Emissions from Washington State Compost Facilities: A Review of Volatile Organic Compound Data, and an Estimation of Greenhouse Gas Emissions

This report analyzes volatile organic compound (VOC) emissions data collected from six Washington state composting facilities between 2010 and 2013 and evaluates implications for air quality regulation and greenhouse gas emissions. The authors assess emission profiles, dominant compounds, and variability across facilities, finding that emissions are primarily composed of light alcohols and monoterpenes, with additional contributions from ketones and sulfur compounds. The report highlights limitations in existing data, including inconsistent analytical methods and lack of lifecycle sampling needed to develop reliable emission factors. It evaluates whether compost facilities may meet thresholds for EPA Title V air permitting based on estimated VOC emissions derived from California emission factors. The report also compares greenhouse gas emissions from composting and landfilling using EPA models, concluding that composting generally results in lower net greenhouse gas emissions, particularly due to avoided methane from landfills and soil carbon benefits. The authors identify key data gaps and recommend further measurement of emissions across composting lifecycles.