Et nylig livssyklusstudie av miljø- og klimaeffektene fra forskjellige type biler publisert i Journal of Industrial Ecology viser at dagens elbiler ikke er så fortreffelige som noen vil ha det til. Her er det vitenskapelige sammendraget, hvor jeg har fremhevet et meget bekymringsverdig funn:
Electric vehicles (EVs) coupled with low-carbon electricity sources offer the potential for reducing greenhouse gas emissions and exposure to tailpipe emissions from personal transportation. In considering these benefits, it is important to address concerns of problem-shifting. In addition, while many studies have focused on the use phase in comparing transportation options, vehicle production is also significant when comparing conventional and EVs. 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. Improving the environmental profile of EVs requires engagement around reducing vehicle production supply chain impacts and promoting clean electricity sources in decision making regarding electricity infrastructure.
Dette er nok en demonstrasjon av den tilsynelatende uungåelige avveining mellom klassisk miljøvern og klimapolitikk. Mer generelt, dette er et eksempel på at alle valg er forbundet med alternativkostnader (ingen ting kommer gratis) og at mange individuelle beslutninger (valg av biltype) og offentlige tiltak (subsidiering av bestemte produkter) har utilsiktede konsekvenser. Buyers, environmentalists, and politicians beware!
Hawkins TR, Singh B,Majeau-Bettez G. Strømman AH (2012): Comparative Environmental Life Cycle Assessment of Conventional and Electric Vehicles. Journal of Industrial Ecology. Forthcoming. Published Online: http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00532.x/pdf