How Clean Are Electric Vehicles?

The Union of Concerned Scientists notes that, whenever we talk about the great potential of electric vehicles (EVs) to reduce our oil use, rein in global warming emissions, and save consumers money at the pump, we always get the same question: how much will these vehicles really reduce emissions if they’re often plugged into electrical outlets that draw their power from dirty sources? Well now we know—a new UCS report finds that not only do EVs produce fewer emissions than average new compact gasoline powered cars, but nearly half of the U.S. population lives in a region where driving on electricity results in fewer emissions than even the best hybrids! Check out all the details and see how your region stacks up in UCS's State of Charge report.

http://www.ucsusa.org/publications/pulse/Pulse_may_2012.html" onclick="window.open(this.href);return false;

Very good find, thank you

All these "studies" are bogus since they assume that gasoline falls down like manna from heaven.

Unless they stop using 7.5 kWh to refine a gallon of gas then it's not a fair comparison (even if electricity comes out on top.) And it's just a simple addition to an equation and somehow everyone fails to mention it.

cracovian said:

All these "studies" are bogus since they assume that gasoline falls down like manna from heaven.

Unless they stop using 7.5 kWh to refine a gallon of gas then it's not a fair comparison (even if electricity comes out on top.) And it's just a simple addition to an equation and somehow everyone fails to mention it.

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Your objection is valid for many situations, however... do you know how I know you didn't actually read this report?

To most accurately compare electric and gasoline vehicles, the emissions from producing the fuel as well as from consuming it must be taken into account. For gasoline vehicles, this means including emissions not only from propelling the car—i.e., by combusting the fuel in the engine—but also the emissions associated with extracting petroleum, refining it, and delivering it to the vehicle. For EVs, no tailpipe emissions occur from consuming electricity to propel the vehicle. However, as described above, there are emissions from producing the electricity. Thus in comparing EVs with gasoline vehicles we include the “wells-to-wheels” emissions, which account for the full fuel cycle.

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Emphasis mine.
=Smidge=

Smidge204 said:

cracovian said:

All these "studies" are bogus since they assume that gasoline falls down like manna from heaven.

Unless they stop using 7.5 kWh to refine a gallon of gas then it's not a fair comparison (even if electricity comes out on top.) And it's just a simple addition to an equation and somehow everyone fails to mention it.

Click to expand...

Your objection is valid for many situations, however... do you know how I know you didn't actually read this report?

To most accurately compare electric and gasoline vehicles, the emissions from producing the fuel as well as from consuming it must be taken into account. For gasoline vehicles, this means including emissions not only from propelling the car—i.e., by combusting the fuel in the engine—but also the emissions associated with extracting petroleum, refining it, and delivering it to the vehicle. For EVs, no tailpipe emissions occur from consuming electricity to propel the vehicle. However, as described above, there are emissions from producing the electricity. Thus in comparing EVs with gasoline vehicles we include the “wells-to-wheels” emissions, which account for the full fuel cycle.

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Emphasis mine.
=Smidge=

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Very nice - thank you so much for catching me in the act - I guess the report is actually good and I should have not given up on those "concerned scientists" so easily

EDIT: I'm taking it back about the quality of the report... Wells to wheels? I don't think so:

"Driving a typical electric vehicle in these regions (good) will result in global warming emissions equivalent to gasoline vehicles with a combined city/highway fuel economy rating between 31 and 40 mpg. This is better than the average compact vehicles on the market today, but the most efficient gasoline hybrid vehicles over 40 mpg will emit lesser amounts of global warming pollutants."

So, basically, they're saying you can get a Prius in some regions or Ford Fiesta in Colorado and you'll emit lesser amount of pollutants. BS and it's EVIL too.

Smidge204 said:

cracovian said:

All these "studies" are bogus since they assume that gasoline falls down like manna from heaven.

Click to expand...

Your objection is valid for many situations, however... do you know how I know you didn't actually read this report?

Click to expand...

Well yes the report says that well-to-wheels (WTW) needs to be used, but I see only tank-to-wheels numbers for the gas cars and no mention of how the well-to-tank numbers were calculated.

It may take 7kWh to refine oil into gas, but there is also a lot of power getting it to the refinery. Oil from Canada tar sands requires more energy to get it out of the ground than oil from the Gulf of Mexico. Oil from Venezuela requires less energy to get from the well to the refinery than Saudi Arabia. The refinery to pump leg is a smaller factor but still varies on geography as some gas is trucked, some by rail car, some in a pipeline each with different energy costs. So I would expect a map just like Table 1.4 (pg 19) to show this. I can't believe that the well-to-pump (WTP) energy (emissions) is the same for gas I buy in southern Texas is the same as upstate Vermont.

While I see pages of details on the electricity sourcing and its costs, I see no details as to how gasoline numbers were computed and what factors they play in the overall WTW, I only see the same MPG ratings for ICE vehicles as the EPA gives. So with only the single sentence that says WTW was used for gasoline, I have to side with Cracovian that this report doesn't appear accurate.

padamson1 said:

Well yes the report says that well-to-wheels (WTH) needs to be used, but I see only tank-to-wheels numbers for the gas cars and no mention of how the well-to-tank numbers were calculated.

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You're not looking hard enough. They do not perform the calculations themselves but rely on the Argonne National Labs' GREET (Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation) data set (from 2011). The GREET data is a complete well-to-wheels analysis and as such any calculations based on that will also include the full fuel cycle effects.

If you want to know how those numbers are calculated, go here.

padamson1 said:

I only see the same MPG ratings for ICE vehicles as the EPA gives.

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Using EPA sticker MPG just gets you gallons used per unit distance driven, and alone says nothing about greenhouse gasses emitted. I hope we can agree on this much. There's no reason to reject the EPA's MPG ratings, either.

So they use the EPA fuel economy and the GREET emissions data combined to generate GHG emissions per unit distance. They coin a unit "MPGghg" which is a greenhouse gas equivalent mile per gallon - the reciprocal of that number is how many miles you can drive to result in the creation of 1 gasoline gallon's worth of greenhouse gas emissions. They summarize some key values in Table 1.1. Example: is 100% of your electricity from coal? The GHGs your EV creates is equivalent to a gasoline ICE getting 30MPG.

cracovian said:

So, basically, they're saying you can get a Prius in some regions or Ford Fiesta in Colorado and you'll emit lesser amount of pollutants. BS and it's EVIL too.

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Do you agree that the environmental impact of the source of your electricity determines the environmental impact of your EV?

Well, if your electricity is especially dirty, your EV is too. Colorado has a lot of coal, so EVs charged using power generated in Colorado suffer higher equivalent GHG emissions. The report determines that EVs suffer so much they are no better than a car that gets 33mpg. Do you have any mathematical/empirical basis for your objection or does it simply not "feel right" to you?
=Smidge=

Smidge204 said:

Well, if your electricity is especially dirty, your EV is too. Colorado has a lot of coal, so EVs charged using power generated in Colorado suffer higher equivalent GHG emissions. The report determines that EVs suffer so much they are no better than a car that gets 33mpg.

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True, but EV can get cleaner while you own them (by cleaning up the grid), while an ICE vehicle is stuck with its emissions for life.

Smidge204 said:

cracovian said:

So, basically, they're saying you can get a Prius in some regions or Ford Fiesta in Colorado and you'll emit lesser amount of pollutants. BS and it's EVIL too.

Click to expand...

Do you agree that the environmental impact of the source of your electricity determines the environmental impact of your EV?

Well, if your electricity is especially dirty, your EV is too. Colorado has a lot of coal, so EVs charged using power generated in Colorado suffer higher equivalent GHG emissions. The report determines that EVs suffer so much they are no better than a car that gets 33mpg. Do you have any mathematical/empirical basis for your objection or does it simply not "feel right" to you?
=Smidge=

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7.5 kWh to refine a single gallon of gas... The LEAF covers ~30 miles on that refining electricity alone (not even accounting for extraction, transport, and burning of that gallon of gas here.) It's that simple and it takes a second to determine that the report claiming 33 MPG cars are better emission-wise in Colorado, is completely bogus.

P.S. It's nice (though to me that's the evil part) that they've added that little asterisk for their deeply thought out wells to wheels equations but it doesn't make it any more true than the bottom of the oil barrel false...

cracovian said:

7.5 kWh to refine a single gallon of gas... The LEAF covers ~30 miles on that refining electricity alone (not even accounting for extraction, transport, and burning of that gallon of gas here.)

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Two things: One, it's more like 22 miles based on the numbers they use, which are in turn based on EPA testing, which have actually been shown to be rather accurate (if pessimistic) for a national average. They also use the EPA's test data for vehicle MPG which are equally pessimistic, so that's consistent at least.

Two, that 7.5kWh does include extraction and transportation - as well as refining - for gasoline. That figure comes as an inference from a DOE study that examines gasoline production efficiency. We had a whole discussion on this already.
=Smidge=

Good arguments and your numbers check out. I'd be almost ready to trade in my LEAF for a Ford Fiesta now if we talked about the same domestic fuel source. But from the emissions perspective, the case can be made.

But here's the clincher... Every time you fire up the gasser, a kitten dies What do you say to that???

cracovian said:

But here's the clincher... Every time you fire up the gasser, a kitten dies What do you say to that???

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I'm a dog owner! :twisted: :twisted: :twisted:

More seriously, even if the numbers work out that an EV like the LEAF does produce more total GHG emissions than a very efficient ICE, there are still good arguments to be made for EVs:

1) They produce no local pollution, so it at least does not poison the air you and your neighbors breathe and does not contribute to urban smog.

2) Any "greening" to power generation automatically makes your EV - and everyone else's - greener for free. Every EV on the road amplifies the environmental and economic benefit of building renewable electricity.

3) As an extension of (2), an EV has the ability to be powered by renewable sources - an ICEv has a much harder time of that.

And if environmental quality isn't your main concern;

4) "Coal power is American power" - America does not import any coal, after all. (Yet..?)

5) Still costs less per mile to operate.

6) The EV driving experience is subjectively better in any number of ways.

I can probably think up a few more, but I get the feeling there was already a thread about this somewhere.
=Smidge=

cracovian said:

Good arguments and your numbers check out. I'd be almost ready to trade in my LEAF for a Ford Fiesta now if we talked about the same domestic fuel source. But from the emissions perspective, the case can be made.

But here's the clincher... Every time you fire up the gasser, a kitten dies What do you say to that???

Click to expand...

http://new.livestream.com/FosterKittenCam/MirandasKittens" onclick="window.open(this.href);return false;

Smidge204 said:

So they use the EPA fuel economy and the GREET emissions data combined to generate GHG emissions per unit distance. They coin a unit "MPGghg" which is a greenhouse gas equivalent mile per gallon - the reciprocal of that number is how many miles you can drive to result in the creation of 1 gasoline gallon's worth of greenhouse gas emissions. They summarize some key values in Table 1.1. Example: is 100% of your electricity from coal? The GHGs your EV creates is equivalent to a gasoline ICE getting 30MPG.

Click to expand...

OK. So I guess my problem was one of units and believability. Re-reading appropriate areas I now get their MPGghg. But I expected that the ICE numbers would have the GHG correction for Well-to-Pump (WTP) applied to the EPA numbers, instead they have apparently applied the correction the MPGghg number for the EVs. I don't like that methodology because it basically hides the true cost for gasoline, but that's life. Instead they could state "the Prius gets 45MPG EPA but 37 MPGghg (made up numbers) after one takes into consideration the GHG used to produce the fuel that goes into the tank" and things are much clearer to the reader as to what is going on in the car they drive.

Additionally I don't see any consideration for off-peak vs on-peak on emissions (there is a discussion on cost, but not of how or if charging at night affects emissions. We know that that there is unused electricity in the grid http://www.torquenews.com/397/senator-alexander-unused-electricity-our-greatest-national-resource charging at night should yield lower GHG's even if coal is the source b/c the EV fuel comes without burning more coal). Also I complained about earlier Well-To-Pump GHG costs for different types of oil from different parts of the world aren't explained, I suppose they've been averaged out somehow in the GREET calculation but common sense makes me think that there is as much variation in WTP with where & how the oil was extracted as the WTP between coal, nuclear, & hydro.

So I guess I'm really having a tough time believing that coal generated EVs have such a low MPGghg number. Coal is bad, but the GHG's to produce a kWh with coal and transport it that I've seen, shouldn't pull the MPG number down that far. When I get some free time, I'll have to do some number crunching on my own to see if I can get something close to that 30MPGghg number. The GREET summary document that I read certainly did not have numbers that low and they should only go up when the ICE WTP numbers are applied to the EV MPG. Other Well-to-Wells white papers have EV powered by coal as bad, but ICE cars far worse (the hit on EVs was the large GHGs to produce the car [which is weird since the batteries are recyclable], not to operate it). I don't have access to the detailed GREET document, maybe the gasoline WTP numbers and the details of the MPGghg are included there, but there must be something awfully big in their calculations to pull the EV numbers so far down.

Smidge204 said:

*snip*
5) Still costs less per mile to operate.

=Smidge=

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You just gave me my new favorite argument. Driving the EV will be cheaper, therefore, I will have more money in my pocket. More money in my pocket means I am buying more things. Me buying more things helps my local economy. Driving the EV will help my local economy.

cracovian said:

Do you agree that the environmental impact of the source of your electricity determines the environmental impact of your EV?

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I've posted this elsewhere but it bears repeating.

The difference with EVs is that there are ways to decrease their carbon footprint even on "dirty" areas.

For example you, can offset your charging electricity with renewables by paying a little extra to your power company. I buy this energy offset from my local electricity provider

http://db.tt/4CrA7sFW" onclick="window.open(this.href);return false;

Also, the study is clear than in more than half the country, EVs are more beneficial even when compared to hybrids.