All's Well That Ends Oil

Umbra on biodiesel vs. hybrids 12

Dear Umbra,

I live in Massachusetts and am trying to decide whether to buy a hybrid or a biodiesel. Since it is cold here, I would need to use 20 percent biodiesel and 80 percent diesel in the winter. How does this compare with a hybrid’s emissions? Which would be better for the environment?

Tom
Conway, Mass.

Dearest Tom,

Either choice is a good one as long as you continue to find alternatives to driving, and your car-n-fuel expenses do not prohibit other environmentally beneficial acts (e.g., insulating your house).  These guidelines apply to everyone, not just you. I usually mention them at the end, but thought I’d try setting them up front.

Don’t drive yourself crazy.

A good passenger diesel car will get about 34 mpg, according to the EPA, and about 50 mpg or more according to the word on the street. A good gas-electric hybrid, the Prius, will get in the mid-40s mpg, according to both accounts. Gasoline emits about 24 pounds of CO2 per gallon, regular diesel about 28, biodiesel (B100) about 7.3, and your 20-80 mix (B20) around 23. We can do a little math to compare the emissions from two cars: using the EPA’s handy charts, I chose the ‘06 diesel VW Bug to go up against the Prius. In 100 miles at 45 mpg, the Prius emits 53.3 pounds of CO2. Over the same 100 miles, the 34 mpg Bug will release 81 pounds on diesel, 21 pounds on B100, and 67 pounds on B20.

To go further with this little cul-de-sac of carbon math, you would then figure out how many months and miles of B100 vs. B20 per year for your climate. Compare those to the emissions from yearly gasoline miles of your chosen hybrid, and there you are. (I’m not going to bother with the further calculations, as we would be delving too far into the theoretical.) Diesel fuels are also responsible for significant particulate matter emissions, which are almost all reduced with both B100 and B20. Nitrogen oxides are slightly increased—here’s a handy chart [PDF]. The Biodiesel Board also provides an interesting Emissions Reduction calculator for diesel fuels.

That’s the emissions roundup, but as to which will be better for the environment ... Down here in the stacks it’s always Clark Williams-Derry Appreciation Week, and Clark has interesting things to say about car comparisons. Here is a thought-provoking Clark piece about the role of spending money in car choices, which you may enjoy: Is it better to put money into a car (and its expensive fuel) or keep the money in your pocket for that insulation project?

As I said at the outset, I think both your choices are good, with the added benefit of pushing the car economy toward more efficient private vehicles. Just avoid plain old diesel, whatever you do.

Asthmatically,
Umbra

 

Yours is to wonder why, hers is to answer (or try). Send your green-living questions to Umbra.

Umbra Fisk is Grist Research Associate II, Hardcover and Periodicals Unit, floors 2B-4B.

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  1. mobrien Posted 2:18 am
    12 Jan 2009

    Full life cycleOne piece I'm not seeing in this comparison is the inclusion of battery production as part of the carbon analysis. The near-Seattle Green Car Company (http://www.thegreencarco.com) has done some excellent research on the topic and weighs this factor into the calculation (including many other considerations other than just fuel). They sell both biodiesels and hybrids and as of 2008, a biodiesel still beat hybrids by a good margin due in large part to battery creation and disposal issues with the hybrids. I'll buy a full electric plug in once the battery issue is resolved. We all have to remember that unless the producer has considered a full life cycle of any product, they're simply delaying the inevitable delivery to the dump or hazardous waste bin.
    Amen on driving less vs. home insulation.
    Contact them directly for more details, or the people I trust at NW Biodiesel Network (http://www.nwbiodiesel.org).
    Best, Michael @ http://www.sustainableindustries.com

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  2. kristen510's avatar

    kristen510 Posted 2:51 am
    12 Jan 2009

    More on VW diesels... bad news for new car buyersJust a few clarifications on the VW biodiesel front.

    First, the pre-2005 TDIs are the ones that are getting 50+ MPG. With each generation after 2006 the mileage keeps going down, with the 2009s getting in the 30's (boo). So buying a used pre-2005 will get you the best MPG for your buck.

    ALSO: VERY IMPORTANT: owners of the new 2009 TDIs are reporting issues with the use of biodiesel, namely that the formulation messes with the computer's expectations of emissions and causes engine problems, Check engine lights etc as a result. Those in the know are recommending early 2000's models for this reason.
    Anyone looking into purchasing a diesel vehicle should read through the TDI 101 thread on TDIClub before buying. There is much you should learn before buying because you are essentially putting your car on a special diet- no switching back and forth from D2 to B100.
    Lastly, there are other added benefits to using biodiesel, such as the fact that most of the retail stations are co-ops, which means that when you buy your fuel you are supporting people in your community. Hybrid drivers are still giving their money to Exxon.

    -Kristen Q.

    2002 Jetta TDI, B100 for 60,000 miles

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  3. gg3 Posted 3:57 am
    12 Jan 2009

    and more...The other important factory to include is whether Tom is planning on buying new or used.  Obviously buying a used Mercedez or VW (that you can find in good shape) is the preferred way to go. There was far less energy put into those cars than a prius. I enjoy the number crunching but buying local and not borrowing from China to give back to the middle east..is FAR less of a footprint.  
    Is biodiesel THE answer to global climate change? No. But it is part of the solution? Absolutely especially when your using recycled fryer oil.  And once algae is understood we will be on our way to a cleaner planet.  The answer for you Tom is what is avail to you in your surrounding community, can you find a reliable auto and where will you be getting your fuel from?  

    Great question (im not a prius hater..just a lover of my 83 mercedez 300TD..20K on B100)

    If you want to get a general quick grasp of all things biodiesel..the bible to check out is From the Fryer To The Fuel Tank
    Driving guilt free,

    Gerard  LA CA

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  4. Erik Hoffner's avatar

    Erik Hoffner Posted 4:02 am
    12 Jan 2009

    ConwayTom: howdy neighbor. I'm from the next town over, Ashfield, and I drive a 98 Jetta TdI and get around 50 mpg most of the time. If you go this route, you should know about Yellow Brand Biodiesel. It's the one sold in the 5 gallon jugs here in W. MA, and it is made from 100% waste, which, if you burn this stuff, will render the comparison to a hybrid moot. It's pretty impeachable for green-ness - nearly zero carbon footprint.
    I use this entirely in the summer and it's great, but this time of year I mix down a lot, and especially lately that's important b/c the Yellow Brand that's on the shelf right now is made of animal tallow, and the freeze point is something near 45 degrees, so it's only workable at a blend of 5 or 10 percent with the weather we're having. Usually this time of year Yellow Brand is 100% waste vegetable oil feedstock and the freeze point is much better, but I guess it's not 'moving' b/c of the weather so the supplier can't replenish with veggie-based. Retail locations here if you're curious:
    http://www.yellowbiodiesel.com/map.html
    Erik

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  5. sje333 Posted 4:06 am
    12 Jan 2009

    asthma and dieselSomething the answer hints at is the fact that the Prius will put off almost no smog-forming pollution, while the diesel will put off a lot.  I love the relative simplicity of diesel engines, but I opted for the Prius because of the smog-forming emissions.  I made that decision despite living in the relatively clean-air state of Florida.  Someone in Boston should (in my humble opinion) put extra weight on the emissions factor because of the pollution problems in the Northeast.  Pollution is still killing people, and diesel is producing a lot of that pollution.  That holds true in most of America's major cities (Houston, Dallas, LA, ATL, etc).
    Yes, the new diesels are cleaner than old diesels.  Yes, biodiesel reduces some emissions (while increasing others).  The more important thing to consider (in my humble opinion) is that the Prius will put off 90% less (perhaps even 98% less) pollution than a diesel.  Please sift through the smog-forming emissions at epa.gov/greenvehicles
    I appreciate the attention to home insulation, though.  For someone in Boston, battening down the hatches would yield impressive savings (monetary and planetary).

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  6. sje333 Posted 4:11 am
    12 Jan 2009

    orang-utans and biodieselAgain, I'm not rabidly anti-diesel, but biodiesel is driving up demand for palm oil (as a feedstock), which is leading to plantations being cut into the jungle in South America and Asia.  If we continue at this rate, Orangutans will be extinct by 2020.
    http://redapes.org/?s=biodiesel
    We also have to consider the immediate impact on CO2 emissions from burning rainforests to plant palm oil plantations.
    Those are problems that can be and should be solved...but until they are I will only buy biofuels very grudgingly.  Unfortunately, E10 is the only gasoline available in the Orlando area.

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  7. sje333 Posted 4:21 am
    12 Jan 2009

    the transportation solutionIn all of my calculations, the winner in the green transportation contest is consistently battery electric vehicles (even after you factor in battery production).
    By the end of January I'll be generating all of my electricity with my rooftop solar array on my house.  Hopefully I'll have an electric car by the end of the year.  Sure, there is a hefty impact from the production of the solar array, but it pales in comparison to the impact of burning fossil fuels or farm-grown biofuels.  I won't even have to depend on fryer oil from my local Chinese restaurant!
    For more info on electric cars:

    http://www.evworld.com
    (BTW, I apologize if the Western Mass readers don't like being lumped together with Boston.  Smog knows no boundaries, and you're upwind from a lot of people in Boston and Hartford)

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  8. kristen510's avatar

    kristen510 Posted 4:36 am
    12 Jan 2009

    Recyled vegetable oil is the way to goRecycled vegetable oil negates the demand for virgin stock and does not cause forests to be cut. Many stations, including mine, purchase only fuel made from recycled vegetable oil. Your supplier will be able to tell you if the oil they use is recycled or virgin. If they don't use recycled, pressure them to find some. There are plenty of potato chip factories in the US.

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  9. mskellyann's avatar

    mskellyann Posted 4:43 am
    12 Jan 2009

    food for cars I'm not convinced that giving one's money to agribusiness is a better choice than giving it to oil companies.  They're symbiotic at best.
    And thank you, sje333, for reminding us about the link between biodiesel and asthma!

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  10. John Fish Kurmann Posted 4:56 am
    12 Jan 2009

    Tangerine to Grapefruit...If you're going to make MPG comparisons, it's vital to match vehicles with comparable capacities. The VW Beetle TDI is classified by the EPA as a subcompact car, with only 85 cubic feet of passenger volume and 12 cubic feet of luggage volume. If that's plenty of space for you (as it probably would be for me), fine, but it's hardly comparable to the current Prius, which is on the low-end of the EPA's midsize range with 96 cubic feet of passenger volume and 16 cubic feet of luggage volume. The current Jetta TDI is a more comparable vehicle to the Prius, but it still only has 91 cubic feet of passenger volume (plus 16 cubic feet of luggage volume). The Passat (96 cubic feet passenger volume) is the most comparable VW to the Prius in capacity but apparently it's not currently offered with a diesel powertrain.
    Umbra's answer also neglects to address the impact of biodiesel from food crops on biodiversity, food supply and prices. If you can get it made from waste veggie oil, that's another matter, of course.

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  11. GreeningTX Posted 7:53 am
    12 Jan 2009

    Don't forget ...Don't forget to
    (1) re-run Umbra's numbers with the actual mileage of the diesel vehicle you would purchase. The carbon numbers of the diesel look a whole lot better if you assume 50 mpg (which is what I get with my 2004 VW Jetta TDI than if you apply EPA numbers for this particular vehicle: 31 city, 42 highway).
    (2) Whichever vehicle you choose, drive it like you care. Learn hypermiling techniques and apply them assiduously and with gusto.
    And:
    When you go to TDIclub.com, don't spend all your time in the TDI 101 Forum dwelling on maintenance and repair issues. Head for the Fuel Economy and Biodiesel forums, which is where the fun is.

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  12. cyril Posted 3:31 pm
    12 Jan 2009

    Not so much the car you get but how you drive itThe answer really depends on how and where you drive IMHO.

    http://www.youtube.com/watch?v=S7yKOJXfpDA is a bit caricatural but you get the rift. :)

    If you do a lot of stop & go city traffic, the Prius will save you the most in gas running on battery.

    If you do more long-distance high-speed highway driving, the Prius' battery won't be enough and the small gas engine will struggle so you'll end up burning more than with a diesel car.

    My 2c.

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