Waste heat keeps water running at -40°C

By Rebecca Sullivan, UMA Group Ltd.

Engineers were given the challenge of designing a community water distribution and sewage collection system for the Northlands First Nation of Lac Brochet. A remote northern community in Manitoba, Lac Brochet has a climate more severe than Yellowknife's, despite being further south, and is in the zone of discontinuous permafrost. Extremely cold winter temperatures, -30°C to -40°C, cold lake temperatures, and sandy soils with deep seasonal frost penetration defied UMA to find an economical way to prevent the water distribution system from freezing.

Crews installing pipe modifications to capture the heat emitted from the generators inside Manitoba Hydro's generating station.

UMA's team of engineers investigated various methods of watermain freezing prevention, including several configurations of heating plants with an oil-fired boiler, an electric boiler, a wood-fired boiler and an 'enhanced' electrical heat-traced system. The Nation was not in favour of any method with environmental risks, e.g., hauling and storing the fuel required for an oil-fired boiler, or operating the existing diesel-powered generating station to produce additional electricity for the electric boiler and heat-trace alternatives. These systems also entailed high annual operation and maintenance costs, so an alternative solution was sought.

UMA proposed an innovative process: utilizing the waste heat emitted from the operation of large engines in Manitoba Hydro's diesel-powered electrical generating station to heat the water in the distribution system. The warm water (heated to approximately 6°C) is recirculated through multiple loops of the community pipeline system. This is the first time this application of utilizing waste heat as a means of watermain freezing protection has been applied to an entire community in Manitoba.

The success of this project is a result of a unique partnership between UMA, Manitoba Hydro, the Northlands First Nation, Indian and Northern Affairs Canada, and Ininew Project Management (who assisted with the negotiations). The energy conservation over the operating life of the waste-heat recovery heating plant will amount to significant savings compared to the alternatives. This innovation also demonstrates a substantial reduction in the use of fossil fuels, a small but important step in the reduction of greenhouse gas emissions.

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