District GeoExchange Systems and Waste Heat Recovery

Remote communities must import energy to sustain life. Diesel powered generators are often used in small communities not connected to the electrical grid. Heat recovery from the generators can become the nucleus of a district geothermal energy system for a community. Other energy sources in the community can be integrated into a district geothermal system. These sources can include heat recovery from refrigeration plants in ice arenas or grocery stores, solar thermal, process heat, bio-mass boilers, etc.

Waste energy is not always available when it’s needed. A ground heat exchanger (GHX) can be used as a thermal storage medium for both short term energy storage (diurnal) as well as seasonal or longer term energy storage. The stored low-grade energy can be extracted as required using ground source heat pumps to provide space heating and domestic hot water.

Working with the people in the community and with other stakeholders in the community, it is possible to develop an integrated district geothermal energy system to take advantage of waste energy sources in the community. Integrating waste energy sources into the system greatly reduces the size and cost of the GHX needed for such a system.

This paper presents a potential scenario demonstrating how a diesel generator in a community could be integrated into a district geothermal energy system, using the community of Lac Brochet in Northern Manitoba, Canada, as a case study.