Expansion of US wood pellet industry points to positive trends but the need for continued monitoring

Abstract

Implementation of the European Union Renewable Energy Directive has triggered exponential growth in trading of pelletized wood fibers. Over 18 million tons of wood pellets were traded by EU member countries in 2018 of which a third were imported from the US. Concerns exist about negative impacts on US forests but systematic assessments are currently lacking. We assessed variability in fundamental attributes for timberland structure and carbon stocks within 123 procurement landscapes of wood pellet mills derived from over 38 thousand forest inventory plots in the eastern US from 2005 to 2017. We found more carbon stocks in live trees, but a fewer number of standing-dead trees, associated with the annual operation of large-scale wood pellet mills. In the US coastal southeast—where US pellet exports to the EU originate—there were fewer live and growing-stock trees and less carbon in soils with every year of milling operation than in the rest of the eastern US—which supplies the domestic market. Greater overlap of mills’ procurement areas exhibited discernible increments across selected carbon stocks. These trends likely reflect more intensive land management practices. Localized forest impacts associated with the wood pellet industry should continue to be monitored.

Continued obstacles to wood‐based biomass production in the southeastern United States

“…As noted by our research participants, concerns about the sustainability and carbon neutrality of wood‐based biomass production have been raised both domestically and internationally, resulting in the call to meet sustainability standards along the wood‐based biomass supply chain (Dale et al, 2016; Hodges et al, 2019a; Kittler et al, 2020). These standards have been implemented in response to concerns that increased demand for wood fibers to supply wood‐based biomass may cause major forestland losses or degrade forests' structure, composition, and nutrient cycles (Aguilar et al, 2020). Although proponents argue that wood‐based biomass markets may prevent deforestation and increase investment in multi‐purpose tree plantations (Aguilar et al, 2020), sustainability standards have been created to ensure carbon neutrality, reforestation after wood harvest, protection of biodiversity, and compliance with best management practices to maintain environmental quality (e.g., water or soil quality) when producing wood‐based biomass (Dale et al, 2016).…”

“…These standards have been implemented in response to concerns that increased demand for wood fibers to supply wood‐based biomass may cause major forestland losses or degrade forests' structure, composition, and nutrient cycles (Aguilar et al, 2020). Although proponents argue that wood‐based biomass markets may prevent deforestation and increase investment in multi‐purpose tree plantations (Aguilar et al, 2020), sustainability standards have been created to ensure carbon neutrality, reforestation after wood harvest, protection of biodiversity, and compliance with best management practices to maintain environmental quality (e.g., water or soil quality) when producing wood‐based biomass (Dale et al, 2016). Importantly, wood fibers cannot be harvested from forestland that is legally withdrawn from timber production (Aguilar et al, 2020).…”

“…Although wood‐based biomass accounted less than 1% of the United States' net electricity generation in 2020 (U.S. Energy Information Administration, 2021a), forest bioenergy supply chains in the United States are growing in response to increased international demand for wood‐based biomass (Kittler et al, 2020). The southeastern United States (Southeast), which contains highly productive pine plantations and forests, plays a key role in supplying wood‐based biomass (notably, wood fibers compressed into pellets) to the UK, Europe, and emerging bioenergy markets in Asia (Aguilar et al, 2020; Kittler et al, 2020; TimberMart‐South, 2019; U.S. International Trade Commission, 2016).…”

“…Moreover, suppliers in the Southeast have contracted to provide Japan with 1.5 million tons of wood pellets (Kittler et al, 2020). International demand for wood pellets triggered construction of new wood pellet mills in the Southeast with an associated increase in pellet manufacturing capacity from ≤0.3 million tons prior to 2009 to an estimated 9.0 million tons currently (Aguilar et al, 2020; see also Dale et al, 2017; concurrently, the number and capacity of wood pellet mills in the rest of the eastern United States expanded to meet domestic demand for wood‐based biomass, although the capacity of these mills is far lower; Aguilar et al, 2020). Wood pellet exports grew by 180% from 2.06 to 5.7 million tons between 2012 and 2017 (Brandeis & Abt, 2019; U. S. International Trade Commission, 2018).…”

“…Wood pellet mills that supply wood‐based biomass to international markets source biomass from NIPF and industrial forestlands in the Southeast (Aguilar et al, 2020; Kittler et al, 2020). Specifically, mills source primary fiber in the form of timber harvest residuals (tree tops, limbs, bark, foliage, and other nonmerchantable materials that are generated during roundwood timber harvests), secondary residuals (sawdust, wood shavings, chips, and other by‐products of sawmills, pulp and paper mills, and wood manufacturers), and occasionally tertiary residuals (post‐consumer wood waste) to generate wood pellets (Kittler et al, 2020; see also Aguilar et al, 2020). Wood pellets are produced from residual wood‐based biomass materials that are generated by larger, higher‐value industries such as lumber and paper (Hodges et al, 2019a).…”