Greenhouse gas emissions – Electric vs Gasoline cars.

Amidst all the scientific studies, academic research and political rhetoric, the debate continues on how much effect converting to electric cars – powered from our existing electrical grid – will have on the emissions of greenhouse gasses – CO2. With the proliferation of these studies, some tracing CO2 contributions all the way back to the first exhalation of breath from the dinosaurs, it can be hard for the average rocket scientist, let alone mere mortal, to come to a conclusion. Therefore, I have decided to shun the scientific calculator, eliminate the variables, and do a simple, empirical analysis of their direct impact.

First, the Coal burning Power Plants.

We are fortunate here in that someone, most likely math challenged, actually had the good sense to measure the CO2 output of power plants. It has been measured and confirmed many times since. Ends up the average Coal burning power plant emits 2.17 pounds of CO2 for every kilowatt-hour it produces. (EIA) Now, coal makes up only 48% of our electrical generation. Natural Gas produces 20% and it also emits CO2 (1.4 pounds per kWh). But, 30% comes from nuclear and renewable sources. So, taken together, our national electrical supply generates, on the high side, 1.51 pounds of CO2 per kWh.

Now for the Cars.

Basic Chemistry tells us that burning 1 gallon of gasoline emits 19.4 pounds of CO2. It also tells us, based on BTU content, there are 36 kWh of energy in that gallon of gas.

One place where all the research gets bogged down is trying to account for the varying efficiencies of our automotive contraptions. Automotive IC (Internal Combustion) engines are anywhere from 15 to 28% efficient in average driving. Well, for our worst case, empirical study, I am going to assume the most efficient – 28%. The most efficient means it is the most work we get for every globule of CO2 emitted. Indeed, the meaning is that 28% of the BTUs in that gallon of gas will get turned into useful, mechanical work. All the rest are wasted as heat. There are 124,000 BTU’s, give or take, in a gallon of gas, so at 28% efficiency 34,720 of them or 10.16 kWh, are actually used for something productive. Yet, we still created 19.4 pounds of CO2 burning that gasoline. A little math, and the emissions result for our car is 1.90 pounds of CO2 per kWh of work produced. Note that at the other end of the scale – at 15% efficiency - those numbers would be 5.4 kWh of useful work, and 3.59 pounds of CO2 per kWh.

Although this article is not about CO2 per mile (remember, simple), for the sake of reference, both the Chevy Volt, and my Chevy Malibu use approximately .240 kWh for each mile at a </i>steady<i> 60 Miles Per Hour. The Tesla Roadster claims to use .217. The Prius is about .220. Your dumptruck, I don't know. However, we do not need to factor in the relative mileage of different vehicles to determine the absolute CO2 emissions potential. Replacing a similar gasoline vehicle, with a similar electric vehicle will still result in similar energy needs.

The answer please!

The results show that burning gasoline in an ICE powered car creates anywhere from 21% to 58% more CO2 than getting the same amount of energy from our electric grid for the same size and shape car. And, that point is important.

The other way many of these studies tend to confuse the issue is trying to relate everything to mileage – like pounds per mile. That is truly putting oranges in an apple barrel. The matter of mileage is irrelevant when comparing similar size and shape vehicles where the only difference is the source of power. They will both use the same amount of energy, which here is expressed in Kilowatt-hours. Regardless of whether they are powered by electricity, gasoline, or soda pop. The difference lies in the source of the power.

Now granted, if you replace your dump truck with a compact car, you will be emitting less CO2, but that is true of either power source, because your small car uses less energy than a dump truck. The reverse would also be true, although good luck finding an electrically powered dump truck.

It should be clear by now that by replacing a gasoline powered ICE vehicle with an electric one, for the same amount of power at the wheels, we would reduce CO2 GHG emissions by anywhere from 21% to 58% - even with our existing electrical supply. And, in fact, those who have bothered to reduce some of the complex, often politically motivated and artistically spun, studies down to their basic conclusions have found exactly the same thing.

Comments

[Thom Milson]

I still don't think electric cars are the answer as coal is still a resource we are running out of. If we switch to electric, it's just delaying the inevitable. It's like having all of your favourite clothes needing to be washed, so you start wearing clothes you don't wear as often. Eventually they will get dirty too and you will have to wash them and it's all because your a lazy so and so. It's just going for a lesser of two evils rather than actually trying to solve the problem.

[free electric energy]

It is so encouraging that many more individuals want independence from the costly regimes we have been under for too long.

[Dealership Penciling]

A lot of people have often asked "what is the most fuel efficient car I can buy?". Ok so even though we've just seen that the Diesel supermini is where you need to be looking if you are after the best fuel economy possible, not everyone wants a diesel because frankly - despite all the leaps and bounds that have been made with diesels over these past few years - they aren't sexy! And not everyone can afford a petrol hybrid like the Honda Insight or Toyota Prius either.

[smokeless electric cigarettes]

Electric cars are mechanically simple compared to the internal combustion engine. More so, electricity rates are much cheaper compared to gasoline.

[Driving Instructors Adelaide]

Electric cars don't pollute the atmosphere around us instead it helps lessen that plus it helps us save money on gas...

[springkussen limburg]

Many are now starting to use electric cars. They do originate this type of car to minimize the pollution that would greatly harm our environment.

[GMC Terrain Miami 2012]

I think this is very good for the future. Using electric cars could overcome environmental problems. Yes, we should be looking for environmentally friendly fuels. I can not imagine what happened in this world if my son has grown up...

[heat pump installers]

very good point you made there, its good to see that this angle was looked at. the grid is having more and more renewable energy sources so the electric car will still be gaining advantage over the coming years

[Electricians Sydney]

The generation efficiency of the source plant, or the energy efficiency of the vehicle are of no consequence to this outcome. Whatever the efficiency, the plant produces a certain amount of CO2 per actual kWh produced, regardless of fuel efficiency. The same with the vehicle. It produces a certain amount of CO2 per mile, regardless of the source, and how well it uses that source. It is attempting to introduce all these extra variables into a calculation, and still ending up with the same conclusion, that unnecessarily complicates most of these analysis.

[Vannessa Gabbett]

It is a known fact that greenhouse gases are one of the causes of global warming. EVs are one of the best solutions to prevent global warming from progressing further. A complete paradigm shift would be needed to turn the automobile industry towards the use of purely electric technology, and the proper technological and social infrastructures would be necessary to promote that.

[Broward County Jail]

Even though an electric car does not have a tailpipe, an electric car produces greenhouse gas emissions where electricity is generated.

[Ambit Energy]

To compare of electric cars, natural gas to point one is they're all environment -friendly but to take you one note if the electricity is from renewable energy then that wouldn't e a number.

[jtcitrus]

did I miss something? I thought the miles/kwh cited by Toyota/Honda were Battery-to-wheel, (as opposed to socket-to-wheel, or generator to wheel).

You stated in a comment that the transmission loss from generator to wall averages about 6.4%. What is lost loading and unloading the battery in EV's?

Also, the point above about batteries is important. while it's hard to quantify the environmental damage, what can be said about the difference in embodied energy over the life of the car?

All interesting, and endless spin online, thanks for the article.

[mini truck parts]

I have both, an electrical car and gasoline run car and if you compare the two the one that stands out is the car that is run by electricity because it doesn't emit smoke and doesn't cause air pollution...

[Ken]

"Now, coal makes up only 48% of our electrical generation."
The Generational mix of the average grid is irrelevant.
New demand will be met by what is called the Marginal Mix. If you charge at night (which is what they want you to do to. To avoid crashing your local grid.) your demand will be met with 30% NG and 70% Coal. This is location dependent.
All Nuclear and hydroelectric is base-load, and already spoken for.
Northeast and Northwest have little to no coal, Ca. has some. The rest of the country, has about 80% to 90%+ in their night-time marginal mix.

Using your 2.17 pounds of CO2 for 70% of every kilowatt-hour of Coal 151.9

And 1.4 pounds per kWh of NG = 45.3 for 30% of every kWh of NG
151.9 + 43,3 = 195.2 pounds of CO2 for every 100 kWh produced.

1.963 per kWh total

"on the high side, 1.51 pounds of CO2 per kWh."
The marginal mix is 1.3 x your "High" number.

At this point we have a 33% increase in CO2 for EVs which puts us well within your 21% to 58% more CO2.
1.963 per kWh vs 1.90 pounds of CO2 per kWh for an efficient ICE

1.963 per kWh vs 3.59 pounds of CO2 per kWh for an inefficient one.

At this point an efficient ICE is cleaner CO2 wise than an EV.

An inefficient ICE?
You ignored all charging and operating losses dealing with an EV. As well as 6.5% transmission losses as noted in the comments above.

"A battery-powered electric car has a fairly high efficiency. The battery is about 90-percent efficient (most batteries generate some heat, or require heating), and the electric motor/inverter is about 80-percent efficient. This gives an overall efficiency of about 72 percent."
http://auto.howstuffworks.com/fuel-efficiency/alternative-fuels/fuel-cell4.htm

Adding the T+D loss of 6.5% to this.
72% x 93.5% = 67.3% efficiency. or an increase of CO2 of 33.7% - 262

1.963# CO2 x 1.337 = 2.62#CO2 vs a hummer at 3.59#CO2
and an efficient ICE at 1.9#CO2

An obvious point: People who have the money and care about CO2 are not buying Hummers. The most common car that owners have in the garage along side the Leaf is a Prius (19% of Leaf owners.)
http://green.autoblog.com/2011/07/21/2011-nissan-leaf-buyers-are/
The Prius at 1.9 #CO2 per is sitting in the garage with the Leaf at 2.62#CO2 is the "Green" alternative.

This is looking at CO2 only. Coal plants have a multitude of poisons which make the environment far worse faster than GHG.

Try listening to the National Academies audio presentation. It's 11 minutes and says When you look at all the environmental costs involved, EVs are worse than traditional ICE.

http://www.nap.edu/audioplayer.php?record_id=12794&n=0

If you want to read the 500+ page report its here. You do have to register but it's free.
http://www.nap.edu/catalog.php?record_id=12794

"in fact, those who have bothered to reduce some of the complex, often politically motivated and artistically spun, studies down to their basic conclusions have found exactly the same thing."

Yes I couldn't agree more. Sarcasm intended.

[Energie]

That is really important for the future. Electric cars can overcome environmental problems. And it is time to look for environmentally friendly fuels and alternativ energies. It it time to change something so that our children can still grow up in a green world.

[Robert Bernal]

I don't know how I came into to this sooo late, but want to add the following:
Ev's are about 20 to 50% more efficient after all the variables are added in. Yet people still argue that they are not much cleaner because of the energy costs needed to make li-ion batteries. Doesn't that simply cancle out the energy costs to refine gasoline (from ever lowering EROEI from oil)?
Also, PLEASE don't use the ordinary li-ion! They have thermal issues and only last like 500 cycles. Instead, use the LiFePO4. It has 2,000 cycles and no thermal issues (thus much faster charging times)! Lithium is about as common as lead, the only problem is that "we" are to cheap to dig it ourselves. Coal presents more enviro hazards per kWh than rechargeable batteries because it is only burned once whereas the LiFePO4 battery goes 2,000 times further "per mining operation"!

[Robert Bernal]

We could do much better, though, if we replaced every expiring coal plant with a LFTR or similar advanced nuclear reactor that fission ALL of its fuel and that requires NO high pressures, no solid fuels and NO water for core cooling (thus no possibility of meltdown and FAR less wastes problem than the LWR).
In the meantime, every solar panel and every wind turbine that can be used to replace the 1.5 pounds of CO2 per kWh from the grid, should be used!

[Anaheim Hills Blinds and Shutters]

I have wanted an electric car since 1982 when I first saw a Porsche 914 converted. It cost $12K to convert a 914 and only goes 80 miles. I'm now looking at the Porsche 356 kit car to be converted. Truth be told Toyota has won this round with the hybrid prius. It's magnificent!

[Rick]

here geniuses, a better calculation... diesel or bio diesel is the way to go
http://www.simple-mathematics.com/3/category/issue%2005%20alternative%20energy6fff78bfef/1.html

[RRashi]

ps LogMeIn D 3.5 slideme AppStore Google dosent

[Priyanka]

The typical patetrn that I have noticed, is that when gas prices rise, politicians make a nice loud, large, splashy spectacle of dragging in the oil execs and then raking them over the coals simply for the benefit of looking as if they are actually trying to accomplish something.As you pointed out in your Fox News piece, Dr. Lott, markets drive the price, not the oil companies themselves.

[Sant]

You are correct. If you look at your eetclric bill you can find the charge per KWH. Be sure to add in any fuel surcharge and tax to the figure. Mine is $ .087. I'd be interested to know how much your power company charges out there. I'm in the midwest.Ret68 could be right too if you are missing a decimal point. How long was your test period?

[Auth]

My personal CPI is +6.71% from January 1 to date over last year. This is led by desiel fuel going from $3.24 to $4.05 per gallon (+25%) and our weekly grocery bill going from $130 to $170 per week (+31%). Neither of these two items has differed in quantity and I have not subtituted them substantially enough to count from last year, but I think my truck is getting parked next year.

[limousine chicago]

Electric cars really green..environmental friendly than car powered by gasoline.