Ag-Powered Options

By Dan Lemke
Morris, Minn. — Is it economical to power an industrial park in Morris with a) manure digested into methane, b) corn stover combusted into electricity or c) biogas generated from stover and other biomass? The three options were evaluated by a recent AURI study and the most viable appears to be
c) biogas.

A biomass gasification system installed at the Morris industrial park would use 69,000 tons of corn stover, roughly 25 percent of Stevens County’s stover production. The system could produce about 507,000 million metric Btu or decatherms at a cost of $10.44 per decatherm, compared to the $14.50 that industry pays for natural gas.

Producers and local businesses are interested, says Michael Sparby, AURI project director. “Where it goes from here is still unknown, but all options are open. The study showed the technical and economic viability from a broad view. There would need to be more specific questions asked and specific structures put into place before any of these options were actually developed.”
 

Sparby says local economic developers are putting a together a task force to move the project forward.

The Sebesta Blomberg engineering firm of Roseville, Minn. conducted the analysis and determined that a methane digester at a 5,800-cow dairy farm would produce about 108,000 decatherms at a cost of $10.59 per decatherm. An on-farm digester with a 12-mile pipeline to the city of Morris would cost
an estimated $6.5 million. The gasification system would produce about five times more biogas for only $2.5 million more.

Producing electricity by burning biomass doesn’t appear to be viable as capital costs would likely exceed $20 million for construction. The plant would likely need 10 cents per kilowatt to be economically feasible. The average price per kilowatt is 4 to 5 cents.

The Morris DENCO ethanol plant is a potential biogas user as it consumes about 760,000 decatherms annually and could use up everything the gasifier produced.

“The continuous availability of corn stover is yet to be determined,” Sparby says, “but other feedstocks could be identified … like distiller’s grains or other biomass available long term.”