A multimillion-dollar investment in geothermal heating and cooling systems is paying big dividends in the renovation of several suburban ice rinks around the Twin Cities.
In Woodbury, the city credits its new system for $100,000 in annual energy savings at the Bielenberg Ice Arena.
Eagan’s natural gas bill has dropped from $68,000 in 2009 to $6,100 in 2012 since the installation of the new geothermal system in its ice rink in 2010.
Brooklyn Park is saving as much as $90,000 a year.
Burnsville, however, is not satisfied with energy savings from the geothermal system it installed in its 38-year-old ice arena in 2010.
It spent $5 million on a rink renovation that included geothermal, expecting to save up to $75,000 a year on natural gas and electric bills for heating the building and making ice.
After three years of operations, the arena has cut natural gas consumption by 80 percent for an annual savings of $30,000. But electric bills have gone up, in part because electric rates have risen, leaving the city well below the savings projected by the system designer.
Eagan, Woodbury and Brooklyn Park all had guaranteed energy-saving performance agreements with their contractors. Burnsville, on the other hand, chose not to pay an annual premium for a savings guarantee from contractor Harty Mechanical of Austin.
Eagan, for example, paid $35,000 the first year and will pay $39,000 next year to Harris Companies of St. Paul, which installed the system. The contractor will monitor the energy use, repair or replace anything that goes wrong, and pay the city the difference if the energy savings projections are not reached.
“There is real value in having somebody monitoring this so we can get quantifiable information,” said Cheryl Mesko, Eagan’s superintendent of operations. The city collected $700 the first year when savings were not as high as Harris projected.
Burnsville, however, chose instead to install the system and see how it performed and then fine-tune it if necessary, said Burnsville Parks and Recreation Director Terry Schultz. “We said we will wait and see how it turns out. We have always known this [retooling] might be needed but we didn’t want to go to this extent if we didn’t have to.”
Woodbury added geothermal in 2009 at a cost of $2.4 million. The system serves two ice sheets and an inflated dome, said Bob Klatt, parks and recreation director.
Eagan’s $3.9 million project did not help with electric costs — they actually have grown from $103,000 in 2009 to $135,000 in 2012. But the payoff in natural gas was so big that Eagan is satisfied with the system and the savings, Mesko said.
Brooklyn Park is likewise happy with the geothermal system it installed for two ice rinks at a cost of $4.6 million in 2009, said Steve Lawrence, central service superintendent for Brooklyn Park.
“The contract we signed stipulated we had to receive a minimum of $60,000 in savings annually in order to feel successful,” Lawrence said. “If we did not realize the savings they would write us a check. Much to our delight, our savings have been ranging from $70,000 and $90,000.”
Burnsville does not know why its geothermal system is under-delivering on energy savings.
Hoping more savings can be achieved, the city has hired Apex Arena Solutions of Coon Rapids for $18,500 to diagnose problems and fine-tune system controls.
Dakota Electric has agreed to pay $13,800 of the $18,500 for the fine tuning. The city’s share will not exceed $5,000.
Burnsville expects to learn something by mid December.
Scott Ward, co-owner of Stevens Engineers of Hudson, Wis., which designed the geothermal system for Burnsville and projected $70,000 to $75,000 energy savings, said he is confident the Apex analysis will improve the energy savings. “We stand by our design,” Ward said. “We strongly feel that they will meet the energy projections in the next year.”