Ethanol and Net Energy Balance

November 15th, 2005

cornpumpMy last post on E85 fuel arriving in St. Joseph County prompted a reply from a reader in the great state of Wisconsin who asked me to discuss more of what he felt were the negative aspects to ethanol.

I thought I was relatively neutral in my posting, and even mentioned the poor fuel economy that E85 gave relative to gasoline. In fact, with gas prices what they are at this writing, E85 is actually a bad buy compared to gasoline.

However, his email did remind me of a familiar topic that comes up whenever ethanol is discussed. That is the common perception that ethanol takes more energy to produce than it actually produces. This is called a “negative energy balance.”

The biggest proponents of this viewpoint seem to be Prof. David Pimentel of Cornell University, and Prof. Tad Patzek of UC Berkley. Prof. Patzek’s updated paper on the issue can be found here.

The main thrust of the argument is that all of the energy that goes into biomass production, distillation, and distribution far outweighs the energy benefit that actually ends up in the tank of your car.

Criticisms of their methodology, though, do exist. For instance, they fail to give energy “credits” for co-products created in the ethanol distillation process (such as animal feed), and include the energy costs associated with the steel in the farmer’s machinery (even the farmer’s food), that would probably still be consumed regardless if the crop were used for ethanol production.

However, the U.S. Department of Energy says that ethanol – while acknowledging high energy and chemical use in its production – has a positive energy balance.

Further, a new study led by Dr. Michael Wang at Argonne National Laboratory Transportation Technology R&D Center concludes that ethanol actually generates 35% more energy than it takes to produce.

More after the jump…

ethanol plantThe Argonne report (summary available here) lays out the following:

One million BTU’s of ethanol takes .74 million BTU’s of fossil energy input, while one million BTU’s of gasoline takes 1.23 million BTU’s of fossil energy input.

In fact, the Fuel to Energy Ratio (energy contained in the fuel / fossil energy input) is even worse when considering other energy sources. Electricity comes in at .45, gasoline is .81, coal is .98, and corn ethanol is 1.36.

Real future potential lies in the development of cellulosic ethanol, derived from plants like switchgrass, which has an astounding FER of 10.31. Switchgrass is more efficient to harvest, doesn’t require re-seeding, and current R&D is focusing on ways to use the unfermentable portion of biomass to generate steam for electricity.

The policy conclusions reached by the study are also interesting. They point out that not all BTU’s are equal – in fact the energy sector routinely spends energy to convert a low-value BTU (like crude oil) into a high value BTU (like refined gasoline).

Further, it seems clear that the net energy balance of any given fuel is arbitrary when considered by itself. To be useful, net energy balances of different fuels need to be compared to each other and weighed against desired results – such as reduction in petroleum consumption and greenhouse gas emissions. When ethanol is put up against petroleum based fuels, the Argonne study says it is clearly superior in those categories.

Of course, new research will continually improve the baseline numbers. Changes in things like the cost of enzymes used in ethanol production have dropped the price per gallon recently.

Companies like General Motors are aware of these developments and build alternative fuel consumption into their market-strategies:

If you compare a vehicle using E85 to a typical hybrid vehicle, the hybrid may get better gas mileage but the E85-powered vehicle saves hundreds more gallons of petroleum per vehicle per year, because only 15 percent of what you put in the tank is petroleum-based, compared with 100 percent in the hybrid’s tank…

In the big picture, E85 is just one of what we see as a number of solutions to the energy equation, and we’re planning for all of them, so that we will be ready when the market decides which way to go. We’re not putting all of our eggs into one fuel tank.

Ethanol is not a catch-all solution to our energy problems. It is just one of the many innovative alternative fuels being developed today that will evolve over time. One of the most interesting potential fuel sources I’ve read of recently comes from Nobel prize-winner Dr. Stephen Chu, Director of Lawrence Berkley National Laboratory. Dr. Chu sees a future in a type of biomass I had never considered:

Now, if you look in the gut of a termite, or the gut of a cow — or even in feedlot manure piles — there are bacteria that are similarly converting biomass into energy for them to live on…

Either we’ll genetically engineer the microorganisms from termite guts to produce more energy from biomass than they need, or we’ll adapt the chemistry within the microorganisms to process the biomass ourselves.

Much of our national energy policy is decided at the Federal level. But in Indiana, we can continue to invest in basic research and encourage the development of many different alternative fuels. For example, in the last legislative session I was a co-author of HB 1032 (written by Representative Steve Heim, R-Culver), which required state vehicles to use biodiesel fuel when possible.

I will continue to work on legislation that leads to a healthy alternative fuel economy and a more far-reaching energy policy in general. As always, let me know if you have any ideas you would like to share.

Entry Filed under: Energy

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