CEDAR FALLS -- Just outside Streeter Station No. 6 lies a pile of coal larger than a football field.

But on a sunny morning last week not even a handful of that coal was loaded into the electric generating facility's stoker.

The facility was up and running all right, just one day removed from a three-day hot spell that may have marked the year's electric use peak. But the fuel came down the road from Independence in the form of pelletized corn cobs.

Last Friday was the second time CFU tested burning corn cobs instead of coal. If the tests go well, CFU could find a way to supply more environmentally friendly power from a renewable resource.

The municipal utility is breaking new ground with this endeavor.

"As far as we know there aren't others doing this right now, so we don't have any other examples to work from," said CFU spokeswoman Betty Zeman.

So far, so good, according to those at CFU.

"Without any capital changes, we were able to turn corn into electricity," said CFU Electric Production Manager David Rusley, boiling it down to the simplest terms.

"We're just taking baby steps. At each step we learn more of what works well, what doesn't," Rusley said.

The tests are run on the smaller of CFU's two Streeter Station turbines. Unit 7 has a capacity of 36.6 megawatts and burns pulverized coal. Last year it produced about 30 percent of the electricity in Cedar Falls.

Unit 6 is 40 years old and hasn't seen much use for about 25 years. Ed Schultz, CFU director of operations, said the turbine has been used only at times of peak electric load recently.

The smaller turbine is a stoker, or what Rusley refers to as "basically an overgrown barbecue grill." It can burn stoker coal or natural gas.

The Iowa Department of Natural Resources cleared the way for the corn cob tests, allowing CFU to burn something other than the coal and natural gas that its permits specify.

CFU found it could burn the corn cob pellets without any major changes, only adjusting the oxygen composition in the stoker.

The biomass testing not only serves as a way to further CFU's endeavors into renewable fuels, but it could give Unit 6 new life. Federal emission standards will require $1.6 million in environmental upgrades.

"We can't justify that investment if we are only using the unit a few days each year to burn coal," said CFU General Manager Jim Krieg. "If we can burn a biomass fuel, we'd like to turn it into a base load unit that operates continuously."

The corn cob pellets aren't necessarily the fuel CFU would use if it decided to go ahead with a continued biomass project on the site. The utility will look at a range of different types of fuels to see what would be most cost effective.

If such a fuel were found and CFU wanted to move ahead, Rusley said it would take about a year to get permits in place and have the unit ready to go.

The biomass project fits into the CFU board's goal of increasing its use of renewable resources. Right now about 5 percent of power used in Cedar Falls comes from renewable resources. Wind power from farms in northern Iowa provide most of that greener power to Cedar Falls.

"The board's goal is to get to 10 percent renewable energy in Cedar Falls, but they want to do it without raising costs to customers," Zeman said.

While the CFU experiment is groundbreaking, it isn't likely to be copied widely around the country. Stoker-type facilities are few and far between, so CFU will likely remain unique if the biomass project goes forward.