What happened in Fernie, B.C. last week was a tragedy. Three people died due to an ammonia leak at a community hockey rink.
The majority of ice rinks in Canada use refrigeration systems that use ammonia. This uses a standard refrigeration process.
BUT – there is alternative system that would eliminate this risk.
Ground Source Heat Pumps (GSHP)
If you are familiar with GSHP systems, the loop field is typically buried in the earth which then transfers energy (heat) either into or from the loop. In the design phase, you must be careful to size the loop field big enough so that it does not take too much heat from the ground and results in a freeze up in the winter. If this happens your loop field cannot operate properly and the heating system will fail.
What would happen if the loop field was installed under an ice rink and you designed the system so that the loop field DOES freeze? You would create a concrete slab cold enough to freeze water and you can maintain an ice surface. These GSHP systems use safe materials so there is no risk to the public. All you need is a little electricity to run the heat pumps.
The traditional ice plant looks like this
Installing a GSHP ice plant would look like this
GSHPs are installed in a mechanical room and the main loop field is installed under the ice surface. There would be a secondary loop field in the earth to dissipate any excess heat. The size of this secondary loop field would depend on the type of facility. In some cases, you may not need the secondary loop field. The heat pumps extract the heat from the main loop field under the ice surface to maintain -10C on the concrete surface.
Now - what to with all this excess heat? Well, typically the buildings have other facilities attached - Community areas, swimming pools, common areas, all need to be heated in the winter. So you take the excess heat from the ice production and heat the rest of the facility. You can use your imagination as to what to do with the excess heat.
- heat the building
- make hot water
- provide ventilation for the building
- heat a swimming pool
- provide snow melting systems at the entrances
- provide heated seats in the spectator areas
What does it cost?
The most expensive part of a GSHP system is drilling the bore holes for the loop field. In the GSHP Ice Plant, you don’t need to drill the bore holes, so the GSHP system will be at a comparable capital cost to conventional systems. And with the operational cost savings of the GSHP you can reduce your utility costs by 50%.
Here is a link to a case study from Natural Resources Canada
Geothermal Ice Plant Efficiently Replaces Aging Ammonia System
Also, here is a great link from a company in Manitoba about the pros, cons, operating and capital costs comparing conventional systems to GSHP ice plants.
The TLJ Team