Power on Wheels
Utilizing a design pioneered by downdraft gasification system developer Community Power Corp., Montana researcher Brian Kerns has developed a mobile biomass gasifier, after collaborating with the company to integrate their design with his own ideas.
So far, his work has resulted in a 25-kilowatt per hour system that can easily be transported to areas where there is a need to manage woody biomass waste, such as pine beetle-killed wood. “Instead of gathering the biomass materials and bringing them to a centralized plant, which is the norm, we wanted to do the opposite,” Kerns says.
That strategy provides several benefits, including avoiding feedstock transportation and storage costs.
The system, which is enclosed on a semi-trailer platform, can be set up and running within an hour.
“It’s a quick, nimble and flexible system,” Kerns says. And though it sounds simple, actual development wasn’t easy. “Even though CPC has been building these things for 15 years, it was a significant challenge to modify and condense it so it fits adequately, and so that the weights and balances were such that it could easily move down the road.”
In a recent demonstration, Kerns gasified pine beetle wood, which is a growing problem in some Western states such as Montana and Colorado, as well as in areas north into British Columbia and Alberta, Canada. “While some of the pine beetle wood is useful as logs, a lot of it is smaller in diameter and is wasted,” Kerns says.
Before the feedstock is fed into the system, it must be chipped. “During our last demonstration, we had a chipper set up and a conduit from the chipper into the enclosed trailer,” Kerns says.
Pine beetle-killed wood is typically dry, around 35 to 40 percent moisture, Kerns says. The material must be at about 10 percent moisture to be gasified, but drying doesn’t have to be done separately. The ambient air in the system that cools the producer gas also dries the feedstock before it undergoes the gasification process. “The CHP (combined-heat-and-power) system recovers the waste heat and uses it to dry the feedstock as it’s running,” Kerns explains.
After the gasification process, the power produced is plugged directly into the grid.
Kern’s next goal is to scale the system up to an economical level. “We’d like to try to figure out the parameters that would make it pencil out,” he said. “It would probably need to be of a size somewhere north of 200 kilowatts.”
Bringing the system up to that scale while keeping it mobile could prove to be a challenge, he notes. “As you start upsizing, you’re talking about more weight and larger pieces of equipment, so it’s a difficult balancing act. It would have to be able to process a lot of wood fairly quickly while producing a lot of electricity, and relatively cheaply.”
Kerns is now seeking a second round of funding from federal or state agencies in order to keep the project going, and to figure out what the next stage is to make the mobile gasifier a commercial reality.