Environmental Assessment of Conventional, Hybrid, and Battery electric Vehicles

Dovetail Partners Consuming Responsibly Report No.6

Over the past decade, initiatives to reduce U.S. greenhouse gas emissions have gained momentum, with conversion of both electric generation and transportation fuels away from fossil fuels toward renewable forms of energy. At the same time, there has been considerable development of vehicle alternatives, and electric-drive vehicles in particular.

Which of these new technologies yields the greatest environmental benefits is not straightforward. The answer depends largely on the extent to which electricity used in recharging vehicle batteries is produced using fossil fuels. Average commute distances and time-of-day when recharging batteries also affect electric vehicle environmental efficiency. 

In general, hybrid-electric vehicles (i.e., vehicles that combine internal combustion engines with battery power) that don’t have plug-in capability reduce vehicle lifetime emissions by 25-30% compared to internal combustion vehicles. Hybrids with plug-in capability and battery electric (all-electric) vehicles are even more effective in reducing emissions, with a 30-50% advantage over internal combustion vehicles. As electricity generation becomes increasingly free of fossil fuels, emissions differences between standard and electric vehicles are likely to increase because achievable emissions reductions are strongly influenced by the greenhouse gas (GHG) intensity of the electricity used to charge vehicle batteries.

A global challenge posed by ongoing electric vehicle development is the corresponding sharp increase in consumption of critical metals in the batteries. Assuring adequate supplies of needed metals, addressing environmental impacts of increased minerals mining and processing activity, and development of substitute materials will all require concerted attention.