Coal, Gas

Matching Old Technology with New: Cogeneration in the Heartland With an Ecological Purpose

By Judd Keene

In Garnett, Kansas, in the middle of America’s agricultural heartland, sits a plant that bridges the gap between today’s high technology and technology that’s been around a very long time. At the receiving end of the plant come truckloads of corn; out the other end comes ethanol, the environmentally friendly alcohol additive for American gasoline touted to help reduce the country’s dependence on oil.

The plant, owned and operated by East Kansas Agri-Energy (EKAE), is as technologically sophisticated as possible to conduct a distillation process that is older than moonshine. The process goes back to antiquity when man first figured out how to distill fermented beverages. Only this product is ethanol, 200 proof ethyl alcohol used to help fuel cars-not men’s spirits.

“It’s much like making corn mash whiskey,” says Kent Calvert, a sales engineer with Hughes Machinery Company in Wichita. Calvert is the Dresser-Rand equipment representative, who helped introduce a steam turbine generator at the plant. “It’s just a big moonshine still.” Now, in addition to the manufacture of ethanol, the plant generates approximately 750 kW of electricity, a first among the nation’s ethanol production sites.

The ethanol concept might be old, but the EKAE plant in Garnett, about 100 miles southwest of Kansas City, is completely modernized. It operates around the clock, pumping out 125,000 gallons of ethanol a day, 353 days a year (a dozen days are for scheduled maintenance outages), according to Doug Sommer, plant manager. In comes 45,000 bushels of corn every day and out goes the ethanol at a rate of 2.8 gallons per bushel of corn.

Completed in June 2005, the $46.8 million plant is one of six ethanol plants in Kansas, and the first dry mill in the United States to incorporate a steam turbine to generate electricity as part of its operation. EKAE, a farmer cooperative with more than 600 owner-members, decided during the design phase to add the steam turbine. “It was on the advice of ICM, Incorporated,” Sommer said. “We were the first plant to do that.”

The electrical generation represents a small portion of the coop’s profits, and profitable it has been. The board authorized a first-year profit distribution of nearly $3.5 million among coop unit holders.

As a gasoline additive, ethanol is both an efficient energy source and a clean burning renewable resource. It is replacing MTBE as a fuel additive throughout much of the United States. Currently cars can use a solution of 10 percent ethanol and 90 percent gasoline. In the industry, this is referred to as E10. Most auto manufacturers are developing engines that will burn E85, or 85 percent ethanol.

ICM, Inc., the Colwich, Kansas, engineering firm that designed the EKAE plant, was formed in 1995. During the past five years, ICM has been extremely active designing ethanol plants being built in the United States, according to John Graham, the applications supervisor at Dresser-Rand’s steam turbine manufacturing facility in Burlington, Iowa. The EKAE plant, however, was the first ICM plant in the U.S. to employ cogeneration.

“The fact that it’s integrating a steam turbine generator set into such an industry that’s trying to be environmentally responsible is indicative of their forward thinking,” Calvert said. “EKAE was willing to consider different innovative things. The steam turbine generator is a technology that’s been around for a long time, since the 1920s, and is being used in a new and innovative process. This plant was the first of its kind.” As part of its ethanol production process, the plant produces 120 psig of steam which later drops to atmospheric pressure in one part of the process. “They have to drop the steam pressure anyway, so why not make electricity?”

The EKAE plant uses 95 percent corn and the balance is sorghum. But ethanol can be produced by a variety of fermented grains and cellulosic sources such as post-harvest stalks, grain straw, switchgrass, and even municipal waste. (In Brazil, the world’s largest ethanol producer uses sugar cane.)

At EKAE the grain is milled, water is added, and the mixture is fermented with yeast. Following fermentation, the mash is distilled and eventually all water is removed, leaving pure ethyl alcohol. A natural gas-fired boiler is used for the total process.

Steam is generated at 120 psig, and for one part of the process the flow is controlled and the steam is close to atmospheric pressure. This necessary pressure drop, however, represents lost opportunities for ethanol producers, according to Ken Ulrich, the ICM design engineer who managed the EKAE account. The pressure drop meant that a turbine application to efficiently generate electricity was available. “We had been recommending this to clients for several years,” Ulrich said. But no one had taken them up on it.

“Their initial response had always been, ‘I don’t want to be in the electrical industry, I just want to make ethanol. Why should I buy a turbine and generator when I can put in a control valve?'”

That was the industry response until EKAE came along and took ICM, Hughes Machinery and Dresser-Rand up on their recommendation. EKAE saw a way to gain income from a steam turbine generator.

The plant is using a Dresser-Rand model KD2 steam turbine generator set, according to Graham. The generator is rated for up to 2000 kW of electricity using 120 psig inlet steam that’s exhausting to atmospheric pressure.

“I have to make the steam anyway to operate the process,” Ulrich explained. “This is a classic cogeneration application that’s been around forever. It’s nearly a perfect conversion of heat to work when you have an application where you use low pressure exhaust steam. The generator is extremely energy efficient for electrical generation.”

And it’s saving EKAE money. Sommer, the plant manager, estimates the plant is saving $15,000 a month in electrical costs. The savings rise as the price of public utility electricity rises. Both he and the coop members are pleased with the results.

In addition to the ethanol, the plant has two byproducts, dry distillers grains with solubles and carbon dioxide. It produces 68,000 pounds of the dry distillers grains, which it sells to area feed lots. “We don’t capture the 92,000 tons of carbon dioxide,” Sommer said. “We run it through a scrubber and return it to the atmosphere.”

The main product, ethanol, is shipped to refineries in Kansas, Oklahoma and Texas.

Dresser-Rand, ICM and Hughes Machinery all think the market for ethanol has just begun, and with it the demand for steam turbines and all the equipment necessary to bring ethanol from the corn field to the gas station. While ethanol plant developers in the past had been hesitant to generate electricity, EKAE has shown that it is a viable solution, especially in areas with higher priced electricity. Since opening the plant in Garnett, “we’ve gotten several more locations to install,” Ulrich said.

Calvert of Hughes Machinery predicted that the ethanol plants of the future will become even more efficient as they embrace new technologies.

Ethanol production has grown from 1.63 billion gallons in 2000 to a predicted five billion gallons this year. It takes 34,000 BTUs of energy to turn corn into ethanol, which offers 77,000 BTUs of energy. If the price of gasoline doesn’t drop terribly low, the demand for ethanol is expected to continue its surge.

“The boom is on,” said John Popek, Dresser-Rand’s regional manager based in Greensburg, Pennsylvania. “It has been compared to the petrochemical industry of the 1920s.”