Renewable Energy Inventory

Residual Heat Recovery

While not generally considered a form of renewable energy, residual heat captured from diesel electrical generation in northern communities is an underused source of heat that will remain available as long as fossil fuel-based generation is used. Approximately one third of the energy in the fuel used in diesel generation is converted into electricity. Another one third of the heat energy is transferred into cooling waters, but this heat can be easily recovered and used to heat nearby buildings, costing less than using heating oil. It is also possible to recover most of the final third of residual energy from exhaust gases using heat exchange technology, although at a higher cost.

Residual heat recovery is not new to the North. Since the 1990s, the Qulliq Energy Corporation in Nunavut and the Northwest Territories Power Corporation have reduced the cost of their operations by recovering heat captured from diesel generators to heat their own facilities. Also, residual heat recovery systems have been installed in several communities to transfer this heat to nearby buildings.

Cost is a major barrier to the expansion of residual heat recovery. Installing the necessary infrastructure for residual heat requires a large initial capital investment. Some residual heat projects have been delayed because many communities eventually want diesel plants moved away from residential areas. However, for residual heat systems to function in an efficient and cost-effective manner, the diesel generator should remain in close proximity to the buildings it heats.

Residual heat systems can provide a backbone for district heating systems and can be designed to accept additional heat from distributed conventional oil boilers or renewable energy sources. Diesel-electric generators only produce heat when there is a demand for electricity and buildings that use residual heat need to maintain their own heating sources for cold periods when electricity demand is low.

District heating systems present an opportunity to combine different forms of renewable energy, such as biomass or geothermal, in order to supplement the available heat load from residual heat recovery.

Figure 8
Current and Planned Residual Heat Recovery
Figure 8 shows Current and planned residual heat recovery systems in the North.
Note: all graph data is from 2007.

Photos courtesy of Patrick Kane/Up Here, Dianne Villesèche/www.ravenink.ca and ArcticNet. © 2016 A Northern Vision