District energy systems provide an efficient and resilient method to meet society’s growing energy demands through providing a centralized thermal energy source. This uses a network of pipes to provide energy to connected buildings. It increases increase efficiency when compared to the traditional concept of individual buildings having onsite heating and cooling production. The centralized energy source also uses common sources of waste heat to offset the energy load on these systems.
Current Energy Uses
A variety of energy sources are critical for powering every aspect of daily life. Just think about the energy requirements of a residential home – components such as heating, cooling, and lighting come to mind immediately, however, energy was also required to build the home, to produce the materials within it, and to process waste produced by the people living in the home, as well as other energy demands.
Adding to this, an increase in global energy use of nearly 50% is projected to occur by the year 2050 [1]. To meet this growing demand, end-use energy use must become more efficient. Figure 1 demonstrates the disparity between domestic energy sources in Canada and the useful energy which results in end uses. What if these energy losses could be reduced?
District Energy
District energy systems are a potential solution to meeting society’s thermal energy needs more efficiently. Figure 2 demonstrates how district energy shifts away from the traditional method of providing heating and cooling as multiple separate and individual systems. Instead, a centralized plant provides thermal energy to a group of buildings using a closed-loop underground distribution system [3].
This thermal grid eliminates the need for connected buildings to have their own furnaces, boilers, chillers or air conditioners, because the thermal energy is delivered through the grid for space heating, domestic hot water heating and air conditioning [3]. The main source of thermal energy in district energy systems is combined heat and power plants, which generates electric power in addition to heating and cooling, and can achieve energy efficiencies of over 80% due to the reuse of exhaust and excess heat [5].
Finally, district energy systems can capture end use energy losses, often in the form of heat and steam, from industrial processes to provide thermal energy. In addition, waste heat from renewable sources such as sewage and wastewater, geothermal, hydrothermal, and others, can contribute to meeting the energy demand of the thermal grid. Not only does this help to address our increasing demand for energy, it also lowers greenhouse gas emissions associated with thermal energy, and increases resiliency towards fluctuating fuel and energy costs, including electricity and natural gas.
References
[1] “EIA projects nearly 50% increase in world energy usage by 2050, led by growth in Asia – Today in Energy – U.S. Energy Information Administration (EIA).” https://www.eia.gov/todayinenergy/detail.php?id=41433# (accessed Jan. 06, 2021).
[2] “Sankey diagrams associated with fuel and electricity production and use in Canada,” CESAR, Jun. 26, 2017. https://www.cesarnet.ca/visualization/sankey-diagrams-canadas-energy-systems (accessed Jan. 06, 2021).
[3] “District Energy: The Basics | Markham District Energy Inc.” http://www.markhamdistrictenergy.com/district-energy-101/ (accessed Jan. 9, 2021).
[4] “What is District Energy? | DISTRICT ENERGY INITIATIVE.” http://www.districtenergyinitiative.org/what-district-energy (accessed Jan. 04, 2021).
[5] “Fact Sheet – What is District Energy? | White Papers | EESI.” https://www.eesi.org/papers/view/fact-sheet-what-is-district-energy (accessed Jan. 9, 2021).
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