By TIM FAULKNER/ecoRI News staff
A new study contends that wood-fueled power plants continue to be a polluting energy source especially as their use grows. The report Not Carbon Neutral, recently published in Environmental Research Letters, challenges the claim that wood pellets, trees and forestry residue have a negligible effect on greenhouse-gas emissions when used to generate energy.
The author, Mary Booth, argues that many biomass/bioenergy plants and pellet manufacturers are using whole tree “rounds” instead of wood byproducts and tree residue, as they claim. And even if the wood-power and pellet industry adhered to sustainable sourcing of wood, carbon dioxide emissions are still much higher than claimed and similar to coal and other fossil fuels, according to the report.
“This analysis shows that power plants burning residues-derived chips and wood pellets are a net source of carbon pollution in the coming decades just when it is most urgent to reduce emissions,” Booth said.
Booth reaches her conclusion by including fossil-fuel emissions from the shipping and manufacturing of wood fuels, such as wood pellets. Wood pellets are produced in the southeastern United States and most are shipped to biomass power plants in the United Kingdom and Belgium. The European Union classifies woody biomass as carbon neutral and offers subsidies for switching from coal and other fossil fuels to wood.
However, a growing body of research claims that it takes decades for replanted forests to recoup the carbon emissions released from trees used as fuel or to make wood pellets. Researchers and environmentalists are raising questions as climate scientists urge greenhouse-gas reductions during the next 10 to 20 years, to curb some of the worst effects of climate change.
While Massachusetts has restrictions on biomass power plants, the state released guidelines in December for biomass boilers and industrial heating systems, systems that qualify for renewable-energy incentives. Gov. Charlie Baker supports woody biomass and sees it as a boost to the state’s lumber industry.
Rhode Island imports electricity from woody biomass power plants in northern New England for its program to deliver renewable energy to the regional grid. As of 2015, according to the latest report available, 34 percent of Rhode Island’s renewable-energy portfolio was supplied by woody biomass power plants.
President Trump supports biomass with his "all of the above" energy policy. On Feb. 13, Environmental Protection Agency director Scott Pruitt visited New Hampshire, which has a handful of biomass power plants, to declare woody biomass a carbon-neutral energy “in appropriate circumstances.”
Booth lives in Pelham, Mass., and advocates against local wood-burning power plants and state efforts to expand biomass. Her organization Partnership for Public Policy offers a global perspective on biomass energy.
“Even under the best-case scenario the carbon footprint is really big,” she said.
Booth directed her latest research toward the Intergovernmental Panel on Climate Change (IPCC), a United Nations organization that studies the causes and impacts of climate change. The IPCC endorses biomass if it is sourced from agriculture and forestry residues. But Booth noted that even if lifecycle emissions are ignored, the report “finds that even assuming the materials burned are true residues, up to 95 percent of the cumulative CO2 emitted represents a net addition to the atmosphere over decades."
And time is one part of the equation that can't be ignored.
“To avoid dangerous climate warming requires us to reduce power sector CO2 emissions immediately,” Booth said.