Producing Energy Efficiently

To an untrained eye all ethanol plants look identical. They’re usually surrounded by corn fields and all have storage vessels, grain receiving equipment and boilers that are nearly indistinguishable from one facility to the next. However, all plants are not created equal. Some operate far more efficiently than others.

The EPA presented East Kansas Agri-Energy (EKAE), located in Garnett, KS, and POET’s Ashton, IA facility with the Energy Star Combined Heat and Power (CHP) Award for achieving excellence in energy efficiency in a ceremony at the 2008 Fuel Ethanol Workshop in Nashville.

POET Biorefining–Ashton and EKAE use turbines to produce heat and power, which, according to their data, reduces emissions by more than 15% in both facilities and reduces operating costs, as well.

East Kansas Agri-Energy

East Kansas Agri-Energy is a dry grind ethanol plant whose Dresser-Rand-built steam turbine generates roughly a third of its electricity needs. The system uses nearly 23% less fuel than typical on-site thermal generation and purchased electricity.

EKAE uses all of the energy its turbine produces in-house, but installing a turbine can present other opportunities for financial gain. “I would encourage any operation that has the capital available to invest in a turbine,” says Doug Sommer, plant manager. “You can use some of it in-house and sell the rest to the power grid.”

EKAE’s location near the local wastewater treatment facility allowed it to take advantage of another money-saving opportunity. The treatment plant pumps the recycled water into the ethanol plant where it’s used for cooling. This process saves them approximately $30,000 a month in water expenses and allows them to produce a gallon of ethanol with only 1 1/2 gallons of water, about half the amount it normally requires.

Sommer expressed how thankful EKAE is for the arrangement. “The wastewater treatment facility provides 75% of our water,” Sommer says. “Without that water we may not be here because the city wouldn’t have been able to support our cooling needs.”

Sommer says plant managers interested in employing a CHP system such as theirs should first contact an engineering firm, such as ICM or CPT, to help reach efficiency goals.

POET Biorefinery

Although POET is immensely proud of their Energy Star Award, the motivation was never to gain bragging rights or glory. They simply had the same goal as countless other facilities: to produce ethanol more cost-effectively.

“The largest cost in operating an ethanol plant is feedstock, followed by energy costs,” explains Nathan Schock, director of public relations at POET. “We can’t use less feedstock because then we’d lose capacity; so we sought out to use less energy.”

They achieved their goal by installing a natural gas-fired turbine to generate the plant’s electricity. The energy needed to fire the boilers requires approximately 16% less fuel than typical on-site thermal generation and purchased electricity systems. The system reduces carbon dioxide emissions by an estimated 18,900 tons/year, the equivalent of removing the annual emissions from 3,100 vehicles.

Although POET’s Ashton facility was originally built with the turbine, made by Solar Turbines, Schock says it is possible that existing ethanol plants could retrofit their electric powered boilers to use heat generated from a turbine instead.

He recommends joining the EPA’s CHP program to gain helpful resources and contacts that can help you get the ball rolling in your plant’s quest to reach higher efficiencies.

Combined Heat and Power Award

Schock described winning the CHP Award as a recent milestone in POET’s history. “It was gratifying to be recognized for something we care deeply about,” says Schock. “This achievement doesn’t mark an end to our innovation. We will continue to make the process more efficient and environmentally friendly.”