A project that turns toilet solids into energy at a Shakopee sewer plant is saving an estimated $500,000 a year.

The Metropolitan Council reports it has been given a $150,000 rebate from its energy supplier, CenterPoint Energy, after achieving savings on that scale.

The facility in question is the Blue Lake Wastewater Treatment Plant, near Valleyfair on Hwy. 101.

Starting last year, the plant is producing methane biogas which can be used for fuel, cutting the need for CenterPoint's natural gas in powering the machinery.

The council has been assisted in getting the energy saving technology in place both through the rebate and through a $2 million grant, tied to federal stimulus funds, and a discount on loan interest from the Minnesota Public Facilities Authority, the council said.

The $28 million project to install the technology started in August 2009. The biogas system, in addition to saving money, was pitched as making the plant more reliable.

David Peterson

dapeterson@startribune.com