December 17, 2011
Cogeneration & On-Site Power Production
As winter descends again, I'm reminded how heating technology is virtually a life support system for almost half of each year in our part of the world.
And with so much of our heating based in some way on fossil fuels, this spells trouble on two counts. Besides the apparent environmental implications of adding tons of new carbon to the atmosphere, fossil fuel prices will continue to trend upwards as rising demand chases oil reserves that are harder and less productive to develop.
Even now, fossil fuel prices are capping economic growth and making us vulnerable to everything from destructive weather events to questionable foreign governments.
There is, however, an alternative to keeping warm in winter, and it springs from technology that's widespread in Europe and catching on more in Canada than the U.S. It's called district energy, and it's a system that I'm gaining personal experience with.
District energy systems use central plants to produce and direct hot water to heat surrounding buildings and also, in some cases, cold water for cooling in summer. This water is pumped through pipes to buildings large and small.
The genius of centralizing the production of heat means that a whole range of different fuels can be used with the main focus on burning biomass. Organic waste, farm-raised energy crops and wood chips are all options depending on what makes sense given local conditions.
Regardless of the source of heat energy, it's always used to produce hot water. This is transferred to buildings via insulated underground pipes where it's then used mostly for space heating. In many Nordic countries, virtually all buildings are connected to district energy systems, both large commercial installations and individual homes.
In Helsinki, for instance, 93 per cent of all buildings are connected to district energy plants, the product of municipal courage that began way back in 1953.
This early adoption in parts of Europe is especially impressive when you realize how challenging district energy systems are to implement. They're typically massive community projects requiring bold, future-oriented government leadership.
These pipes are the unsung heroes because they're key to the efficiency of the system. Besides the obvious fact that these pipes must remain reliably leak-free for decades, they also need to keep insulation dry in potentially wet soil conditions. It's not as simple as it sounds, and the challenges have led to some innovative Canadian technology.
Urecon (www.urecon.com, 1-450-455-0961) developed a unique process to create insulated pipes in their Montreal plant back in 1972, and this is one reason district heating is technically possible and so energy efficient.
You'll find new district energy installations in Markham (Markham District Energy), Toronto (Regent Park Community Energy System), Calgary (Enmax District Energy Centre), Prince George, Victoria (Dockside Green), Quebec City (Cite Verte), Charlottetown, and several locations in Vancouver, according to Carl Vreugde, district energy manager with Urecon.
A small project is even unfolding right now in my own backyard.
While most district energy involves communities on a municipal level, it's also an option for rural properties.
Any day now I'll be firing up the clean-burning, outdoor wood furnace I've installed to heat my house, my workshop and the domestic hot water for both buildings.
The pipe I used is called Logstor PEX-Flex (www.pexflex.net). It's made in Denmark. PEX-Flex comes in different sizes, and the kind I used is 4 1/2 inches in diameter on the outside, made with three main parts.
The outer husk of the pipe is continuous and waterproof. Inside this pipe are two smaller pipes, each about an inch in diameter.
One of these delivers hot water to buildings from the outdoor furnace, and the other brings cooler water back to the furnace. The space between inner and outer pipes is filled with closed-cell polyurethane foam insulation. The whole arrangement is so effective that 180F water entering one end of the pipe loses only a degree or two of temperature after travelling 100 feet. Read more
District energy holds a lot of promise for large Canadian communities and even tiny installations like my own. In both cases, it always boils down to simple, high-tech pipes that are a lot more sophisticated than they look.
