By Michael Pearson
Biomass energy generated by burning fuel made from trees can play a significant role in meeting the energy needs of the future while helping keep climate change in check -- if the correct incentives are used, according to a new analysis led by a Georgia Institute of Technology School of Public Policy researcher.
The study, published this month in Science Advances, examines the impact of rising demand for biomass energy from trees alongside two proposals to offset the carbon emissions produced by burning such fuel: a carbon tax on bio-energy production and carbon rental policies in which landowners are paid periodic rents allowing their trees to continue to grow, keeping the carbon they absorb locked up in the wood, instead of the atmosphere.
While growing bio-energy demand increases the amount of forest coverage globally, regardless of the policy implemented, carbon rental or other subsidy policies result in significantly more land covered by trees — and consequently more carbon removed from the atmosphere — across virtually all climate scenarios, according to the analysis led by Alice Favero, an academic professional and environmental economist. Adam Daigneault of the University of Maine and Brent Sohngen of Ohio State University also participated in the study.
Under a carbon tax, the ability of the world’s forests to hold carbon dioxide would increase by the equivalent of about 3 gigatons of (GtC02) per year when compared to a model in which biomass energy is not part of the energy mix. By using carbon rentals, the team’s analysis shows, the amount of carbon kept out of the atmosphere could be quadrupled because landowners would plant more trees as an investment.
Such policies could go a long way toward offsetting the 33 GtCO2 created by the energy sector each year, Favero said.
“Our study finds that carbon rental is the most efficient policy to encourage landowners to increase the amount of carbon stored in trees, while still allowing for biomass energy to be a significant component of our future energy mix,” Favero said.
The carbon rental approach also leads to more even increases in forest coverage globally. While the carbon tax approach could result in 10% to 25% less forest cover in parts of the tropics by 2100 when compared with carbon rentals, forest cover would increase by 50% or more in many parts of the world under the carbon rental approach, according to the study.
Favero and her co-authors also conclude that the carbon rental scheme would help shield natural forests from being harvested. This is especially true in tropical regions, where low opportunity costs associated with land make such rentals an attractive proposition.
Many climate-change scenarios anticipate increasing use of biomass to meet future energy demands, but it remains a controversial fuel source because of its greenhouse gas emissions. Favero said models that are critical of biomass energy often do not include the impact of demand-induced price changes on forestry management practices, a component she and her colleagues set out to study with their paper.
“If models include management responses, higher prices invariably encourage more management and forest area, and thus, biomass energy policies reduce net emissions over time,” according to the study.
The study does not include the impact of climate change on forest growth or how emerging technologies or other issues may shape the projected demand for woody biomass. The authors say such data would not necessarily change the overall findings, “but rather provide more insight into additional risks that could be considered when designing efficient bioenergy and forest carbon sequestration policies.”
The paper, “Forests: Carbon Sequestration, Biomass Energy, or Both?”, appears in the March 25 edition of Science Advances.