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翻译：Jiaqi 校对：Ryan，Jiawen DRIVING an electric car confers a badge of greenery, or so the marketing departments of their makers would have you believe. Yet a report which analyses the life cycle of car emissions (ie, all the way from those created by the mining of materials for batteries, via the ones from the production of fuel and the generation of electricity, to the muck that actually comes out of the exhaust) presents a rather different picture. A battery-powered car recharged with electricity generated by coal-fired power stations, it found, is likely to cause more than three times as many deaths from pollution as a conventional petrol-driven vehicle. Even a battery car running on the average mix of electrical power generated in America is much more hazardous than the conventional alternative. 驾驶电动车象征着绿色环保，至少汽车生产商的市场部会使你相信这一点。但是最近一份研究汽车排放物的生命周期（比如说，从挖掘生产电池所需材料而产生的排放，经过制造燃料和发电产生的排放，再到实际排放出的废物）的报告向我们展示了一个不同的观点（比如说，去比较——通过完全由采掘而出的矿物做成的电池和由使用燃料而得到电能——它们排出的污染物）。研究表明一辆通过火电站获得电能的电动车所引起的污染，比起传统的汽油车更可能导致超过三倍的死亡率。如果一台电动车的电的来源和美国电的来源比例一致，这种车比传统汽车的危害性更大。
Christopher Tessum, Jason Hill and Julian Marshall of the University of Minnesota have just published this study in the Proceedings of the National Academy of Sciences. They estimate how levels of fine particulate matter and ground-level ozone—two important constituents of air pollution, which kills more than 100,000 people a year in America—would change if each of 11 ways of powering a car were to be responsible for 10% of the vehicle-miles expected to be driven in America in 2020. 来自明尼苏达大学的Christopher Tessum, Jason Hill 和 Julian Marshall 已经将他们的研究发布在《美国国家科学院院刊》（Proceedings of the National Academy of Sciences.）上。他们预测微小颗粒物和地表臭氧水平—每年在美国致使10万人死亡的两个主要空气污染成分-将怎样改变，如果11种不同的驱动汽车的方法各占了美国2020年10%的汽车行驶里程。 It was no surprise that electric cars whose batteries were topped up from wind, solar or hydroelectric sources came out cleanest, causing 231 putative deaths over the course of a year, compared with 878 for petrol cars. Electric cars recharged with power from natural-gas-fired stations were also a lot less lethal than petrol-driven ones, with 439 deaths. But if those same electric cars were recharged ultimately by coal, they would be responsible, according to the model, for just over 3,000 deaths. 相比汽油车一年中会导致878人死亡，那么那些经由风力，太阳能或者水电得到最清洁电能的电动车，导致的231人次死亡就显得并不奇怪。通过天然气发电站得到电能的电动车也凭借439人比汽油车导致死亡的案例少得多。但是如果那些同样的电动车都是通过燃煤来充电的话，那么根据建模，它将对超过3000名的死者负责。 Biofuels also caused more health problems than petrol. But diesel, which is generating concern about pollution in parts of Europe, where it is a more popular fuel than in America, was marginally cleaner than petrol. This is because the Minnesota model assumes for all cars that present and future emission-control technologies will be more widely used in 2020, especially particulate filters which have a marked effect on cleaning diesel exhausts. Diesel cars also have better fuel economy than petrol-driven ones. 生物燃料也比汽油会导致更多的健康问题。和美国相比，柴油在欧洲是更加受欢迎的燃料。虽然在欧洲一些国家，人民关注柴油带来的污染问题，但柴油比汽油略微清洁些。这是因为在明尼苏达模型中对于所有车假定了现今的和未来的排放控制科技在2020年会被更广泛得使用，特别是颗粒物过滤器将会在清洁柴油排放物上产生一个显著的效果。柴油车比起汽油车有更好的燃油经济性。 Overall, the research shows that electric cars are cleaner than those that rely on internal-combustion engines only if the power used to charge them is also clean. That is hardly a surprise, but the magnitude of the difference is. How green electric cars really are, then, will depend mainly on where they are driven. In France, which obtains more than half its power from nuclear stations, they look like a good bet. In China—which is keen on electric cars, but produces some 80% of its electricity from coal—rather less so. 总的来说，这个研究表明了只有在给电动车充电的电能也是绿色环保的情况下，电动车才比依赖于内燃机的车更干净。电动车不环保并不奇怪，但没想到它居然这么脏。电动车有多环保主要取决于它在哪开。在法国的话一般以上的电力来自核电厂，这看上去像一个不错的赌局。中国比法国少些，那里的人们很热衷于电动车，但是80%的电来自烧煤。
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