On-Site Energy Consumption and Life-Cycle Environmental Impacts of Sawmills in California

Abstract Addressing climate change is a global priority. Life-cycle assessment (LCA) quantifies the carbon footprint of products and can provide strategies for climate change mitigation. This novel study analyzed the energy consumption of softwood sawmills and used attributional LCA to estimate cradle-to-gate environmental impacts of softwood lumber manufactured in California. Using a representative sample size, 16 California sawmills (capturing ∼88% of lumber production) were surveyed. Sawmills’ energy consumption was characterized and evaluated by fuel type and on-site energy generation for annual lumber output in thousand board feet (MBF). Electric energy (194 kWh/MBF), with 85 percent of it coming from on-site generation and diesel fuel (5.55 L/MBF), was the main hot spot in the energy analysis. For cradle-to-gate environmental impacts, LCA of 1 m 3 of lumber was conducted on three lumber types. Using the survey data and secondary data specific to western US forest industry operations and raw material transportation, a cradle-to-gate life-cycle inventory was developed. For different impact categories, environmental impact indicators per cubic meter were reported and discussed; for instance, 36 to 48.4 kg CO 2 eq for global warming, 0.34 to 0.61 kg SO 2 eq for acidification, and 60.1 to 94.4 MJ surplus for fossil fuel depletion. As expected, planed-dry lumber had the highest environmental impacts per cubic meter. Energy analysis and environmental hot spots in lumber manufacturing were discussed in connection with carbon emission reduction strategies by the California forest products industry. California sawmills have adapted climate change mitigation strategies including on-site combined heat and power generation from renewable and sustainable wood residues, as evident in the results.