Avista Corp., which operates one of the nation's oldest and biggest wood-fired generating plants at Kettle Falls, Wash., says it would be interested in the results of a planned University of Idaho study of the use of a crop-drying trailer to dry biomass fuel.

APT Advanced Trailer and Equipment LP, an Abilene, Texas, company, says it has awarded a research grant to the university to study the use of the Texas company's crop-drying trailers to dry biomass, which can be wood fiber or other plant materials or animal waste used as a fuel.

APT, which modifies railroad trailers at its plant in Vienna, Ga., to dry peanuts, says it began exploring two years ago at a materials development center in Savannah, Ga., the possibility of using its drying trailers to remove moisture from woody mass. It says that application will be studied as one of the trailers is used to remove moisture from wood chips that the university's steam boiler plant at its Moscow, Idaho, campus burns as fuel.

"The prior testing has shown that the trailer works and it does the job," says Randy Hill, president and CEO of APT Advanced Trailer. "But we were looking for a facility or institution that had an actual application where we could daily see the benefits of lowering moisture in biomass products used to fuel a plant."

Hill, whose company's trailers also are used to dry almonds in California and crops of seed in Kansas, believes there's a lot of potential to use drying trailers in the biomass industry.

Ron Gray, fuel manager at Avista's 50-megawatt wood waste-fired generating plant at Kettle Falls, says, "We've looked at the drying systems that are out there, but nothing has made economical sense yet." He says such systems draw waste heat off the emissions stacks of biomass plants and circulate it to dry fuel that will be fed into the plants. A megawatt of electricity is enough to meet the needs of 750 homes on Avista's system, so the company's 25-year-old Kettle Falls plant can serve up to 37,500 homes.

The plant has the capacity to burn 500,000 tons of green wood waste a year, but was limited to burning 350,000 tons last year because the supply of wood-waste fuel has dwindled as the recession has idled Pacific Northwest sawmills. Because of that, Avista is looking at logging slash as potential fuel, Gray says.

The company, which obtains about 50 percent of its fuel from nearby British Columbia, Canada, burns wood chips, sawdust and shavings, bark, and mill trim ends and other scraps, all processed so it's small enough to be fed into the plant's burner. Its fuel has about 45 percent water content, and Gray says, "The drier it is the better, up to a certain point. You throw a wet log onto your fire, you're not going to get the heat value."

The company would like for its fuel to be about 37 percent to 40 percent water, but if it were any drier than that, it would burn "in suspension" instead of lying on the burner as it burns, and would produce less heat, Gray says.

Hill says that cutting the moisture content of wood increases its output of heat and reduces the amount of fuel a biomass operation needs.

"There's a brand new wood chip power plant in New Hampshire," he says. A utility there says it has converted a coal-fired generating plant to a wood chip-fired plant, and another energy company says it's converting a former paper mill to a wood chip-fired plant. In Hill's native Texas, mesquite grows so fast that Texans have a hard time keeping it cut back, and its wood burns hot, giving it potential as a fuel in biomass projects, Hill says.

APT Advanced Trailer says it transported one of its trailers and a dryer from Georgia to the University of Idaho's campus in late January. The company says, "The grant will provide written research on lowering fuel cost while reducing carbon emissions by lowering the moisture content in woody mass products." The company says the initial 12-month testing period is expected to begin within the next few weeks.