Environmental Benefits of Plug-ins Called Into Question

By · July 30, 2010

With roughly $6 billion in incentives for plug-in vehicles working its way through the United States Congress as part of the trimmed-down energy bill, the question of how much cleaner EV's actually are, has re-emerged.

The Great 'Zero-Emissions' Debate

BMW ad

Recently, BMW was forced to pull an advertising campaign from British media markets after the Advertising Standards Authority decided that the ads were misleading in their description of the Concept ActiveE as a “zero-emissions” vehicle. The campaign's tagline, "100 percent joy, zero percent emissions," was found by regulators to misrepresent the lifecycle carbon footprint of the car, because much of the electricity used to power plug-in cars currently comes from burning coal.

This isn't the first time that a carmaker has run afoul with the ASA for claiming to sell a zero-emissions product. Renault has twice been banned by the watchdog for the a similar offense—with their second ad having been amended to claim only a 90 percent reduction in emissions. Even though that statement was found to be true in the company's native France, the French electricity generation mix is cleaner than Britain's, meaning that emissions savings over diesel would be lower in the U.K.

So Just How Much Better Are Plug-ins?

The disagreement over how to classify emissions from EVs is an old one. Plug-in fans see the glass half-full: Since the vehicles themselves produce no emissions and are theoretically capable of running purely on renewable energy, why should they be blamed for society's refusal to move off of dirty, coal-powered electricity? Skeptics say that using 'zero-emissions' terminology is fundamentally misleading, and serves no purpose but to distort the environmental benefits of electric cars.

Both sides have a point. If manufacturers and supporters of electric cars are going to use lifecycle emissions in their arguments against ethanol, they should at least be willing to admit that under most current conditions—and absent an expensive and well-designed renewable energy setup—charging an EV will result in some level of carbon emissions.

Solar Parking Lot height="269" />

The debate over just how big those emissions are is even more contentious and difficult to resolve than any semantic argument over advertising slogans. The U.S. Department of Energy has estimated total carbon savings from electric vehicles to be about 50 percent compared to ICE's. That calculation uses the current combined fuel economy average for the United States (about 22 mpg,) but doesn't take into account the effect that hybrids and more efficient gasoline and clean diesel cars will soon have as more and more are rolled out to meet future CAFE standards.

A Ford-funded study out of M.I.T. found that when vehicles are powered by electricity derived from nuclear and renewable energy, they provide vast carbon savings over gasoline-fueled autos. But if that electricity comes from the currently available mix of coal and other emissions-heavy energy sources, the study says that emissions are actually higher.

The M.I.T. study has come under heavy criticism since its release, and is a bit of an outlier compared to the other limited research that has been presented on the subject. Nevertheless, representatives from the Auto Alliance and advocates for competing fuels like ethanol have used the findings to argue that it's far too soon to "pick winners" in the clean fuels race.

NRDC Says Already-Significant Carbon Savings Will Only Get Bigger

According to a report from the National Resources Defense Council and the Electric Power Research Institute, plug-in vehicles that rely primarily on energy from coal provide a significant emissions drop-off over conventional cars. The 18-month study looked at nine different scenarios involving different energy mixes and rates of electric vehicle adoption, finding that each scenario represented an improvement over petroleum based fuels.

Of course, the biggest immediate carbon pay-off for EVs will come in places like the Pacific Northwest, where renewables already make up a significant portion of the energy mix. As other regions blend in more and more renewables, they should see increased benefits as well. Advancements in the power grid should also pay big dividends, and overnight vehicle charging saves energy by helping to even-out demand for energy between day and nighttime consumption.

No Easy Answers

Coal Plant

Though the environmental benefits of electric vehicles currently vary depending upon region and usage, nearly all of the available research on the subject indicates that they represent the cleanest available transportation technology that doesn't require pedaling. But the discussion does underline an important issue that will need to be addressed as the world works to get off of fossil fuels and reduce greenhouse gas emissions. If the electrical power we use doesn't get cleaner—and the methods we use to distribute it don't get more efficient—replacing gasoline with electricity will only make a modest dent in global emissions.

Even as the world's leading car culture, the United States is estimated to derive less than 30 percent of its overall carbon emissions from transportation. In order to maximize the positive impact that the electric cars of tomorrow will have on the environment, a lot of work has to be done to clean up the infrastructure that they plug into.


· · 7 years ago

In writing this post I had a certain degree of difficulty tracking down research that could be easily contrasted. Some studies focus more on the projected effect of long-term EV adoption, while others look at this purely from a kW to CO2 perspective. If anyone knows of other studies or papers that might shed some light on this question, please share them.

· · 7 years ago

I wonder if they would be OK if they changed the wording to "Zero tailpipe emissions"?

After 6 months with my MINI-E I realized that I wanted to drive an electric car from now on. I then installed an 8.8kwh solar PV system. It produces enough electricity to power my EV and most of my household electricity.

There are many other MINI-E drivers that did the same thing, in fact I'm going to a "solar + MINI-E" party on Saturday as a fellow MINI-E driver in NJ is celebrating his just installed solar system with a BBQ.

I believe others will follow this model and you will see many LEAF & Volt owners installing solar PV systems at their home. I had always thought about going solar, but it wasn't until I had an EV that I realized I really should install one now and take advantage of the great combination of solar and electric cars.

With electric cars you CAN power them with clean, renewable energy that you produce yourself. You can never say that about gasoline or diesel.

· · 7 years ago

Nice job on the story.

A few points (some of which Tom already made):
1. Unlike ICEs, plug-ins can be powered by fuel generated by renewables. That's a hugely important difference.

2. If we're going to go upstream on plug-ins, let's also do so with ICEs, whose tailpipe extends to the coal plant smokestacks and to natural gas wells (big emitters of methane, etc.) via the oil refining process.

3. It's not just about CO2. It's also about carbon monoxide, nitrous oxide, sulfur dioxide, ozone, particulate pollutants and, finally, our lungs in urban areas. On these counts, plug-ins win, hands down.

4. I think zero emissions is generally misleading. I agree that Zero Tailpipe emissions is better -- although in Tom's case, and soon in our case, where people do EV+PV (or EV+wind, etc.), we truly are talking about Zero Emissions.

5. Tom, would love to hear more about the party, possibly even do a story on it and/or on the person who's hosting it.

· Magnus (not verified) · 7 years ago

Great post.

You could read och discuss:

T. J. Wallington, M. Grahn, J. E. Anderson, S. A. Mueller, M. I. Williander and K. Lindgren (2010) Low-CO2 Electricity and Hydrogen: A Help or Hindrance for Electric and Hydrogen Vehicles? Environ. Sci. Technol., Article ASAP

doi: 10.1021/es902329h

A short review of the article:

· Folsomev (not verified) · 7 years ago

Just say "zero tailpipe emissions."

Don't forget all the electricity used in the refining and delivery of gasoline.

· Steven (not verified) · 7 years ago

Some questions:
1- Zach mentions the benefits of evening out the demand for electricity by night-time charging of EVs. I (believe I) was told by someone who used to work for a local electric utility that is powered almost totally by coal that it is not possible to spin down coal-fired generators for short periods of time - like overnight. The spin-up time is so lengthy the generators must be fueled at enough of a load to reach desired generating capacity each day. In other words, it appears that a large percentage of the fuel for coal-powered generators is currently being wasted. Utilities can use natural gas generators which have a much shorter spin-up time or buy power from the grid. But that is much more expensive.

2- Christof hints at but doesn't clearly state another potential advantage of plug-ins. It is much easier and less expensive to install 'tail pipe scrubbers' on the smokestacks of coal-fired eletric utilities than on hundreds of millions of cars. (Just ask GM with the Volt.)

3- I've yet to find definitive information on the energy costs of manufacturing either PV panels or the battery packs that go into plugins. (I've heard estimates the energy payback on PV could be as long as 7 years. Most panels are warrantied for 20-25 years so even if this is correct it is worth doing.)

4- Is there a charging station that will allow you to draw from as well as charging an EV battery - iow use the EV battery as backup for a PV system?

· TrasKY (not verified) · 7 years ago

Here is the best comparison I have been able to find:
The worst case scenario, in which all electricity is derived from coal results in a statistically insignificant reduction in greenhouse gasses produced. This of course, doesn't take into account the energy used to mine and produce gasoline vs. coal, or the fact that coal is a domestically produced product.

· Steven (not verified) · 7 years ago

It might be kind of difficult to see the questions in the first 3 of my "questions" posed above. So I'm going to take another shot:
1- is it true that coal-fired generators have to consume a good chunk of the coal they would be burning anyway charging EV batteries just to be ready for the next day's peak loads?
2- is it cheaper, easier, more effective to install 'tailpipe scrubbers' on power company smokestacks rather than tailpipes?
3- is EV battery manufacturing energy-intensive? What is the energy return on energy invested for batteries? And PV if anyone knows?

Thanks, Steven

· Anonymous (not verified) · 7 years ago

A 2010 U.S. Department of Transportation analysis found that plug-in hybrid electrics vehicles can reduce greenhouse gas emissions by between 49 percent and 75 percent compared with a conventional vehicle — including the emissions created by plants generating the electricity the cars use.


· Anonymous (not verified) · 7 years ago

There's also the issue of what will happen when you shock the grid by adding a few million electric cars to the demand side. Slowly increasing (not to even mention replacing current plants) the electricity supply over a couple decades will allow a greater mix of clean energy, but if we have a quick spike in demand, utilities will be forced to go to the easiest (ie dirtiest) sources for that power.

Clean electricity requires a slower, measured approach. The question is, can we wait?

· · 7 years ago

Anonymous: If we added 1,000,000 EV's tomorrow it might be a "shock" to the grid, but that's not going to happen. We are talking about tens of thousands of cars slowly added over the next few years across the entire country. There really won't be a shock, just a slow, gradual increase in demand.

Plus, most(as much as 75%) of charging may take place overnight when we have a surplus of electricity. These cars can be programmed to charge at any specific time to utilize off peak rates if available, but still most people will simply charge while they are sleeping.

Also, like I stated above, the many people that can invest in a solar electric system will, like I did and this will help the grid not hurt it, as feed the grid during high demand(daytime) and charge during low demand(overnight). I really only invested in the solar system because I plan on driving electric cars from now on and I wanted to lower my fuel costs for the next 30 years or so. In this regard, the proliferation of plug-ins can actually help the grid by providing many points of local generation instead of relying entirely on the powerplants to supply our electric.

· Paul A. (not verified) · 7 years ago

A few points that are apparently missing from this article and comments:
1- urban use (involving KERS) compared to highway use (no braking, therefore all energy is used to overcome aerodynamic and mechanical resistance) indicates much better savings of CO2 for the former, and basically no savings for the latter.
2 - cost of ownership: the EV+PV, while admirable environmentally, is financially well beyond "average" domestic budgets.
3 - longevity of batteries: two aspects, first they do not last as long as an ICE and are more expensive to replace and second the "charge in" increases and "power out" decreases substantially with age, well prior to final replacement.
4 - "smart meters" allowing charging at lesser cost in the middle of the night do NOT save energy as stated in the article ("overnight vehicle charging saves energy by helping to even-out demand"). While they might save costs, they significantly increase CO2 (coal fired plants, see comment by Steven, point 1)
While the bottom line is that EVs can and do have some positive effect on CO2 emissions and that this is likely to improve as technology advances, the economics are much less evident - and much of this at taxpayers' subsidies expense. It would be most useful to see numbers for "cost per passenger mile" urban and highway. I am trying to budget my [limited] dollars to reducing CO2, and this article does not give sufficient information.

· Anonymous (not verified) · 7 years ago


You pretty much proved my point. There are 250 million cars in the U.S., and 1 million would be a "shock" to the system, according to you. You're talking about "tens of thousands of cars slowly added over the next few years across the entire country". At that rate, it will take more than 1,000 years to replace our vehicle fleet with electrics.

On the other hand, we could rapidly change over the fleet, but stress the system and force us to use more of the same dirty sources of electricity we use today, while sending electricity rates through the roof.

I think we need a solution that works in the internal combustion engine.

· Anonymous (not verified) · 7 years ago

Correction. If your "tens of thousands" is 50,000 (I assume it's less than 100,000, or you wouldn't have said "tens"), that would take 5,000 years. At 100,000, it would only take 2,500 years!

· Anonymous (not verified) · 7 years ago

Your solar system on individual houses idea is great (in some parts of the country), of course. But you’re not going to get most Americans to buy into a system in which they have to significantly change their habits or make modifications to their homes and vehicles.

That’s just the unfortunate reality, and that’s why it’s got to be something like a drop-in fuel or biofuel, something that is at least similar to what they’re used to using now.

Try to force people too far out of their comfort zones, and they’ll fight you at every step. And if the people don’t back it, the politicians won’t back it. If the politicians don’t back it, it won’t happen.

And how long can we wait for the electric infrastructure to get built up, EVs to be affordable, battery technology to improve and public sentiment to support it all? The problem needs a "now" solution while we continue to find even better solutions for the future.

· · 7 years ago

Ok, you're right, its hopeless. Let's just give up and let our society decay as gas prices increase while we're waiting for a perfect solution that won't require anyone to change anything or spend any more on anything.
While you're waiting for your perfect 'Now' solution, the rest of us will work on actually making some changes. Some of us more ambitious dreamers are already buying EV + PV which is bring the prices of EV and PV down by increasing demand which will also increase the quality.
I also think you took Tom M's 1,000,000 EV number too literally. Adding an EV to the grid won't have any more affect than adding a new air conditioner or pool. Minor upgrades adding more existing technology (a few new transformers) will be needed in some places although night time charging will preclude it in most places. Additional generating capability won't be needed because of the natural nighttime usage pattern as well so all that is left is the energy to generate the electricity.
Interestingly enough, having an on-demand energy use as an EV does will make non-steady energy sources such as solar and wind more viable to add to the grid. An EV driver who's car is plugged in only needs about 1 kWhr per mile driven per day. Since most cars sit for most of the time, this 1 kWhr can be added whenever the electricity is available, not at any particular time.
Adding solar panels to your roof after you start driving an EV is a natural attraction (as is an EV after you install PV). It's even affordable if you consider that you're just buying your energy from a Home Equity Loan payment instead of the gas station, except that your energy price is fixed and can't go up. It is similar to owning a house versus renting it.

· · 7 years ago

oops! error, I said "needs about 1 kWhr per mile driven per day". I meant "1 kWhr per 4 miles driven per day."

· Freddy (not verified) · 7 years ago

Without an ICE engine and tranny and no exhaust components EV will be lighter of that weight and so can compensate for the battery weight.

· Anonymous (not verified) · 7 years ago

Read my comments, ex-EV1. I'm not saying do nothing. I said drop-in fuels, biofuels are the answer. Maybe in hybrids.

Your solution is decades from realization, and we need to act now with what we have.

· Anonymous (not verified) · 7 years ago

Your solution is "It's hopeless, let's give up" since it pretty much sentences us to decades of reliance on, gasoline while the vehicle fleet turns over and coal while the electricity sources turn over.

Biofuels, on the other hand, are here today. You can use them NOW. As in RIGHT NOW. As in, any single person who owns a vehicle and is reading this can start using more of them RIGHT NOW.

And it doesn't require them to get a new car or change the electrical grid. Bingo.

While we use them RIGHT NOW, we continue to develop even better ways to make them for the future.

And don't believe those BS oil talking points the media's been throwing out about biofuels for the past few years.

· · 7 years ago

I used the "tens of thousands over the next few years" because that's all that will be available for sale so even if every Volt & LEAF that is made sells it won't be until 2013 that we have over 100,000 of them on the roads here in the US.
There have been plenty of studies that show we have a huge surplus of electricity during off peak hours which is when the overwhelming majority of EV charging will take place.
As ex-EV1 driver stated, "adding solar panels to your roof after you start driving an EV is a natural attraction" this is really true. Being part of the MINI-E program I have met and keep in touch with many of the others in the program. Many of them, like me, installed a Solar PV system after they got the car and realized how great the combination is. Since many of us loved the car so much, we decided that we will be buying an electric car once they are available so we might as well set up the solar refueling station at home now. Now before you chirp about how expensive a solar system is, and nobody but rich people can afford one, you should realize that there are plenty of companies that will install solar systems for no money out of pocket, or will provide guaranteed 100% financing. Then there are utilities that will finance the system for you if you want them to. PSE&G in NJ has a program for it. My system will pay itself off in 5 years and after I'll put about $8,000/year in my pocket with the electricity savings and the green tickets(SREC) I'll get. Plus, it adds tangible value to your home. Statistics show a home with solar electric sells on average for $25,000 more than a comparable home and 20% faster.

Electric cars on the roads will initiate a huge increase in home based solar PV systems. I am 100% certain of that.

· Anonymous (not verified) · 7 years ago

I believe in ethanol, methanol, butanol, hybrids, etc. in every combination. But I do not believe we can flip our fleet to all electric. That's a bad idea for the environment and our economy. Everything in moderation working together will ultimately keep us from getting back into the trouble we're in today with oil.

You can't use all the corn to make ethanol, but you can use some. You can use some grass to make ethanol or butanol. You can use some wood waste, but not chop down forests. You can use some electricity as long as its at a pace where it can be increased with renewable sources ONLY.

For instance, you can't use all the country's corn to make ethanol. That's dumb. But we should support using a reasonable amount of corn to make ethanol, since there has always been an incredible surplus in the US (war, govt corruption causes world hunger, we've always overproduced food BTW). That gets rid of some oil.

We can use hybrid technology that's already implemented today. That gets rid of some oil.

We can reinstall the methanol program California used in the 1970s that worked but got no political backing. That gets rid of some oil.

Then, if one source becomes unsustainable, we have multiple fall-back options.

I thinks it's wasteful and a folly to try to move to all-electric vehicles.

· Anonymous (not verified) · 7 years ago

And if you're talking about tailpipe emissions only, then ethanol should get a lot more credit than it does, since most of its carbon penalties are due to farming inputs, not actual tailpipe emissions.

Apples to apples.

· · 7 years ago

I guess you're on the biofuel side. While I have no fundamental problem with biofuel, nature or planet earth aren't so open minded. It all comes down to miles driven per acre of land.
Depending on where you are, it would take many state's worth of land and water to produce enough bio-fuel to meet our energy needs. We just plain don't have enough land in the US to do this.
With Solar energy, a patch of desert land in the Southwest US of approximately 100 mile X 100 miles can produce enough electricity to meet all of our electricity and driving needs and it won't even need any water.
Plant production just isn't so efficient.
Let's keep our bio-fuel for those applications where we absolutely must carry a lot of stored energy such as for rural areas and farming and let the big cities convert over to electric. It won't be nearly as hard as you make it out to be.

· · 7 years ago

I've reserved a Tesla Model S.

I will buy into a private cooperation which operates wind turbines. (Big turbines, as small turbines are far less efficient. ca. 1500 members, 6 wind turbines )

I will have a true zero emission vehicle. Where's the problem?

· Anonymous (not verified) · 7 years ago

No problem for you Ad, and congrats. Do you think that's an option for the other 300 million people in America, though?
Flex fuel hybrids are the answer. Reliance on one energy source is our biggest problem. Everything in moderation.

· · 7 years ago

Clearly, there is not one single answer to our needs for energy independence and environmental protection. Thankfully, here on God's green earth, we have been blessed with many options. Biofuels will play an important role. But the real beauty of electricity is that it can be generated in so many different ways, without end users knowing the difference. Electric vehicles will allow us the flexibility to draw from diverse, domestic energy sources, including nuclear, clean coal, solar, wind, hydropower, etc. And EV costs will come down.

· · 7 years ago

Probably should be a subject to itself,but did anyone know to date that a special blend of gasoline is produced for all manufactures of auto's for EPA Milage testing uses same basic Octane rating but dif. blend
to be constant.also @ this point it does not take in account ethanol.to Date !

· Freddy (not verified) · 7 years ago

1 - Eventually the car makers can put a solar panels on the roof and hood to trickle charge the batteries.

2- The traditional gas cars have a lot more parts in them that
takes electricity to manufacture.
Electric cars have fewer parts in them to be manufactured.
So they are less poluting in that sense.

3 - Electric cars have less parts to be disposed of when the car goes to the wrecker.

4 - not as much brake dust

5 - no oil and coolant and other fluids to dispose of.
no oil to go into the ground or into the lakes.

I hear it all the time about how electric cars are no good - blah blah blah.

People against the electric cars are brainwashed puppets of the oil industry.

I hope this current electric car momentum doesn't go down the drain like the EV1.

You gotta see the DVD: "who killed the electric car?"

I got a copy at my local library.

· Freddy (not verified) · 7 years ago

Since electric cars have less moving parts than ICE cars,
then the manufacturers should be able to give electric cars longer warranties, (10 years ?) which will help get more people into electric cars.

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