Comments sought on proposed Minn. AD power plant

By Anna Austin | February 15, 2012

The Minnesota Pollution Control Agency is requesting public comment on plans for an 8 MW anaerobic digestion power plant in Le Sueur County, Minn.

Proposed by the Minnesota Municipal Power Agency (MMPA), the Hometown Bioenergy facility would use a wet anaerobic digestion process provided by Danish company Xergi A/S to convert up to 45,000 tons per year of agricultural and food processing wastes into biogas, a liquid soil amendment and a solid pellet fuel.

Xergi A/S has significant experience in Europe with AD plants and has researched, installed, and operated nearly 40 similar biogas plants worldwide.

Biogas produced at the Le Sueur plant will power four 2 MW reciprocating engine gensets, and electricity will be delivered directly to the city of Le Sueur, which is located about 40 miles southwest of the Twin Cities. The plant’s total building area would be 25,500 square feet on a 35-acre site, which is a depleted gravel pit surrounded by cropland, an airport, and an operating gravel mine. The nearest home is more than 1,000 feet from the proposed area, according to the MPCA.

According to the Environmental Assessment Worksheet prepared by the MPCA, the facility will require an average of 15 feedstock deliveries per day on an annual basis, a number which may vary by season. Feedstock deliveries other than silage will be received in a fully enclosed building, dumped into receiving pits and tanks.

The EAW discusses measures the MMPA will take to prevent contamination, as the feedstock trucks will be rinsed with well water, and the rinse water will be incorporated into the pretreatment process with the feedstock. MMPA will also incorporate several odor management practices, including operating the indoor unloading area with a negative pressure system to keep odors inside.

The Hometown BioEnergy project would contribute to MMPA’s compliance with Minnesota’s renewable portfolio standard, which requires renewable electricity to consist of 25 percent of all retail sales by 2025.

The EAW can be accessed here, and public comments or concerns can be emailed to through March 7.