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Do electric cars cause more or less climate pollution than gasoline cars? Take a look.

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Electricity has arrived as a fuel source for an increasing number of vehicles. Will this increase or decrease climate pollution compared to using gasoline?

I've heard so much confusion about this that I decided to make one of my Visual Carbon charts to allow informed comparisons at a glance. Turns out this was easier imagined than done. Determining the climate pollution from electric-fuelled vehicles requires compiling data on three new variables:

  1. ELECTRICITY: The amount of climate pollution released when generating electricity varies dramatically between regions. This is the primary factor determining how much climate pollution an electric vehicle causes.
  2. MAKING THE CARS: Making electric cars and their batteries is significantly different than making old-school gasoline cars. Studies show that the climate pollution is higher to make electric vehicles.
  3. BATTERY REPLACEMENT: The climate impact of replacing traction batteries during the lifespan of an electric car needs to be considered.

After two weeks of dissecting geeky studies, wading through energy databases and hunting through industry websites I found what I needed. The result is the chart below.

Chart notes:

  • Each bar in my chart shows the climate pollution released from building, and then driving, a particular vehicle.
  • The different colours in each bar represent: making the car (black); making the traction battery (purple); burning gasoline (brown) and generating electricity for fuel (orange).
  • The top rows show climate pollution from a typical all-electric vehicle. Next is a plug-in hybrid that uses both electricity and gasoline. At the bottom is a range of gasoline-only vehicles.
  • For electric-fuelled vehicles, several electricity scenarios are provided to show a range from dirtiest to cleanest.
  • You can click the chart to view it full size.

 

The big picture

Four main conclusions leap out of this chart for me.

1 -- In most regions, cars fuelled by electricity create less climate pollution than the very best all-gasoline fuelled car.

In regions with very high percentages of renewable electricity -- like BC, Ontario and Quebec -- the total climate pollution from electric vehicle is less than half what is created by the best gasoline-only cars. In BC, for example, an electric Nissan Leaf will create just 30% of the climate pollution that the best all-gasoline car does.

2 -- In dirty electricity regions, driving on electricity creates similar climate pollution to gasoline.

Regions that burn mostly coal and natural gas to generate electricity create high levels of climate pollution for each kWh. In Alberta, for example, a Plug-In Prius will cause a similar amount of climate pollution driving on gasoline as it does driving on Alberta's electricity.

Some electric car owners have worked around this problem by putting up their own solar panels, or by purchasing cleaner electricity directly from their utility.  

3 -- The climate pollution from burning gasoline vastly exceeds the climate pollution from making the car.

The average US car weighs around 1.5 tonnes but burns nearly 30 tonnes of gasoline. Thirty tonnes. For perspective that much gasoline would fill a stack of oil barrels much higher than the world's tallest tree, the Statue of Liberty or the Canadian Parliament.

As my chart shows, this gasoline causes 102 tonnes of CO2 (tCO2) while building the vehicle itself causes just 7 tCO2. Driving the car, not making it, causes almost all the climate damage.

4 -- There is a gigantic difference in how much climate pollution comes from today's cars.

For example an electric car fuelled by BC electricity will emit a tenth as much climate pollution (15 tCO2) as a large gasoline fuelled SUV (over 160 tCO2). Even within the ranks of all-gasoline cars, the difference can be over 100 tCO2.

Q&A

Below I answer some of the most common questions I come across about climate pollution from electric and gasoline vehicles.

Q: How much climate pollution is created making an electric car and its battery?

A: Around 14 tCO2 = twice as much as for making an average gasoline-only car

DISCUSSION: Researchers have done several studies on this. The study I used estimates that twice as much CO2 is released building an EV as building an average gasoline-only car. Most of the difference is caused by creating the large traction battery. Specifically the study estimated:

(22) Comments

James Thurber April 18th 2013 | 8:08 AM

Thanks for this excellent article.

While it demonstrates that electric vehicles do indeed reduce CO2 emissions, it also provides the basis for evaluating current policies.

For example, it appears from your chart that building and driving a Nissan Leaf versus a Toyota Prius in California reduces CO2 emissions by about 28 tons over the lifetime of the vehicles.  The incentives for  purchasing the Leaf in California total $10,000US ($2,500US California rebate and $7,500US federal tax credit), or about $360US per ton of CO2 conserved.

This is of, course, and extremely high value.  One has to wonder if it would not be a more effective use of the public funds to expand public transport, or perhaps subsidize the conversion of large trucks and busses to using LNG, for example.

 

 

Phil April 18th 2013 | 10:10 AM

Nice article!

I'd love to see diesel cars factored into the comparison.

They are a slowly growing component, but get excellent gas mileage that competes with the best all gasoline hybrids but don't have the battery issues. However, I'm not sure if other factors influence their overall output. With North American diesel, they still have some particulate problems (although far improved now).

 

Stephen Rees April 18th 2013 | 11:11 AM

Very useful and well presented information. I look forward to your further analysis of urban transit. Right now my bet would be that the electric trolleybus is one of the least polluting, since it uses existing roads and most of the new rail options - like building more Sktrain lines or doing lots of tunnelling - require huge amounts of energy and concrete.

EVs are indeed necessary as a way of mitigating the climate impact of driving, but there are a whole raft of problems that ae caused by chosing a car over other modes for most journeys. It does not help that our built environment is designed for cars - and that domination continues in new development. So traffic congestion, diabetes, heart disease, obesity, casualties from collisions will continue to dominate our discussions long after every car is an EV.   

Eric Doherty April 19th 2013 | 12:12 PM

Great analysis, but there are a few crucial pieces that seem to be missing.

One is the distance traveled for cars, the benefit of replacing a gas guzzling taxi that is driven 50,000 km a year with a much more efficient car is obvious. The benefit of repacing a small car that is only driven 5,000 km a year may be non-existant or negative. (For example, an older 1 litre / 3 cylinder geo metro)


Another point is the overall carbon footprint (lifecycle emissions) of transportation. For gasoline powered automobiles you can add about a third to tailpipe emissions http://www.hydroquebec.com/sustainable-development/documentation/pdf/opt...


This points out the potential advantage of sharing cars, you can use the vehicle enough to justify the carbon footprint of an electric or hybrid and share the parking too. Building an underground parking space costs about $35,000; and involves considerable carbon intensive concrete and steel.

Mike April 19th 2013 | 12:12 PM

Nice work. I might suggest you expand the study to include fuel cell electric vehicles that fuel in under 5 minutes, travel 300- 400 miles on a tank and can seat as many passengers as any conventional vehicle can. I see a role for battery electrics, but for true versatility ease of use, the fuel cell vehicles are pretty compelling. The site cleancaroptions.com has taken a look at the environmental impact as well -- a pretty good story. 

Walter April 19th 2013 | 12:12 PM

Barry - Good methodology and similar to what I do in comparison between my sustainable agriculture and industrial agriculture using embedded energy values. However, did you factor in the efficiency lost in the transmission of the electricity through the grid? For example, if a power plant produces electricity at 30% efficiency and the grid is 40% efficient, the electricity at the householder level is only 12%.

[And no snotty comments all you wannabe trolls - this is an important factor.]

Smokey Dymny April 19th 2013 | 1:13 PM

While the study states that batteries for an e-vehicle will need to be replaced at least once, and lists the ghg's implicit of that, Mr. Saxifrage does not state what will happen to the old batteries. I have been dismayed in my own reasearch to find that battery recycling is a farce. U.S. sources claim 90% recycling rates for lead-acid, yet I found that 90% are actually shipped to poor countries to be dismantled by hand in people's ponds and streams causing pollution and death and disease. Of the rest maybe 90% are recycled but no system exists to monitor compliance. 

Hi-tech batteries offer NO recycling posibilities and are the cause of terrible labour conditions in South American mines.

Cradle-to-grave analysis of technology requires the tallying of ALL effects. Please do more research.

Bob Conibear April 19th 2013 | 4:16 PM

Good report also but a few items stand out for me.  Also mentined in comments above there is no diesel driven engine comparisons.  Diesel engines are more efficient (about 30% more-- presently) therefore less Co2 emissions per km.  Europe is much ahead on this ie diesel vehicles account for over 50% of on road vehicles while in USA it is 3%.  Go to Carpages.uk to check out the least carbon emission vehicles ( in grams per kilometer).  Plug-in vehicles with diesel should run less than 2l/100km consuption on combined cycle.  Life times for PHEV's should be greatly extended with engines running in their sweet spot for extended periods.  Less CAPEX.  Reason why diesel not popullar here is we have too much sulfur in our fuels and not able to take advantage of the common rail injection system.  Diesel also allows bio-fuel mixing easily.

EV's presently do not have range--that is changing but it takes more battery power--higher costs.  Then what hapens when the power goes off--for a day--week?  PHEV's are critical part of this senerio--they even act as emergency gen. A mix will be vital.

The other major feature that needs adressing is effect on CO2 emissions when power is generated by nuclear reactors replacing coal and gas fired generators.  If you are serious about effects of GHG's on environment you cannot ignore them.  Look up SMR's, small modular reactors--wikipedia has a good write-up.  Fourth or fifth gen technology.

 

 

eric April 21st 2013 | 2:14 PM

 

 

Nice job on bringing all this information together.  It's amazing how much anti-electric car people have twisted this information to their own ends to try and make the blanket case that electric cars aren't cleaner and like you point out if depends, but in general an electric cars is the cleanest option.  I've seen Mr.Lomborg's claim about this reprinted many many times now and other "journalists" take this information and republish his claims as fact.  Thanks for this.

 

 

AMD April 22nd 2013 | 9:09 AM

The chart report the pollution created from producing electricity vs the pollution created from burning gas.  Does it include the pollution created from extracting the gas?

Richard Lane April 23rd 2013 | 4:04 AM

When comparing the CO2 produced by electric  cars vs gas cars you included the CO2 made during the production of the electricity but what happened to the CO2 created to make and distribute the gas?  More energy is consumed to make the gas than is used to drive the electric car down the road.

D Brown April 23rd 2013 | 10:22 PM

The toys manufacturers have become much tech savvy these days. No wonder, you can find wide range of kids electric cars in the market, and most of them have been inspired from the famous car brands available in the current times. You can choose one for your kid and make him feel on the top of world.

Anymous April 24th 2013 | 12:00 AM

All cars after running needs some maintenance, it shows different types of problem which is repair by mechanic. I am not totally agreed with the above article. EVs not solves all problems of a car

The tips or solutions given above are right but other techniques are also present for repair a used car.

Porsche Repair Pasadena

Mark Gemmell April 24th 2013 | 7:07 AM

Great work.

This really puts in perspective the questions over manufacture versus use of ICE and electric cars.

If you have any updates please let me know. The quality of your work and the rigor you have applied are an excellent reflection of the honesty and diligence Canadians have earned a reputation for.

Thanks Canada! ;)

Mark

Rebel Nichols May 3rd 2013 | 7:19 PM

How much CO2 is produced extracting crude, transtporting it to refinery, refining it and transporting it to the various regions?  I heard, but have not confirmed, that it takes about the same amount of electricity to refine one gallon of gas as to propel an EV 20 miles.  That doesn't even account for the other sources of CO2 needed to get a gallon to my tank or CO2 from military protection of shipping lanes etc.

Allan Poulsen May 5th 2013 | 7:07 AM

Gas cars also use electricity, which isn't shown - it takes about 5kWh of electricity to refine 1 US Gallon of gasoline:

http://www.businessinsider.com/elon-musk-and-chris-paine-explain-how-the...

"you have enough electricity to power all the cars in the country if you stop refining gasoline" - quote from the article above.

I don't know if this includes also distribution, gas station electricity usage, etc, but if not, then this should also be added.

I'd like to see a followup article with this analysis included.

alke May 21st 2013 | 5:05 AM

I think that electric vehicles will protect our environment

 

Albert Berry June 1st 2013 | 5:05 AM

How would world look like if you interduce an eletric car? how our life will be ?- you will find very interesting results in  yopreneur.com 

George July 2nd 2013 | 3:15 PM

If you are going to take into account the fuel source and the emissions associated with the production of that source fuel you need to be fair and factor that in across ALL fuel sources.

One factor that is missed time and time again is the amount of emissions created to distill petroleum products.  If the distillation process uses 100% electricity than all your assumptions about how clean or dirty power production is in that region applies 100% then to the creation of the petroleum based fuel as well. So if it takes 1kWh to create one gallon of gas that has to be factored into the pollution statement.  You also have to factor in the delivery method. Since electricity is delivered over a grid into our homes there is no pollution in transportation (well, not necessarily any pollution). And there is more to transport those petroleum fuels to their ultimate fueling destination before they end up in your car.

Threesides February 21st 2014 | 5:05 AM

While reading through the comments, I noticed that many seem to "disagree" with people just asking a question. What's that about?

Q: "I wonder how much CO2 is caused by the production of fuel."

C: "I strongly disagree with that!"

 

Personally I think people need to start thinking before clicking the disagree button.

Yngveb March 11th 2014 | 8:08 AM
Walter wrote:

Barry - Good methodology and similar to what I do in comparison between my sustainable agriculture and industrial agriculture using embedded energy values. However, did you factor in the efficiency lost in the transmission of the electricity through the grid? For example, if a power plant produces electricity at 30% efficiency and the grid is 40% efficient, the electricity at the householder level is only 12%.

[And no snotty comments all you wannabe trolls - this is an important factor.]

This is very important, but then we also have to include the supply side of the gasoline. Transportation to the gas station, production in the oil fields and so forth. And you have to include the supply side for the power plant. My guess is it complicates things.

http://www.nema.org/Products/Documents/TDEnergyEff.pdf This source from ABB estimates 6-8% loss in the transmission and distribution system, and 30-60% efficiency for the coal power plant depending on technology which leaves us at somewhere between 27.5% and 56% efficiency of electricity generation. Modern gasoline engines are only 25-30 % efficient.