STUDY: Even with electricity from coal, electric vehicles beat gas in CO2 emissions
A common attack on electric vehicles is to claim that all Americans switching their cars from gasoline to electric would be counterproductive in the effort to reduce carbon emissions. The reason is that we'd simply need more polluting coal plants pumping out more carbon dioxide and get collapsed electric grids as a result. Well, we know there are emerging solutions to the grid problem but how about calculating the actual carbon numbers that result from gasoline vs. electricity from coal? Dvice has gone and done just this, and found that, when it comes to CO2, electricity sourced from coal has a 60 percent lower impact than gasoline. Of course, this equation doesn't take in consideration other pollutants that result from burning either fuel.
Let's take our calculators out and check Dvice's numbers: Americans have 250 million cars. Supposing each of these cars could be fitted to a 25 kWh battery (the Tesla Roadster holds 53 kWh, the Chevy Volt will use a 16 kWh pack) and that we can drive 2 or 3 miles per kWh. Assuming that all these cars are used at current average levels (something the source doesn't exactly specify), this translates into 100 charge cycles per year. Total electricity bill: 600 billion kWh per year, and that's just 15 percent of current production (about 4 trillion kWh).
Now, onto the carbon figures: Every kWh from a coal plant produces two pounds of CO2, so we're talking 1.2 trillion pounds of CO2. The U.S. burned 3.3 billion barrels of gasoline in 2008, and a single gallon becomes 20 pounds of CO2 at the exhaust pipe, which turns out to be which about 3 trillion pounds of CO2. Ergo, coal emits 60 percent less.
[Source: Dvice]
Reader Comments (Page 1 of 3)
locoyocal 2:52PM (7/24/2009)
not to mention the fact that, a gas/crude power-plant is more efficient than a gas powered car also.
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BillySharps 3:13PM (7/24/2009)
That's kinda the point. The powerplant to EV cycle is more efficient than the gasoline to engine cycle such that the carbon emissions are reduced by close to two thirds.
Ray 3:09PM (7/24/2009)
Yea, I just knew it but could not convey it. Go EV. Every one says the same thing, they don't want to drive a small car. Trust me you would like it just fine if it was a small EV.
Range is to short. Yet my gas cars just sit since I got my EV. The only problem is some people don't want me plugged in as they think they will have a big electric bill. Even with this the batteries go dead on my ICE cars because of no use.
Not hwy capable. Mine is and many others.
Heater, air conditioning limit rang further. I have not noticed this drain at all, I admit I was worried in the beginning but now I am very comfortable with my EV's range and it is very consistent.
I do admit I drive more, mostly it is because I feel free er to do so than I have with my ICE cars. Can't really explain it I just do. Part of it is I do not contribute to the vicious circle that is the oil monopoly economy and all it's deceit and lobbying and speculators making money by driving up price. Car companies want to keep things the same (Keep incrementally improving the ICE) as this is where they make the most money. I don't agree with it and am happy to get further away from it.
I enjoy the fact I can put 10,500 (with out tax breaks) dollars in solar panels on my house (contractors price) and the electricity they produce will take care of 12,000 miles of driving per year. Better yet the panels will be tied into the grid so as electricity prices rise the electricity produced by my panels will rise as also. So yea. yea, yahoo, whee!
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John Pelletier 3:16PM (7/24/2009)
one point source vs millions. i would go for a single point source even if it was coal every single time. it just makes more sense and is easier to regulate and control
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Dave 3:23PM (7/24/2009)
"Of course, this equation doesn't take in consideration other pollutants that result from burning either fuel."
Yup. Burning coal emits mercury and other toxins into the environment.
CO2 is only part of the equation.
And this doesnt change the fact that it takes much more energy to manufacture an EV than an equivalent gas powered car.
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dg 8:24PM (7/24/2009)
Yes, you're right on both counts. Ideally, though, we can get more and more electricity from renewable sources as time goes on. This will cut out the other pollutants and make the extra power that it takes to make an EV less destructive than nearly any amount that would be used to make anything else with electricity from coal.
why not the LS2LS7? 1:28AM (7/25/2009)
Burning gas emits NOx, unburned hydrocarbons and formaldehyde into the environment.
Jeff 3:52AM (7/25/2009)
EPA provides detailed numbers for emissions of all the major power plants in the US, covering CO2, NOx, and SO2. I found them easily with a little googling. I did my own research paper on exactly this topic, taking into account the energy required to manufacture batteries, and also taking into account the limited lifespan of a battery pack.
I took a more generous 5 mile/kWh which I based on such examples as the EV1, Chevy Volt, and Reva G-Wiz (all very similar numbers, probably thanks to regen braking which somewhat negates the effect of vehicle mass, and also thanks to the pretty consistent efficiency of an electric motor). The conventional vehicle used for comparison was a 30mpg Ford Focus. I also took into account electricity transmission losses, as well as the losses associated with gasoline refining and distribution (well-to-wheel analysis is often applied to electrics but forgotten for ICEs). For the comparison I looked at a car driving 40 miles a day, 5 days a week over a 10 year vehicle life span.
I found similar results in terms of CO2 as these guys, looking at a purely coal-charged electric car. I also found that modern cars (which have come a LONG way in terms of reducing NOx and SO2 emissions over the past 20 years) are actually cleaner in terms of NOx and SO2 for this imaginary "coal-only" grid. Needless to say, the case for the EV is much stronger when looking at the actual grid emissions for the US, and especially for Canada with over 50% hydroelectricity.
@Dave - as you'll see in any life cycle analysis on cars, the manufacturing energy for a car is much lower than the energy used during the life of the car. Just look at any of the critiques of that lame Hummer vs Prius report. My report found that even with a li-ion EV, assuming the battery had to be replaced twice over 10 years (I doubt that would be the case anyways!), the energy requirements to make 3 8kWh packs was much less than the energy required to charge the car over 10 years.
Sac 3:55AM (7/25/2009)
Don't forget that you can't pump gasoline out of the ground. We pump crude and then expend a lot of energy to refine it into light distillates and other fuels. But what's left over will often be prepared for fueling large ships. And it's very nasty stuff that's full of murcury, sulfur, other heavy metals etc. Even if it's not burned near populated areas it still gets out there. And it's very difficult to scrub at point of use.
While coal is the dirtiest of fossil fuels it can be very efficiently converted to power and today environmental regs require a lot of high efficiecy aftertreatment that is much cleaner than the essentially untreated exhaust coming out if ships stacks.
Ghen 4:13PM (7/27/2009)
The final plug for EV in the comparison between gasoline cars and coal power plants is the requirement to "start somewhere"
Even if they came out equal in pollutants ya gotta start somewhere ;) Can't build better EVs without building mediocre ones first.
Dave 4:37PM (7/27/2009)
"Even if they came out equal in pollutants ya gotta start somewhere ;) Can't build better EVs without building mediocre ones first." - ghen
Agreed.
As long as the mediocrity isn't forced down anyone's throat in a hurry, we will be okay in the long run.
GenKhan2 3:49PM (7/24/2009)
If only I could get that efficient coal burning, turbine based technology into an electric drive train hybrid car. Remove the range restriction of batteries and still have less CO2.
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paulwesterberg 3:36PM (7/24/2009)
Burning coal for electricity is still nasty because of the toxic elements released such as mercury, Sulfur, nitrogen oxide & radioactive isotopes. But the smokestack is not the only problem, coal ash is toxic and mining for coal takes its toll on people and the environment.
But thankfully the electric energy we use comes from a variety of sources depending on where you live. A natural gas plant in my neighborhood is 70% efficient because it uses waste heat to warm campus buildings. I buy wind energy for my house for 1 cent per kWh extra.
Recently 1.2 billion dollar 300MW coal power plant proposed for Cassville WI that was able to "burn up to 10%* organic waste" was denied by the public service commission because of its high costs and poor emissions. *The actual permit application only listed different types of coal and refinery waste.
A friend of mine at the electric utility says that payback time on an electric wind turbine is 7 years. When wind is combined with hydro electric and pumped storage there is no good reason to build any more new coal power plants.
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B 7:14PM (7/24/2009)
Coal isn't nice indeed. But I'm not sure if all those oil related cost are nice too (refineries, drill platforms, geopolitical tensions...). At least with EV it looks like being workable alternative to ICE powered cars. Hopefully there will be bigger push for solar technologies and modern nuclear power plants.
flabby 3:41PM (7/24/2009)
The equation also doesn't take into account how much CO2 is produced during the transportation and processing of gasoling...or, for that matter, the transportation and processing of coal.
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amtoro 3:59PM (7/24/2009)
I have different numbers for coal CO2 emission:
A conventional Coal-burning power plant produces 6150 kWh per Ton of Coal burned or it burns 0.325 lb per kWh that produces. 1 lb of Coal burning releases 3.667 lb of CO2; therefore, 0.325x3.667=1.19 lb(CO2) per kWh.
With an EV traveling between 2 and 3 miles per kWh, it would compare to a gasoline vehicle that can travel between 32 and 48 miles on one gallon of gasoline. However, EV's are more efficient than that, my conversion EV, a 1994 Saturn could travel 3 miles on one kWh using Lead acid batteries, but the Tesla roadster can do about 4 miles on one kWh, about 64 miles per gallon-equivalent.
I also think there is an inconsistency on your data, 100 charging cycles per year equals to 2500 kWh per car, at 2 to 3 miles per kWh, that is 5000 to 7500 miles per car per year. 3.3 billion barrels of gasoline is 138.6 billion gallons of gasoline, if each vehicle travels the same 5000 to 7500 miles per year and there are 250 million vehicles, that would be 138600/250=554 gallons per car per year, each one would have to travel only 9 to 13.5 miles per gallon, not realistic.
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david burgdorff 4:01PM (7/24/2009)
Now do an analysis of a natural gas car vs. an electric car charged by coal. I bet the natural gas car wins and is much cheaper meaning many more on the roads in the next ten years.
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amtoro 4:15PM (7/24/2009)
Using natural gas to produce electricity produces about 0.394 lb of CO2 per kWh, only 33% of what coal does. (310kWh per 1000 ft^3 and 122 lb per 1000 ft^3) ***
Currently, an average of 57% of the electricity produced in the US is coal and the majority of the balance is natural gas leaving a small percentage to hydroelectric, nuclear and biomass, etc.
*** Data from the DOE
locoyocal 4:27PM (7/24/2009)
I don't think the numbers compared to electric will look good.
The 2007 Civic CNG (Natural gas) cost $1.46 to drive 25 miles.
The 2007 Civic Unleaded Cost $2.10 to drive 25 miles.
http://www.fueleconomy.gov/FEG/noframes/23862.shtml
TimeZone4 4:12PM (7/24/2009)
I'm really all for electric and other forms of alternate energy vehicles, but still have a few concerns about them.
I wonder about possible emissions such as during the manufacture of the batteries, but I doubt this is such a huge amount that it would make much of a percentage of pollution over the life of the vehicle.
How long are these batteries going to last though? In how many years / miles am I going to have to replace the batteries and how much is this going to cost. I imagine this is a fairly expensive part of an electric vehicle and really haven't heard much said about it. Also, is the whole battery able to be recycled in some way or is there waste that is caused by material that can't be recycled?
I also have to wonder about what if something on an electric motor goes out or something else in the electrical system, etc. How much might this cost and I doubt you can just have any mechanic fix this quickly if you were on say a trip or something.
I think electric seems to be the way of the future, especially if we are able to get cheap solar panels or wind power that can recharge our batteries without using other energy sources at the house and maybe quickcharge type stations readily available for when traveling longer distances. I just have the other concerns I mentioned above though, on what this technology might actually cost when you might have to eventually replace the batteries or if something goes out on you.
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