Just 24 miles southwest of Minneapolis there is a gentle hum rising from a freshly installed set of anaerobic digesters. The digesters are stationed at the Blue Lake Wastewater Treatment Plant in Shakopee, MN where they process the waste water from over a quarter of a million residents. That amounts to 29 million gallons of sludge being processed every day.
The Blue Lake facility was built back in the 70’s, but has only recently made the switch to waste-to-energy technology after realizing the benefits of deriving energy from the sludge they treat every day. The newly installed digesters are already churning out energy equivalent to the demands of 900 homes. This energy production is made possible thanks to the variety of organic material contained within the waste water. As the sludge enters the facility, it is diverted to the digesters where microbes eat up the organic matter producing potent methane gas. This gas is then burned to drive electric turbines.
The resulting energy can be used to power the facility itself or sold to a local utility. In the case of the Blue Lake plant, they received a rebate from CenterPoint Energy (a regional electric company) to the tune of $150,000 for reducing their natural gas consumption. There are many such incentives available to municipal and private waste processing plants across the country.
The new anaerobic digesters are just the latest in an ever-growing trend among waste management service providers. There are currently 12 other anaerobic digesters in various stages of development across the Midwest, with several plants already in operation elsewhere. The largest digester, Hometown Bioenergy, is currently scheduled to open this year and will convert potato waste, among other things, into an estimated 8 megawatts of electricity.
The drive towards using waste to generate power is a result of economics and a renewed sense of responsibility. As landfills start to fill up, the costs of disposal go up as well. And with land in short supply and little will to invest in new landfill construction, more energy and waste disposal companies are turning to waste-to-energy technology. Even big name brands like Wal-Mart and Target are pushing for more digesters, along with other foodstuff providers.
Hopefully, this new trend will result in a sharp reduction in organic waste going to waste. Meanwhile, expect to see more of your electricity coming form that bag of chips you just threw away!
Source: Finance & Commerce