New report: EVs produce half the emissions of typical petrol car on life-cycle basis
Fri 27 November 2015
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Over their lifetime, battery electric vehicles produce far less global warming pollution than their gasoline counterparts -and they’re getting cleaner - according to a new report from the US-based Union of Concerned Scientists.
The new report, 'Cleaner Cars from Cradle to Grave', was a two year study comparing battery-electric vehicles (BEVs) with similar gasoline vehicles by examining their global warming emissions over their “life cycles” - from the raw materials to make the car through manufacturing, driving, and disposal or recycling. The study looked at up-to-date assessments of the carbon footprints of BEVs, taking into account the latest information about electricity generation and BEV models.
The two BEVs modeled, midsize and fullsize, are not specific to any particular manufacturer but are based on the two most popular BEV models sold in the United States today: the Nissan LEAF and the Tesla Model S.
The analysis revealed that from cradle to grave, BEVs are cleaner. On average, BEVs representative of those sold today produce less than half the global warming emissions of comparable gasoline-powered vehicles, even when the higher emissions associated with BEV manufacturing are taken into consideration. Based on modeling of the two most popular BEVs available today and the regions where they are currently being sold, excess manufacturing emissions are offset within 6 to 16 months of driving.
Both types of vehicle begin in much the same way. Raw materials are extracted, refined, transported, and manufactured into various components that are assembled into the car itself. Because electric cars store power in large lithium-ion batteries, which are particularly material- and energy-intensive to produce, their global warming emissions at this early stage usually exceed those of conventional vehicles.
The report says that manufacturing a mid-sized EV with an 84-mile range results in about 15 percent more emissions than manufacturing an equivalent gasoline vehicle. For larger, longer-range EVs that travel more than 250 miles per charge, the manufacturing emissions can be as much as 68 percent higher.
These differences change as soon as the cars are driven. EVs are powered by electricity, which is generally a cleaner energy source than gasoline. Battery electric cars make up for their higher manufacturing emissions within eighteen months of driving—shorter range models can offset the extra emissions within 6 months—and continue to outperform gasoline cars until the end of their lives.
The study says that the disposal process for EVs and their batteries typically accounts for less than 5 percent of the global warming emissions attributable to production of the vehicles. Nevertheless, the data available for BEV end-of life procedures are limited because the majority of BEVs are still on the road—i.e., they have not yet been retired. In the absence of pertinent data, the authors have made conservative assumptions by allocating no emissions savings to the reuse or recycling of the lithium-ion battery and by applying industry averages to other recycled materials.
The study concludes that electric vehicles already result in far less climate pollution than their conventionally-powered counterparts, and they’re getting cleaner. Optimizing EV production and the disposal or reuse of batteries could further increase their environmental benefits it says. And as electricity becomes cleaner (which it is), the difference between electric cars and gasoline cars will only grow—cementing the role of electric vehicles, according to the report, in halving U.S. oil use and cutting global warming emissions.
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video supporting the study has been published on Youtube.
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