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New Study Demonstrates Wood Pellets’ Potential Greenhouse Gas Benefits

LeAndra Spicer : March 28, 2014

Wood Pellets

The US exported approximately 3 million tons of wood pellets last year, and wood pellet exports are forecasted to grow to 5.6 million tons by 2020[1]. Amidst the negative arguments against this emerging trade, one new study shows wood pellets imported into the United Kingdom from the southern United States have positive environmental impacts.

The recently published study, Potential Greenhouse Gas Benefits of Transatlantic Wood Pellet Trade, concludes a unit of electricity generated from wood pellets results in greenhouse gas (GHG) emissions 50 percent to 68 percent lower than electricity derived from fossil fuels.

Researchers determined wood pellets manufactured from logging residues and pulpwood yield the highest emissions savings, and feedstock sourced from both intensive and non-intensively managed plantations results in reduced GHG emissions. It was also determined that relative savings in GHG emissions increase along with power plant capacity, in part due to the higher conversion efficiencies found at high capacity plants.

Overall, the study considered 930 scenarios created out of the following variables:

Three feedstocks: logging residues, pulpwood, logging residues + pulpwood
Two forest management models: intensive and non-intensive
Thirty-one plantation rotation ages: from years 10-40, in one-year increments
Five power plant capacities: from 20-100 MW, in 20 MW increments

Through these various scenarios, researchers addressed the limitations of existing studies that assume feedstock is sourced from a forest or mill located at a fixed distance from the wood pellet plant and account for only one harvest cycle. These assumptions are limiting in that the majority of forestland in the US South is privately owned, resulting in wood sourced from tracts at a range of distances and managed according to various forest management choices. In addition, most private forest landowners replant their lands for repeated use as plantations.

Researchers calculated the GHG intensity of electricity generated using imported wood pellets as the sum of emissions associated with each step in the supply chain (production of feedstock, transportation to manufacturing facility, manufacture into wood pellets, transportation to port, transatlantic shipment, transportation to power plant, electricity generation) divided by total electricity generation at a 100 MW power plant. The result was then compared to the average GHG intensity of a unit of electricity produced from fossil fuels to determine the relative savings in GHG emissions.

The authors conclude by noting the “dynamics of sourcing required wood for manufacturing of wood pellets or any other wood-based product is much more complex at the landscape level” than allowed by the study. Nevertheless, the study lends credible evidence to the benefits of wood-based bioenergy and should serve as a guide future research.

[1] Pinchot Institute for Conservation. The Transatlantic Trade in Wood for Energy: A Dialogue on Sustainability Standards and Greenhouse Gas Emissions. October 2013.