Environment

OBQ: Do electric cars really harm the environment less than gasoline-powered cars?

Electric vehicles might look clean and green, but where that electricity is coming from makes a big difference
Electric vehicles might look clean and green, but where that electricity is coming from makes a big difference
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Electric vehicles might look clean and green, but where that electricity is coming from makes a big difference
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Electric vehicles might look clean and green, but where that electricity is coming from makes a big difference
While the tailpipe of an electric vehicle doesn't put out any pollution, the smokestacks at coal plants used to produce electricity certainly do
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While the tailpipe of an electric vehicle doesn't put out any pollution, the smokestacks at coal plants used to produce electricity certainly do

Electric vehicles are often touted as a more environmentally friendly than cars powered by gasoline. But all that electricity has to be produced somewhere, so it got us to wondering if EVs really are better for our planet than traditional vehicles.

To find out, as part of our regular One Big Question series (OBQ), we put the question to John B. Heywood, Sun Jae Professor of Mechanical Engineering at MIT.

Here's what he had to say ...

The short answer is: At present yes, electric cars are somewhat better.

But of course, many details matter, especially how the electricity used to propel the car is generated. If coal is a major primary electricity source, then the environmental impacts of battery-powered electric vehicles (BEVs) are worsened. These include the land and water impacts of coal mining and transport, the air pollution that burning coal generates, and the greenhouse gas (GHG, largely CO2) emissions use of coal produces. In most of the world's larger countries today, coal is used to generate some 40 to 60 percent of the electricity produced; this is a significant amount.

In the United States, where coal use in electricity generation has now decreased to less than 40 percent as a consequence of the greening of the grid, BEVs emit about half the GHGs per mile than does a comparable gasoline-fueled car. This comparison is done on a full life-cycle basis – as it should be – from cradle to grave. In Eastern Europe, where coal-based electricity generation is close to 60 percent of the total, the current GHG benefits of BEVs are some 30 percent.
As renewable electricity supply increases and coal use decreases over the next twenty years, these BEV environmental benefits will likely increase on-average to about a two-thirds reduction in GHG emissions, and the air pollution benefits will significantly increase. Note that the fuel efficiency of conventionally-powered vehicles, over the same twenty year period, will improve by about one-third through use of new and better technology. This is good news and helps us all, but it does reduce the comparative benefits of BEVs, some.
While the tailpipe of an electric vehicle doesn't put out any pollution, the smokestacks at coal plants used to produce electricity certainly do
While the tailpipe of an electric vehicle doesn't put out any pollution, the smokestacks at coal plants used to produce electricity certainly do

There are several major uncertainties and questions in this "look ahead."

Individual people buy and use cars, the market is intensely competitive, and whatever technology we want to use in vehicles must appeal on its merits. Current challenges include the difference in costs of these two propulsion technologies, and the availability and convenience of their supporting refueling or recharging infrastructures.

BEVs are currently more expensive than gasoline vehicles, and now rely on substantial rebates at time of purchase to promote sales. Range anxiety with BEVs due to limited battery electricity-storage capacity (due to battery cost and weight) is of concern: When coupled with the current shortage of recharging stations and the inherently long battery-recharging times, BEV use for at least some driving tasks becomes much less convenient for the user. Then, how rapidly the renewable component of the electricity supply system will grow in different countries, and to what levels, is uncertain. As yet, the long-term availability of the raw materials for batteries, and the environmental impacts of their large-scale material extraction and processing, and battery production, have yet to be adequately examined. It is thought that the environmental impacts of producing batteries will be worse than such impacts for producing engines.

Battery-powered electric vehicles have been purchased by the public and are being used in the real world at the several-hundred-thousand vehicles level total, worldwide, though currently sales are lagging expectations. The total number of cars in use today is approaching one billion. Large reductions in environmental impacts, requires large volume vehicle sales and use. Note, there are alternative forms of plug-in electrified vehicles such as plug-in hybrids, which have an engine on board to augment the electric drive and to recharge the battery when needed. These are also being produced, sold, and used, at comparable scale to BEVs. Plug-in hybrid vehicles provide normal driving range and greater recharging flexibility, and may well, overall, drive the same number of electric miles, annually, as do BEVs.
Major efforts to push the transition from petroleum-based fuel vehicles towards greater use of electrified vehicles are now occurring. The likely extent of their eventual success is unclear.
39 comments
VincentWolf
BEVs are more expensive solely because the manufacturers are marking them up to get people to file for the Federal rebates and state rebates knowing full well that the simplicity in making electric cars costs less in the long run that ICE vehicles with hundreds of moving parts. It's called 'markup' and they are not loosing thousands on vehicle that's a lie by the factories. Detroit doesn't want to produce EVs and lose it's cash cows--ICE trucks and SUVS. But Tesla is going & the global community is going to force them to make them in order to stay competitive. That's competition and Detroit will lose. The world gains.
Jeff J Carlson
and mining, refining and processing the exotic materials in EV's add a lot of environmental harm as well ... CO2 is not a pollutant, its plant food ...
FrankFitzgerald
Power generation is only half of the formula. The second half is the battery. You can't honestly talk about the difference between gas and electric driven vehicles without addressing mining for the rare earth minerals that go into battery manufacturing process.
guzmanchinky
Excellent thought out answer. I do believe, however, that as soon as someone brings out an electric that charges in 5 minutes the complexity and geo-political insecurity of petroleum based passenger vehicles will be their undoing. Whover invents that quick charging battery will be the next billionaire...
WilliamHinshaw
You also have to account for the production all of all the materials that go into making the batteries, what happens to those batteries once they go bad and all the extremely toxic waste that is produced from that. The amount of energy that goes into the production of these respective products. SO really as a measure of just how damaging to the environment vs regular vehicles. Think about it. The burning of hydrocarbons vs the very toxic chemicals produced from the making of the batteries and electronics that go into making electric vehicles.
Ptodd
What about the impact of producing the materials for the battery packs? What about the end-of-life impact of the batterie packs and their disposal?
GLW
This comment is in relation to the part of the article that compares emissions of battery powered electric cars to petrol powered cars. Obviously the electric has zero tailpipe emissions compared to the petrol car. Then the article points out that there are emissions generated in making the electricity to charge the batteries, particularly coal powered plants (awful, I agree). Consider that the majority of electric cars in the USA are in California. California electricity is largely generated using natural gas, far less harmful emissions than coal, and geothermal, wind and dams. Also, consider that a person buying an electric car in California may very well have solar PV panels on their house. Now let’s get to the good part, looking at the emissions generated by the production of gasoline to provide fuel for petrol powered cars. Emissions from tanker trucks delivering the gas to the station, emissions from the refinery to make the gas, emissions from delivering the crude oil to the refinery, emissions from the oil rigs used to get it out of the ground, particularly the environmental impact of fracking, and let’s not forget oil spills, did you happen to see DEEP WATER HORIZEN, a great reminder of the environmental impact the oil industry has on our world. The author did say that electric vehicles are somewhat better regarding emissions, but after looking at all the emissions generated in either case, I think electric vehicles are far and away better than petrol powered vehicles.
DavidRogerBrown
Costly rare earth lithium mining is damaging to the environment. Until there is a lower cost,higher efficiency battery made from common material,electric vehicles are slow growth. Cold weather cuts their efficiency even more.
JohnJames
All these arguments are spurious. Electricity used to charge the cars batteries can be produced by hydro, wind or solar, not to mention solar cells on your garage roof. All zero emission.
habakak
Wow. Very one-way logic in the comments. You also have to account for all the chemicals and environmental destruction being caused by EXTRACTING, REFINING AND DISTRIBUTION OF PETROLEUM PRODUCTS. And we all know that burning gasoline and diesel releases CO2 locally. At least electric cars keeps local air cleaner. Besides that, electric cars are up to 3 times as efficient in converting chemical energy to kinetic energy. And that is why (no matter if ICE's will get more efficient, it will always be less efficient) eventually electric cars will replace gasoline cars. Once batteries become cheap enough (energy density is doubling every 7 to 10 years so that will happen, and recharging times are also improving all the time) it WILL replace ICE's. Unfortunately people are shortsighted and impatient. Look at the transformations the world has undergone during the 1st and 2nd Industrial revolutions. Coal powered steam took more than a century since discovery to peak before being replaced by oil powered ICE's. The next revolution is renewable powered electric motors. Each time the world experienced huge transformation and massive increases in wealth. Coal powered steam engines powering factories got replaced by electricity consuming electric motors powering factories. This caused a much better work environment (cleaner air, quieter work environment, more efficient process, etc.). Now electrification is moving to transportation. And at the same time the generation of the electricity is moving to renewable sources. Unfortunately people balk about this and make all these feeble arguments because they expect change overnight. An oil-combustion economy took 40 to 50 years to supplant an steam-coal powered economy. The renewable-electric economy will take another 40 years or more to replace our current oil/ICE economy. The renewable electric age is just starting. The people who today deny that and talk about the dominance and superiority of oil and ICE's are the same people who argued for coal and steam engines 100+ years ago. Or for horse and buggy's vs ICE's 100 years ago. Or wood and whale oil vs steam and coal 200+ years ago. After more than 100 years of development and progress, the renewable age is finally dawning.