E85: Spinning our Wheels
If you listen to the news lately, you know that E85 is going to lead the U.S. to energy independence, just like it did in Brazil. Senator Hillary Clinton has announced that she is getting into the act:
"President Bush and other elected officials have called for a greater expansion of E-85, a fuel made of 85 percent ethanol that can be used in vehicles built to run on both regular unleaded gasoline and E-85. E-85 is currently available in less than one percent of the country's gas stations, and Clinton wants to accelerate the spread of the fuel to half of the nation's gas stations by 2015 by offering a 50 percent tax credit for station owners who install ethanol pumps.
`We've got to take action on this pump issue or we're just spinning our wheels,' she said."
Just spinning our wheels. Indeed. But let's do a reality check and see whose wheels are spinning. These claims deserve a mathematical analysis, which none of the E85 proponents appear to have done.
According to http://www.corn.org/CRAR2005.PDF (Warning: 1.9 meg file) the estimated corn harvest in 2005 was 10.35 billion bushels, and corn exports were 1.95 billion bushels. According to the 2002 USDA study Estimating the Net Energy Balance of Corn Ethanol, you can get 2.7 gallons of ethanol from a bushel of corn. That means if we turned the entire corn crop into ethanol, we could make 27.9 billion gallons of ethanol. But as we all know, the BTU value of ethanol is around 67% that of gasoline, meaning that on a BTU basis this much ethanol is equivalent to 18.8 billion gallons of gasoline.
According to the Bureau of Transportation Statistics, our annual gasoline consumption is up to almost 140 billion gallons. That means on a BTU equivalent basis, converting the entire corn crop into ethanol would amount to 13.4% of our annual gasoline demand. Putting all of that ethanol into the gasoline supply would mean ethanol could comprise 19% of the gasoline supply on a volumetric basis (while consuming all of our corn production). In other words, all of the gasoline in the country could be E19 if we wanted to use 100% of the corn crop. Of course if we only want to turn all of our current exports into ethanol (ignoring the many implications), that would amount to 2.5% of our annual gasoline demand. In that case, E10 could make up about a third of our gasoline supply on a volumetric basis. If we want to convert all of the corn exports into E85, it could make up 3.3% of our total gasoline pool.
But that's the good news. According to the previously mentioned USDA study, it takes 77,228 BTUs of fossil fuel inputs to make 83,961 BTUs of "green, renewable" ethanol. Ignoring co-products for a moment, that means the created energy was a mere 8% in excess of the input energy. Given that the fossil fuels (primarily natural gas) that went into making the ethanol can usually serve as transportation fuels, the amount of transportation fuel that is displaced is only the 8% that was "created". That means that in reality, using our entire corn crop would only displace 1% of our annual gasoline consumption. If we only decide to use our exports, the net displacement of gasoline would be 0.2% of our annual gasoline consumption.
Now, a word about co-products. Energy balance studies of grain ethanol almost always include a BTU credit for the co-products (mostly animal feed). I think this is appropriate, provided that a proper analysis is made of the energy inputs into the products that were displaced. Let's ignore for a moment the fact that some estimates indicate that the "byproduct markets could saturate well short of 11 billion gallons of production". Let's give full credit for the byproducts, just as if they are liquid fuels to be burned. This has no effect on the BTU equivalent calculation, but will affect the displacement calculation. With by-products included, the USDA report has 77,228 BTUs of fossil fuel inputs for 98,333 BTUs of total outputs. In this best case scenario, the ratio of energy out/energy in is 1.27. Converting 100% of the corn crop into ethanol, presuming we had a market for the byproducts, would then displace an incredible 2.0% of our annual gasoline consumption.
So, why the big rush to get E85 pumps at 50% of the nation's gas stations? We can't possibly produce enough E85 to justify putting in all those pumps. Wouldn't it be much better just to push for E10 at more locations? In that case, expensive new pumps are not required, and E10 can already be burned in most vehicles on the road. Or how about encouraging more natural gas vehicles, instead of inefficiently and expensively turning natural gas into ethanol? But I suppose those would be rational solutions, as opposed to feel-good solutions that promise energy independence.
This post was inspired by comments made by Odograph.
1. What is the energy content of a gallon of the renewable fuel? (In megajoules or another standard energy unit.) 2. How much biomass feedstock (corn, etc.) does it take to produce a gallon of the fuel? How much energy was required to produce that biomass? (Consider farm equipment, fertilizers, pest management, transportation, storage, etc.) 3. What other substances are required, in which quantities, to produce a gallon of the fuel? (Process chemicals, etc.) How much energy was required to produce each of these? 4. How much energy is required to manufacture a gallon of the renewable fuel? And, on average, to transport and store it? ...Add the answers to 2, 3, and 4 together, and subtract that figure from 1. If the answer is a positive number, ethanol is net energy positive in that case. Perform similar calculations to determine the energy economics of gasoline in your region. You can also extrapolate from this calculation to compare greenhouse gas emissions. The energy and environmental impacts of ethanol, and how they compare to those of gasoline, can vary substantially by region, feedstock (or petroleum source), and manufacturing process.EB editor BA proposed two further questions:
5. What will be the effect of constant cropping on soils, if ethanol production is expanded to a large scale? 6. What will be the effect on the food prices and the foodsupply?-AF UPDATE: Reader JG writes:
If we're going to widen the analysis boundary to include the coproducts as a positive addition to the output of ethanol, then consistency requires that we look beyond the simple addition and consider the uses of those coproducts. The point being that dried distillers' grain (DDG)--the main coproduct that the ethanol lobby wants us to count--is used to prop up an insanely energy-wasteful system of beef production, which uses incredible amounts of grain and water for each kilo of beef product, which is then shipped incredible distances using petroleum products. And the greenhouse gas contribution of beef cattle is anything but negligible: cows fed on grains fart and belch a LOT (just as you would if you were not being fed your natural diet staple), making a significant contribution to global methane production (20x more heat-trapping than an equal volume of CO2). If you're not ready to add all that into your calculus to determine whether corn ethanol is beneficial or a net negative, then a rigorous analysis would exclude the DDG entirely. Not to mention that corn is a voracious soil waster--probably the best thing one could do with corn ethanol coproducts is figure out how rapidly they can be reintroduced into the soil as a step toward preserving some of the tilth that corn destroys.-BA
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