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By Robert Rapier on Apr 8, 2006 with 12 responses

Energy Balance For Ethanol Better Than For Gasoline?

Surely you have heard the claim. Proponents of ethanol will claim that it takes less fossil fuels to produce a BTU of ethanol than to produce a BTU of gasoline. Here is the claim from a Minnesota Department of Agriculture site (1):

A United States Department of Agriculture (USDA), Economic Research Service Report number 814 titled “Estimating The Net Energy Balance Of Corn Ethanol: An Update” was published in July of 2002. The Conclusion states in part: “Corn ethanol is energy efficient, as indicated by an energy ratio of 1.34; that is, for every Btu dedicated to producing ethanol, there is a 34-percent energy gain.” A similar study done in 1995 indicated only a 1.24 energy ratio.

The concept of “input efficiencies for fossil energy sources” was introduced as a component of the study. This was meant to account for the fossil energy used to extract, transport and manufacture the raw material (crude oil) into the final energy product (gasoline). According to the study, gasoline has an energy ratio of 0.805. In other words, for every unit of energy dedicated to the production of gasoline there is a 19.5 percent energy loss.

In summary, the finished liquid fuel energy yield for fossil fuel dedicated to the production of ethanol is 1.34 but only 0.74 for gasoline. In other words the energy yield of ethanol is (1.34/0.74) or 81 percent greater than the comparable yield for gasoline.

I have dealt with the USDA studies in previous essays, showing the shoddy and misleading methodology they use. But let’s now examine this claim of energy efficiency. Would it surprise you to know that not only is this claim false, it is WAY FALSE?

Let’s do some quick calculations to demonstrate this. A barrel of crude oil contains 5.8 million BTUs (2) of material that will ultimately be turned into gasoline, diesel, jet fuel, etc. It is well-documented that the average energy return on energy invested (EROEI) for crude oil production is around 10/1 (3). Therefore, we will use up about 580,000 BTUs from our barrel getting it out of the ground. The other major input occurs during the refining process, and it also takes roughly 10% of the contained BTUs in the barrel of oil. The total energy input into the process is 1.16 million BTUs, and the energy output was 5.8 million BTUs. The EROEI is then 5.8 million/1.16 million, or 5/1.

For ethanol, the USDA study reference above showed that for an energy input of 77,228 BTUs, an energy output (when co-products were included) of 98,333 BTUs were generated. The EROEI is then 98,333/77,228, or 1.27/1. The efficiency of producing gasoline is then 4 times higher than for ethanol, which makes sense when you think about it.

Crude oil is a highly energy dense mixture. It is contained in underground deposits, and just needs to be pumped out of the ground. During the refining step, large amounts of water don’t need to be distilled out of the product. Contrast this to ethanol. The corn must be planted, grown, and harvested. Processing must take place to turn the corn into crude ethanol. The crude ethanol is actually mostly water, which must be removed in a highly energy intensive distillation. The final product, ethanol, contains only about 70% of the BTU value of the same volume of gasoline. So it would appear that even without doing any rigorous calculations, producing ethanol would be far less energy efficient than producing gasoline.

So, where did the claim that ethanol is more energy efficient originate? I believe it originates with researchers from Argonne National Laboratory, who developed a model (GREET) that is used to determine the energy inputs to turn crude oil into products (4). Since it will take some amount of energy to refine a barrel of crude oil, by definition the efficiency is less than 100% in the way they measured it. For example, if I have 1 BTU of energy, but it took .2 BTUs to turn it into a useable form, then the efficiency is 80%. This is the kind of calculation people use to show that the gasoline efficiency is less than 100%. However, ethanol is not measured in the same way. Look again at the example from the USDA paper, and lets do the equivalent calculation for ethanol. In that case, we got 98,333 BTUs out of the process, but we had to input 77,228 to get it out. In this case, comparing apples to apples, the efficiency of producing ethanol is just 21%. Again, gasoline is about 4 times higher.

OK, so Argonne originated the calculation. But are they really at fault here? Yes, they are. Not only did they promote the efficiency calculation for petroleum products with their GREET model, but they have proceeded to make apples and oranges comparisons in order to show ethanol in a positive light. They have themselves muddied the waters. Michael Wang, from Argonne, (and author of the GREET model) made a remarkable claim last September at The 15th Annual Symposium on Alcohol Fuels in San Diego (5). On his 4th slide , he claimed that it takes 0.74 MMBTU to make 1 MMBTU of ethanol, but 1.23 MMBTU to make 1 MMBTU of gasoline. That simply can’t be correct, as the calculations in the preceding paragraphs have shown.

Not only is his claim incorrect, but it is terribly irresponsible for someone from a government agency to make such a claim. I don’t know whether he is being intentionally misleading, but it certainly looks that way. Wang is also the co-author of the earlier USDA studies that I have critiqued and shown to be full of errors and misleading arguments. These people are publishing articles that bypass the peer review process designed to ferret out these kinds of blatant errors. I suspect a politically driven agenda in which they are putting out intentionally misleading information.

One of the reasons I haven’t written this up already, is that 2 weeks ago I sent an e-mail to Wang bringing this error to his attention. I immediately got an auto-reply saying that he was out of the office until March 31st. I have given him a week to reply and explain himself, but he has not done so. Therefore, at this time I must conclude that he knows the calculation is in error, but does not wish to address it. In the interim, ethanol proponents everywhere are pushing this false information in an effort to boost support for ethanol.

Look at the Minnesota Department of Agriculture claim again: “the energy yield of ethanol is (1.34/0.74) or 81 percent greater than the comparable yield for gasoline”. If the energy balance was really this good for ethanol and that bad for gasoline, why would anyone ever make gasoline? Where would the economics be? Why would ethanol need subsidies to compete? It should be clear that the proponents in this case are promoting false information.

References

1. Ethanol versus Gasoline
2. BTU Content of Common Energy Units
3. Alternative energy: evaluating our options
4. Allocation of Energy Use in Petroleum Refineries to Petroleum Products
5. Updated Energy and Greenhouse Gas Emissions Results of Fuel Ethanol

  1. By Michael Scheidt on April 11, 2010 at 5:12 pm

    From what I understand the GREET model also takes into account the GHG emissions from refining and the eventual burning of gasoline, which would skew the data toward ethanol which is a GHG neutral product.

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  2. By Robert Rapier on April 11, 2010 at 5:22 pm

    Michael, it is true that GREET takes into account the refining, but it isn’t true that ethanol is GHG neutral. Far from it. In fact, GREET said that the emissions from ethanol are almost as great as those from gasoline due to the heavy reliance of ethanol on fossil fuel inputs.

    RR

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  3. By skierpage on May 20, 2010 at 2:04 am

    This outlandish claim is bouncing around pro-ethanol folks. A Bob Moffitt from the American Lung Association in Minnesota showed up at Autoblog Green to say “it takes more energy to make gasoline from crude oil than it delivers as gasoline.”

    But if you look at slide 19 of Michael Wang’s 2007 GREET model overview, he seems to be saying it takes 0.23 Btu of fossil fuel to produce 1 Btu of gasoline that’s 100% fossil fuel, while it takes 0.7 Btu of fossil fuel transforming the wonder material of biomass to produce a Btu that’s 0% fossil fuel. He’s measuring fossil fuel intensity, not energy intensity. Or something, it’s a ridiculous slide.

    Why is the American Lung Association involved in this stuff? Go read http://arclightzero.wordpress.com/2007/11/14/exposing-the-american-lung-association/ , sad.

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  4. By Mauricio Carvalho on July 31, 2011 at 1:49 am

    What about sugar cane ethanol? Sugar cane ethanol in Brazil has an EROEI of 8/1, while corn ethanol in the US has 1,3/1.

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  5. By Robert Rapier on July 31, 2011 at 4:06 am

    “What about sugar cane ethanol?”

    Brazilian Ethanol is Sustainable

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  6. By ejcrosland on February 28, 2012 at 3:02 pm

    Just saw the doc “Fuel” but noticed it was partly funded by a company that makes biodiesel. In the spirit of transparency (which I fervently believe is necessary in these days when most data is derived by organizations that profit from their own findings), I am a member of the Green Party in Canada and do not have a formal science background.

    That said, I think science is a key tool in helping us find the most appropriate methods for dealing with current environmental issues.

    1. What’s the EROEI on biodiesel made from algae?
    2. Do you think that increased energy efficiency in the transporation and home heating/cooling sectors can play a significant role in reducing our need for any kind of fuel/energy AND be sustainable?
    3. Would fossil fuel production still be economically sustainable without subsidies/tax breaks? I suspect that a lot of alternative energy industries would not survive without assistance right now but the fossil fuel industry received financial assistance in its infancy and it is my understanding that they still get public money???
    4. I was reading in Discover (http://discovermagazine.com/nsf/changing-planet-energy-jobs) that a ‘green energy’  sector may not provide as many jobs as the fossil fuel industry sectors do. Really?! What’s your take on that?

    I hope that’s not too many questions. I have a lot of them. I appreciate that someone is trying to cut through the rhetoric to help best solve our ecological dilemmas.

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    • By Robert Rapier on February 28, 2012 at 5:27 pm

      1. I don’t think that is known, because there is no large-scale commercial production. It is very possible that it is less than 1.

      2. Yes, and if you look at the trends, energy efficiency has greatly improved over the past few decades. I expect this trend to continue, especially in the face of much higher energy prices.
      3. The subsidies that are kicked around aren’t so much subsidies as they are tax deductions, and many of the so-called oil company subsidies are the same tax deductions taken by companies like Apple and Google. The number that is often kicked around is $4 billion per year; add that to our oil consumption of 19 million barrels of oil per day and it is about 1 cent per gallon.
      4. Green energy will definitely add more jobs, because it takes more people to produce 1 BTU of green energy than it does to produce 1 BTU of fossil energy. But that’s also one of the reasons green energy tends to be more expensive.
      RR
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      • By ejcrosland on March 1, 2012 at 5:33 pm

        Thanks for the quick reply!

        The doc Fuel was saying that biodiesel has the best EROEI of any manufactured fuel including ethanol and gasoline. And certain kinds of algae offer the promise of quickly producing a lot of biomass in areas not suitable for agriculture. Are you saying that traditional gasoline or diesel (from fossil fuels) really still has the best EROEI?

        So Green jobs would not be able to pay well to keep energy prices competitive or would we have to learn to accept higher energy prices but have more people working with decent pay so they could afford the higher costs?

        I know one of the Green Party promises is to be able to grow a Green energy manufacturing sector in North America and bring back some decent jobs. Will there be much opportunity for green manufacturing in N.A. or will those jobs go to China, too? Can we realistically see lots of chances for more design and engineering jobs in N.A. in the alternative energy sector?

        Where do you see the greatest resistance from the fossil fuel sector to embrace alternative energy models/industries – denial of climate change? fear of losing their jobs? fear of change? unable to see past the status quo? fear of losing out on the large profits still being wrung from the fossil fuel industry? … or do we really have no viable alternatives to fossil fuels at this point?

        Which leads me to – considering everything you know right now, what is our best (most affordable, efficient, top EROEI, least GHG emitting) alternative to fossil fuels currently? What will be our best bets in the near future? 

        Thanks!

        EJC

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  7. By Robert Rapier on March 1, 2012 at 5:49 pm

    The doc Fuel was saying that biodiesel has the best EROEI of any manufactured fuel including ethanol and gasoline.

    It is certainly not true for gasoline or conventional diesel. I haven’t seen the Fuel, so I don’t know the basis of their claim, but it is in all likelihood a misuse of EROEI. With respect to other biofuels, that depends on the source of the oil. It is probably true for biodiesel created from soybeans or rapeseed. It will not be true for algae that have to be harvested, separated from water, and then have the oil removed. 

    Are you saying that traditional gasoline or diesel (from fossil fuels) really still has the best EROEI?

    Conventional gasoline has an EROEI in the range of 5 to 10, depending on the crude source. The only biofuel with an EROEI competitive to that is sugarcane ethanol, and that is only because the biomass inputs are not typically counted in the equation. 

    Where do you see the greatest resistance from the fossil fuel sector to embrace alternative energy models/industries

    It’s just economics. If they think they can make money at it, they will do it.

    Which leads me to – considering everything you know right now, what is our best (most affordable, efficient, top EROEI, least GHG emitting) alternative to fossil fuels currently?

    The best alternative hypothetically is solar power and electric cars. Or, depending on your feelings about nuclear power, nukes and electric cars. But this is still not a broadly applicable solution until the costs of the cars come down, the range improves, and storage of solar improves.

    RR 

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    • By ejcrosland on March 14, 2012 at 8:46 pm

      Sorry for the delay. Thanks for all your responses.

       

       

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  8. By Steve in 44444 on September 12, 2013 at 5:18 pm

    Does anyone consider into the equation the amount of good land that could be used for food production, and what that is doing to our food supply? Fertilizer uses energy to produce. The ground gets depleted. Food that is not locally grown is imported, which requires energy. Food costs go up. There is less available for hungry people, which is a more important moral issue than fuel for our over-sized SUVs!

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  9. By Ponyexpress on July 6, 2015 at 12:09 pm

    Not sure why this is so difficult for the experts to determine! Energy in versus energy out.
    Any questions?
    Nature did all the hard work for free with crude, over millions of years.
    Growing corn to turn it into a fuel is absurd…and stupid.

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