Characterization of greenhouse gas emissions from storage of woody biomass: an incubation study

Biomass energy plays a small but significant role in the current renewable energy portfolio and is a promising alternative pathway for woody residues that would otherwise be considered waste. These woody residues are often stored in large piles prior to combustion, and greenhouse gas emissions from this storage phase of the bioenergy supply chain are uncertain and understudied. This incubation study investigates the effects of three environmental factors on emissions from decomposition of woody biomass stored in chip piles. Incubation experiments were conducted, subjecting chambers of Sequoia sempervirens woodchips to different levels of temperature, oxygen concentration, and moisture content, and measuring the resulting greenhouse gas emissions (CO2, CH4, N2O) over thirty days. Notably, CH4 was detected in concentrations above ambient levels, indicating that environmental conditions used in this study were conducive to anaerobic decomposition. Using a three-way repeated measures ANOVA, we found that temperature and moisture had significant effects on CO2 emissions (p \u3c 0.005 and p \u3c 0.001, respectively). Oxygen and moisture had significant effects on CH4 emissions (p \u3c 0.05). No significant effects of these variables were detected for N2O emissions. High temperature and high oxygen treatments were found to be positively correlated with increased total CO2 and CH4 emissions. Understanding the key drivers of emissions from woody biomass can allow for better estimation of greenhouse gas emissions from the storage phase of the bioenergy supply chain

Smoke, Air, Fire, Energy (SAFE) in Rural California: Critical Reflections on an Interdisciplinary Research Collaboration

This article provides a synthesis of the interconnected problems of tenuous energy access, wildfires, and exposures to high air pollution in Indigenous communities in rural California through the lens of ongoing collaborative research being carried out by researchers at Cal Poly Humboldt, Schatz Energy Research Center, Karuk Department of Natural Resources, and the Blue Lake Rancheria Tribe. The collaboration is funded by the Strategic Growth Council of the state of California, and we hope is the beginning of a longer term relationship between all partners. We are an interdisciplinary team of researchers drawing on energy engineering, air pollution science, and qualitative social sciences to better understand the intersecting challenges of expanding clean energy access, and building climate resilience in Tribal communities in rural California in the context of the multiple challenges of climate change, increasing risk of dangerous wildfires, and high exposures to air pollution. Individuals and communities need to make decisions about energy and air quality infrastructure with implications for public health, climate change, energy resilience, and Tribal sovereignty. This article will reflect on the joys, challenges, ethical questions, and epistemological constraints involved with academic researchers working on interdisciplinary research projects across disciplines, and in partnership with Tribal nations. Grounded in the reflections and experience of an ongoing project, this article sheds light on the challenges and unique opportunities of conducting collaborative interdisciplinary research in close engagement with communities, and also reflects on the structural constraints posed within current institutional structures

Climate and air pollution impacts of generating biopower from forest management residues in California

California faces crisis conditions on its forested landscapes. A century of aggressive logging and fire suppression in combination with conditions exacerbated by climate change have created an ongoing ecological, economic, and public health emergency. Between commercial harvests on California’s working forestlands and the increasing number of acres the state treats each year for fire risk reduction and carbon sequestration, California forests generate millions of tons of woody residues annually—residues that are typically left or burned in the field. State policymakers have turned to biomass electricity generation as a key market for woody biomass in the hope that it can support sustainable forest management activities while also providing low-carbon renewable electricity. However, open questions surrounding the climate and air pollution performance of electricity generation from woody biomass have made it difficult to determine how best to manage the risks and opportunities posed by forest residues. The California Biomass Residue Emissions Characterization (C-BREC) model offers a spatially-explicit life cycle assessment framework to rigorously and transparently establish the climate and air pollution impacts of biopower from forest residues in California under current conditions. The C-BREC model characterizes the variable emissions from different biomass supply chains as well as the counterfactual emissions from prescribed burn, wildfire, and decay avoided by residue mobilization. We find that the life cycle ‘carbon footprint’ of biopower from woody residues generated by recent forest treatments in California ranges widely—from comparable with solar photovoltaic on the low end to comparable with natural gas on the high end. This variation stems largely from the heterogeneity in the fire and decay conditions these residues would encounter if left in the field, with utilization of residue that would otherwise have been burned in place offering the best climate and air quality performance. California’s energy and forest management policies should account for this variation to ensure desired climate benefits are achieved