What Is Deep Water Source Cooling?

Deep Water Source Cooling - Lake Ontario

As discussed in a previous article, many developers are looking for innovative ways to lower carbon emissions. Reducing the amount of concrete we produce and finding eco-friendly alternatives is one solution. Another is to reduce the energy consumption that comes from operating large buildings. A vast majority of our greenhouse gas emissions is due to the energy we consume everyday. In fact, a major contributor to the growing climate crisis is thanks to our reliance on non-renewable resources. Tackling this global problem has been met with many challenges, but fortunately there are some ingenious ways for us to keep energy consumption down and ultimately cut costs in the process. In this article, we will discuss what deep water source cooling is and how large development projects are utilising the environment to save money and reduce our carbon footprint.

Deep Water Source Cooling 2

What Is Deep Water Source Cooling And How Does It Work?

So what is deep water source cooling? As a very basic concept, Deep Water Source Cooling or DWSC is a form of air cooling by utilizing naturally cold water from large reservoirs and using it as a heat sink. Water is first pumped from lakes, oceans, rivers, etc, and transported through a large set of heat exchangers: one side of the exchanger receiving cool water from the reservoir which in turn cools the water on the other side of the exchanger. This is then transferred as cooling energy to wherever it is needed. For large buildings, this cooling energy is used in lieu of traditional cooling systems like industrial chillers or air conditioners. Heat Exchangers swap out the heat produced by large buildings with chilled water which will ultimately cool it and act as a heat sink.

The massive amount of heat produced by buildings are most often attributed to air conditioning units. Unlike in residential sectors, large buildings usually do not transfer heat back into the outside air. Because large structures can produce a significant amount of heat from air conditioning units and other energy demanding sources, they often require a form of heat sink in order to operate more efficiently. DWSC uses the cooling effects of cold water, originally pumped from the bottom of large reservoirs of water, as a heat sink for climate control systems such as air conditioning units. This means that heat pumps can operate more efficiently and reduce the large energy demands to keep them running.

For this system to work, the water used for DWSC needs to be cold enough for heat exchangers. Water is most dense when it is at a stable temperature of around 4°C ( or 39°F). Most large bodies of water will only provide this cool, dense water at the bottom of lakes, oceans, rivers, etc – up to about 50 to 80 meters depending on the location. Density of the water will decrease as the temperature rises, which is why lakes and oceans are warmer on the surface during the summer. Provided these water sources are away from the equator and near urban areas, these reservoirs can provide a constant source of cool water at 4°C throughout the year and therefore be used as heat sinks for large commercial buildings that consume a lot of energy.


The Advantages To Deep Water Source Cooling

Deep water source cooling can save buildings a lot of money. In fact, DWSC often only uses 1/10 of the average energy required by traditional cooling systems, which can result in huge savings in energy costs. Also, when set up correctly, DWSC can be very eco-friendly for the development as a whole due to the constant renewable energy source from lakes, rivers, etc. DWSC can reduce CO2 emissions, air pollution, and eliminate ozone depleting CFCs. Additionally, provided conditions are right, DWSC often satisfies a significant portion of building’s cooling demand, which reduces the reliance on chillers and cooling towers. This has an added bonus as cooling towers can harbor legionella pneumophila, a bacteria that can bring on Legionnaires’ disease which can be fatal.

The Disadvantages To Deep Water Source Cooling

There are some drawbacks to deep water source cooling, but less to do with operation and more to do with set up. Primarily, DWSC systems must be near a large body of cool water that is relatively deep (up to 50 meters or more) to ensure the right density and to achieve the 4°C (or 39°F) threshold required. The entire process of setting up and extracting deep water can be extremely expensive and labour intensive. A vast network of pipes and materials are needed to connect the cool water energy from large reservoirs to buildings. If older buildings relied on conventional cooling systems, then they would have to be retrofitted first which is also a laborious process. Finally, DWSC is not actually “free cooling” as it’s often referred because it often relies on a considerable amount of energy to operate the pumps.

Examples Of Deep Water Source Cooling

Some of the first major examples DWSC can be traced to Cornell University, who used Cayuga Lake as a heat sink to operate the central chilled water system for its campus and Ithaca School District. Perhaps one of the most impressive and extensive networks can be found in Toronto, Canada where Enwave Energy Corporation operates a deep lake water cooling system. Since 2004, this unique DWSC system draws cool water from Lake Ontario at depths of around 83 meters where the temperature remains at a steady 4°C. The cool water is then transferred through a filtration plant and energy transfer station, where the water goes through a set of closed-loop heat exchangers which allows for the transfer of thermal energy. This cool water continues on a closed loop through Toronto’s financial district, with each site within the loop receiving chilled water for the building’s cooling system. See the diagram below for more details.

Deep Lake Water Cooling System Diagram

Deep Lake Water Cooling & Knightsbridge Development Corporation

Recently we have utilized deep lake water cooling district energy for The Well: a mixed-use development which encompasses 3.5 million square feet in downtown Toronto. This involved incorporating a new state-of-the-art thermal storage facility underneath the site, consisting of a large temperature-controlled tank. The tank is fed by the DLWC system and acts as a “thermal battery” where the system can store thermal energy at night during off-peak times, easing strain on the electricity grid and reducing costs. The system is super efficient, resilient, and supplies low-carbon heating and cooling.

To learn more about the development of The Well in Toronto, as well as some of our other projects, then be sure to to check out our construction portfolio. You can also follow us on LinkedIn, Facebook, and Instagram for more frequent news, updates and helpful articles. If you would like to get in-touch, then be sure to do so right here: https://knightsbridgecorp.ca/contacts/