Yes, Electric Cars Will Reduce Carbon Emissions

Coalplant There are a lot of benefits to electrifying automobile transportation, but one of the best to keep in mind when you’re getting into debates with your naysaying friends is that electric cars will greatly reduce carbon-dioxide emissions. And yes, they will do so even if the electricity they’re powered on comes from coal.

The website Dvice did a little basic math to demonstrate that even when their power comes from coal, electric cars have a 60% lower CO2 impact than cars that burn gasoline.

There are 250 million cars in this country, so, hypothetically, let’s say that overnight all those cars become EVs with 25 kWh batteries. For some perspective, the Chevy Volt will use a 16 kWh battery and the Tesla Roadster has a 53 kWh battery.

Each kWh takes a car two to three miles, so let’s be conservative and say the average driver would charge their car twice a week, or about 100 charge cycles per year. All told, Americans would use 600 billion kWh per year, which is only 15% of our current total production of 4 trillion kWh per year.

This is a modest increase when considering the enormity of running every single car on the electric grid, but it gets even better in terms of CO2 reduction. Each kWh produced by a coal-fired power plant creates two pounds of CO2, so our car-related CO2 footprint would be 1.2 trillion pounds.

Yes, that’s a lot, but burning just one gallon of gas puts out 20 pounds of CO2 from the tailpipe. In 2008, we burned 3.3 billion barrels of gas, for roughly 3 trillion pounds of CO2. Therefore, a switch to electric vehicles would create a 60% reduction in C02 emissions, even if we only burned coal to generate that power.

Sorry, Critics — Electric Cars Really Are Greener (Dvice)

Comments 

Hug a tree today

Actually the greatest cause of this "CO2 pollution" is air breathing mammals, including humans, exhaling. You see, these greedy, capitatalistic, evil creatures have the temerity to breathe, exhaling all that CO2 and polluting mother earth. If we simply eliminate 90% of all air breathing animals, the world will blossom into zillions of moonbeams, upon which fairy princesses of GAIA will ride.

By the way, did the Vikings who were farming in Greenland, and the farmers that were farming the higher Alps during the warm period of the 1200s to 1400s adopt electric cars, or get rid of their SUVs? They must have, because the world then went into the Little Ice Age in the mid 1400s.

Dan

Hug-
Ummmmm..... go get some sleep, and lay off the drugs for a while. You are scaring the children.

worst 3

Hug is right about animals creating most green house gasses, cows actually produce more green house gasses then cars do. but it a hard choice between muscle cars and steak. but electric cars are good step especial if we increase are use of nuclear power and wind solar not efficient enough to put money in to it.

Dan

Worst 3-

"cows actually produce more green house gasses then cars do"

This is a common myth that isn't true. The confusion comes from the fact that cows release methane, which is a much more powerful green house gas than CO2. However, there is so much more CO2 emitted from non-cyclical sources (I.e. sources that create a net contribution of CO2 to the atmosphere, unlike plant and animal life) that the impact it has still outweighs the impact of the methane.

Austin

Cars to cows. I love the automobile community.

Hybrit

Thanks for posting this story - it will help educate lots of people. While the author of the article has come up with the right conclusion, his "back of the envelope" calculations are likely a bit off. The Electric Power Research Institute (EPRI) and others have done extensive "wheel to well" studies comparing electric cars to internal combustion engine cars. The conclusion of those studies is that the per-mile reduction in emissions in an electric car charged up only by coal power is more like 21 percent compared to a conventional car. However, our nation's electric grid is only 50 percent coal, with more and more high efficiency natural gas combined-cycle plants, wind and solar and about 20 percent zero-air-emission nuclear in the mix, so the emissions savings promised by electric cars are substantial indeed when compared to conventional vehicles.

Dan

Hybrit -
Exactly! Thank you! You sound like you've done your reading. Good to see that on the internet every once in a while.

Those same well-to-wheel studies also show that if you used oil to produce electricity (which in turn you transmit and power an electric car) in a heavy fuel oil plant instead of turning it into gasoline and burning it in an automobile engine there is still a small CO2 savings. If you use the gasoline in a combined cycle gas turbine plant, then the savings are much greater. The main difference here is that a common automobile engine isn't terribly efficient, (<30%), but a CCGT plant can reach 50% efficiency.

tony

If a gallon of gas weighs about 8 pounds...how do you get 20 pounds of CO2 out of it?

Will Bain

tony:

Gasoline has an approximate ratio of about eight carbon atoms to 18 hydrogen atoms. Carbon has an atomic weight of 12, and hydrogen has an atomic weight of 1, so gas is about 85% carbon by weight.

Each carbon atom in the gasoline combines with two oxygen atoms (atomic weight 16 each) from the air. So the overall effect is to produce about three times the weight of the fuel in CO2.

Math_is_Fun

If 1 kWh takes you 2 to 3 miles, and produces 2 pounds of CO2, and 1 gallon takes you 25 to 35 miles (I can easily get 35 mpg with my Honda Civic, more if I drive carefully) and produces 20 pounds of CO2, then the gas powered car is more environmentally friendly, is it not? 20 to 30 miles for 20 pounds on electric and 25 to 35 (or more) miles for 20 pounds on gas.

brian

"Actually the greatest cause of this "CO2 pollution" is air breathing mammals, including humans, exhaling. You see, these greedy, capitatalistic, evil creatures have the temerity to breathe, exhaling all that CO2 and polluting mother earth. If we simply eliminate 90% of all air breathing animals, the world will blossom into zillions of moonbeams, upon which fairy princesses of GAIA will ride."


Hug are you very stupid or just joking?

there is a natural carbon cycle that is balanced even if people are breathing. but the cow thing about releasing methane is correct, and people like dan make me realize tha there are actually educated people on the internet

Bruce

OK Let's use your numbers. I get 33mpg with my gasoline car. Let's be conservative and say I only get 30MPG. So, every 30 miles I spew 20 pounds of CO2. Now the electric. Now let's be liberal, and say we get 3 miles per KiloWattHour. To go the same 30 miles that the gas car went, we need 10 KWH. Each kWh produced by a coal-fired power plant creates two pounds of CO2, so the super-efficient car spews 20 pounds of CO2 (OOPS!). So when does 20 pounds represent a 60% reduction from 20 pounds? Sorry my friend. I like electrics also, but until everyone wants a nuclear plant in our backyards, it just isn't going to save the planet.

Dan

Math is fun, Bruce-
You are right, if the power comes from coal, electric cars contribute about 20% more CO2 than gasoline.
But only about 50% of power comes from coal. Natural gas only releases 1/3 the CO2 per kWh of coal, and ofcourse wind, solar, hydro, and nuclear release none. That means that your average kWh of electricity actually generates much less than 2 pounds of CO2.
Also consider where the electricity for electric vehicles will come from. The existing plants are meeting the existing needs. When you add a new source of power demand to the grid, namely electric cars, that power will have to come from new sources. So what really matters is the carbon intensity of the new plants. About 40% of new power plants in the US are wind, and most of the rest are natural gas. Considering that mix, electric vehicles actually can reduce CO2 emissions as long as we don't build coal plants to power them. With the high prices of the cement and steel today that go into building the plant, plus the high cost of the diesel fuel that powers the trains that deliver the coal, coal is no longer actually all that cheap. Wind often underprices it, and natural gas has tremendous flexibility advantages making both very popular with electrical utilities. As a result, most planned new coal construction has been canceled in the last 15 years, and very little has been planned for the future.

Hybrit

Dan, thanks for you comments. A couple clarifications: per mile emissions of an electric car charged only by coal plants is still 20 percent less than internal combustion engine cars - meanwhile, the overall grid does much better. As you mention, one big factor is the nation's energy mix: 20 percent of our electricity comes from nuclear plants, which have no carbon dioxide emissions. Wind, Hydro and Solar are other emission free sources that grow daily. Natural gas combined cycle plants emit 30 percent less CO2 than coal plants.
The real flaw in the logic of Math is Fun and Bruce is that they don't take into account the electricity recovered through regenerative braking in an electric car. That potentially adds many miles to the range of the electric car without adding battery capacity. They also don't factor in the wasteful idling of their 30 mpg cars in the city. A car that gets 33 mpg on the highway gets half that in pure city driving - just look at Consumer Reports numbers for city driving, which are based on carefully calibrated tests. The biggest benefit of the electric car charged from the grid is that they will be used almost exclusively in our large cities, where their zero emission performance will have an immediate and dramatic positive impact on urban air quality and the urban quality of life.

Math_is_Fun

Hi Guys
I agree that electric cars will no doubt make a vast improvement to our lives and have no axe to grind one way or the other. I was just pointing out the obvious errors (or possible headline-grabbing bias?) in the original article, which states "even when their power comes from coal, electric cars have a 60% lower CO2 impact than cars that burn gasoline". Which, using the figures given, is not true. Just using the facts as presented, not taking into account anything else.

steve

the figures do not add up and break the laws of thermodynamics. 1 pound of carbon burnt in an interanal combustion engine releasess at least 4 times more energy as burnt at a power station.Thats why we dumped steam engines!

joe

One big mistake in this calculation is not considering trasnsmission and distribution losses. These numbers would be more accurate if we could all plug our cars directly into coal fired power plants.

When it comes to solar energy for the future, we must start thinking outside the box. In fact, we have to forget that there ever was a box at all.

Jake

As joe points out, transmission and distribution losses have to be considered. The percentage of electricity lost is generally estimated at about 6.5% in the US. That's not a massive amount, but is non-trivial as well.

Additionally, comparing electric cars to all vehicles is misleading. Electric cars, right now, are small commuter type vehicles. They should be compared to other similar vehicles. That is, they should be compared to vehicles that average 30+ mpg as those are the vehicles they will be replacing. The lack of electric semis, SUV's, and trucks makes electric cars seem, superficially, much more efficient than they actually are if they are being compared to gas powered vehicles that include those categories.

I am not taking a side in this debate. I find the evidence as to the environmental value of electrics to be non-conclusive at this point. What is certainly true is that as/if we continue to move toward having more electricity produced from green sources, the balance will ultimately tip overwhelmingly in favor of electrics. So, their existence, even if it has a negative impact on carbon emissions right now, is probably still a positive from a future-oriented perspective.

also...

I feel like people often forget to consider a very important measure: the relationship between electric cars and urban sprawl.

Cars and other transit (but, chiefly, cars) have been the primary variable shaping our metropolitan areas in the past 2/3 century, enabling and even encouraging sprawl. The form of our metro areas determines not only how much carbon we emit via transit, but also the density of our communities and the amount of carbon we emit in other areas of our lives.

In my mind, the jury is still out on whether electric cars will further enable sprawl or begin to enable the solution. On the one hand, their short driving range may disincentivize sprawl. On the other hand, replacing the private automobile with higher reliance on rail would be more ideal.

Anyway, in my mind this series of questions is far more significant than various measures of tailpipe emissions. Transit shapes energy use in all facets of life- not just commuting.

Lee

@Joe & @Jake: Valid point about transmission loss in electricity. But conversely, wouldn't you then factor in the carbon emissions of transporting gasoline from refinery to the local gas station? Or would that be a rabbit hole?

I am not taking a side in this debate

M

Actually, this article proves that EV's carbon footprint is higher than gasoline vehicles. The author presents the numbers that seem to show a 60% reduction in CO2, but what the author failed to realize is that 2/3 of all the power generated by powerplants is lost during transmission, so for every kWh you consume at home (or charging your EV), the powerplant needs to produce 3 kWh's. Multiply the author's numbers by 3 and you get 3.6 Billion lbs of CO2 vs. 3.3 with gasoline powered vehicles...

Zack

M, I don't think two-thirds of the electricity produced by a power plant is lost in transmission lines - please explain your logic on that. Powerplant emissions are measured in pounds of CO2 per kilowatt hour produced, and line losses are figured in on the studies. Some power plants reach 60 percent efficiency when they recover waste heat and drive a second turbine. As others have pointed out, twenty percent of the electric grid is nuclear, with no air emissions. Then theres hydro power, wind power and solar all contributing to the electricity mix, all with no air emissions. I think EVs have a much smaller carbon footprint than an internal combustion vehicle.

Jim

Winston Churchill said, after WW2, that.."You can always count on the Americans to do the right thing, but only after they have exhausted all the other possibilities." That's what we are doing today. When we get serious about energy and emmissions impact on the environment, we'll build 100s of nuclear plants and have a zero emmission, price stable source of power for all kinds of uses, including maybe electric cars!

What an idiot.

The US consumes 3.3 B bbl gas that is (42 g/barrel) = 138 Billion gallons of gas.

If each car gets 30 mpg that would be 4.1 Trilliom miles we could travel on the 138 B gllons.

If we travelled the SAME distance with EVs, that would mean we would need nearly 2 TRILLON kw-hr of electricity to recharge the batteries.

And 2 T kw-hr would produce 4 Trillion lbs of CO2 to charge these batteries.

Your fallacy is that you don't keep the same miles travelled by EV vs. gas.

You failed 4th grade math, didn't you?

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