SAIC Canada Helps Create North America’s First Solar Community

Drake Landing — First Solar Community in North America

The Drake Landing Solar Community, in Okotoks, Alberta, is the first solar community in North America. The 52-home suburban community uses a solar-thermal design concept that SAIC Canada helped to create to store the summer's heat underground for reuse in the winter.

SAIC Canada's Renewable Energy and Climate Change Program was project manager and lead consultant for the effort, and instrumental in the development and successful completion of the Drake Landing Solar Community. The community was built with the help of a large team from both the public and private sectors.

Drake Landing has been honored with several awards, including the Emerald Award for Climate Change from the Alberta Emerald Foundation and the Gold Award from the International Awards for Livable Communities program. SAIC received the Outstanding Achievement Award of the 2010 Innovation and Energy Technology Sector Merit Awards presented by Natural Resources Canada. In addition, all 52 three-bedroom homes in the development were snapped up long before the project was complete.

"Okotoks can fairly call itself the greenest community in Canada, maybe the world," said Canadian Prime Minister Stephen Harper at the International Environmental Technology Trade Show and Conference in Quebec last year.

Technology Converts Solar Energy into Heat

Each home in the development is connected to the others by a system of solar thermal collectors. Unlike photovoltaic, or PV, cells, which convert sunlight into electricity, solar thermal collectors convert solar energy into heat.

A solar collector is essentially a flat black box with a transparent top that traps heat like a greenhouse or a closed car on a summer day. The collectors are filled with water that's mixed with food-grade glycol to prevent freezing in the winter. Eight hundred collectors are arrayed on the roofs of the garages of the homes in the subdivision. During the summer, these solar thermal collectors can generate about 1.5 megawatts of thermal energy on an average summer day.

Summer's Heat Stored Underground for Reuse in the Winter

A community power station pumps the water-glycol solution through the closed system of collectors and into a grid of holes bored in the earth, known as the borehole thermal energy storage (BTES) system. Each borehole is 37 meters deep and fitted with grouted U-shaped pipes that radiate the collected solar heat into the ground and warm the subterranean soil. The BTES itself is insulated on top to retain heat during the winter.

Although there is some loss, the heated earth remains warm through the winter, much the way a rock, warmed by the sun, retains heat late into the night. Over the summer, the BTES system will heat up to about 80 degrees Celsius (176 degrees Fahrenheit) as sun-heated water circulates through it. The power station runs on conventional electric power, but has PV cells on the roof and batteries to power the system in the event of an outage.

Also in the power station are two large, short-term storage tanks. Each tank holds 30,000 gallons. When heat is needed, hot water from one of those tanks circulates through the district heating loop, which supplies each of the homes with heat. Inside the homes, heat is distributed through specially designed heat exchangers. If heat from the solar collectors in winter is insufficient to send the warm water to the district heating loop at an appropriate temperature for heating, then it's sent to the BTES for a boost of additional heat stored from the summer. After delivering heat to the homes, cooled water returns to the power station's other storage tank.

Winter Solar Plays a Role

The temperature in Okotoks in winter can be minus 10 to minus 20 degrees Celsius, which is a range of about 14 above to 4 degrees below zero Fahrenheit. But the area gets plenty of sunshine.

Winter solar plays an important part of the Drake Landing project, as southern Alberta receives a lot of sunshine in the winter and this contributes to space heating through short-term thermal energy storage. The project could have gone with short-term storage alone and achieved 65-70 percent solar fraction. Solar fraction is the portion of the system's total energy needs replaced by solar energy.

As of early 2008, the homes in the Drake Landing Solar Community received about 80 percent of their heat in the winter from solar energy collected during the summer. The remaining percentage is made up by conventional natural gas. By year three, that fraction should approach 90 percent, with 100 percent soon possible in average years. That equates to a reduced carbon footprint of about 5 metric tons (or slightly more than 5 1/2 tons) of carbon into the atmosphere per house, per year.

Further Reducing the Carbon Footprint

In addition to the solar thermal collectors on the garages, each home has a discrete solar thermal collection system on its roof that provides about 60 percent of household hot water. The remainder is made up by conventional natural gas.

Also, the homes were built with the highest thermal rating for Canadian homes, R-2000, which is 30 percent more energy efficient than typical homes. The system adds about 5-10 percent to the cost of the home.

Insulating Homeowners from Escalating Energy Prices

SAIC Canada's Renewable Energy and Climate Change Program team has completed a field test to integrate solar and aquifer thermal energy storage (ATES) at a large condominium complex for the City of Medicine Hat, Alberta. It is here, in higher density housing, and particularly in retirement homes, that the team sees the greatest potential for solar thermal projects.

"In the long run," said SAIC Canada's Bill Wong, project manager for the Drake Landing Solar Community and manager of SAIC Canada's Renewable Energy and Climate Change Program, "homeowners may be protected from crazy escalations in the price of natural gas. They may be seeing a cost of living increase of maybe 2 or 3 percent per year for the simple maintenance of the system. With our aging population on a fixed income, that's going to be an important factor for the marketplace."