NOTE: Two corrections have been made to this transcript. One involves the megawatts produced by EKPC’s landfill gas plant in Hardin County. The other involves the energy potential of a pound of switchgrass. Thanks to employees of Eastern Kentucky Power Cooperative for catching the errors. – K.E.
Biomass is organic plant or animal matter, and even household garbage, that can be used to generate energy. Everything from saw dust to corn cobs, from animal manure to landfill gas can be turned into electricity. Biomass is attractive because it’s when it’s used to produce electricity, it’s low on greenhouse gases—which contribute to global warming. But just a handful of utilities in Kentucky have started down the biomass road. And one of those has headed for the dumps.
At the Hardin County landfill, Eastern Kentucky Power Cooperative’s Ralph Tyree stops his truck at a dirt-covered section of dump. He points to some metal pipes sticking out of it.
“Those are the gas collection wells at this site. We have a total of about 24 of them. And they’re tied together in a common system,” Tyree says.
The wells go deep into the layers of compacted household garbage, which has been stewing in the landfill.
“Basically you’ve got the bacteria that’s feeding upon this waste.”
And in the process, that hungry army of bacteria digests the waste and produces a gas called methane. And methane can be burned to produce electricity. Pipes carry the gas to a generating plant down the hill.
“We’re inside the Hardin County landfill gas plant. This is about a 5500 square foot facility,” Tyree says.
Behind two panels of glass three giant yellow engines are chugging along, combusting the methane.
Tyree says the plant generates about two and a half megawatts of power — enough to power about 1400 homes. It’s capable of producing two or three times that. But Tyree says the amount of gas predicted to come from this landfill –even as it grows—will still be less than 10 megawatts. With the amount of garbage Americans generate each year, you’d think that firing up every landfill could solve our energy dilemma. But Tyree says that even if every Kentucky landfill were tapped, they wouldn’t generate nearly enough power on their own to meet statewide demand.
But other kinds of biomass could one day help meet that demand on a large scale. For example, switchgrass. It’s a tall, native prairie grass that can be cultivated. A hundred acres of switchgrass could produce 750 megawatts over the course of a year. The University of Kentucky’s Tom Keene says the grass is well suited to Kentucky’s climate—and it’s got a range of uses.
“We know that we have the soils, the fertility, the climate to grow it. We can burn it, we can make ethanol out of it,” Keene says.
But Keene says it can be a tough sell for farmers. The grass takes about three years to mature before you can harvest it. Still, he’s managed to convince enough farmers to start 100 acres on plots throughout the state.
“Here in Kentucky we’ve just done very little to explore alternative energy sources. And this project was an endeavor to start that if you will, to get the ball rolling, by getting switchgrass established in some areas of eastern Kentucky, primarily in an area that’s been hard hit by the loss of the tobacco quotas we had,” says Keene.
Once Keene’s plots mature, he estimates they’ll produce about 5 tons of switchgrass. Energy Information Administration biomass expert Bob Smith says large scale switchgrass use faces two hurdles on the production side.
“You have the actual cultivation, and then you have the harvesting, transport, storage issue.”
In other words, the infrastructure isn’t yet in place to handle large amounts of switchgrass. Another hurdle is the technology to produce energy from the grass. Smith says it can be combusted, but there are few biomass generators in the U.S., and those few are relatively small. The more efficient technology would be gasificiation, in which biomass is heated and turned into gas. Bob Smith says it’s also better suited for large plants.
“However, that technology is probably about 10 to 15 years out, and it’s largely untested.”
Smith says getting investors to embrace what’s untested will not be easy. And in the current climate, biomass for transportation fuels is getting a lot more of the spotlight than biomass for electricity.