Lynne Kiesling
A forthcoming article in the Journal of Industrial Ecology reports on a lifecycle analysis comparing electric vehicles with internal combustion vehicles (at the moment the full article is available for our edification!). This thorough analysis looks at the resource use and environmental impact of the production, use, and disposal of the vehicle. From the abstract:
We develop and provide a transparent life cycle inventory of conventional and electric vehicles and apply our inventory to assess conventional and EVs over a range of impact categories. We find that EVs powered by the present European electricity mix offer a 10% to 24% decrease in global warming potential (GWP) relative to conventional diesel or gasoline vehicles assuming lifetimes of 150,000 km. However, EVs exhibit the potential for significant increases in human toxicity, freshwater eco-toxicity, freshwater eutrophication, and metal depletion impacts, largely emanating from the vehicle supply chain. Results are sensitive to assumptions regarding electricity source, use phase energy consumption, vehicle lifetime, and battery replacement schedules. Because production impacts are more significant for EVs than conventional vehicles, assuming a vehicle lifetime of 200,000 km exaggerates the GWP benefits of EVs to 27% to 29% relative to gasoline vehicles or 17% to 20% relative to diesel. An assumption of 100,000 km decreases the benefit of EVs to 9% to 14% with respect to gasoline vehicles and results in impacts indistinguishable from those of a diesel vehicle.
The actual effects of switching to EVs rely predominantly on three variables: the fuel used to generate the electricity that powers the production and charging of the EV, the energy intensity of the production process, and the actual vehicle miles traveled. On the first, the researchers found that
For all scenarios analyzed, the use phase is responsible for the majority of the GWP impact, either directly through fuel combustion or indirectly during electricity production. When powered by average European electricity, EVs are found to reduce GWP by 20% to 24% compared to gasoline ICEVs and by 10% to 14% relative to diesel ICEVs under the base case assumption of a 150,000 km vehicle lifetime. When powered by electricity from natural gas, we estimate LiNCM EVs offer a reduction in GHG emissions of 12% compared to gasoline ICEVs, and break even with diesel ICEVs. EVs powered by coal electricity are expected to cause an increase in GWP of 17% to 27% compared with diesel and gasoline ICEVs.
In other words, if the EV manufacturer and owner use coal-generated electricity, the switch to EVs increases greenhouse gas production, because of the increased electricity use. Note also that the production process for an EV is extremely energy intensive, largely because of the energy intensity of producing the battery (and, as noted in the abstract, the battery involves using and disposing of toxic trace metals). Finally, what if the EV has a shorter useful life than the equivalent ICEV? That would mean having to weight any beneficial effects to reflect that shorter life and the need to replace the EV more quickly than the equivalent ICEV.
So the electric vehicle is not a slam-dunk, silver bullet, mix your favorite metaphors way to innovate around the environmental effects of fossil fuel use. See also this Guardian blog post on the study, including some back-and-forth in the comments and from Twitter with one of the study’s authors — a very illuminating exchange.
I mention this study not to argue that we should avoid EVs, nor to argue that we should/should not pay attention to greenhouse gas emissions, but rather to point out that good, detailed, careful analyses of actual effects of likely actual changes are important data for us to have as we evaluate policy alternatives in a complex system like our environment + economy. Among other things, this study highlights the marginal greenhouse gas impact of electricity generation relative to other greenhouse gas sources. This is not new, but in this context where the researchers can show how big the share of the impact is coming from electricity generation, that’s an important data point. It also highlights the overall impact of battery production, use, and disposal, which suggests the importance (and not just for greenhouse effects, but for other environmental effects too) of research on alternative battery and energy storage technologies, and the durability of the battery, which currently limits vehicle life.