Renewables could replace some fossil fuels in power plants

Scientists and innovators in Iowa have been studying the possibility of burning renewable fuels in power plants to generate electricity.

When we think of renewable fuels, we often think of the liquid fuels we pump into our cars. Renewable fuels such as ethanol and biodiesel are already replacing a significant percentage of the petroleum-based gasoline and diesel we use to power our automobiles.

But someday we could also be generating electricity by burning renewable fuels in power plants instead of fossil fuels like coal.

From 2001 through 2005, a series of tests were conducted at the Ottumwa Generating Station to study the feasibility of burning pulverized switchgrass mixed with coal. These tests, conducted by the Chariton Valley Biomass Project, successfully showed that a renewable commodity such as switchgrass could replace at least some of the coal used to generate power.

The goals of the switchgrass test-burn were to identify the effects of co-firing on the power plant, to study changes in emissions, and to gather information to improve the design of the switchgrass handling equipment. According to the first test project report, all of the goals were met.

Now there are other possible renewable fuels that are being studied in power plants in Iowa.

Early this spring, the Wisdom Station power plant in Spencer conducted a test-burn using a different renewable fuel source. The power plant is owned and operated by Corn Belt Power Cooperative of Humboldt. The test created electricity using 90 percent coal and 10 percent pelletized dried distiller grains.

The Wisdom Station test showed some promising results, and demonstrated that there are new possible uses for dried distiller grains, the main by-product of the process of making ethanol from corn.

Dried distiller grains are most often fed to cattle and other livestock, and will no doubt become more readily available as the production of ethanol grows.

One of the main drawbacks of dried distiller grain is the fact that it is cumbersome to ship and store. But a new technology may provide the solution to some of those problems.

According to Bruce Hansen of the Iowa Area Development Group, a company called Ag Pellet Energy has developed a new pellet product that could make transportation of dried distiller grains more efficient.

Ag Pellet Energy, based in Indiana, and Landers Machine, located in Texas, have produced a new pellet product derived from 100 percent dried distiller grain that can be burned in a power plant or as a feed for livestock.

These pelletized distiller grains were used in the test burn at the Wisdom Station power plant.  Corn Belt Power vice president Mike Thatcher said that the power plant did not achieve full generation output with the blended fuel, but there was a reduction in emissions during the test. "With the fuel mixture, we saw a reduction in the percent opacity, which is the measurement of visual emissions coming out of the stack. We believe the DDG ash causes the precipitator to perform better," said Thatcher.

The company is also testing the pelletized distiller grain as cattle feed, and Iowa State University is involved with the research. Dr. Dan Loy, an ISU researcher, will be working with producers on the tests.

"Until now, a 100 percent DDG pellet was considered to be impossible to pelletize for livestock feed due to the amount of oil and fat found in the standard DDG material," said Loy. "This new product is very unique and should have a distinct advantage for the feed industry and livestock producers."