ARB Research Seminar

This page updated March 16, 2015

Assessment of the Emissions and Energy Impacts of Biomass and Biogas Use in California

Photo of Donald Dabdub

Donald Dabdub

Photo of Marc Carreras-Sospedra

Marc Carreras-Sospedra

Donald Dabdub, Ph.D. and Marc Carreras-Sospedra, Ph.D., Mechanical and Aerospace Engineering, Advanced Power and Energy Program, University of California, Irvine

March 17, 2015
Cal EPA Headquarters, 1001 "I" Street, Sacramento, CA

Video: 1. 2.
Research Project


Biomass contributes more than 5,700 Gigawatt-hour to California's in-state renewable power, approximately 19% of in-state renewable power, and 2% of full California power mix. Current operating biopower capacity is about 900 Megawatt (MW), including approximately 550 MW of woody biomass solid fuel combustion, 280 MW of landfill gas-to-energy and 75 MW from wastewater treatment biogas. It is estimated that there is sufficient in-state 'technically' recoverable biomass to support another 2,800 MW of capacity or 21 Terawatt-hour of electricity. While most biomass energy is derived from woody material (including urban wood waste, and forest product and agricultural residues), there is a growing interest in using municipal solid waste, food processing waste, animal manure, and wastewater (co-digestion at wastewater treatment facilities) to generate electricity and renewable fuels. Increasing production of bioenergy contributes to energy sustainability while reducing greenhouse gas (GHG) emissions, and also could help reduce criteria pollutant emissions.

This study assesses the air quality impacts of new and existing bioenergy capacity in California, focusing on feedstocks and advanced technologies utilizing biomass resources predominant in the state's regions. The options for bioresources include the production of biopower, renewable natural gas, and ethanol. Emissions of criteria pollutants and greenhouse gases are evaluated for a set of scenarios that span the emission factors for power generation, and the uses of renewable natural gas for vehicle fueling and pipeline injection. Emission factors are combined with geospatially-resolved bioenergy outputs (facility locations) to generate new emission source locations and magnitudes. These are input to the Community Multiscale Air Quality model (CMAQ) to predict regional and statewide temporal air quality impacts from the biopower scenarios. With current technology and at the emission levels of current installations, maximum biopower production could increase NOX emissions by 10% in 2020, which would cause increases in ozone and PM concentrations in large areas of the Central Valley where ozone and PM concentrations often exceed air quality standards.

Among the alternatives for biomass use, technology upgrades would achieve the lowest criteria pollutant emissions. Conversion of biomass to compressed natural gas (CNG) for vehicles would achieve comparable emission reductions of criteria pollutants and minimize emissions of greenhouse gases. Air quality modeling of biomass scenarios suggest that applying technological changes and emission controls would minimize the air quality impacts of biopower generation. And a shift from biopower production to CNG production for vehicles would reduce air quality impacts further. From a co-benefits standpoint, CNG production for vehicles appears to provide the greatest combined benefit in terms of GHG emissions and air quality.

This investigation provides a consistent analysis of air quality impacts and greenhouse gases emissions for scenarios examining increased biomass use in California. The findings should help inform policy makers and industry with respect to further development and direction of biomass policy and bioenergy technology alternatives needed to meet energy and environmental goals in California.

Speaker Biographies

Donald Dabdub, Ph.D., is Professor of Mechanical and Aerospace Engineering in the Advanced Power and Energy Program, niversity of California, Irvine (UCI). Dr. Dabdub has developed new physics and chemistry for air quality models, designed new algorithms for the numerical solution of the governing equations of air pollution dynamics, and studied the impact of various energy-related scenarios on urban airsheds. In the area of atmospheric sciences, his work has been aimed at the mathematical modeling of urban and global air pollution, understanding the dynamics of atmospheric aerosols, and global climate change. Within the realm of computational sciences, Dr. Dabdub is interested in massively parallel computations, the numerical analysis of partial differential equations, and the development of problem-solving environments. Professor Dabdub's research topics have included mathematical modeling of urban and global air pollution, dynamics of atmospheric aerosols, and global climate change. Dr. Dabdub's work can be applied to foster a better understanding of air pollution and the dynamics of global climate change. Dr. Dabdub has served as advisor to various state and federal agencies which include the Air Resources Board, the California Energy Commission, John Wayne Airport, Lake Tahoe Science Consortium, the U.S. Environmental Protection Agency, and the U.S. Department of Energy. Professor Dabdub received his Ph.D. in Chemical Engineering at the California Institute of Technology in 1995.

Marc Carreras-Sospedra, Ph.D., is a project scientist in the Mechanical and Aerospace Engineering Department at the University of California, Irvine. Dr. Carreras-Sospedra's area of expertise is in air quality modeling of energy infrastructure. Dr. Carreras-Sospedra has contributed to the development of methodologies for allocating energy infrastructure, such as distributed electricity generation, and natural gas, hydrogen and biomass infrastructure, using geospatial information. Dr. Carreras-Sospedra has also worked on the development and improvement of numerical routines for three-dimensional air quality models. Dr. Carreras-Sospedra holds a bachelor's degree in Chemical Engineering by the Universitat de Barcelona, Spain and a doctor of philosophy degree in mechanical engineering from UCI.

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