Defining the Balance

A recently published study conducted by researchers at the University of Minnesota and St. Olaf College in Northfield, Minn., blows fresh air on the smoldering "net energy" debate for biodiesel and fuel ethanol. Ultimately, the results are favorable to renewable fuels and their ability to provide more energy than the sum of their inputs.
By Nicholas Zeman | September 01, 2006
Imagine an island in the middle of the ocean devoted exclusively to biodiesel production. On this island, everything that is needed to grow soybeans and transform them into methyl esters-down to the energy and nutrients needed to support farmers, laborers and processing plants-is imported onto the shores. All that ever leaves is the renewable fuel.

This is the conceptual model that led researcher Jason Hill and his team from the Department of Applied Economics and the Department of Ecology, Evolution and Behavior at the University of Minnesota (UM) and the Department of Biology at neighboring St. Olaf College used to explain principles of their lifecycle analysis of the predominant alternative fuels. "The Environmental, Economic and Energetic Costs and Benefits of Biodiesel and Ethanol Biofuels" was funded in part by UM's Initiative for Renewable Energy and the Environment, and first published in the Proceedings of the National Academy of Sciences in July.

Perhaps looking to ground bandwagon politicians and the agricultural community that have been accused of being in a euphoric, if not delusional, renewables "haze," academic research aims to review the legitimacy of ethanol and biodiesel as crucial alternatives in a world looking to transition away from its overzealous petroleum use. Few if any, however, in the ethanol or biodiesel industries have touted either fuel as a panacea destined to solve the world's energy problems.

Setting the Proper Boundaries
The parameters of the study proceeded from the following thesis: "To be a viable substitute for a fossil fuel, an alternative fuel should not only have superior environmental benefits over the fossil fuel it displaces, be economically competitive with it and be producible to make a meaningful impact on energy demands, but it should also provide a net energy gain over the energy sources used to produce it."

Everything down to the energy used to support the laborers should be included in the machinations of the green island cycle, the researchers decided. "This has been debated back and forth in the literature, [whether to] include these sorts of inputs," Hill tells Biodiesel Magazine. "We settled on the conclusion that, yes you should to be fair and do it properly."

The study states: "Biofuel production requires energy to grow crops and convert them to biofuels. We estimate farm energy use for producing corn and soybeans, including energy use for growing the hybrid or varietal seed planted to produce the crop, powering farm machinery, producing farm machinery and buildings, producing fertilizers and pesticide, and sustaining farmers and their households." Some experts believe that these inputs are unnecessary and, even when included, don't drastically change the outcome of a lifecycle analysis. "There are formulae that estimate how much energy individual households use on a daily basis with transportation costs and so forth," says Jim Duffield, senior agriculture economist for the USDA. "In my mind, you need to do that anyway to sustain life; no matter what their occupation is, they're going to use that energy."

The amount of energy it takes to grow and harvest soybeans, and to transport them either to biorefineries or processing outlets, requires irrigation, the application of fertilizers and pesticides, and many other steps that are all rather straightforward in terms of data collection. "When [researchers] go beyond that to look at how much energy it takes to produce machinery, equipment, facilities and labor, then it gets pretty murky," Duffield says. "In the work I've been involved with in the past, we haven't gone that far, and [data] is pretty scarce in that area. I don't agree that you should include labor in a lifecycle analysis."

The good news is that even though all of these inputs are included in the formula that Hill and his colleagues used in calculating the net energy balance for ethanol and biodiesel, the results were still favorable to both fuels.

Standing Up to the Competition
In an analysis of an alternative fuel, the subject should be compared with the mainstream products. "They don't talk about the lifecycle analysis of petroleum diesel," Duffield says. "If they did not include similar research on the lifecycle analysis of comparable petroleum products in their story, than it's biased."

Bruce Dale, professor of chemical engineering at Michigan State University who has published extensively on this subject, agrees with Duffield that "net-energy talk" can be deceptive because it doesn't take place in the context of a comparison with petroleum-based products. "The fact is, if you accept the argument and the assumption that bio-ethanol and biodiesel provide positive energy balances, they both compare very, very favorably to petroleum," Dale says. "That's the point."

The work of David Pimentel and others who have reported a negative energy balance have misled people, Dale says. "If you apply the same approach that they apply using the exact same numbers and the exact definitions that they use and apply it to gasoline and diesel, you find out that gasoline and diesel have a worse net energy than ethanol does."

Duffield says he remembers a lifecycle analysis of petroleum diesel performed by Michael Long of the Argon Corporation several years ago. "He did an excellent job on that study, and as I recall, it showed that petroleum diesel had a [negative energy balance] of about 17 percent," Duffield tells Biodiesel Magazine.

"Ethanol and biodiesel will both have a better net energy balance than either gasoline or petroleum diesel," Dale says. "That is the key part as far as I'm concerned, and that is that both ethanol and biodiesel are much better than their petroleum counterparts."
Nevertheless, petroleum is going to be around for a lot of years and will continue to be used. How it will be used is the linchpin for Dale. "You can take a barrel of petroleum and use it to support the production of ethanol or biodiesel, either one," he says. "Or you can take that barrel of petroleum and use it to make gasoline or diesel." Ultimately, Dale says the more intelligent application of the petroleum product is when it is used to support the production of renewable energy.

Asking the Appropriate Questions
Getting back to Hill's conceptual model, a green island has no energy or a limited amount of energy, and it wants to produce more. Of course, energy is never created or destroyed; it only changes form. "We want to find a process that gives us more energy out than we put in," Hill says. "That is how we can produce more energy. Essentially, we identified the energy inputs that would be directly or indirectly related to that process that gives you more energy out. Then, you look at how much energy you actually get out of the process, so we look at this whole energy process."

A product can be analyzed in terms of its energy content, but to understand the "energy return," all inputs and outputs should be considered. Dale says the question is, "How much liquid fuel do you get out, if you use petroleum to support ethanol production or you put the petroleum into gasoline or diesel?" He says nearly 20 times more liquid fuel is produced if the petroleum is used to support ethanol production to make gasoline or diesel. "It's a huge multiplier," Dale says. "It's a huge leverage."

Soy-based biodiesel, however, is ultimately the superior biofuel, Hill's report states. This is primarily because of two factors. One is that soybeans are less energy-intensive to grow and require less harmful pesticides, herbicides and fertilizers. Secondly, far less energy is required in the processing of soybean oil to biodiesel. "Among current food-based biofuels, soybean biodiesel has major advantages over corn grain alcohol," the report says.

As for the future of biofuels, the UM study recommends that "synfuel hydrocarbons or cellulosic ethanol that can be produced agriculturally on marginal lands with minimal fertilizer, pesticide and fossil energy inputs, or produced with agricultural residues, has potential to provide fuel supplies with greater environmental benefits than either petroleum or current food-based fuels."

Some of the conclusions in the paper could be drawn from the wrong position, from the wrong perspective, Dale says. There are different measures of efficiency used in the paper, but this information is not pointed out very well. The paper draws its conclusions based on per-mile-driven impact in a comparison of ethanol and biodiesel in the reduction of greenhouse gases and petroleum displacement.

"In other words, what they're saying is that when you compare those two fuels on per-mile-driven, it looks as if biodiesel is better than ethanol, and it is somewhat," Dale says. "A much more appropriate basis is to compare those two fuels per acre of land devoted to production, and then the conclusion changes dramatically if you talk about total petroleum or greenhouse gases you can place per acre of cropland."

With an acre of available cropland, there is the choice to either plant soybeans or devote it to corn or other ethanol feedstocks. When the question is, "How much petroleum savings or how much fossil fuel or greenhouse gases are being saved per acre of land?" the conclusion changes completely. "Now ethanol looks better, and until we get biodiesel yields up per acre, you just can't make enough of it to have an impact on our total liquid fuel use," Dale says. "We're not limited to miles driven. What we're limited in is the amount of land we can devote to these biofuels; for me, that is the more appropriate question to ask."

Nicholas Zeman is a Biodiesel Magazine staff writer. Reach him at or (701) 746-8385.
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