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Metropolitan Council Environmental Services (MCES) energy saving initiatives

December 2011

MCES is responsible for collecting and treating wastewater for about 90% of the region’s population, as well as businesses and industries. In 2006, MCES set an ambitious goal to reduce purchased energy by 15% over four years. MCES hired an energy manager and partnered with Xcel Energy to study ways to meet the goals, with impressive results.

 

MCES reduced its annual electrical costs by $2.5 million annually between 2006 and 2010

Energy saving initiatives focused on the massive Metro Plant in St. Paul, which treated an average of 190 million gallons of wastewater a day in 2011, and included several strategies:

• Cleaning the fine air bubble diffusers at the bottom of all the plants aeration tanks on a regular basis (10 million kWh annual savings).
• Refining the dissolved oxygen set point in the aeration tanks (6 million kWh savings).
• Replacing and redesigning the lighting in more than five miles of tunnels (3 million kWh).
• Initiating a new dissolved oxygen strategy at the Seneca Plant (3 million kWh).

 

42 million kWh saved annually

All told, the 27 energy projects completed between 2007 and 2010 resulted in an annual savings of 42 million kWh.

In 2011, MCES received earned a Gold Award from Xcel Energy for achieving the highest electrical savings of all the utility’s large commercial and industrial customers in Minnesota between January 2010 and June 2011. MCES cut its electrical use by 11.2 million kilowatt hours, the equivalent of unplugging more than 1,200 homes from the grid.

 

Higher goals and new initiatives

Because of the agency’s success, in 2011 MCES General Manager Bill Moore set new, aggressive goals for energy conservation: reduce purchased energy 25% by 2015 (from the 2006 baseline) and 50% by 2020.

About three dozen additional projects are already under way at multiple facilities, expected to result in a total annual savings of 15 million kWh. A few highlights:

• Install anaerobic digesters at Blue Lake Wastewater Treatment Plant to produce enough digester gas to offset the drying operation’s natural gas load.
• Install a non-condensing steam electric generating turbine at the Metro Plant.
• Complete lighting redesign measures.
• Decommission buildings no longer in use.

 

MCES is also considering a large solar project at Blue Lake, biogas optimization at the Empire Plant, and other initiatives in the future.

 

Collaborating for better results

MCES engages in several collaborations to move energy conservation efforts forward, partnering with:

• The Metropolitan Energy Policy Coalition,
• The Climate Registry,
• State Interagency Energy Team,
• University of Minnesota,
• Chamber of Commerce, and
• Xcel Energy.

 

MCES is keeping rates low

The Council’s wastewater collection and treatment system is financed entirely by user fees. Municipal customer rates are about 40% lower than the national average, according to the National Association of Clean Water Agencies.