Doublecheck My Math: Hybrids Can Be Greener Than Electric Cars

By · November 05, 2010


Photo by Afroswede via flickr/creativecommons.

It started with an assignment from Home Power magazine. They asked me to create a graph to visualize the relative efficiency and green-ness of various cars—so I decided to undertake a comparison of CO2 emissions and cost for a typical gas, hybrid and electric car.

I specifically wanted to know about the relative carbon emissions of pure electric cars in different parts of the country, depending on the coal/renewable mix at various electricity generation plants. People repeatedly ask, “Are electric cars really green?” and I want to finally shoot down EV critics—as we frequently do on—with some hard data.

So, I reached out to experts in the field of environmental lifecycle analysis, like Costa Samaras at the non-profit Rand Corporation, who led me to the EPA’s eGrid analysis, which provides a count on the kg of CO2 equivalents for a kWh of electricity in different regions of the country.

The latest data comes from 2005. Is it accurate? Is the methodology correct? Has the grid gotten a lot greener since 2005? I don’t know, but it’s the ONLY data out there with CO2 counts for different regions. On top of those questions, Costa’s research makes it very clear that it’s impossible to trace the exact source of electricity for any individual household. We have a national grid, and electrons don’t respect state or regional borders.

Break Out the Calculator

Stick with me folks, the numbers are going to start flying.

With kg/CO2 per kWh numbers in hand, I was able to convert that number to pounds of CO2 per mile by using a factor of 3.6 miles per kWh of EV driving. That’s lower than the rule-of-thumb for EV efficiency—4 kWh per mile—and way lower than many EV drivers experience, but that’s what the EPA used to account for total consumption, including losses during transmission and charging, for their 2012 to 2016 fuel efficiency rules. (If you don't like it, don't call me. Call Lisa Jackson.)

I took a similar lifecycle approach to determining the pounds of CO2 for a 30-mpg gas-powered car and a 50-mpg hybrid. Yes, I know that most Toyota Prius drivers, for example, don’t routinely get 50 miles to the gallon, but that’s just one of many assumptions that I decided to make. (Careful hybrid drivers do get 50-mpg, and I anticipate a lot more will in coming years as hybrids, along with all cars, get more efficient to meet rising federal standards.)

I used 23.7 pounds of CO2 for each gallon of gas burned. That comes right from the DOE Argonne National Lab’s GREET (Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation) model, that includes the primary energy source extraction, transportation and processing for gasoline. Is that accurate and complete? Who knows?

So, if you look at a driver who clocks 15,000 miles per year, then it’s easy enough to calculate CO2 for 500 gallons (for the 30-mpg car); 300 gallons (for the 50-mpg hybrid); and 4,167 kilowatt hours for the pure EV. (15,000 miles divided by 3.6 miles per kWh produced the 4,167 number.) For
fuel costs
and electricity rates, I pulled up regional numbers from the DOE’s U.S. Energy Information Agency. I couldn’t find some of the regional gas prices, so I found those from gas-buddy-type sites on the web.

Sum It Up

With all this data, and all those assumptions, I started crunching numbers for 10 different cities. The cities are just representative locations, because again it’s impossible to know where the electrons came from.

For San Francisco, near where I live, I used a CO2 average of three different grids (from eGrid)—listed in kg/CO2 per kWh of 0.1 to 0.183 as .36, .45 and .66 (this is right now)—to indicate emissions for 15,000 miles of driving as follows:

  • 4,345 pounds of CO2 for the EV
  • That’s tremendously cleaner than the 30-mpg car’s 11,850 pounds of CO2
  • It’s also way better than the 50-mpg hybrid’s 7,110 pounds of CO2

On a cost basis, the EV also comes out way ahead. Even at $0.1552 per kWh—I know that time-of-use rates might be significantly lower, but that’s what the USEIA is using for California—the EV beats the competition. I used $3.12 for the cost of gas to reveal the cost of a year’s worth of driving in San Francisco:

  • The EV tallied at $647, compared to the hybrid’s $936, and the gas car’s $1,560.

So far, so good. But the numbers become troubling when you start looking at parts of the country with dirty grids and expensive electricity. Warning: Don’t shoot me. I’m just the number cruncher and I’ve told you about all my assumptions. But for Phoenix and Boston, I show the EV emitting at least a couple of hundred pounds MORE CO2 respectively than the 50-mpg hybrid. And in Boston, the annual cost of driving the EV only beats the hybrid by $191.


I've probably confused everybody with my back-and-forth calculations, and the incorrect descriptions, but to me, the situation is confirmed (as much as it can be confirmed based on government numbers). In a couple of cities where electricity is dirty, the 50-mpg hybrid actually beats the electric car for low CO2. At first, that surprised me, but I quickly came to see it as the exception that proves the bigger and more important rule: for a myriad of reasons—from less local air pollution to greater reduction of our dependence on foreign oil and lower fuel costs—the pure electric car is as green as it gets. At the same time, the critical importance of the conventional (no-plug) hybrid—especially considering that adoption rates (sales) that are likely to be faster and higher than EVs—should be appreciated. I'm sure users will fill in a bunch of other gaps in the comments below.

The final graphic showing a comparison of 10 different cities will appear in Home Power in a couple of months. I'll let you know when it hits the stands.


· Max (not verified) · 7 years ago

It looks like your numbers for the electric car might be wrong:

For San Francisco
Electric: (15000 mi) / (3.6 mi/kWhr) * (0.183 kg CO2/kWhr) * (2.2 lbs / kg) = 1677.5 lbs CO2 (my numbers are lower by a factor of ~2.6)
Hybrid: (15000 mi) / (50 mpg) * (23.7 lbs CO2/gal) = 7110 lbs CO2 (same as article's)
Gas: (15000 mi) / (30 mpg) * (23.7 lbs CO2/gal) = 11850 lbs CO2 (same as article's)

I suppose whatever error you made in calculating the electric cars CO2 output probably carried over to your calculations for other cities (assuming I didn't make a mistake).

· Michael Corder (not verified) · 7 years ago

I appreciate that you tried to simplify the calculations. However, my take is that on average, for the general debate on this subject, that the average savings in CO2 is more important than pegging it to a specific locale (Unless you happen to be from that locale). Trying to simplify things to the lowest common denominator, I made the same calculations a while back using the average CO2 emissions figure for our electric grid.

· Ernie (not verified) · 7 years ago

Something you don't mention is your conversion from kg of CO2 per kilowatt hour to pounds of CO2 (the units you use in the rest of your calculations) per kilowatt hour. Those unit conversions will really kill you (ask NASA, or the pilot who landed the Gimli Glider) if you get that part wrong. Not doing the conversion will result in powerplant emissions that are way lower for the electric grid in your calculations than they are in reality. Also, it's good form to round off at a large number of decimal places (say at least 5) to reduce compound rounding error in equations.

The best way of doing things is to either convert everything before doing calculations, or otherwise start with the right unit measure to begin with.

· · 7 years ago

I agree with Max in his calculations. Well almost, 2.205 lbs to the kg so I get 1681.313 lbs co2

I wonder if there is enough data to include PHEV's in this comparison.

· Ben Rose (not verified) · 7 years ago

I did these numbers for the UK some time ago, comparing Nissan Leaf with Toyota Prius. Link below if you're interested. I found the results to be considerably closer, like within 10%. I haven't checked your numbers but I think the main difference is that you're using theoretical, not real, numbers.

· · 7 years ago

I just ran the numbers myself, and I also think Max got it right. That would mean that EVs come out ahead even when electricity generation is comparatively dirty, which is consistent with other articles I've come across.

That said, any EV's environmental benefits are only as good as the gasoline-powered driving it is able to offset. For those who often require more range than current EV's provide, a hybrid can be a better choice. For that reason, we are now leaning toward buying a Prius rather than a LEAF at this time, in hopes of being able to purchase a longer range EV next time we are in the market for a car. Of course, some families might be able to really optimize their driving in the near-term by owning both a Prius and a LEAF.

· · 7 years ago

[Note 11/6: I was too quick to apologize. The calculations in the main body of this article are correct. What I say in this comment is actually incorrect.]

YES! Max and the others are right. I plead complete stupidity for multiplying the CO2 factor by 15,000 miles rather than 4,167 kilowatt hours. No doubt about it. Using established DOE and EPA numbers, EVs have a huge advantage in reducing CO2 emissions.

I don't expect these revised numbers to change anybody's opinion one way or the other--or to change the rate of market adoption. As abisile points out, there are a multitude of factors for buying one car versus another, and a greener choice will different for individual consumers, based on their needs and pocketbook. But the cost, CO2 and petroleum displacement numbers for EVs do tell a compelling story.

· Jose Freire (not verified) · 7 years ago

I think your findings are correct since it all depends on how the electricity is produced.

Take Portugal for example (my country). We have wind power excess at night time, so if we charge our cars at night we'll have close to 0Kg/CO2 per kWh.

It's not a surprise we're one of the first markets to see the Nissan Leaf.

However, we shouldn't look at how the electricity is produced today, but how it will be produced in the future. It's easier to double the efficiency of a coal plant (by using combined cycle), than to increase the efficiency of an internal combustion engine.

· Ben Rose (not verified) · 7 years ago

I simply don't believe your "DOE and EPA numbers" are anything like a true representation. In the UK, every new car has the official CO2 output on the windscreen sticker - the Prius is about as low as it gets and within 10% of those for the Leaf.

Given the pollution levels across the country, and general resistance to sign any commitment to reduce them, I find it hard to believe that US power generation is any cleaner than the UK.

· John V (not verified) · 7 years ago

I covered much of the same ground a couple of years ago in an article discussing the 2007 EPRI-NRDC study.

I used the state-by-state grid CO2 emissions of electricity (measured in g/kWh) as published by the DoE (you'll have to convert pounds to grams). Excerpt:

In the United States, the three cleanest states—at well below 200 grams of CO 2 per kWh—are Idaho, Washington, and Oregon, due to their extremely high percentage of hydroelectric generation. The worst—at just over 1000 g/kWh—are North Dakota and Wyoming, which use large amounts of coal. California, the state that buys the most Priuses, comes in at roughly 450 g/kWh, about 25 percent better than the U.S. average. Be aware, though, that much electricity crosses state lines.

Based on some further math, I concluded that 25 mpg (210 g/km of CO2), every plug-in has a lower CO2 footprint per mile even if fueled on the dirtiest grid in the U.S.

But at 50 mpg (e.g. 2011 Toyota Prius), which translates to 104 g/km, plus about one-third more for extraction, refining, etc. (let's say 140 g/km total), in a handful of edge cases, a plug-in operating on the dirtiest grids in the country (at 1000 g/kWh divided by 5 miles/kWh = 200 g/km) has a higher overall carbon footprint. In that case, the pure hybrid is better.

Hope this helps.

· John V (not verified) · 7 years ago

Links got stripped out of my comment above:

My article:

The DoE data:

· · 7 years ago

John - Thanks for your comments. How are you getting 450 g/kWh for CO2 from California electricity? I see in the 2001 DOE doc you linked to where it shows .305 pounds (not grams) of per kWh in California. That converts to about 138 grams per kWh, right? Incidentally, based on the 2005 eGrid averages of three California grids, I used 136 grams (almost exactly the same).

The 136 g/kWh would obviously bring down the CO2 for the California grid compared to your 450 number? Again, how did you get that? Is my math off again somewhere. I don't doubt your number, because it sorta matches what we published on earlier this year:

That article came to the same conclusion that pure hybrids, in places where the grid is dirty, work out better.

Thanks for helping sort this out. Great conversation to be having as EVs start arriving soon.

· · 7 years ago

The kind of driving required to get 50 mpg with a Prius should easily get you 4 mi/kWhr for an EV with similar aerodynamics and weight. There's nothing wrong with using conservative numbers but any numbers you do get will be biased an additional 25% against the EV with your assumptions.
I've seen many other, different computations, some come up with the EV from pure coal beating the Prius and others with the Prius edging slightly ahead. My rationality towards EVs then is that their carbon footprints are 'about the same' in the worst case as a Prius but the EV wins by a landslide when compared with the national average grid mix, any future grid mix with more clean or renewable sources, the California mix, particulate emissions, and ICE vehicles other than the Prius. I also can and have put up solar panels that offset the electricity used by my EV so the issue can be in the hands of the owner, should the owner choose to do so.

· Steven (not verified) · 7 years ago

Now for a real challenge!

Let’s start with the batteries of EVs. Maybe I’ve been ingesting too much carbon washing but I seem to recall articles suggesting the production of EV batteries is extremely energy-intensive. I believe one even suggested this is so much the case that any efficiencies gained in actual operation are more than offset in the EV battery production. If that’s not enough, how about tacking on using solar panels to charge the EV battery? Years ago I worked with a guy who had a PhD in physics. He claimed that with the efficiencies then achievable, PV panels wouldn’t even repay the energy it cost to produce them. And if you take it this far, how about factoring in the energy it takes to produce the aluminum mounting rails for the PV panels?

· · 7 years ago

Okay, folks, sorry about this. But Max was misled by the 0.183 number I provided in the article at first. The eGrid numbers for the three California grids are .36, .45, and .66.

Throw away the 0.183 number if you're using Max's formula. That was my intermediate number of g/CO2 per mile based on 3.6 miles per kilowatt hour (for the worst of three grids). In other words, the worst of the California grids is rated at .66. Divide that by 3.6 miles to produce 0.183 g/CO2 per mile. Convert that to .403 pounds/CO2 per mile x 15k miles and you come back to my original number.

This jives with what John V and ex-EV1 have said. The best case scenario for hybrids put them slightly better than EVs charged from the dirtiest grid.

ex-EV1 - Of course, all your other points make total sense, especially about solar panels.

Sorry for confusion, gang. A calculator is a dangerous thing to put in the wrong hands.

· · 7 years ago

I'm not really sure how much energy it takes to produce the panels, inverters, racking system and wiring needed to build a solar PV system but I'm pretty sure it's not anywhere near the amount of energy the system will produce over it's lifetime. I have 39 Sunpower 225w panels and produce about 10.5mWh per year. The system is guaranteed to be at least 80% efficient for 25 years and I'm told I can really expect 30+ years of solid production. Based on this I would assume the system will generate between 280 and 300 mWh of electricity in it's lifetime. That's enough electricity to power an EV well over a million miles and save me from buying nearly 50,000 gallons of gasoline driving a car that gets 25mpg. That's a good amount of energy if you ask me.

· · 7 years ago

Great question, one that all PV manufacturers should be answering for their products. This same question was posed to Tesla a few years ago and their financier and Chairman, Elon Musk and their then-President Martin Eberhart saw it is worthy of answering personally. You can find their response and some references at:

· Steven (not verified) · 7 years ago

Ask and you shall receive! Effortlessly! Thanks ex-EV1 driver!! And PluginCars!! I can't tell you how long I've been asking this question without getting hard answers like the one you provided,

· · 7 years ago

Its open-minded thinkers like you that ask the tough questions that we really need today. Otherwise, snake-oil schemes and perochial interests will be warped and promoted so that we'll never progress.
Thank you for the question. Keep them coming!
I'll also add that PV isn't the most efficient or cheapest way to generate electricity. That honor generally goes to solar thermal system. The solar thermal systems, however, require a lot operations and maintenance labor to keep them running so they generally have to be large-solar facilities, run by corporations. The energy payback for solar thermal can be a whole lot faster because they're a bunch of mirror for the most part. Solar thermal also can sometimes use natural gas burner when the sun isn't shining for higher availability.
PV is great in that it can use already ruined land (our homes and businesses), we can control it, and, once installed, it just runs and you don't have to worry about it.

· · 7 years ago

Yes, great link ex. I had previously heard that it takes about one year to generate the energy used to make a solar array, but never saw anyone really explain it like Elon & Martin did. I'll have to save that link for future use!

· Randal (not verified) · 7 years ago

I know that CO2 is the focus of your calculations. Here is my experience with real-world decisions about commuting. Steven's question about battery production is very relevant to anyone looking closely at their own total cost per mile. At 100 watts per mile on a scooter, I am looking at under a penny per mile for energy, but 20 cents per mile battery replacement cost for Lead-Acid. Lithiums promise to reduce that to a nickel a mile battery cost, for triple the money up front.

I could almost buy a 20 year old Civic VX and get 50 mpg with no depreciation for the price of the lithium batteries alone, and have an equal total cost per mile. A little dirtier, but much better when a deer jumps on the road in front of me.

· · 7 years ago

Brad, this is an important question that needs to be answered. California and Oregon are making an attempt to determine a "fair" kg of CO2/kwh for electric miles based on their recently passed Low Carbon Fuel Standards. Emissions can look wildly different depending upon your assumptions of the source of electricity. Even within the state of Oregon, the amount of CO2 swings wildly from utility to utility depending on the mix of renewables. Plus, many utilities buy electricity on the spot market where they have almost no information on the generation source. Also, time of day when you charge matters too, with solar and wind contributions varying wildly. This is a significant and challenging question that needs to be answered with accurate data, and we're paying attention to it.

· Steven (not verified) · 7 years ago

Getting some numbers for current costs would be an interesting and possibly useful exercise. My real interest, however, is in energy costs. 'free markets' with monetary costs based upon honest physics and social cost / environmental accounting may ultimately be a good way to make production decisions. For the foreseeable future, however, monetary costs are likely to remain wildly out of sync with these criteria. Even '"fair" kg of CO2/kwh for electric miles' might not be persuasive for those who don't buy climate change. (Full disclosure. I do after reading Dr. Tim Flannery's "The Weather Makers" several years ago.) How about we just limit the discussion to the cost of gasoline after the cost of US oil wars is factored in - and maybe factor in a few more deep-water oil spills to boot? Nothing more than what everyone would consider necessary and reasonable. If it was just limited to war costs, the figure ought to be easier to determine and a new tax reflecting real cost of production could be imposed.

· · 7 years ago

If you are making your decisions solely on what is best for you, today, and you don't care about having to fix your car regularly, go to the gas station, fight wars (either in the military or as a tax payer paying for the war) to protect our oil interests, oil stains in your driveway or polluting, then clearly buying an old used ICE junker that gets reasonable mpg is the cheapest and best way for you to drive a mile. You should not, however, be wasting your time at These cars aren't going to be cheaper than oil burners for a decade or more.
Instead should be perusing or where you can buy a used junker for the price of a few tankfuls of gas.
If, however, you are interested in being able to live better in the future or enabling your grandchildren to live as well as you do, you should stick around here as we explore whether plug-in vehicles might be able to solve the problems, where to get the cars so you can do your part, how and whether you'll need to adapt your life to live with them, as well as many other things related to this new concept in driving. You may have to divert a few of those extra shekels in your pocket away from frivolties or that shiny new Lexus you've had your eye on but the payoff could be priceless. If you actually don't have those extra clams in your pocket then I encourage you to stick around here and help us all be come better educated so that we can pursuade those with the extra dough to spend it wisely, not on farces such as Hydrogen or Ethanol.

· · 7 years ago

@John Gartner,
With all due respect to your profession, I don't believe that our current problems are within the comprehension or capability of the lawyers and public policy wonks that make up our government and it's associated camp-followers. "fair" is just a concept that lawyers and policy wonks can handle, therefore, that is what they do. To a little boy with a hammer, everything looks like a nail.
Fair only has merit if one takes technology as a given that cannot be changed and one must weigh each fairly as one would allocate the water from a stream. While not a bad assumptions for lawyers and politicians, in this case, all that fairly treating various incumbent and alternative technologies will do is to forestall the inevitable if the incuments depend on a finite resource thats going to run out or emit an element that will eventually wipe out our species. Its going to take the geeks who studied across campus to find new technologies that do not depend on that finite resource or emit toxics to our bodies or our planet.
Since EVs do not depend on oil or hydrocarbons at all, it seems unfair to saddle them with any of the legacy problems but rather, treat them as independent issues.
1) EVs can run off of zero emission, sustainable renewables. Therefore, they are good.
2) Energy can come from limited or dirty sources or it can come from clean, sustainable renewable sources. Here is where the 'fairness' should be assessed.
Let's instead of blaming the EVs for the energy source, instead, reward the electric companies for every EV that they fuel, relative to their grid mix. This can be handled with a $20 cellular modem installed in the charger that transmits the amount of electricity used and when it was used to a central clearing house. Regulators can then look at the grid supply mix at that time and the amout of pollutants and other junk that went into the mix, subtracting off the amount of junk that would have been caused by the same energy amount of gasoline and determine the credit. Since we've determined that the worst case coal is about the same but slightly worse than ICE, I don't see any reason for punishment.
This will not only get the government away from EV's -vs- well funded ICE interests but it will also encourage the electric companies to support EV infrastructure since they'll receive more profit from the kWhrs they sell to EVs.

· · 7 years ago

@John Gartner
I forgot to mention that my suggestion would encourage electrical utilities to move toward renewables in addition to supporting EVs.
Also sorry for the rambling nature. I don't have much time to spend on this today.

· · 7 years ago

@ex - Bingo! For me, this is ultimately a moral issue. The end of the oil supply chain ends in war and body bags.

As you say, we need to build this community (and movement) to work through the dynamics of choosing the right cars and overcoming any obstacles. And as John G points out, we need to get some clarity on the CO2 issues (which will be very difficult).

But it's time for as many of us as possible to bring about the transition to cars that use a lot less oil or none at all. We might not have all the answers, but we know enough to move in the right general direction (and course correct as we go).

· Steven (not verified) · 7 years ago

Hey ex,

It takes everything I've got to put together a coherent sentence so I'm going to have to leave the number-crunching to refute your contention - "These cars aren't going to be cheaper than oil burners for a decade or more." - up to you or someone else. But I was wondering, given the zero-opportunity cost for those of us who are not Wall Street sharks, whether your contention is true even now. Perhaps when you factor in depreciation - but what about viewing the cost premium for an EV as pre-purchasing a significant percentage of your gas for say the next 8 years? Maybe a special tax law permitting people to tap their IRA / 401k's is merited - even if the cost of gas remains constant over the next x years?



· Jim1961 (not verified) · 7 years ago

There is good article in the July, 2010 issue of Scientific American about this very subject. Unfortunately in my area of the country 85% of the dispatchable power generation comes from coal. I would generate less CO2 with a hybrid.

Some people say installing solar EV panels will make an electric car emit less CO2 than a hybrid. That seems logical but it's completely wrong. Let's assume I put a huge array of solar panels on my roof. These panels reduce the amount of electricity I use from the grid. When my solar panel output exceeds what I'm using in my home this energy will get sent INTO the grid and the power company will pay me. This will reduce greenhouse gas emissions by an amount I will call X. If I buy an electric car I will use more electrical power which will offset the amount of energy being generated by my solar panels. If an electric car generates Y amount of CO2 then the resulting CO2 reduction will be X-Y. It would not matter if I put 5 megawatts of solar panels on my roof. A hybrid will still generate less CO2 in my neck of the woods.

· Alexei (not verified) · 7 years ago

Hi Brad,

Did the calculations include the amount of CO2 needed to extract and refine the oil? As different regions might use different oil sources which require more or less energy to refine. For example how much of real CO2 would be produced directly and indirectly by a Prius driver in the region which is supplied by gasoline produced from tar sands?

· · 7 years ago

@Jim1961: While at this point I own neither an EV nor PV panels on my roof, I don't agree with your logic in a practical sense. Yes, we could all install solar, not use it for EVs, and simply out of a sense of altruism sell the power back to our respective utilities at low, wholesale rates. But I am not aware of a single homeowner who intends to incur the expense of installing solar just to benefit the grid.

If my family chooses to install solar in the future, it will be to offset our use of grid power. Right now it's hardly worth the hassle/expense because our electricity usage is pretty low (~300 kWh/month) thanks to some straightforward conservation measures. Eventually, however, I expect that an EV purchase will make solar "worthwhile" for us.

· eddie (not verified) · 7 years ago

Let's keep this simple...assume 100% coal-fired electricity as is the case here in Ohio. The coal plant runs 24/7 so it will pollute whether or not I plug in my car at night...

· Randal (not verified) · 7 years ago


I put 2700 miles on an electric scooter this year, and convinced my employer to install a metered outlet so I could fairly pay for the juice. I buy extra blocks of "blue sky" wind power.

I would be happy to hang around and participate here, but veiled insults based on faulty assumptions about me aren't encouraging.

I am a professional driver. I am intently watching the marketplace as safe, clean, efficient, and affordable vehicles are developed. My original post was to point out that all four of those factors are relevant. I get it that there are huge external costs for oil burners. I get it that early adopters pay for the privilege of advancing the market.

No Lexus for me, I lust for an Edison VLC, actually. And if I get a 20 year old Civic, I will tinker with it to put electric power to the rear in a thru-the-road set up.

Happy Trails.

· · 7 years ago

@Alexei - Yes, as I mentioned in the main article, the use of 23.7 pounds of CO2 per gallon does include extraction and refinement.

"I used 23.7 pounds of CO2 for each gallon of gas burned. That comes right from the DOE Argonne National Lab’s GREET (Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation) model, that includes the primary energy source extraction, transportation and processing for gasoline."

· · 7 years ago

@Randal - Please stick around and continue to participate in our forums. There may be the occasional barb here and there, but we pride ourselves on keeping the conversation very civil and open. Sometimes, there are fly-by anti-plug attacks, which can quickly raise blood pressure. It's a good idea to get an account on the site, so we can read a brief bio and follow your participation in various discussions. Cheers.

· Steven (not verified) · 7 years ago

@Brad, @ex & @Randal - Brad, ex: if I've been following the discussion right, you are not so bad with the calculator after all. I would still like to know if there is any scenario under which EVs could be considered cost-effective now as opposed to the 10 years ex-EV thinks it might take.

Randal: your approach to this issue is obviously way beyond that of a green eyeshade bookkeepers'. To the extent that you, the rest of us or the engineers who design our cars use cost as a controlling consideration in their decision-making, I think we can all be forgiven. That's the way the system in SUPPOSED to work. Anyone who believes in free markets has their work cut out for them to insure the operation of those markets reflects the laws governing the physical universe and not those passed by purchased politicians.

· · 7 years ago

Thank you Brad, for this article. This is a complex and confusing subject, and the more clarity we have, the better.

It needs to be pointed out that petroleum uses carbon before extraction: exploration and test drilling are non-trivial tasks. The energy, materials and equipment used in these pre-production steps should be amortized into the carbon used to produce gasoline. Also, the refinement of heavy "sour" crude (or tar-sands!) requires a lot more energy/carbon /gallon than does light sweet crude.

And, the whole morass of ethanol production should be included, if it isn't already. Corn is a very inefficient crop; requiring much more fertilizer (which is made from natural gas!) and a lot of pesticides, as well as diesel for the tractors and transport -- and the refinery process to make the ethanol, all need to be included in the carbon numbers.

Lastly, the amount of money and energy we expend on our military efforts to defend our petroleum interests is truly staggering. This would be incredibly difficult to add to the already complex calculations -- but we should not take it for granted.

Sincerely, Neil

· · 7 years ago

I meant to ask if the carbon of the electricity and natural gas used all along the production process for oil is included? If so, do you have the specific numbers for the carbon used for the oil refinement, and extraction steps in particular; and/or how much electricity and natural gas is used during these steps?

Sincerely, Neil

· · 7 years ago

Hey Neil - I should have included a link to DOE's GREET model from the beginning, but here you go:

This is the model that produces 23.7 pounds per gallon of CO2. I would need to dig deeper to see how far they go, such as pre-production emissions from test-drilling, etc.

I'm almost positive that military expense/emissions are NOT included. That would send the scale flying. As mentioned above, when you get into costs for wars (in $ and blood), the economics and moral calculus becomes a very compelling case for going electric. But let's not forget market and other realities that create a need to reduce oil consumption in every form of transportation and car.

· · 7 years ago

Sorry about the barb. I definitely shot from the hip. Since you're back, let's explore things a bit further.
EVs certainly are not cheaper now. Nothing new is usually cheaper.
You probably could have picked up a used Chinese Vespa clone for less than $1000 yet you probably paid a lot more for an electric scooter. The same will apply to an electric car.
Clearly, if you are one who has the ability to take care of an old car, the most ecological and economical thing one can do is to run a car for a long time. This will significantly reduce the energy, pollution and costs of building a new car, probably a lot more than the energy used by the car overall. You probably don't even need to go back to that old Civic to see a huge financial and energy improvement over any new ICE car for short term benefits.
EVs, on the other hand are expensive today. This includes the Edison VLC and the rest of the X-Prize entries. Fortunately, a lot of the initial costs are being absorbed by someone else today. I suspect that it wouldn't be too difficult to show that a Nissan Leaf, after the tax breaks, is going to be a very cheap car since the government and Nissan are both eating a lot of the startup costs. I still figure that a $15K Kia, however, will still have a lower cost per mile to you, at least for the first 100K miles or so. This will all depend on the cost you place on maintenance labor and whether you count the true cost of oil.

· Randal (not verified) · 7 years ago

@ex et al...

Will consider an account here, and I've been barbed at enough forums to know it's no big deal if things cool off after a "whoa, pal."

I've done spread sheets on numerous combinations of vehicles. Depreciation and insurance eat you up on new rigs. Repairs eat you up on old ones. And wouldn't it be nice to have the option on our 1040 returns to opt out of war taxes if we could prove renewable energy investement?

Ya - I paid $2,400 for the electric scooter with lead acid batts.
They're done at 2700 miles. So looking at $1,500 for lithiums which should go 20,000 miles or more isn't too bad. Except in my climate a scooter can handle MAYBE half of my 17,000 annual commute miles. Which lead me to do exactly as suggested, ex, look on ebay and autotrader at what was happening with low-depreciable high mpg cars. All miles I can drive with electric drive or high mpg ICE are replacing 18 mpg diesel, so Emissions are in my calculus....


· · 7 years ago

Certainly the pre-purchasing concept is a reasonable one but it depends a lot on the future price of gasoline, what kind of a car you're comparing with, and the expected age the car will last. At a low $3.00/gal, without heavy subsidy, you'll still come out better by buying a $1000 old used car and milking it for as long as you can.
If you're comparing with a middle-of-the-road new car such as an Accord then a heavily subsidized car like the Leaf may work out financially for you, even today, especially if you are a heavy commuter. With the $7.5K federal and California's $5K tax breaks, a $34K Leaf can be had for $21.5K. Compare that to a $27K Accord V-6 (comparable performance) and the Leaf will win. There's no question if you compare with a $34K BMW 328i. But, compare with a base Kia Rio at $12K and you'll probably lose money with the Leaf.
Its hard to predict a lot of the EV costs today so it will be hard to determine a lifetime cost:
-How much will the replacement battery cost in 10 years?
-How will the rest of the car hold up in 10 years?
-Will all of the auxiliary junk (power windows, mirrors, remote entry, radio, upholstery, paint, rust, etc) hold up or will you want to junk the car just because all the little things are falling apart?
If everything is designed to last, the EV should last nearly forever, with batteries that could cost less than $5K for a 100 mile battery pack - every 10 years. This will easily offset the up-front capital costs. Your operational costs should be very minimal.
We can analyze this to death but, in the end, without any useful data to analyze its all academic.
I'm not a big proponent of government meddling because they generally screw everything they try to accomplish up. I, personally prefer to count on a few rugged visionaries taking a few risks to blaze the way. They will find out by foregoing their BMWs and sucking it up a bit to do the right thing for their kids. This way, we can actually get some real information and run the prices down so everyone can afford them.
Tesla owners are already doing this and I credit Tesla and their owners for the resurgence in EV production after the miserable failure by the government the last time. The measly subsidies that the government takes from everyone and plans to give to the EV purchasers came about well after Tesla had embarrassed the auto industry by proving what could be done.
If you don't feel you are ready to lay out the money for an EV today, that's ok. Don't. You can do just as much good if you:
- keep whatever you're driving today as long as you feel you can
- tell your favorite car company you will buy a plug-in when they build it.
- be fiscally responsible so that you can afford that EV when it comes out. You'll be saving a lot on car payments by keeping your old car. Save it!
- if you absolutely must buy a car, look at used hybrids or something else, cheap so you will be ready for an EV when its available at your price.

· Jeff N (not verified) · 7 years ago

The article says:
"For San Francisco, near where I live, I used a CO2 average of three different grids (from eGrid)—listed in kg/CO2 per kWh as .36, .45 and .66 (this is right now)—to indicate emissions for 15,000 miles of driving as follows:

4,345 pounds of CO2 for the EV
That’s tremendously cleaner than the 30-mpg car’s 11,850 pounds of CO2
It’s also way better than the 50-mpg hybrid’s 7,110 pounds of CO2"


As another example of how volatile these numbers can be, San Francisco is served by PG&E and they self-report their average CO2 emissions for retail customer electricity as .524 Lbs. per KWh which is .145 Lbs. per mile (using 3.6 miles per KWh) which is 2,183 pounds of CO2 for 15,000 miles.

That's almost precisely half the CO2 you calculated for an EV in San Francisco.

Google: "pacific electric co2 kwh" and click the first link for the PG&E "assumptions.pdf" file.

· Aaron D. Allen (not verified) · 7 years ago

Why does everyone assume that oil is so bad? As far as gas car emmisions go they account for only a small fraction of the total gaseous toxins being introduced into the atmosphere, most of it is industrial pollution. Oil companies buy crude oil from the Middle-East and other less developed area of the world, and then they convert it into gasoline and other usable products. The profit margin for Exxon and other companies, many of them American, is huge. Without the taxes generated by these companies the American economy would collapse. So please think twice before you say bad things about the oil companies.

· · 7 years ago

@Aaron D. Allen


Your post is dead wrong on so many aspects. i've to congradulate you on your high errors/words ratio there.

I'll just touch upon one thing. Instead of the tiny amount of tax the oil generates, if we stopped spending on that money "securing" oil in the middle east (say a Trillion dollars in the last decade, for eg.) - then we would having a roaring economy than a great recession we have now.

· · 7 years ago

Hi Brad,
I'd have to say that your site is addictive. I should be doing other things, but wanted to respond. The method for measuring “greenness” and “goodness” of vehicles caused my falling out with the X Prize people, so it is an issue near and dear.

I have not read through all the replies, nor have I read your calculations, (and will do both when I am not running out the door). But the short answer is this: until last week, the EPA published CO2 numbers for the 2002 RAV4 EV, and for (of course) the Prius. The numbers are essentially the same, So that today, with the current grid mix, the two vehicles are identical from the standpoint of CO2 generation, which for me is a key concern. (Point source vs central source, etc, are largely distractions from the central issues.)

RMI uses a chart, in promoting EVs, that shows this fact, but they contend (correctly) that in many areas, our generation is done at better than the national grid average. This same chart is used by Peterson at Seeking Alpha to “dis” EVs. He (correctly) contends that, at night, more coal (base load generation) is used, making charging time more carbon-intensive than the grid average. He then draws many conclusions with which I have argued at length.

That is the too-short answer, so I'll come back to this very good and important thread.

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