HURLEY - The piles of corn cobs sitting on Darrin Ihnen's family farm that not too long ago would have been considered field waste represent energy potential to ethanol producer Poet.

The Sioux Falls-based company, which has been making ethanol from corn for more than 20 years, is working with Ihnen and several farm equipment manufacturers to develop ways to harvest, store and transport cobs that could one day join kernels as an alternative fuel feedstock.

"Cobs surround our facilities," said Jeff Broin, Poet's president and chief executive officer.

"It's a natural feedstock for us."

Privately held Poet, formerly Broin Cos., plans to expand its 50-million-gallon-per-year dry-mill plant in Emmetsburg, Iowa, to produce 125 million gallons per year - 25 percent of them from corn cobs and fiber.

Farmers typically leave cobs and stalks behind in the fields, but cobs - which are the densest part of corn - can be removed without causing soil erosion or stealing soil nutrients.

Poet is about halfway through its harvest of 4,000 acres on Ihnen's farm using several methods to gather the cobs.

One method uses a John Deere 9860 STS Combine with a 12-row corn head modified to collect a mix of both kernels and broken-up cobs.

The mix is then fed into a corn cob mix separator built by Salem-based Feterl Manufacturing Corp., which sorts the kernels from the cobs.

Randy Bauer, Feterl's president and chief executive officer, said the company spent about 5 months developing the prototype and is now ready to go into production design.