Plug-in hybrids: even old coal is better than gasoline (but renewables are best of all)

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All the cool kids have been linking to a new report that concludes plug-in hybrids are a potentially significant source of greenhouse gas reductions if adopted on a wide scale in the United States. This conclusion is not surprising — conventional wisdom has favored plug-ins for a while — but the study’s use of sophisticated models and scenario analysis puts some hard figures around the possible benefits.

Plug-in hybrids, as you probably know, are a form of hybrid-electric vehicle that you can charge by plugging into a wall socket. Although not yet commercially available, the technology is not exotic. You can buy a conversion kit for your Prius for about $10,000.

Update: The cost of a conversion kit does not indicate the cost to an average car buyer. The study projects trends out to 2050. When plug-ins are mass produced, assume that the vehicles will cost roughly the same as gasoline-powered cars do today.

The report mapped out nine different scenarios by varying both the market penetration of plug-ins and the carbon intensity of the U.S. electrical grid. In even the most pessimistic scenario, plug-ins result in significant emissions reductions. In the median (and presumably most likely) scenario, plug-ins shave about half a gigaton of carbon from annual U.S. emissions. To put this in perspective, this is about 10% of the reductions we need to stabilize the climate. Not bad.

The study’s authors also modeled changes to air quality under each scenario. One criticism of plug-ins is that, by shifting fuel consumption from cars to electric utilities, they potentially concentrate particulates and other nasty emissions in certain geographical areas. The study mostly allays these concerns. A small number of areas do see an increase in pollutants, but the large majority of the U.S. will experience a meaningful improvement in air quality.

Because plug-ins run mostly on electricity, their environmental benefit depends heavily on the carbon intensity of the grid. If your local grid is powered by old coal plants, plug-ins actually emit slightly more emissions than regular hybrids (but still far less than conventional cars). In aggregate, though, plug-ins are somewhat better than hybrids using even today’s grid, and the benefits quickly grow larger if we assume future legislation further tilts energy production towards cleaner technologies.

This is a story we like a lot for two reasons that don’t get emphasized often enough: the first is that plug-ins are commercially realizable in the very near term. We can’t wait for exotic technologies to save us from climate change. The second is that plug-in hybrids don’t require significant changes to consumer behavior. Somewhat perversely, some environmentalists see this as a negative. We don’t. The more comparatively easy reductions in greenhouse gas emissions we can find, the better.

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  1. Riddim Guy - July 25, 2007

    Call me stupid, but I don’t understand the chart with this article.. Where is the legend that allows a layman to read it?

  2. Brad - July 25, 2007

    Hey Stupid! No, I’m just kidding, you actually do need a legend to truly understand that graph.

  3. richard schumacher - July 25, 2007

    From the original report:

    Blue = gasoline, well-to-tank
    Red = gasoline, tank-to-wheels
    Yellow = electricity well-to-wheels

    The “High CO2″ scenarios shown here assume that most electricity generation continues to come from fossil fuels without significant CO2 capture. The original report also discusses other scenarios.

    Notice that if all electricity came from CO2-neutral sources (nuclear, wind, hydro, Solar) the yellow portions of the bar graph would entirely disappear.

  4. richard schumacher - July 25, 2007

    Also, PHEV10/20/40 means results assuming a fleet of vehicles with an average electric-only range of 10/20/40 miles, respectively.

  5. Al - July 25, 2007

    I suspect that the operation of the hybrid assumes that neither air-conditioning or heat is required. Using either of those would drain the batteries very quickly. Of course we could bundle up in cold weather and keep the windows open in hot weather, but I doubt if that appeals to very many. That has and will be the downfall of electric cars, including plug-in hybrids.

  6. Andrea - July 25, 2007

    I’m curious as to how would this affect consumers’ electricity bills? If the conversion kit would cost an additional $10,000, on top of the original cost of the car, an increase in other bills could really make this unfeasible for a lot of people.

  7. Corky - July 25, 2007

    While the “PHV” craze is a great idea for those already owning hybrids, what about the rest of the world? I own a Prius and looked into the conversion kit–$10K! I’ve talked to lots of folks who would love to own a hybrid but cannot afford it–now we are working to make it even more expensive in the guise of improved emissions/mileage–all noble concepts but fully impractical for the general public! What if we took all of our energies we are expending to modify the American “horseless carriages” of the past two centuries into something they aren’t and actually conceived/built the “hyper car” described in “Natural Capitalism”? What if we found a way to help every American own an energy efficient, environmentally safe, and completely recyclable transporter instead of vehicles that only wealthy folks can afford? Does anyone else see anything wrong with this picture but me?

  8. Anonymous - July 25, 2007

    Call me stupid….but when you plug in your hybrid, the electricity is being produced by Coal, Natural gas, etc……does this really help? If so By how much? I would think we should over increase the size of our PV arrays to cover the Plug in hybrid.

  9. David - July 25, 2007

    I find this article to be a misleading plug for “plug-ins”. Larger batteries have their own toxic disposal issues that haven\’t been fully addressed, and often involve shipping long distances for any recycling that may be desired. I agree that the graph without a legend is not very useful.

    Furthermore, as a resident of a “dirty coal” state who already drives a hybrid and bikes to work, I noted with interest that:
    “If your local grid is powered by old coal plants, plug-ins actually emit slightly MORE emissions than regular hybrids (but still far less than conventional cars).”

    I am unsure what to make of the statement that, “In aggregate, though, plug-ins are somewhat better…” Whose aggregate is that? Not my utility\’s. Not my state\’s, probably.

    Also, the aside that, “A small number of areas do see an increase in pollutants…” should not be ignored. I assume that would include towns like Cheshire, Ohio that suffer under the nearby smokestacks of the large coal fired electric plants and have been partially abandoned as a result.

    My utility\’s electricity is all coal and nuclear. Therefore, I think I\’m better off investing in conserving, and driving my hybrid, and in biking or taking the bus to work.

    The best redeeming quality I can think of for plug-ins is they would charge at night, when the grid load is less anyway. I have to wonder about the old, inefficient centralized coal fired power plants, electric line transmission losses, and other factors that mitigate this “plug in” nirvana.

    And, pardon me, but 10 percent of the way there is not far enough. I suspect that tougher choices will need to be made soon as well.

  10. Mary Florence - July 25, 2007

    I\’ve always thought that once they marketed the plug-in hybrid, the car makers should offer an optional rooftop solar collector package for your house or garage to replenish the battery when it is parked at home. Also, why not offer a car with optional solar panels built into the roof for powering the air-conditioner on hot summer days?

  11. Bruce - July 25, 2007

    Actually, the assumption that using heat or AC will drain the batteries quickly is wrong. I drive an all-electric Toyota RAV4-EV which uses a heat pump for heating and cooling. It is very efficient (just like the heat pump on my house) and only results in a minimal decrease in range. In fact, I don’t even know what the decrease is since I never really notice it.

  12. Shane - July 25, 2007

    This idea is all well and good for people who can afford it…but what about simple, DIY ideas to make your own old gasoline car drive cleaner? Is there any way to convert an existing gasoline engine (say for a 1990 Subaru) into something environmentally friendly(er)? I would be very interested in hearing some of those ideas, since the likelihood I’ll ever be able to own a hybrid or electric car is very slim.

  13. Adam Stein - July 25, 2007

    Hi all,
    Couple of comments:
    1) Sorry about the cropped chart. This is a pretty lame excuse, but it’s really just meant to be a pretty picture accompanying the post, not a full graph. But I can see why this causes confusion, so I won’t do this in the future. As always, I do recommend clicking through to the report itself if you want the details.
    2) No one is suggesting that Americans go out tomorrow and spend $30k on a hybrid plus plug-in conversion kit. This report analyzes a period of time going out to 2050, which is enough time for technology costs to drop considerably and for the entire U.S. fleet to turn over several times. The conversion kits are expensive in large part because they’re offered as a one-at-a-time add-on to a car that’s already been built. Obviously the technology would be much cheaper in mass production, and costs will drop over time. In fact, the scenarios basically envision a future in which conventional gasoline cars pretty much go away by 2050, which seems to me to be reasonably likely.
    3) One has to assume that the detailed computer model the report is based on accounts for the fact that in the real world consumers use heat and air conditioning.
    4)

    when you plug in your hybrid, the electricity is being produced by Coal, Natural gas, etc…does this really help? If so By how much?

    Yes, it does. This is the question the study addresses. How much it helps depends on which of the nine scenarios comes to pass, but the median case seems to be about half a gigaton of CO2 by 2050 — which is a lot.
    5.
    I am unsure what to make of the statement that, “In aggregate, though, plug-ins are somewhat better…” Whose aggregate is that?
    The U.S. aggregate.
    And, pardon me, but 10 percent of the way there is not far enough.
    Yep. If I were to put numbers around it, I’d say it’s about 10% enough. This represents considerable progress.

  14. Andy Angelos - July 25, 2007

    Corky’s concerns point to the fundamental problem of altering technologies rather than instilling the public with a new culture (Understandably a more difficult task).

    Switching to plug-in hybrids is an acceptable temporary solution, but is in no means a move toward “stabilizing” the climate. Human nature demands expansion(In terrain, possesions, offspring, etc.) which places increased burden on the facilities using coal, natural gas, or wind to generate the electricity for our vehicles. The benefits of plug-in hybrids could quickly vanish if a content populace continues expansion as normal.

    When will Steorn’s free-energy technology come to fruition?

    [Ed: -- We hear the Steorn Mr. Energy home perpetual motion machine will be available soon in Sharper Image and the Sky Mall catalog!
    P.S. You were joking, right? Right?]

  15. Jim - July 25, 2007

    Good point Andy (Comment No. 14). Humans behave, and I hope to not offend anyone here, almost exactly as cancer cells in that we grow for no apparent reason other than for growth’s sake. Eventually we will kill our host and suffer either total extinction or severe population declines. As Al Gore said (and I paraphrase); “…that human population growth will be tempered is not in doubt. The question is will this be done humanely by us or harshly by nature.” (Or something like that). The point is, as Andy pointed out, us humans are driven to expand, reproduce, and proliferate. As with all life it is the fundamental basis of our nature whether we like to admit it or not. There are studies that indicate that the world’s population will eventually stabilize but unfortunately it will not be much fun. I just hope that our congress can take responsibility and put forth some legislation that is pro-green and not pro-big business in order to make this a more humane ride. Then again, when was the last time congress did something like that?

  16. Al - July 25, 2007

    To Bruce:
    I live in an area that has been over 90 for all of July, and in the winter falls to 20 below quite frequently. Heat pumps are not usable much below freezing, and even when they are in optimum conditions they don’t put out more than twice the energy input. An air conditioner for a car might require about a kilowatt to operate. Electric car batteries for a short range vehicle only hold a few kilowatt hours, so the air conditioning load is a big percent of the total storage. You might live in an area with a quite moderate climate, where the heat pump approach could work. Most heat pump systems switch on the resistance heaters when the temp drops below freezing.

  17. M.J. Christensen - July 25, 2007

    There are also alternative fuel vehicles available that will make a significant difference, as well. A great example, and one that has been ignored since Bush cut funding for programs, is Compressed Natural Gas. Honda still makes a CNG-Powered Civic (the Civic GX – we own one) that runs exclusively on natural gas. I read an article recently that the emissions for one Civic GX for 100,000 miles are less than what is put into the atmosphere by spilling one quart of gasoline on the ground. (How often does this happen?)
    Is this THE alternative – no, but it is one step in the right direction. And, if you live in an area where CNG fueling stations are prevalent, you can see significant cost savings as well as emission savings. We, unfortunately, live in Denver, where the CNG is controlled by a monopoly which charges some of the highest rates in the country – $2.499 per gallon gasoline equivalent. In the Salt Lake Valley of Utah, the price is about 75 cents per gallon (gasoline equivalent).
    This is a great first step for those of us who can’t afford $35,000 worth of car and conversion to reduce our environmental impact. My everyday driver is a CNG-ONLY 1996 Ford Crown Victoria. It’s carbon emissions are estimated to be less than a gasoline Civic (though not quite as good as a hybrid, it’s close). It cost us $1200 three years ago, and I think with regular maintenance, brake job, etc., we now have about $2000 in this highly reliable vehicle (which, incidentally, is fun to drive, comfortable, and has kick-ass A/C)
    My partner drives the 1998 Civic GX. All-told, we have about $3200 in purchasing and restoring this vehicle (it was off-fleet and needed some work to make it a good daily driver again). It gets over 30 MPG on CNG, and is actually rated as clean or cleaner than a hybrid.
    I’m not saying hybrids aren’t a good step – or that plug-ins aren’t even better – I’m just saying for those of us who are on a tighter budget, there are great alternatives that help reduce our impact.
    Kind regards,
    M.J. Christensen

  18. Adam Stein - July 25, 2007

    Just to emphasize — the new study does not suggest that we should all buy $35,000 plug-in hybrids. It’s not a green guide for car buyers. Rather, it’s a look at what the impact of plug-in could be over the next four decades if the technology goes into mass production.
    For car buyers today, this question is much simpler. Get the car with best mileage you can afford. For some this might be a hybrid. For some it might be an efficient conventional car. And then figure out ways to drive it as little as possible.

  19. Adam (not TerraPass Adam) - July 25, 2007

    I know of no more inportant specific technology that is more important than this one. MOST efforts should go into lobbying to governments (local, state, federal, and UN) and advertising to the conusmer about PHEV’s. Convincing people of the arguement that warming is real and that man can help should be secondary to focusing efforts on realizing actual hands on available technology that truly makes an impact. People want PHEV’s – make it priority one.

    Adam

  20. Ted - July 25, 2007

    Nobody has mentioned biodiesel, which is a great alternative to gasoline, at least in terms of carbon emissions. We traded our Prius for a Jeep Liberty CRD, and run it on biodiesel. However, on a recent trip to Iowa and back, it was very difficult to find bio; we were happy to be back in Washington state, where it is readily available.
    Yes, I am well aware of the potential problems with biofuels, as more and more croplands are converted to production for these fuels, but anything that any of us can do to relieve our oil dependance is a plus.
    TC

  21. Patrick - July 25, 2007

    I think the overriding point here is that plug-in electric overall reduces emissions significantly over other options (biofuels still result in emissions when you combust them in the engine.) At least we have a number of options as far as developing cleaner electricity sources. Moreover, the increased drain on the grid is expected to be minimal, given that most people work the day shift and would be recharging their batteries at night, when much of our energy is simply generated and wasted on nothing. Finally, new battery technologies such as Lithium Ion do not result in significant environmental issues during disposal – certainly not as much as the side effects of pumping oil, creating liquefied coal or even the energy required to pump, store and ship CNG. In the worst-case scenario, a LiO battery drops to around 80-85% of its original total range, which can still be considerable if you own something like the Tesla Roadster.
    I’m glad to see someone finally was able to put together a study that incorporated as many of the factors involved as possible. Adam (Stein), if you happen to have a link to the original full report, I would really like to see it.
    Thanks,
    Patrick

  22. Patrick - July 25, 2007

    Whoops! Sorry Adam, missed the link in the first line of the article. Silly me!

  23. Anonymous - July 26, 2007

    The notion that Plug-in Cars have to be expensive happens to be a convenient myth that suits the current auto industry only. Hybrid-Electric cars double up on propulsion units, and yes they are more expensive than just plain ICE (Internal Combustion Engine). However if you remove the expensive parts entirely — the engine — and go for full battery electric then the mass produced cost of the Electric car comes way down. For starters you remove about 600 machined, assembled, lubricated and cooled moving parts. Battery costs for the latest technology (Li-ion, etc) are high right now. So were the first computers. Theres a good reason why Detroit doesn’t want to go to plug-ins. People will have to decide whether they want to pay 2 cents a mile for energy, or 15. They’ll have to decide if they want a car propulsion system requires virtually no maintenance, and will last a lifetime. They’ll have to chose from Zero emissions and the leading contributor to our lung h!
    ealth. Electric cars were proven during the CARB ZEV mandate of the late 90′s and early 2000′s in California. The auto industry crushed the EV because they don’t want to see their revenues shrink by 30% should the EV ever take market share. (Hydrogen Fuel cells maintain the high-cost high revenue paradigm) But Consumers should demand the battery electric car, such as the Chevy Volt and support up and comers such as Tesla and Phoenix Motorcars. In short order, they will be much cheaper than the ICE addiction we have now and, the world will be a better place for them.

  24. Liz B - July 27, 2007

    I always thought that direct energy is more efficient than indirect energy. To be more specific, that in the transfer and storage of power to a battery there is a net energy loss. A significant energy loss. Which means more coal burned than the equivocal amount of gasoline, yes?

  25. Aaron A. - July 27, 2007

    The study is quite encouraging, and I’d just like to point out a couple of things:

    1) Hybrids, such as those currently available, already represent roughly a 30% drop in emissions from well to wheel (compared to ICE).
    2) Those two columns on the right side, the median and optimistic projections, are analogous to the rumored specifications for the next-gen Prius (20 mile range) and Volt concept (40 mile range). Those are expected to hit the market in about three years, meaning that within ten years, used PHEV’s should be widely available, and today’s gas-electrics would be pretty cheap.
    3) If you live in an area like mine, where your power comes from natural gas, the yellow section of each column shrinks considerably.
    4) As Anon. #25 pointed out, the technology is still quite young, and it should only become cheaper with time. Within three years, in fact, Toyota’s engineers said they expect to close the price gap between hybrid-electric and ICE vehicles.
    5) I don’t recall anybody saying that this would solve climate change on its own. But it’s a big big step in the right direction.

  26. Adam Stein - July 27, 2007

    Liz –
    Energy is lost during transmission through power lines. However, utilities are way more efficient at creating power than a typical car engine. These two effects counterbalance one another, but overall, there is a net gain in efficiency.
    Allen –
    Thanks for the details. Interesting stuff.

  27. Patrick - July 30, 2007

    Liz,

    A surprising amount of energy efficiency (90+%)is lost in vehicles with internal combustion engines. I would highly recommend watching Dr. Amory Lovins’ presentation, “Winning the Oil Endgame.” He describes some very key points about auto physics and proposes a very viable way to reduce and eliminate our oil dependence in the next 40 years. The best part is that he only uses technology that is available today for his models, which means that progress could potentially be much faster once new technologies begin to develop.

    http://mitworld.mit.edu/video/346/

    On a related note, it is worth noting that many of those who do not wish to see change in their industry (usually the most powerful entities in that business sector) employ a logical fallacy to discourage investment in competing technologies. Basically their tactic is to point at the current state of technology in the as-yet undeveloped technology and proclaim that it is the end state (i.e., will never get any better than it currently is.) This was the case with solar energy; naysayers said that it would never be a viable energy source because it can only convert up to 20-25% of the sun’s energy at best. This spring, a team of scientists working with NREL developed a cell that broke the 40% conversion efficiency barrier.

    http://www.eurekalert.org/pub_releases/2007-07/drel-nst072007.php

    Lovins’ presentation deserves a great deal more exposure than it has gotten. Fortunately, he has been talking with Detroit’s Big Three, the DOD, and other producers and consumers of fossil fuels to discuss his ideas., but it never hurts to increase awareness at the consumer level.

    Patrick

  28. Patrick - July 30, 2007

    Note: the 90% energy loss is based on Lovins’ explanation of the energy used related to its ultimate goal (moving a person or cargo). Sorry if it came across as confusing.
    Patrick

  29. richard schumacher - August 1, 2007

    Anyone who cares enough to buy a PHEV when they become available should already be buying (read: paying more for) all-renewable electricity through their utility. Then when they get a PHEV there will be no question of using coal-fired power. My house buys wind-only power from Green Mountain, so we run our lights and air conditioner as much as we feel like, guilt-free.

    An earlier poster coupled the notions of increased consumption with increased progeny. This is historically not the case: going back at least as far as ancient Greece a higher standard of living always results in lower birth rates. More children are a net economic asset only in rural agricultural societies, and are a net economic burden for relatively rich city dwellers.

  30. Patrick - August 1, 2007

    Good point, Richard. Two points about guilt-free clean energy use, however:
    1. You may still be using coal and other, dirtier sources without knowing it. As we discovered in Portland with PGE’s wind program, we are paying more for our energy not because we can all use clean energy right now, but as an investment that will bring cleaner energy to us sooner. The actual capacity to power homes strictly with wind energy right now is fairly low in many areas, so it pays to check your power company’s energy profile.
    2. Regardless of the energy source, conservation is often the most potent way to improve our energy situation, since it only makes clean energy go further. Every watt you don’t use from wind can be used by someone else, and it doesn’t make sense to use more than one needs just because one can. Maybe someday this will be a non-issue, but I have a feeling that we’re going to go through some really tight times before we find other energy sources as cheap and abundant as oil has been.

  31. Patrick - August 1, 2007

    Good point, Richard. Two points about guilt-free clean energy use, however:
    1. You may still be using coal and other fossil fuel sources without knowing it. As we discovered in Portland with PGE’s wind program, we are paying more for our energy not because we can all use clean energy right now, but as an investment that will bring wind energy to us sooner. The actual capacity to power homes strictly with wind energy right now is fairly low in many areas, so it pays to check your power company’s energy profile.
    2. Regardless of the energy source, conservation is usually the most simple and effective way to improve our energy situation, since it only helps make clean energy go further. Every watt you don’t use from wind can be used by someone else, and it doesn’t make sense to use more than one needs just because one can. Maybe someday this will be a non-issue, but I have a feeling that we’re going to go through some really tight times before we find other energy sources as cheap and abundant as oil has been.