重庆合川区2017高考英语阅读理解九月指导题：6（含解析）_高考复习指南

重庆合川区2017高考英语阅读理解九月指导题：6（含解析）

　　Electric cars are dirty. In fact, not only are they dirty, they might even be dirtier than their gasoline-powered cousins.

　　People in California love to talk about “zero-emissions (零排放的) vehicles,” but people in California seem to be clueless about where electricity comes from. Power plants most all use fire to make it. Aside from the few folks who have their roofs covered with solar cells, we get our electricity from generators (发电机). Generators are fueled by something — usually coal, oil, but also by heat generated in nuclear power plants. There are a few wind farms and geothermal plants as well, but by far we get electricity mainly by burning something.

　　In other words, those “zero-emissions” cars are likely coal-burning cars. It’s just that the coal is burned somewhere else so it looks clean. It is not. It’s as if the California Greens (加州绿党) are covering their eyes — “If I can’t see it, it’s not happening.” Gasoline is an incredibly efficient way to power a vehicle; a gallon of gas has a lot of energy in it. But when you take that gas (or another fuel) and first use it to make electricity, you waste a nice part of that energy, mostly in the form of wasted heat — at the generator, through the transmission lines, etc.

　　A gallon of gas may power your car 25 miles. But the electricity you get from that gallon of gas won’t get you nearly as far — so electric cars burn more fuel than gas-powered ones. If our electricity came mostly from nukes, or geothermal, or hydro, or solar, or wind, then an electric car truly would be clean. But for political, technical, and economic reasons, we don’t use much of those energy sources.