Basing policy on current science and technology is fraught with difficulties. I have written about the problems of legislating to limit those gases currently thought to contribute to the greenhouse effect, and advocated instead rewarding people for achieving that which we actually want to achieve: a reduction in adverse climatic events. On a smaller scale, I am sceptical about governments promoting battery electric vehicles (BEVs). The reasoning is similar: our knowledge of the causes and the effects of our environmental depredations is incomplete and rapidly expanding. Take this excerpt from US research into a comparison of the environmental impacts of BEVs and internal combustion engine vehicles (ICEVs):
BEVs may be responsible for greater human toxicity and ecosystems effects than their ICEV equivalents, due to (1) the mining and processing of metals to produce batteries, and (2) the potential mining and combustion of coal to produce electricity. These results are global effects, based on the system boundaries and input assumptions of the respective studies. In addition to a review of the literature, CRS focused on the results of one study in order to present an internally consistent example of an LCA [Life Cycle Analysis]. This specific study finds that the life cycle of selected lithium-ion BEVs emits, on average, an estimated 33% less GHGs [greenhouse gases], 61% less volatile organic compounds, 93% less carbon monoxide, 28% less nitrogen oxides, and 32% less black carbon than the life cycle of ICEVs in the United States. However, the life cycle of the selected lithium-ion BEVs emits, on average, an estimated 15% more fine particulate matter and 273% more sulfur oxides, largely due to battery production and the electricity generation source used to charge the vehicle batteries. Further, the life cycle of the selected lithium-ion BEVs consumes, on average, an estimated 29% less total energy resources and 37% less fossil fuel resources, but 56% more water resources. Environmental Effects of Battery Electric and Internal Combustion Engine Vehicles (pdf), [US] Congressional Research Service, 16 June 2020
This is not to say that BEVs are worse than ICEVs. It is clear that there is no single way of weighting and aggregating the adverse environmental impacts that points to a clear winner. And, even if there were, that could change, depending on either developments in technology, or improved knowledge about how the environmental depredations affect human, animal and plant life. On that basis then, I would argue that legislation to promote BEVs is misguided. Instead we'd do better, in my view, to stipulate those environmental outcomes that we want to achieve, and reward those who bring about those outcomes, however they do so.