Waste heat to fuel Nunavut’s new hospital

SARA MINOGUE

Nunavut Power Corp. could cut its diesel fuel consumption by 10 per cent if two waste heat projects come to fruition in Iqaluit and Rankin Inlet.

“Waste heat,” also referred to as “residual heat,” is the heat that is produced when diesel-fueled generators create electrical power. Instead of letting this heat melt into the air, it can be trapped and distributed through what is called a district heating system.

District heating systems are used in many parts of the world, but the system has a heightened significance in Nunavut, which is 100 per cent dependent on imported fossil fuels.

Nunavut imports 40 million litres of diesel fuel per year to run its generators, says Lee Douglas, senior planning engineer for the Qulliq Energy Corporation, the parent company of NPC.

But diesel generators are inefficient. Less than 40 per cent of the energy potential in the fuel winds up as electricity. “The balance of that wasted energy is lost in the form of heat,” Douglas says.

In its 2002 Ikuma II report on meeting Nunavut’s energy needs, NPC estimated that this wasted heat cost the GN over $12 million a year. Since then, both fuel consumption and costs have risen, making heat recovery even more urgent.

“District heating systems offer the greatest immediate potential to reduce the demand for imported fossil fuels in Nunavut,” Douglas says.

The two proposed district heating systems could save Nunavut a combined four million litres of diesel fuel per year.

“That will also significantly reduce the greenhouse gas emissions in the territory, which affects the Arctic climate,” Douglas says.

Iqaluit has not had a district heating system since the one that was installed by the Government of the Northwest Territories fell out of use in the early 1990s and was later dismantled.

QEC is now planning to use waste heat as the primary heating source for the new Qikiqtani General Hospital when it opens in 2006. The project will save about three million litres of diesel fuel a year.

The power company is also proposing to extend a district heating system to several buildings that are within a close enough range of the power plant, including: the water treatment plant, Inuksuk High School, the white row housing complex, the Browne Building, the CBC offices, and the small reheat building located just west of the new hospital site.

The GNWT first installed a district heating system in Rankin Inlet in 1979. The infrastructure from that system still remains.

QEC wants to expand that system to several new buildings, including the new Kivalliq Health Centre, the new high school and the water treatment plant.

This project, which will be commissioned in late 2005, has the potential to save about 900,000 litres of heating oil every year.

How it works
Power plants across Nunavut use radiators, or water cooling systems, to keep the plants from overheating. As the generators heat up, the water that runs through pipes surrounding the plant gets hotter.

Instead of allowing this heat to dissipate into the air, the hot water can be sent to a “heat exchanger,” where the hot water from the radiator comes into close contact with a separate pipe of water, transferring the heat without actually mixing the two water systems.

Nunavut’s new hospital, now under construction, is located just downhill from the power plant on the northernmost edge of Iqaluit.

An insulated pipeline will deliver the freshly heated water (mixed with antifreeze) directly to the hospital when it is still at a temperature of about 95 C.

When the hot water reaches the hospital, it will go through another heat exchanger, where the hot water from the power plant comes into close contact with cool water within the hospital’s own heating system.

The hospital, and other buildings using waste heat, will continue to keep their own boiler systems for emergencies. Generally, however, these boiler systems will be tricked into not generating heat – the buildings will already be warm enough without kick-starting the boilers into burning more fuel.

In Rankin Inlet, heat will also be captured from the power plant’s exhaust system.

The amount of heat lost through exhaust is even greater than the amount of heat lost through radiator cooling systems, reaching temperatures of 350 C.

What it costs
To make up for the cost of building and maintaining a district heating system, QEC is proposing in its General Rate Application to charge customers about 90 per cent of what they would pay if they were using their own boiler system to generate heat.

Customers will continue to pay regular rates for their electricity, which is not affected by the district heating system.

The Utility Rates Review Council is reviewing that proposal.

Why not use it everywhere?
Economies of scale dictate where heat recovery systems can be installed, but there are already several in Nunavut.

Since 1999, both Alookie and Attagoyuk schools in Panniqtuuq have relied on waste heat transferred from the hamlet’s power plant through above ground pipes.

In Arviat, a district heating system connects Qitikliq and Angmak schools, the Arctic Co-op Hotel and Nunavut Arctic College. This will soon be expanded to the new school.

In Kugluktuk and Taloyoak, waste heat is used to warm the water treatment plants.

QEC also provides thermal heat energy to district heating systems in Cambridge Bay and Sanikiluaq.