14

Imagine an electric car in a country where most energy come from coal (which i believe is the dirtiest). Add this to the pollution that disposing the batteries will create, or the carbon footprint generated during its production.

Is this car really beneficial in terms of carbon emission and pollution compared to a modern petrol or diesel engine car?

  • While the claim is implicit here, I think it is a valid question. Manufactures and proponents of electric car often claim such cars are ecological. Still, some link to some particular claim would probably make the question better. – Suma Aug 5 '11 at 19:41
  • 1
    related: skeptics.stackexchange.com/questions/351/… – Borror0 Aug 5 '11 at 20:15
  • 2
    Cars powered by gasoline are getting quite efficient (including hybrid vehicles). Nevertheless, a real advantage of vehicles that get their power by the grid is adaptability. As new methods of generating power (including green) come on-line, vehicles can automatically use them. They aren't necessarily tied to oil. – Mike Dunlavey Aug 6 '11 at 3:00
  • 2
    Your question has an explicit assumption of coal-sourced electricity. You've set the parameters to the question, and that is legitimate. But, it means the title to the question is misleading. In countries that are have, or are trying to have, less fossil-fuel-based electricity, the answer may be very different. – Oddthinking Aug 7 '11 at 2:23
  • @oddthinking i believe the answer to this question is pretty obvious for a country where most electric energy is from low carbon sources, isn't it? – ariel Aug 8 '11 at 4:53
10

This question can be answered using a Life Cycle Analysis, which looks at emissions over the total life cycle of a product - including manufacture, use, and disposal. Many such studies have been performed, here are two examples:

A 2012 UCLA study for the California Air Resources Board, and

A 2015 study by The Union of Concerned Scientists

Both of these conclude that electric vehicles produce lower greenhouse gas emissions than conventional vehicles using California or US electric mix.

From the UCLA study (where BEV means Battery Electric Vehicle, and CV means Conventional Vehicle):

In terms of environmental impacts, the BEV was determined to have the least overall impact, followed by the hybrid, and lastly the CV.

Here is a chart from that report showing the life cycle impacts using California's electric grid fuel mix [coal (7%), nuclear (14%), natural gas (42%), total hydropower (13%), wind (5%), geothermal (5%), solar (0%), and biomass (2%)]. The Battery electric vehicle emits about half the CO2 of the conventional vehicle over its lifetime.

enter image description here

The question specifically asks about the worst case for CO2 emissions - a country where most electricity comes from coal. This is also addressed in the CARB report, through the following figure which looks at different electricity mixes. The study used this mix for China: coal (79%), nuclear (2%), natural gas (2%), hydropower (16%), oil (2%), wind (0%), geothermal (0%), solar (6%), and biomass (0%).

The BEV emissions from the China electric mix are about 2.25 times higher than for the California mix, which would put them at slightly higher than a conventional vehicle, based on the first figure.

enter image description here

It is clear that the cradle-to-grave CO2 emissions are comparable to a conventional vehicle in the most coal-intensive electric grid, and considerably better as the percentage of coal drops. Given that the trend is toward less coal globally, it is clear that the situation will improve from here.

The Union of Concerned Scientists report is focused on the United States, and concludes that electric vehicles produce less CO2 than typical conventional vehicles everywhere in the US

We found that: (1) driving the average electric vehicle in any region of the country produces lower global warming emissions than the average new gasoline car achieving 29 MPG; (2) our ratings in 20 out of 26 regions have improved since our 2012 report; and (3) about 66 percent of Americans—up from 45 percent just three years ago—live in regions where power- ing an EV on the regional electricity grid produces lower global warming emissions than a 50 MPG gasoline car.

  • You mentioned greenhouse gas emissions only! What about all other forms of pollution??? – elliot svensson Jan 14 at 15:50
6

No, not really.

An electric car uses around 250-300 Wh per mile (1,2) or 155-186 Wh/km. Let's be generous and assume 250 Wh per mile. Coal produces around 2.3 lb of Carbon Dioxide (CO2) per kWh (3) or about 1 kg/kWh. That means your electric car produces 250 g/mile or 155 g/km on average. Even a good petrol engine will beat this; a VW Golf BlueMotion Diesel gets 99 g/mile (4) or 62 g/km.

However, it's not all bleak for electric cars. As an example, in the UK only uses 33% coal (5), so an electric car in the UK would only produce 83 g/mile or 52 g/km CO2, although other fuels produce CO2 as well, they produce it in smaller amounts. It will especially become more environmentally friendly as wind power and other renewable sources are used more.

You also have to take into account the distribution of the fuel; after all, it has to be transported to the fuel station for you to fill up your car, and you have to drive to the fuel station in question, compared to electricity which loses minimal energy in the transmission process, and charging can be done at home.

  • 2
    @ratchet Charge/discharge of lithium polymer batteries is about 99% efficient. – Thomas O Aug 6 '11 at 10:59
  • 1
    You will need many more references to support this post... – Sklivvz Aug 6 '11 at 17:08
  • 2
    What I meant is that you should really point to studies confirming that your line of thought is correct and not put together bits of information. The environmental impact of a car isn't only determined by its running usage emissions. For example, if you buy a car and never drive it, you are still impacting the environment. – Sklivvz Aug 7 '11 at 9:19
  • 3
    @ratchet. It's also worth noting that gas and coal don't just appear out of thin air. If you really want to get a thorough analysis of which is cleaner, you should probably look at the total carbon footprint of collecting the raw materials, crude oil, coal, uranium (if you use nuclear power for the electric), or whatever else when figuring out how much carbon is produced when comparing electric to gas engines. – Kibbee Aug 8 '11 at 0:05
  • 2
    @thomas O - This covers the CO2 but what about the more signifigant immediate air pollutants like CO and other exhaust fumes created by combustion engines. These are not as naturally occuring and to my mind make a more signifigant threat to the environment. – Chad Aug 8 '11 at 16:11
-2

If you can install solar panels on your roof, then yes. If you're getting your power from the grid, then no.

Keep in mind, that the solution to CO2 emissions isn't "should we make all cars electric, or should we replace all of our coal power plants", it's both. You can't say "Oh, well, electric cars are no good then" because your local electricity generators are too dirty. Both need to be replaced ASAP. Full stop. And as we do the work to replace the dirty power plants, we simultaneously make existing electric cars cleaner. No further work needs to be done.

So let's stop complaining about how this solution or that solution isn't perfect, and get to work.

  • 1
    Please provide some references to support your claims. – Oddthinking Mar 18 '16 at 16:15
  • 1
    Claim #1: If you can install solar panels on your roof, (or otherwise get power from a zero-emissions source, like hydro or wind power), then yeah, you're reducing the emissions from your electricity to pretty much zero. I don't see how this needs verification. – Ernie Mar 18 '16 at 17:15
  • 1
    Claim #2: We need to replace both gas cars and coal power plants to effectively reduce CO2 emissions. What are you looking for here, basic chemistry? – Ernie Mar 18 '16 at 17:17
  • The hypothetical question asked about a hypothetical country that gets all its grid power from coal power plants. Those are literally the dirtiest powerplants in the world. Anything would be an improvement over that. – Ernie Mar 18 '16 at 17:25
  • 1
    If this hypothetical question was asked today, rather than in the Beta period where we were still developing our standards, it probably would have been closed as a strawman. – Oddthinking Mar 18 '16 at 23:46

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .