The California Energy Modeling Group is is organized by Dr. Sonia Yeh, Dr. Chris Yang and Dr. Joan Ogden. The group will initially focus on modeling the energy system of California using the Integrated Markal-Efom System (TIMES). The goal is to provide a tool that helps us analyzing the social, economic and technological impacts of future vehicle penetration within the integrated energy system.

Team Members:

Faculty: Dr. Sonia Yeh, Dr. Chris Yang, Professor Joan Ogden, Professor Yueyue Fan

Students:

• Ryan W. McCarthy, PhD Student
• David L. McCollum, PhD Student

Modeling Tool:  TIMES (The Integrated MARKAL EFOM System)

TIMES is a technology-rich (or typically called bottom-up) model that estimates energy dynamics over a long-term, multi-period time horizon within a reference energy system (RES). The TIMES model aims to supply energy services at minimum global cost (more accurately at minimum loss of surplus by reaching a supply-demand equilibrium with endogenous energy service demands) with perfect foresight.

Further details of the model, information about the program supporting the TIMES model, and model documentation can be found at: www.etsap.org/

MARKAL and TIMES model documentation. http://www.etsap.org/documentation.asp

Richard Loulou, The MARKAL-TIMES modelling paradigms -- Least cost, partial and general equilibrium versions

Uwe Remme, Overview of TIMES: Parameters, Primal Variables & Equations

Uwe Remme and GianCarlo Tosato, Primal and Dual Problems of Linear Programming Economic Models: Marginal Prices and Price Formation Equations

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Publication:

• Yeh, Sonia, Alex Farrell, Richard Plevin, Alan H. Sanstad, and John Weyant. 2008. Optimizing the U.S. transportation mitigation strategies: what do we learn from a bottom-up model. Environmental Science & Technology, 42(22): 8202-8210. link Supporting Info

Optimized Economy-wide Emission Reduction Wedges: Cap & Trade (and Carbon Taxes) Aren’t Enough for Transport Sector

All the proposed cap-and-trade programs gain 90% of reductions from electric sector—and almost none from transportation. Cap & trade and taxes are not effective at introducing new fuels since producers just pass on the extra fuel cost to consumers, and they are too indirect to overcome resistance by fuel suppliers and consumers. More effective and direct policy (for transport sector) is needed.

Optimized Transportation Mitigation Wedges (efficiency, fuel carbon intensity, and demand reduction)

The contributions of the optimized light-duty vehicle CO2 emission reductions from vehicle efficiency improvement, fuel GHG intensity reduction, and vehicle travel demand reduction is shown in here. Overall we found that vehicle efficiency improvement is the first and the most cost-effective wedge through the use of smaller, more efficient vehicles. Then  followed by low-C biofuels and electricity (shown as "others" in the figure). We found travel demand is not responsive to the most strignent cap examined in this paepr (travel demand elasticity -0.3). Therefore, government actions, rather than relying on consumer behaviors, are needed to stimulate demand reductions.

* Note that these are the emission reductions on top of the biofuel mandates under the Energy Independence and Security Act (EISA) and the new CAFE standard, which are incorporated in our reference case.

Lessons Learned:

• How we get there, and how cost affects adoption?
  - Without a separate cap, transportation sector is not likely to contribute to significant reductions
  - The least-cost stabilization wedges for the transportation sector include fuel use reduction and the adoption of low-GHG fuels, the adoption of advanced vehicle technologies, and increased vehicle efficiency

• The nature of the transition: smooth, abrupt, or transitional?
  Depending on the dynamics of supply and demand, price equilibrium, and constraints such as the details of the policies, the least-cost adoption pathway can be
  - smooth,
  - high-growth:  some of the advanced hybrid and plug-in hybrid wedges
  - transitional:  some of the ethanol flex-fuel vehicles under most stringent scenarios are appropriate for short- to medium-term solutions, but need to be replaced by more advanced vehicle technologies in the long term
• The interactions between these wedges: substitutes or complements?
  - Substitutes: the more the electricity system becomes decarbonized, the less the available savings from greater efficiency of electricity use, and vice versa.
  - Substitutes: the effect of demand reductions (both fuel use demand and travel demand) becomes smaller as a vehicle fleet becomes more efficient, and vice versa.
  - Complementary: the wedges for plug-in hybrid vehicles and electric vehicles expand as the electricity powering these vehicles is decarbonized

• Robustness of the wedges to various uncertainties such as policy uncertainties, the levels of caps, or the modeling time horizon?
  - Some mitigation wedges play important roles in all scenarios: adoptions of HEVs and increases in vehicle efficiency (these two wedges are not mutually exclusive)
  - Other wedges are sensitive to the level of CO2 mitigation policies (e.g., the PHEV wedge), the details of certain policies (e.g., the ethanol wedge), consumer preferences (the demand reduction wedge), technology costs (the hydrogen wedge), and modeling period (hydrogen )
  - Maintaining a portfolio of viable technologies is essential to the success of policies aiming to achieve significant CO2 emission caps
  - More work is required to guide policies that aim to achieve the highest degree of successful outcome in the face of uncertainties
  

Presentation: "Optimizing the US transportation wedges: what do we learn from a bottom-up model," 2009 STEPS Policy Symposium, Davis, CA (March 10, 2009)

Presentation: "Optimizing the US transportation wedges: what do we learn from a bottom-up model," International Energy Workshop, Paris, France (June 30- July 2, 2008)

• Sanstad, Alan H. , John Weyant, Alex Farrell, P.S. Koutsourelakis, and Sonia Yeh. 2007. A stochastic framework for analyzing long-run CO2 abatement strategies. In 4th Annual California Climate Change Conference. Sacramento, CA. link
• Yeh, Sonia, Daniel Loughlin, Carol Shay, and Cynthia Gage. 2006. Impacts of hydrogen economy on transportation, energy use, and air emissions: an integrated assessment," Proceedings of the IEEE, 94(10): 1838-1851. link