Renowned Ice Skating Club Slashes Operational Costs by 40-60% Using Chillers

The Skating Club of Boston is a not-for-profit figure skating club founded in 1912 and is based out of Norwood, Massachusetts. The current facility, opened in 2020, features three rinks including a 2,500-seat Olympic-sized arena that hosts nationally televised events and a world class training facility for Olympic athletes. The rinks are used to host training for some of the most notable figure skaters, national and international figure skating championships, and Theatre on Ice shows. At The Skating Club of Boston, there is currently 1000 tons of nominal cooling capacity produced by five 200-ton engine-driven water-cooled chillers. They’re used to reliably maintain their three sheets of ice as well as provide air conditioning throughout the building.

Cost Savings

The highly efficient chillers are powered by natural gas engines instead of electric motors, and thus can provide cooling at a significantly lower cost compared to conventional electric chillers. Electric chillers are also primarily driven by natural gas as well as other sources, albeit inefficiently when considering the relatively low central powerplant efficiency as well as transmission and distribution losses to deliver the electricity. These inefficiencies result in a significantly higher cost of energy as well as higher greenhouse gas emissions. By instead locating the natural gas power plant locally within their facility, The Skating Club of Boston can realize a much higher efficiency and benefit from additional operational savings by capturing the waste heat from the power generation process. It’s not possible to feasibly capture and utilize the waste heat from centralized power plants, as such customers typically need to run boiler alongside their electric motor driven refrigeration compressors in order to generate heat for the various requirements in an ice rink. The captured engine waste heat is used by ice rinks to serve dehumidification, space heating, sub-soil heating, domestic hot water, ice pit melting, and refilling of Zamboni hot water tanks for ice resurfacing. Utilizing natural gas to keep the ice frozen 24/7 can reduce utility bills by 40-60% when compared to electric alternatives and reduce carbon emissions by a similar amount.

This efficient simultaneous use of the engines’ shaft power and captured waste heat is considered a form of “mechanical Combined Heat & Power (CHP)” by utilities and government agencies. As a result, refrigeration systems and chillers that leverage the principles of CHP can qualify for significant state, federal, and utility incentives. These incentives can reduce a facility’s upfront capital investment significantly. Currently there is up to a 50% Investment Tax Credit (ITC) offered by the federal government’s recent passing of the Inflation Reduction Act (IRA) granted to all combined heat and power systems as well as a substantial portion of the installation cost to implement them. The Skating Club of Boston received a massive energy efficiency incentive from the local utility, discounting the total cost significantly.

Chiller Makeup

The chillers are powered by robust, efficient, industrialized V8 engines that have been perfected over decades for this application. The use of an engine inherently provides variable speed operation for the compressor, akin to an electric VFD drive, but without the losses imposed by an inverter, allowing for high part load efficiency and exceptional turn-down. The engine powers a screw compressor that’s designed to use a low GWP synthetic refrigerant (R-513a) as well as many other refrigerants. To minimize any criteria emissions produced, the chillers feature an ultra-low-emission package, which ensures the emissions are kept at ultra-low levels enough to be permittable in all parts of the country, including Southern CA. Installation is simple and the footprint and connections are comparable to an electric chiller system.

In an ice rink application, where resiliency is important, the engine power can maintain operation with minimal electrical service, only 1-2 kW of the facility’s electric power is required for the controls and ancillary equipment. In the case of an outage, a very small back-up generator would be necessary to keep the ice from melting, only large enough to provide power to floor pumps and cooling tower. For comparison, an electric chiller alternative requires 190-300 kW and needs massive backup generators to remain active during power outages.

Emission Savings

As we move towards the future of decarbonization, combined heat and power (CHP) systems are a transitional pathway to zero carbon. Natural gas-fired chillers can reduce carbon emissions by replacing the marginal fuel source. When an ice rink installs a CHP system, the system produces its own power. Therefore, each CHP system installed at the site allows the natural gas usage at the power plants to ramp down by a commensurate amount. The clean sources, like solar, wind and arguably nuclear, are must-take sources and the next piece is the natural gas plant ramping up and down to cover the demand. When the engine-driven chiller turns on, it is offsetting the natural gas power plant but without the T&D losses or the inefficiency of the central power plant, instead with 2X the efficiency thanks to the principles of combined heat and power.

In The Skating Club of Boston, it is estimated that the five 200-ton chillers are saving roughly 1,000 tons of CO2 emissions annually. The advantage of using an engine-driven chiller is that it saves energy while also saving a lot on the cost of energy, a win-win for rinks