Photographer: Drew Angerer/Bloomberg

How Much Cleaner Really Is a Tesla? Depends on Where You Are

  • Powering up on coal-heavy grids still releases carbon dioxide
  • Japan’s EVs may get dirtier as fossil fuels replace nuclear

How much cleaner are electric cars than the fossil-fuel powered alternative? The answer depends on exactly where you charge the batteries.

QuickTake Cleaner Cars

In places that use low-carbon energy sources like renewables and nuclear, electric vehicles dramatically reduce emissions. There’s less of a difference in regions where most of the power comes from coal, like China.

While an electric vehicle on average may produce as little as half the pollution as a gasoline or diesel car, there’s great variation within the range. Running on battery power in China was just 15 percent cleaner than a fossil-fuel car last year, according to data compiled by Bloomberg New Energy Finance.

“In countries with large amounts of coal in the generation mix, EVs still look better, but the benefit is smaller and depends on when and where charging takes place,” said Colin McKerracher, head of advanced transport analysis at Bloomberg New Energy Finance. 

The London-based research arm of Bloomberg LP and the Union of Concerned Scientists both have analyzed the ultimate contribution that electric cars make to emissions and found that on average they’re 40 percent to 50 percent cleaner than those that fuel from gasoline or diesel.

Those estimates -- and the forward view on where emissions from the power generation industry are going -- are crucial to understand how much global-warming pollution will come from transportation in the decades ahead. 

Electric cars are gaining popularity quickly. 

Sales were up 44 percent in the first half of the year and may finish 2016 at a record 647,000 worldwide, according to BNEF’s forecasts. Manufacturers from Toyota Motor Corp. to General Motors Co. are joining Elon Musk’s Tesla Motors Inc. in developing new models. Volkswagen AG plans to produce 3 million of them a year within the next decade. At the Paris auto show this month, Volkswagen is due to unveil a prototype for the 2018-19 model year with a range of 400 to 600 kilometers (248 to 372 miles), enough for most drivers.

Those cars may run twice as clean when they’re charged in a place that gets a lot of power from green energy, but the same car driving in a coal-burning region may yield a gain of just 20 percent, according to the Union of Concerned Scientists, based in Cambridge, Massachusetts.

In 2015, driving a mile in an electric vehicle emitted 40 percent less pollution on average than traveling the same distance in a regular car, according to Bloomberg New Energy Finance. 

Those calculations are changing rapidly, partly because most nations are cleaning up emissions from utilities and also because fuel-efficiency standards are forcing manufacturers to make more efficient engines. The chart below shows the mileage improvements made in the past 15 years in the U.S.

Every nation has a different energy mix. Norway generates almost all of its electricity from hydroelectric dams fed by mountain rivers. It’s a similar story in France, where more than 90 percent of power came from nuclear and renewables. Yet in France, the gap between pollution flowing from traditional cars and those from electric vehicles will narrow in the coming decade because regular engines are getting cleaner.

In China, car pollution is declining at about the same pace as from the power industry, so electric vehicles are still a good bet. There, as in India, Germany and Spain, solar and wind plants are producing more and more megawatts.

“Essentially, the generation mix gets cleaner faster than internal combustion engines can improve over the next 25 years. The future is electric,” said McKerracher at Bloomberg New Energy Finance.

In Japan, emissions from driving electric vehicles may rise in the future because utilities are building new coal and natural-gas plants to replace the nuclear stations taken out of service after the devastating earthquake in 2011.

Still, that’s an anomaly. As more renewables come onto the grid, power produced globally is apt to be much cleaner in the coming years.

For those places where drivers can charge up on nothing but solar, driving electric cars will be almost 11 times cleaner than the fossil-fueled alternative, if you count the emissions that come from making cars and photovoltaic panels, according to Don Anair, research and deputy director of the clean vehicles program at the Union of Concerned Scientists. 

Wind power is cleanest of all -- as much as 85 times less polluting -- because building turbines isn’t as hard on the environment, he said.

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