Large digester tanks in Le Sueur, Minn., use manure and corn silage to produce methane that powers engines that produce electricity; the white domes hold biogas at Hometown BioEnergy. About 2,000 such sites around the United States produce biogas.
St. Louis Park, where new apartment and condo buildings sprout like weeds, may become home to a far more unusual development: a community powered by organic waste.
Developer Chris Velasco of Minneapolis-based PLACE wants to build a community of apartments, studios and work spaces at the former McGarvey Coffee site on Hwy. 7, with a sustainable feature that in Minnesota is more commonly seen on dairy farms: an anaerobic digester.
Crudely put, the digester would turn what is now garbage into biogas that powers an engine to produce electricity that would heat and cool the development. Liquid fertilizer from the digester would be used to grow food in greenhouses on the property.
“We live in a society where we don’t think of where our food and energy comes from and where our waste goes,” said Velasco, a co-founder of PLACE. “There is real value in having people understand how these things work together. It ends up making living more affordable and reduces their footprint at the same time.”
St. Louis Park is reworking its ordinances to permit anaerobic digesters.
“We like the sustainable idea; it’s innovative,” said Meg McMonigal, city planning and zoning supervisor. “We’re working on the ordinance, and then they would come back with a plan.”
Anaerobic digesters are used on dairy farms to turn manure and plant waste into energy. In South St. Paul, a $30 million digester is planned this year at a business called Sanimax, where it would produce electricity. In Le Sueur, anaerobic digesters are using manure and corn silage to produce methane that powers engines that produce electricity. About 2,000 such sites around the United States produce biogas.
In Europe, anaerobic digesters have been built near hotels, and in Denmark one is connected to a Burger King, Velasco said. But residential use has been rare. Tim Farnan, an organics recycling specialist with the Minnesota Pollution Control Agency, said he doesn’t know of any digesters that are tied to residential developments in Minnesota.
An unobtrusive technology
Using residential organic waste to reliably produce biogas may be more difficult than using manure, Farnan said. While agricultural digesters use the same mix of ingredients every day, he said, residential organic waste might be heavy on watermelon at one time of year and some other kind of food at another.
Velasco said his company is working with a firm that has built digesters to create a patented process that suits a residential site. St. Louis Park officials have said they want no smell or noise associated with the digester. Velasco said the sealed digester, with an auger that would slowly turn waste, would turn food scraps into biogas in 21 days.
“These are very different from the manure digesters,” he said. “It will be enclosed and quiet and filtered. … We want people living and working and playing around it without really knowing it’s there.”
The digester would convert 35,000 tons of organic waste per year, producing about a megawatt and a half of energy. The development also would have solar, wind and geothermal energy. Velasco said the community would be connected to the power grid as a backup, “but we’re imagining that at the end of the year we will be a net producer of energy, and clean up more [waste] than we produce.”
Goal is sustainability
If a deal can be worked out, Velasco said he would like the digester to take organic waste that is already being collected in St. Louis Park, as well as organic waste from Hennepin County. He said he has talked with one county commissioner about a possible pilot project.
PLACE has a master lease on the McGarvey property at 5725 State Hwy. 7 with an option to buy, Velasco said. He envisions a “live-work” community of apartments and business or studio space, aimed at tenants with a range of incomes.
“We are thinking of the creative class, including makers who are interested in building things, sharing new technology … entrepreneurs for business and tech infrastructure, all in a collaborative environment,” he said.
With all the renewable energy systems on site, he said the goal would be to make the development self-sustaining. It would have greenhouses to produce food year-round, using liquid fertilizer produced by the digester.