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Electric Vehicle Greenhouse Gas Emission Assessment for Hawaii

This study estimates greenhouse gas (GHG) emissions of electric vehicles (EVs) compared to that of other popular and similar cars in Hawaii, by county over an assumption of 150,000 miles driven. The GHG benefits of EVs depend critically on the electricity system from which they derive their power. The analysis shows that EVs statewide are an improvement in GHG emissions over similar and popular internal combustion engine vehicles (ICEVs). Due to Oahu’s relatively high dependence on fossil fuels, including coal-burning, however, hybrid electric vehicles (HEVs) offer an improvement over EVs. Notably, Oahu also has the most EVs on the road. Hawaii Island, where there are few EVs on the road, shows a clear GHG benefit from EVs because of its high penetration of low carbon sources for electricity. This difference in benefits suggests that policies supporting EV uptake should consider impacts per island, based on available types of electricity generation. For example, because EVs on Hawaii Island provide near to mid-term GHG benefits, there should be assessment of provision of fast-charging stations to overcome potential range anxiety. Until Oahu substantially transitions towards greater penetration of renewable sources for electricity, it may be too early to tout EVs on Oahu as a GHG emissions reduction strategy. This of course depends on the type of vehicle from which drivers switch to EVs. If EV drivers largely pull from potential HEV consumers, as is suggested in prior studies, then there is no gain in GHG emissions reduction. On the other hand, if EV consumers switch from ICEVs, there are GHG emissions savings. Oahu’s electricity generation mix must become similar to that in carbon intensity of Kauai and Maui to make high performing EVs at least comparable to high performing HEVs in GHG emissions.

Read the full report at the Electric Vehicle Transportation Center.

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