Calmac was selected to provide energy storage technology that would accommodate the increasing cooling demands of the state of Michigan Secondary Complex’s 13-building campus while meeting state energy conservation goals.

The complex is utilizing two 1.2 megawatt natural gas fired turbine generators to produce steam and electricity for central heating and cooling operations. Steam generated from the turbines is used to heat complex and is also utilized by two absorption chillers to create chilled water for cooling operations. Earlier this year, the Dimondale, Mich., complex installed one 900-ton, centrifugal, dual-mode, water-cooled Nelson Trane chillers, which operates using energy from the state’s power grid. This Trane Tracer-controlled chiller is paired with Calmac’s IceBank energy storage tanks to create and store cooling in the form of ice. This cooling is used if demand exceeds the capacity of the steam driven chillers.

The incorporation of ice-based thermal energy storage has allowed the 2 million-square-foot complex to create cooling hours during nighttime off-peak hours, when only the most efficient power plants are online and the price of electricity is reduced by roughly 50 percent compared with daytime prices. By storing and using cooling as needed, the complex can avoid expensive peak demand hours and reduce stress on the power grid.

Facilities supervisor Scott Davis said the equipment has made a big difference.

 “Calmac’s energy storage technology has allowed us to make our system extremely flexible in order to meet changing heating and cooling needs,” he said. “Utilizing cheaper nighttime energy has always been an attractive opportunity, especially for a large complex like ours. Now it’s a reality.”