Hennepin County officials say proposed anaerobic digester too expensive, prompting a look at other options for organic waste

Hennepin County has given up on building an anaerobic digester to process residents’ compostable trash because the cost is too high and other options exist to deal with organic waste.

In a Jan. 16 letter to CenterPoint Energy, Dave McNary, assistant director of Hennepin County environmental services, said that shifting market conditions have made the project unfeasible since the digester plan launched in 2018. The county had planned to sell renewable natural gas from the digester to CenterPoint.

Anaerobic digesters use microorganisms to break down organic material into biogas and compost.

“The region now has composting sites expanding their capacity, and other public and private entities are developing anaerobic digestion facilities with greater capacity than what the county’s site could manage,” McNary’s letter said.

In a statement, county officials wrote they are exploring a “recycling recovery facility to pull reusables, recyclables and organics from the trash prior to disposal. This type of facility, when paired with existing recycling programs, has the greatest potential to increase recycling rates.”

County officials estimated the anaerobic digester would cost about $45 million and planned to build it next to the Brooklyn Park Transfer Station where trash haulers take waste to be recycled or sent to disposal sites. Last May, the Legislature approved $26 million to help fund the project.

The state money was dependent on county officials agreeing to a timeline to close the Hennepin County Energy Recovery Center on the edge of downtown Minneapolis. The center each year incinerates about half of the roughly 750,000 tons of trash the county produces that cannot be recycled. The plant is controversial with some residents who’ve long pushed county leaders to close it, citing detrimental health effects from emissions.

County officials and workers who run the Energy Recovery Center say the site is well within its permitted level of emissions and that the facility creates a very small fraction of the county’s air pollution. They say trucking garbage to landfills, instead of burning it, would create other environmental problems and much more pollution.

Next Thursday, the Hennepin County Board expects staff to detail a timeline for closing the center. In October, commissioners said they wanted it done between 2028 and 2040 with an emphasis on sooner rather than later.

The County Board approved a zero-waste plan in June and is expected to update its solid waste management plan later this year with both actions mapping a future with considerably less garbage by 2030. Unfortunately, the county is heading in the wrong direction: The Minnesota Pollution Control Agency estimates residents will create 20 percent more trash annually by 2042.

Reporter Walker Orenstein contributed.