Thursday, May 19, 2011

Does the Charging of Hybrid Cars Produce Significant Pollution?

Air quality impacts of plug-in hybrid electric vehicles in Texas: evaluating three battery charging scenarios (12 page pdf, Tammy M Thompson, Carey W King, David T Allen and Michael E Webber, Environmental Research Letters, Volume 6, Number 2, Apr. 19, 2011)

Today’s focus is on the impact of the charging of hybrid cars on air quality because of emissions from the sources of electricity (at night) which would replace the emissions from the mobile sources mainly daytime. The modelling experiment took place in one of the states with higher levels of pollution. The conclusion appears to be that the shift does not have a significant impact on the environment.



Key Quotes:

“Two of the largest sources of emissions that lead to ozone formation are vehicles and electricity generating units (EGUs). Increasingly, these two emission source categories are becoming intertwined, through the use of plug-in hybrid electric vehicles (PHEVs)”

“When operating on electricity, PHEVs have no tailpipe emissions. However, emissions are released when fuel is burned to generate electricity at power plants for charging these vehicles”

“shifting emission sources from urban, daytime tailpipes of gasoline-powered cars to (often) rural, stacks of power plants burning coal or gas can have a significant impact on photochemical air pollutant formation.”

“The impact of PHEVs on ozone is dominated by the impact associated with mobile NO x emissions decreases”

“The potential air quality impact of PHEVs is dominated by the impact of the NO x decreases from mobile sources. In most cases the decrease in NO x emissions due to PHEVs causes a decrease in 8 h average ozone concentrations during the day when the maximum value is likely to occur. The result is a likely decrease in the daily maximum 8 h average ozone concentration, the value used to determine attainment of the 8 h standard”

“Nighttime increases in ozone are less likely to impact humans because fewer people are awake and outside and therefore fewer people are being exposed to higher ozone during nighttime hours. Thus, the switch of 20% of LDV VMT from gasoline to electric travel shifts ozone formation to a time period that is likely less harmful to humans”
Enhanced by Zemanta

No comments:

Post a Comment