5/4/2025
WT Staff
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Can drinking water serve as an urban energy source?
Toronto, ON: Looking back on two decades of sustainable energy harnessing the cooling power of the Great Lakes
Toronto, Ontario in Canada perches on the edge of the last of the trans-boundary freshwater Great Lakes. The smallest by surface area, Lake Ontario is one of the deepest, storing potential energy in the form of cold, cold water.
Among the five largest cities in North America, Greater Toronto's 2023 population 6.3 million ranks third, behind Mexico City and New York City with a steady growth curve pointing toward 7 million by 2030. The high-density downtown core deals with punishing heat in the summer, approximately 75% of the city's energy generated by nuclear power plants.
See picture book by Toronto engineer, "Where does it comes from, where does it go?, here.
Toronto is well-known for innovation to preserve natural infrastructure. The Port Authority operates a regional airport within walking distance of the bustling business district and millions of downtown residents. Billy Bishop City Airport was the first in North America to successfully deploy alternative firefighting foam, eliminating toxic PFAS for the long term health of staff and to preserve drinking water quality for millions of people in Canada and hundreds of thousands in New York State. Read Blazing the Innovation Trail - Billy Bishop Airport eliminates forever-toxic PFAS, full article, here.
Municipal and industrial growth in North America depends on access to abundant clean water and affordable, sustainable energy. For cities located near large bodies of water, great energy savings and grid efficiency are within reach, the latent energy capture requires planning and investment, with well tested cases to follow, well worth serious consideration. The ground-breaking City of Toronto Deep Lake Water Cooling project has been tested and tried, performing and expanding since commissioning was commissioned twenty-one years ago, setting to motion what has become an investment powerhouse fueling one of the largest and most successful retirement funds, the Ontario Teachers Pension Plan. The City of Toronto partnered with the globally-diversified investment giant, OTPP to establish the sustainable energy operating company, Enwave. Enwave engineers planned and built out the novel district energy system, anchoring the company as the leader in sustainable municipal development. The DLWC project is the largest of its kind, currently cooling more than 180 buildings including the iconic Fairmont Royal York Hotel, Toronto Maple Leafs ScotiaCentre arena, numerous world-class hospitals, heat monster data centres and Toronto City Hall.
Large urban developments are summer heat traps at the best of times. As the heatwaves get higher, last longer and land closer together, urban power grids are tested to failure . Central air conditioning is no longer an option, it is a life-preserving necessity. High density downtown dwellers encased in towers of cement, glass and steel, become weaker as passive solar gain charges up the thermostat. In the absense of a powerful and fail-safe countervailing action, residents increasingly succomb to heat stroke, challenging the hospital emergency rooms. Where paving has displaced the naturally cooling effect of grass and trees, the "heat island" effect demands mitigation. See the US EPA guide to heat islands, here. Stats Canada studied population mortality data through extreme heat events in twelve Canadian cities, finding an increase in non-accidental and respiratory deaths, mainly impacting those over 65 years of age.
District Energy Use Case - The Fairmont Royal York Hotel
In the days when the Port of Toronto on Lake Ontario was wet right up to Front Street and rail lines occupied much of today's downtown scene, the iconic Royal York Hotel rose up from its foundation of ---, the largest hotel in the British Empire of the day. Situated at the epicenter of the young city on Front Street, adjoined to transport hub Union Station, the grand hotel filled five ballrooms with impeccably dressed guests on opening night. The night of July- 1929, was each with fine dining and live entertainment. A room full of telephone operators held ready at the switchboard to link --- guest rooms, the great boiler room and electric power generation station for the building managed by the in-house engineer and a team of technicians. With --- kitchens, laundry and a magnificent library, the hotel even housed a surgical theatre. A team of black horses, driver, footman were appointed to transport golfers 26 km to the course, easily a day-long affair. How the times have changed.
See the Royal York, here.
In ninety-six years, some things have not changed. Uniformed doormen still usher in guests from around the world. The dedicated entrance and upper level wing remains ready for visiting Royals. The lobby is adorned with some of the world's finest live floral installations, including the Faberge Egg, the Earth and elaborate holiday-themed arrangements. Restaurants and shops provide classic personal services, tailored suits, barbershops and spa. Lovers and dreamers still meet at the Clock, tycoons and moguls seal deals at the Library Bar. The Royal York Hotel has also modernized. Operators are no longer needed, the switchboard room replaced by a rack in a server ---. The surgical suite is gone, top docs operate in the best hospitals just blocks away on University Ave. The library that once delivered the world's news in ink and paper has been replaced with access to the world wide web of information, the hotel is connected on the backbone of Canada's internet architecture, direct to each user's personal devices as all modern facilities, only faster. No longer an off-grid facility, surrounded by highrises, Royal York's energy needs are now provided by the City of Toronto grid. Summer cooling of 1343 guest rooms, meeting rooms, ball rooms and common areas is done via district energy from Enwave's Deep Lake Water Cooling system.
District energy is a system of shared heating and cooling equipment with distribution to multiple adjacent buildings. The district model eliminates the need for mechanical rooms and equipment in each building. Centralizing the heating and cooling equipment and operators in a dedicated facility maintained and managed on behalf of the clients in the system improves overall efficiency for the local power grid. Space freed up in the clients' buildings is available for alternative productive uses, maximizing revenue. Capturing and redirecting waste energy is a high point of district energy projects. In the DLWC system, it was the raw drinking water intakes that supply one of Toronto's three main water treatment plants targeted for waste energy capture, that formerly disregarded energy source cools more than 180 buildings.
Enwave Energy Corporation is owned in part by the City of Toronto and the Ontario Teachers Pension Plan, a collaboration that gave wings to the Deep Lake Water Cooling system, imagined by ---. The project started with heat exchange units running off three raw drinking water intake pipes in 2004. The heat units extracted from the closed loop hydraulic cooling grid then circulated back through the district, eighteen buildings in the early days.
See Enwave Energy Corporation, Celebrating 20 years of Deep Lake Water Cooling, here.
What does all of this mean for my city?
Two hundred million dollars saved.
The City of Toronto power grid still reaches red-line status on the hottest days of summer, even as the DLWC system pulls minimally for heat exchangers and pumps, circulating Lake Ontario water to cool 40 million square feet of prime retail and commercial space, including the pedestrian communter PATH below ground level, including major league sports arena ScotiaCentre, a number of hospitals, City Hall, Union Station and the Royal York Hotel. Load relief on the power grid amounts to 61 megawatts less daily demand, 1.7 billion kW hours saved per year, equivalent to the annual draw of 150 thousand homes. The carbon footprint, a reduction of 129,360 tonnes, sparing the annual emissions of 40 thousand cars.
In terms of fresh water use, 5.6 billion gallons of water have been saved over a decade. The raw drinking water absorbs heat units from the closed loop cooling system via heat exchangers, the water itself carries on to the treatment plant as usual, and is delivered to --- residential and commercial taps, not in any way depleted or deteriorated for the waste energy recovered in passing. The latest addition, a fourth intake line is not run to the drinking water plant, this volume lends its cooling power and is returned to the lake.
Mission: Net Zero
Thirty-one million square feet of interior living and working space in Toronto has already achieved "Net Zero".
Related:
INTERVIEW WITH MARIKO UDA
Author of" Where does it all come from? Where does it all go?"
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