International Biomass Conference & Expo tours biopower plants

By Chris Hanson | April 08, 2013

Koda Energy LLC and Elk River Resource Recovery Project were the first two biomass industry tours at the International Biomass Conference & Expo being held April 8-10 in Minneapolis.

Early in the morning, over 40 IBCE attendees climbed aboard a tour bus to head to the first stop, Koda Energy. Upon entering the facility’s grounds, Stacy Cook, vice president of operations at Koda, greeted the bus and commenced the tour.  It began at Koda’s shipment building, where Cook said they receive 24 loads of biomass materials each day. About 20 percent of the facility’s fuel comes from neighbor Rahr Matling, and other sources include oat and barley hulls from General Mills, wood chips, grass seed and corn cobs. “We get about 95 percent of their products,” said Cook. He added the plant consumes 500 tons of biomass fuel each day.

From there, Cook showcased the facility’s towering storage silos and milling area. From the silos, Cook said Koda creates a “biomass sandwich” recipe of the available feedstocks that are fired inside one of the six boilers. Tour attendees witnessed feedstock being ground to a fine powder and sent to the fuel metering bins.

Koda’s boilers, which are rated at 60 MMBtu per hour, are suspended from the ceiling. Attendees were able to view the 2,150-degree Fahrenheit fireball burning inside the boiler, as well as the water seal and thermal expansions. From the boiler facility, the generated steam—and tour attendees—moved to the generator housing unit. 

Cook demonstrated how steam from the boiler is used to spin the turbine rotor at 6,834 rotations per minute. After spinning the rotor, the steam goes through one of two extraction ports. One is to heat propylene glycol, a heat source for Rahr’s kilns for the production of malted barley. The other port is to preheat Koda’s feedwater.

The second IBCE tour stop was Great River Energy’s Elk River Resource Recovery Project. At the ERRRP, attendees were shown how municipal solid waste is utilized as a feedstock for power generation, and company personnel explained to them that after common garbage is processed, it is brought to a pit on a tipping floor where cranes remove potentially harmful items, such as propane tanks, tires and mattresses. The material is then sent to a flail mill where 24 150-pound hammers shred the solid waste into smaller pieces, which are then further separated and transported to the energy recovery station. Attendees were allowed to climb into the crane control room and witness the operators sift through the solid waste and picking out items such as twisted bed frames and large steel pipes.

A former coal plant, the ERRRS currently generates 30 MW using refuse-derived fuel (RDF). The tour was able to view its three boilers units that utilize over 700 tons of RFD per day. In the control room, plant experts said they yield roughly 5,500 Btu per pound of RFD material in the boilers.

The second set of the International Biomass Conference & Expo tours will take place on April 11, and include stops at District Energy of St. Paul and Target Field, home of the Minnesota Twins.