Thursday, March 17, 2016

How do Carbon Emissions from Electric Vehicles Compare to Conventional Ones on a Life Cycle Basis?

Consequential life cycle air emissions externalities for plug-in electric vehicles in the PJM interconnection (13 page pdf, Allison Weis, Paulina Jaramillo and Jeremy Michalek, Environ. Res. Lett., Feb 9, 2016)

 Today we review an assessment of the life cycle emissions their costs from hybrid, plug-in hybrid vehicles compared to conventional ones, driven in states where the majority of the electric power generated is from coal or natural gas. Not surprisingly, the conclusion is that plug-in hybrid emissions are more damaging than hybrid and conventional vehicles under current conditions. The same analysis was done in a future power regulated scenario where renewable energy sources partly replace the carbon burning sources (e.g. 3 to 20% more wind power). Here, the hybrid and plug-in vehicles have higher SO2 and other pollutant emissions and lower PM 2.5 emissions while NO2 and greenhouse gas emissions can be higher or lower than conventional, depending on the individual case. In summary, as applied to Canada, it appears that electric cars make sense in regions where the power sources are largely renewable (e.g. Ontario, Quebec and BC where almost all electric power is nuclear or hydro) but do NOT make sense in regions were power is generated from carbon fuels (such as Alberta, Saskatchewan and the Maritimes). e car emissions  

Key Quotes:

“the emissions associated with producing PEVs [plug-in electric vehicles] and generating the electricity to charge PEVs affect whether these vehicles have higher or lower life cycle environmental and health impacts compared to efficient gasoline vehicles”

 “We estimate the life cycle emissions of CO2, CO, SO2, PM2.5, NOx, and VOCs for conventional, hybrid, and PEVs, including the emissions from vehicle manufacturing, fuel production, and use.”

 “the PEVs have higher GHG, SO2, NOx, and PM2.5 emissions and lower CO and VOC emissions than the HEV [hybrid electric vehicles]. Compared to the CV, PEVs have higher SO2 emissions and lower CO and VOC emissions, while GHG, NOx and PM2.5 emissions may be higher or lower, depending on the PEV characteristics and the charging scenario.”

 “In the future grid scenarios, compared to the HEV, the PHEV-35 [plug-in hybrid electric vehicles] has higher SO2 emissions and lower PM2.5, VOC, and CO emissions, while GHG and NOx emissions may be higher or lower, depending on the charging scenario and wind power scenario.”

 “PEVs have higher expected life cycle damages than hybrid vehicles in the recent PJM [(an independent system operator in Pennsylvania, New Jersey, Maryland, Ohio, and several other states)] scenario in all cases examined…Their expected damages are also higher than those of conventional vehicles”

“PEVs have higher life cycle air emissions damages than gasoline HEVs in the recent grid scenario, which has a high percentage of coal generation on the margin.“

“While near-term benefits of PEV adoption in PJM are estimated to be small or negative, a transition of the transportation system could lead to long-term benefits outside the scope of this analysis, including greater benefits in other regions and future emissions savings enabled by a transition to electric vehicles as the electricity grid becomes cleaner and as public policy adjusts”

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