. Sixty percent of the 30 million acres of hardwood bottoms once found in the Southeast have already been destroyed to make way for agricultural land and timber tracts. The woodlands that remain cloak river corridors and swamp borders with dark, Gothic forests that serve as critical habitats for such birds as Cerulean and Prothonotary warblers and 28 other species of conservation concern, 14 of them listed in Audubon’s newly released report on climate change. Conservationists also worry that in upland forests, the skyrocketing demand for pellets could accelerate the conversion of natural forests to short-rotation pine timber, which would be a devastating blow to local biodiversity.
Despite the evidence against wood pellets, the industry isn’t slowing down. In 2015, the pellet trade from North America to Europe increased by 15 percent over the previous year, reaching 6 million tons. That trade is supported by industry growth in the southeast U.S., where 22 wood pellet plants are currently operating and a dozen more are proposed, according to the Southern Environmental Law Center. Unfortunately, it seems it’s going to take more than a think tank report and a reminder to get in the way of this rapidly expanding industry.