Toronto’s Deep Lake Water Cooling System
I am going to geek out some on this post because when I learned about this on our trip to Toronto in July 2023, I thought this was just so cool. And so sensible. So Canadian… sigh.
Over 100 buildings in downtown Toronto, including hospitals, sports arenas and city hall, are cooled in warmer months by a deep lake water cooling (DLWC) system.
What is a deep lake water cooling system?
The technology uses the renewable energy source of the cold waters of Lake Ontario to create air conditioning instead of using massive air compressors that require a lot of energy to run.
The 101 on how this works:
- The pipes of the system reach 5 km out in Lake Ontario.
- There, they pull in water from 83 m down in the lake.
- The water is piped to Toronto Water Authority’s Island Water Filtration Site.
- The water goes through the drinking water treatment process.
- The water is moved to a pumping station where large heat exchangers transfer heat or coolness between loops of pipes.
- The water used for cooling downtown buildings is chilled; drinking water is slightly heated.
- After providing air conditioning, the cold water is returned to the pumping station to merge again into the cycle.
Toronto’s DLWC system was built by a company called Enwave. f you would like to read more, please see this article on Enwave’s site.
The stats that demonstrate the efficacy and sustainability of the DLWC system:
- The system saves the city 90,000 mega-watt hours of electricity use annually, which can be equated to the energy needed to power a town of 25,000.
- It saves 220 million gallons of water each year – equivalent to 350 Olympic pools.
- The initial system is now at maximum capacity and there is discussion of an expansion due to demand.
- It’s expected that 30% of the city’s floor space will be connected to low-carbon heating and cooling by the year 2050.
In general Canada has shifted towards green in their energy sources. They have moved away from coal and gas and approximately 82% of electricity comes from hydro, nuclear, solar or wind power. Toronto’s deep lake water cooling system is an element of TransformTO, a strategic plan to reach net zero emissions in the city.
Why are deep lake water cooling systems not more prevalent?
There are two main challenges. First is cost. Initial build of this system has an expensive upfront pricetag. Toronto’s system cost an estimated $100M CD in 2004 (around the equivalent of $104M USD in today’s value). The potential expansion of the system will cost an additional $100M CD.
The second challenge is the specificity of place and whether cities where a system like this is a possibility are located within a reasonable distance of cold water at the needed depth for piping.
After learning about Toronto’s system, I was left with a question whether Chicago could use a DLWC system. That would really be the only Great Lakes city that could benefit from it. Lake Erie is just too shallow so poor Toledo, Cleveland and Buffalo are already out of the running.
Given the age we’re now in, I asked Mr. Google this question about Chicago. He passed it on to his friend Google Gemini. She told me that “yes, Chicago could have a DLWC system” but she failed to make clear the citations where she was pulling that from when I looked at them. Mr. Google offered a couple of other leads, but they were not legitimate enough sites for me to feel the information can be shared with confidence. I did find a chatroom exchange where an individual (who did link to some maps, adding some credibility) indicated that Chicago’s exact location is a limitation. They stated that Lake Michigan, within a reasonable distance for pipes, is unfortunately not deep enough.
So, today, I leave you with an unknown answer as to whether other Great Lakes cities could utilize this technology. But no matter what, a bravo to you, Toronto.
