Sunday, July 09, 2006

Green energy in Montreal

Gazoline/electric hybrid cars are getting all the headlines. But stories like the ones in the August 2006 Popular Science and the July 9 Gazette (see below) will have as big an impact in transforming the way we harness energy in the next few decades.

I figure I'm doing my part by driving a low-emission vehicle, riding a hydro-electrically-powered metro to work and switching all the lights in my apartment to compact fluorescent light bulbs.

Benny Farm taps into green energy
Geothermal wells, solar panels heat homes at fraction of cost from power grid

The Gazette

Sunday, July 09, 2006

The game of Monopoly is the closest most of us will ever come to owning a utility company. But for some residents of the sprawling Benny Farm site in Notre Dame de Grace, the fantasy will soon become reality.

Come winter, several hundred occupants will be generating about half of their energy "off grid," thanks to a network of renewable energy sources and their own in-house utility, known as Green Energy Benny Farm.

The backbone of the utility's green energy infrastructure are 21 200-metre-deep geothermal wells drilled this spring.

Those springs will heat the water used in radiators and floor heating.

Combined with other systems including a four-storey-high solar panel, they are expected to help reduce water and energy consumption by 30 to 50 per cent.

"It's more than just a utility; it's a green energy promoter," said Alex Hill, whom the utility's 11-member board of residents and community members hired to manage the project.

The non-profit micro-utility will own and operate the renewable energy infrastructure for three housing projects on the east side of Cavendish Blvd. between Sherbrooke St. and Monkland Ave.

These are the Chez Soi seniors' residence, the Zone of Opportunity (or ZOO) family rental housing co-operative and the Habitations communautaires N.D.G., a 50-unit affordable home-ownership development the construction of which is to begin in the fall.

The three properties, which comprise 187 units and occupy about one-quarter of the 7.2-hectare Benny Farm site, are part of an award-winning affordable housing development designed by local architectural firm L'OEUF (L'Office de l'eclectisme urbain et fonctionnel) and engineers Martin Roy et Associes.

The project is a mix of new construction and refurbished, red-brick low-rise apartment blocks built in the 1940s to house war veterans.

It already contains many examples of "green" design - air-tight, energy-efficient structures; low-wattage lighting; radiant floor heating; ample natural ventilation; and recycled bricks, radiators, hardwood floors and other materials salvaged from demolished units.

But perhaps the most innovative and as yet untested aspect is the use of various energy sources linked by a common distribution network to balance different kinds of energy needs and capacites across the site.

"The idea is to tailor each source to the need according to what is most efficient and affordable," Hill said.

The sun, Hill explained, is a much more concentrated heat source than the ground, for example. Hence it is the project's solar collectors, not its geothermal wells, that will be used to heat domestic hot water, which must be brought to a much higher temperature than the water in radiator and floor heating.

Both will be put to the test for the first time this winter.

The wells are part of a geo-thermal system that extracts heat from the ground through a series of pipes and heat pumps using the same principles of heat exchange as a fridge.

They facilitate heat transfer between the earth, which because of its efficiency at storing energy remains around 8 Celsius at a certain depth regardless of the temperature above, and a cooler fluid circulating in the pipes.

The process is reversed in summer, when excess heat from indoors is pumped back into the ground.

A gas boiler supplements the geothermal supply at times of extreme cold.

Rooftop solar collectors, spanning 225 square metres, to be installed this summer, will heat incoming city water, while a black solar panel that rises four storeys on the side of Chez Soi preheats incoming air.

"On a sunny day when the temperature is minus 20, you're paying for no energy to preheat that fresh air beyond the fan that moves it through the building," said L'OEUF architect Daniel Pearl.

Similarly, a ventilator on the roof uses energy from the stale air flowing out to heat or cool fresh incoming air.

Simple energy recovery systems that get the most out of the energy consumed on site are key to the utility's green energy supply.

Forty per cent of the energy usually lost down the drain with hot water from showers and sinks is recovered to heat clean water.

Eventually, that grey water, as it's known, will also be filtered on site and reused in toilets.

Structural elements built into the two existing properties will allow for the grey water, geothermal and solar energy supplies of all three projects to be linked and shared in the future.

There are also plans to set up a French drain, which uses rocks to percolate rainwater back into the water table, diverting it from municipal sewers.

The three projects are expected to eliminate 313 tonnes of greenhouse gas emissions, conserve 6.7 million litres of potable water and divert 15.2 million litres of waste water per year.

The in-house utility estimates that by charging residents a rate for their green energy that is slightly higher than what it costs to provide - but still less than what they would be paying on the conventional grid - it will accumulate savings of $640,000 over 15 years.

That money will be used to maintain the system, add new green technology and promote green energy in the community.

Indeed, Green Energy Benny Farm also aims to replicate the micro-utility model elsewhere, possibly by incorporating other sites into its energy grid and/or administrative structure.

It has already begun exploring the possibility of linking up with the community health clinic to be built next to the ZOO co-op and diverting its excess heat to the co-op's geothermal wells.

"Once we get the provision of energy to these three projects under our belt, the mandate is to use the lessons learned to support other projects and to educate," said Bob Butler, head of Green Energy Benny Farm's board of directors.

Developers and residents agree that the greatest advantage of such a self-reliant utility system is protection against future hikes in energy prices - no small factor for seniors and others on a fixed-income.

Benny Farm's green infrastructure was funded mainly by a $3-million grant from the Federation of Municipalities.

Still about two years from completion, the project is already receiving accolades. It has been honoured by the Canadian Urban Institute and the Swiss-based Holcim Foundation for Sustainable Construction, among others.


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