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Impacts of PHEV and Renewable Energy Technologies on Marginal Displacement of GHG Emissions

CSS Publication Number
Full Publication Date
June 20, 2009

Gasoline and diesel automobiles dominate current personal transportation in the United States. The automotive industry has been developing PHEVs (plug in hybrid electric vehicles) in response to increased concerns related to US reliance on these petroleum products and the adverse effects of the related GHG emissions. The wide spread acceptance of a need to move away from reliance upon these fuels has lead to the emergence of public interest in PHEVs for personal transport. PHEVs reduce reliance on liquid fuels by coupling a traditional internal combustion (IC) engine with electric motors and batteries. Some PHEVs are driven entirely by an electrical motor. This differs from current hybrid vehicles which can use the IC engine to drive the automobile. For short trips (~50 km) PHEVs are expected to be capable of running entirely on battery power thus all electrical power would come from the existing electrical grid. For longer journeys an onboard IC engine would provide the needed energy.

As PHEVs achieve market penetration the current electrical grid will be subject to increased demands to meet the additional capacity of charging the PHEV batteries. Half of the US grid electricity is generated from burning coal a highly carbon intensive fuel source. In order to drastically reduce GHG emissions a transformation of the grid to renewable sources is required. Wind and photovoltaic energy systems are the fastest growing renewables that can generate electricity and displace carbon intense sources

It is important to understand how the grid will respond to the penetration of both PHEVs and renewable energy technologies specifically photovoltaics and wind turbines. It is equally important to quantify the impact that those technologies will have on GHG reduction. This paper looks at the impact of increasing electrical demand by simulating this new PHEV load with historical electrical demand data. This new load will place increased stress on the current electrical system and require more electrical power supplies to be dispatched to meet that load. An analysis is conducted to examine the mix of generating assets (renewable vs nonrenewable)that would be utilized in a test case that explores deployment of PHEV in Texas. The findings show the reductions in GHG emissions given in grams per mile driven for differing rates of PHEV penetration and for the type of renewable technology used photovoltaics or wind turbine. All results show a significant decrease in GHG emissions versus the baseline of traditional automobiles and the current electrical grid.

Research Areas
Mobility Systems
Publication Type
Conference Proceeding
Full Citation
Kelly, Jarod and Greg Keoleian. “Impacts of PHEV and Renewable Energy Technologies on Marginal Displacement of GHG Emissions.” Book of Abstracts of the 2009 ISIE Conference– Transitions Toward Sustainability. Lisbon, Portugal, June 21-24, 2009: 211.