ARB Research Seminar

This page updated April 7, 2014

Modeling Optimal Transition Pathways to a Low Carbon Economy in California

Photo of Sonia Yeh

Sonia Yeh

Photo of Christopher Yang

Christopher Yang

Sonia Yeh, Ph.D., and Christopher Yang, Ph.D., Institute of Transportation Studies, University of California, Davis

May 01, 2014
Cal EPA Headquarters, 1001 "I" Street, Sacramento, CA

Video: 1. 2.
Research Project


An optimization model of the California Energy System (CA-TIMES) is used to understand how California can meet the 2050 targets for greenhouse gas (GHG) emissions (80% below 1990 levels). This model represents energy supply (energy resources electricity generation, and fuel production and infrastructure) and energy demand (commercial, residential, transportation, industrial and agriculture) sectors in California and simulates the technology and resource requirements needed to meet projected energy service demands. These model choices vary based upon policy constraints (e.g. a carbon cap, fuel economy standards, renewable electricity requirements), as well as technology and resource costs and availability. Multiple scenarios are developed to analyze the changes and investments in low-carbon electricity generation, alternative fuels and advanced vehicles in transportation, resource utilization, and efficiency improvements across many sectors.

Results show that major energy transformations are needed but that achieving the 80% reduction goal for California is possible at reasonable average carbon reduction cost (-$75 to $124/tonne CO2 discounted cost) relative to the baseline scenario. Availability of low-carbon resources such as nuclear power, carbon capture and sequestration, increased availability of biomass/biofuels and wind and solar generation, and demand reduction all serve to lower the mitigation costs.

Speaker Biography

Sonia Yeh, Ph.D., is a Research Scientist at the Institute of Transportation Studies, and Lecturer at the Department of Environmental Science and Policy, College of Agricultural and Environment at the University of California, Davis. Dr. Yeh is also an adjunct professor at the Department of Engineering and Public Policy, Carnegie Mellon University. Her primary research interest is to advance the understanding of future energy systems and their environmental and social impacts, and to seek solutions that improve the societal process of making decisions toward a low-carbon energy system. Her expertise is in energy economics and energy system modeling, lifecycle analysis of greenhouse gas emissions, alternative transportation fuels, sustainability standards, and technological change induced by government policy. She co-leads the UC research teams with UC Davis and UC Berkeley in supporting the implementation of California's Low Carbon Fuel Standard since 2007 and is the co-director of the National Low Carbon Fuel Standard Project. Dr. Yeh serves on many governmental advisory panels and chaired expert workgroups for governments and NGOs.

Christopher Yang, Ph.D., is a Research Scientist working within the Sustainable Transportation Energy Pathways program at ITS-Davis. Dr. Yang's research focuses on the role of alternative fuels and advanced vehicles in reducing transportation greenhouse gas emissions, with an emphasis on hydrogen and electricity supply and infrastructure. Current projects include energy system modeling of electricity and hydrogen supply to understand the role that these sectors can play in very deep reductions in greenhouse gas emissions in California (i.e. CA-TIMES model) and the broader role of transportation in meeting these emissions targets. Other research areas include modeling of hydrogen fuel infrastructure and the electricity grid to understand supply mix, cost and emissions from the use of these fuels in transportation. He is a co-director for infrastructure system analysis research within the STEPS/NextSTEPS program. He holds undergraduate and masters degrees from Stanford University and a PhD from Princeton University.oratory.

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