Solar, hydro and wind energy systems may have enjoyed a higher profile, but earth energy systems are becoming the preferred choice of builders and owners wanting to install cost-effective heating systems in homes and large buildings. Given the Yukon's climate, isolation and dependence on fossil fuels, ground source heat pump technology is well-suited to the north, says the Energy Solutions Centre's Don Flinn.

"Heat pumps can be up to 600 times more efficient than conventional energy sources," he continues, "As the cost of fossil fuels are increasing, this technology is becoming very competitive and attractive."

In addition to significant environmental benefits, cost savings are very appealing. Over two-thirds of earth energy is renewable energy stored in the ground, which is free. Consumers only pay for the electricity to operate the system-the remaining one-third.

"Ground source heat pumps have been around for a very long time," says Flinn, "The technology was first patented in 1912, and the first buildings in Canada to incorporate ground source heat pumps were built in 1943."

According to Flinn, earth energy has already been used in the Yukon in limited ways, mostly to stabilize permafrost areas. A few buildings in the territory, including structures in Ross River and Old Crow, have ground source heat pumps to prevent the slumping that often occurs in areas of discontinuous permafrost.

A few metres of surface soil insulates the earth and ground water below. This warmth provides a free, renewable source of energy. In fact, the earth under an average residential lot can easily provide enough free energy to heat and cool the home built on it.

"The idea is that you pick up latent heat in the ground," explains Flinn, "All that is needed is a temperature differential of 4 degrees, above or below freezing."

The challenge is to move this free energy into the building. This is done with a circuit of HDPE piping buried in the soil through which fluid is pumped. The fluid in the loop is a biodegradable mix of approximately 25% methanol and 75% water. The methanol acts as antifreeze to prevent ice-clogged loops.

The fluid in the pipe absorbs heat from the soil or ground water and cycles it back to the heat pump. "After the loops return the warmed fluid, it runs through a compressor-a heat pump. Then you just move the heat to where you want it," Flinn explains.

With the heat removed, the now-chilled fluid circulates back through the loop system over and over to continuously extract more heat from the earth.

Although earth energy is considered low-grade heat-not warm enough to heat a building without being concentrated or upgraded-there is plenty of it. Plus, the underground temperature is remarkably constant, says Flinn, which is why this kind of system works so efficiently.

After the system takes heat from the loop and upgrades it to a temperature usable in the home, heat is delivered evenly to all parts of the building through a forced air or hydronic system.

The in-building footprint for earth energy systems is smaller than a conventional furnace. The pump units are small and quiet, and heat distribution systems are often built into the floor.

"And the beauty of this system is that you can run it backwards to create a cooling effect," Flinn points out, eliminating the need for an air conditioner.

He describes a ground source heat pump project in Cochrane, Alberta. "As the city grew and they needed a second indoor hockey rink, someone had the foresight to step back and investigate the technology options before they just built the same thing again."

The community's existing skating rink employed traditional ice-making and heating. The new one uses earth energy and a heat pump specifically designed for making ice.

"They knew they'd have enough energy to generate heat for the building too. So they decided to bring the excess heat in to the building through the seats," says Flinn.

In effect, radiant floor heat that keeps the stands warm comes from the same energy source that creates the arena's ice sheet.

And they didn't stop there. "The system generates enough to heat the sidewalks around the building," he adds, "So there's no ice build-up and people's feet are clean by the time they reach the building."

The new Cochrane hockey rink uses no fossil fuels, and delivers huge savings to the municipality. "Energy costs for the new arena are just 30% of what it costs for the older facility."

Heat pump technology is beginning to generate considerable interest in the Yukon. The Energy Solutions Centre offered a course on ground source heat pumps several months ago, attended by close to 30 contractors and suppliers.

"Ours was the largest course ever given by the International Ground Source Heat Pump Association," says Flinn, "They were somewhat astounded by the interest here."

Flinn says that the Energy Solutions Centre is planning demonstration earth energy projects in the near future. For now, the public can learn more about ground source heat pumps at the Trade Show on the first weekend in May, where technicians will be demonstrating a unit that makes ice and heat a hot tub at the same time.