Written by Jonathan Eisenthal
The secret to ethanol’s phenomenal energy return — 2.34 BTUs out for every 1 BTU of fossil energy input — begins with the corn plant’s excellence as a solar capture medium, says Randall Doyal, CEO of Al-Corn Energy in Claremont, Minn.
“What people don’t understand is that we are not creating new energy when we make ethanol. We’re capturing solar energy,” Doyal said. “There are always people who want to tell you how great voltaics and other solar energy capture devices are, but there’s nothing that beats a corn plant. A corn plant is a very effective solar capture device. It takes that solar energy and CO2 from the air, water and nutrients from the soil and converts it into sugars that it stores in the form of carbohydrate starch. We then convert that back into liquid and turn it into fuel. So the original energy there is not so much energy we are putting in, it’s energy that’s coming from the sun.”
The majority of studies that have examined the energy balance issue show not only ethanol’s positive energy return, but also note the negative balance of both gasoline and electricity as fuel sources. The fraction of petroleum used to power the extraction and refining into gasoline has always been taken for granted, but a little more than 10 percent of the gross petroleum capture is burned up in this process. It takes more than twice as many fossil BTUs to make electricity as the actual BTUs of electricity delivered by the process. From the standpoint of carbon intensity, corn ethanol generates 20 percent fewer greenhouse gases than gasoline.
In Minnesota — where we have no fossil fuel sources of our own and most of our gasoline comes from the Alberta tar sands — ethanol makes even more of a positive difference. Producing a barrel oil from the tar sands produces three times the amount of greenhouse gas as a traditional barrel.
“Ethanol’s way ahead when it comes to energy balance. Just from the energy produced at the ethanol plant versus how much we put into it you can see the huge advantage in ethanol production,” Doyal said. “You’ve got 78,000 BTUs coming out (per gallon), and we’re putting less than 30,000 in. When you start adding up the BTUs from farming, transportation, etc, you still have a net positive. You have to take account of how we are doing farming today. Farmers are so much more efficient than they have been in the past. With the new technologies. GPS-driven steering, for instance, their fuel consumption, their fertilizer applications are so much lower than they were before, so that energy balance is even better than before.”
The Renewable Fuels Association Pocket Ethanol factbook states that ethanol renders 2.34 BTUs of energy for every 1 BTU used to produce it.
The modern ethanol industry is more than three decades old, and Doyal has seen its development firsthand. What he reports is the constant drive for efficiency, and the resulting reduced inputs and increased energy yield. Water use, for instance, has dropped by two-thirds.
“When we started this plant, 18 years ago, our water consumption was six gallons of water per gallon of ethanol produced,” said Doyal. “We have trimmed that back to about two gallons now. We’ve gotten more efficient in terms of our yield. When we process a bushel of corn we get more alcohol out of it than we used to get. We’ve gone from 2.5 gallons per bushel to 2.9 gallons per bushel. That four-tenths of a gallon doesn’t seem like a lot, until you start multiplying it by the 17 million bushels of corn we process — that’s a heck of a lot extra ethanol.”
Incremental changes to every link in the ethanol fuel chain, from seed to fueling station, mean fewer inputs per gallon of ethanol.
“We don’t discharge anything from our plant. We have no liquid discharge anywhere. We don’t send water to a sewer, we don’t send it to a city, we don’t send it to a ditch,” said Doyal. “We were the first plant here to go completely zero liquid discharge. That means we’re not hauling anything off, we’re not doing any crystallization. We re-use our water completely. The only water that leaves our plant is the water that comes in (as moisture inside the) corn in the first place, and that goes out the dryer stack (as steam). Everything else we re-use. And that practice is becoming much more common. Compare that to water used to produce gasoline. It was somewhere around the four to five gallons mark back then and that’s still where it’s at. So, we’re down to half. If you want to have less water impact, it seems like you would be using more ethanol.”
The U.S. Environmental Protection Agency has proposed slashing the amount of ethanol we blend in our gasoline by 1.4 billion gallons in 2014. Click here to make your voice heard and tell EPA “Don’t mess with the RFS!”