EnerWorks Schematic of a community solar heating plan being deployed in Alberta. Last month, North Carolina’s Vanir Energy and EnerWorks, of London, Ontario, completed what the two renewable companies describe as the world’s largest solar thermal heating and cooling installation – 640 collectors on the 1-million square-foot Fletcher Business Park in North Carolina.
The project provides more proof of the growing acceptance of solar thermal as an economical means of reducing emissions in large structures.
But EnerWorks officials have their eyes on another solar thermal venture, this one in tiny Okotoks, Alberta. For the past year, the Drake Landing subdivision in the prairie town has been a testing ground for an innovative variation on traditional district heating — one that sources and stores heat with solar panels and geothermal tubing.
“The idea was to prove, based on previous projects in Europe and using North American technology, that it is possible to build district heating systems for communities,” says Florin Plavosin, director of application engineering at EnerWorks.
District heating – the distribution of steam cogenerated by coal or gas-fired boilers — has been around for over a century in cities like New York and Philadelphia. Some district energy companies (Thermal Chicago, for instance) have attracted private equity investors like Macquarie Infrastructure, while others, including Toronto’s Enwave, expanded into deep water cooling to reduce emissions related to air conditioning.
Such systems, however, are much more popular in Scandinavian countries like Denmark, where 60 percent of homes are tied to district heating utilities, says Jens Overgaard, who heads the district heating division of the engineering giant Ramboll.
Mr. Overgaard points out that the growth of residential district heating in Europe was spurred by soaring heating oil prices after the OPEC oil crisis, as well as design improvements.
The North American residential development industry, with its low-density subdivisions, has been largely inhospitable to district heating. Drake Landing aims to challenge that mindset. “People have embraced the project,” says Mr. Plavosin. “There was actually a waiting list for people who wanted to buy the homes.”
About 800 EnerWorks solar thermal panels were installed on the garages of 52 homes. The panels heat water that is piped to a pair of central storage tanks. In the winter, homes draw hot water from these tanks as needed. In the summer, the excess heat is pumped into a ring of geothermal bore-hole tubes that extend about 140 feet down into bedrock. The rock can store the heat until it is needed in cold weather months.
One interesting detail with the undertaking is that ATCO Gas, an Alberta utility, is delivering both the back-up natural gas and the heat distribution, a sign that there may be synergies between the two sources; ATCO is also working on a similar venture in Calgary.
The Canadian government invested $5 million in Drake Landing, and is monitoring the project to assess its commercial viability.
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