A Windsor company developing a system that uses animal manure to generate heat is among several Canadian efforts to tap into new sources of energy in the face of rising fuel and electricity prices and increased demand for environmental protection.

Agrilab Technologies is beta-testing what it bills as the first commercial-sized prototype heat-transfer system for extracting thermal energy produced by water vapour generated as a byproduct of composting cattle manure.

The test site, a farm in Vermont, has been operational since January. Agrilab takes manure from 2,000 calves plus bedding waste, composts it and captures naturally occurring wastewater vapour.

The heat-transfer system generates water temperatures of 55°C, up to three million BTUs per day. Agrilab says composting is done year-round in an uninsulated, ventilated building, and the only external energy needed is to run a modest-size air-fan blower.

Tom Adams

Describing the system as win-win environmentally and economically, Agrilab president Joe Ouellette says the system literally rescues a resource that is otherwise wasted.

"It permits the no-cost capture of commercially viable quantities of thermal energy, provides additional value streams in terms of producing high-grade compost and successfully remediates manure to permit safe field spreading," Ouellette notes.

The volume and temperature of thermal energy generated from composting 400 to 800 tons of manure and bedding material over four to eight weeks generates continuous thermal energy in the form of hot water stored in an insulated 800-gallon tank. Ouellette says the water is used as radiant floor heating in a calf barn and also for process water requirements.

Ouellette compares the system to placing freshly mown grass clippings in a sealed plastic bag.

"Leave it overnight, then open it and put in your hand. It will be hot. Energy is created by the decomposing materials in the presence of moisture and oxygen. If you seal the bag, the oxygen will be depleted, but the moisture will still be there in the form of water vapour on the inside surface of the bag.

"We take a natural process - the aerobic decomposition of organic materials - and potentiate that aerobic decomposition to generate heat. The water vapour is condensed on a series of superconductors, or heat pipes, which absorb and transfer that energy into an insulated water pipe."

Agrilab isn't alone in its quest to bypass traditional energy sources. In suburban Toronto, Oakville Hydro and the Regional Municipality of Halton announced a plan in April to build a facility to generate electricity from landfill gas.

A byproduct of decomposing refuse, landfill gas contains approximately 50 per cent methane, the main ingredient of natural gas. When released into the atmosphere, however, methane is a pollutant and potent contributor to global warming.

Jose Menendez, Oakville Hydro's general manager of construction and generation, says the landfill gas will be collected, with the methane separated and used to fuel internal combustion engines that drive electrical generators feeding the provincial power grid.

Scheduled to be completed before the end of 2007, the plant is expected to initially generate two megawatts of power - enough to supply 800 to 1,000 homes for more than 20 years.

Menendez says Oakville Hydro expects this capacity to double as the landfill, now less than half full, reaches capacity in 25 to 30 years.

Menendez concedes the project is small-scale, but says it will reduce landfill odour and pollution and lessen reliance on conventional power plants. "It's a small project in the context of Ontario's peak generation, but there are a number of projects, and if you add them up they make an impact."

Not far from Oakville, another energy-producing operation is already under way. Two summers ago, Enwave Energy Corp. announced a plan to use the frigid depths of Lake Ontario to cool buildings in downtown Toronto.

Deep-lake water cooling technology draws water at 4°C from a permanent, renewable supply 83 metres below the surface of Lake Ontario and pipes it to heat exchangers at Toronto's John Street pumping station.

There the water's 'coldness' is literally diverted through underground pipes to buildings where it is again processed through heat exchangers and used instead of traditional electricity-dependent chillers to cool the water used by air conditioners.

"Deep-lake water cooling conserves energy," explains Enwave chief operating officer Chris Asimakis. "We don't actually produce it - we displace it."

The concept isn't entirely new. Air conditioners are enormous electricity consumers, and the city's engineering community considered a similar plan during an energy crisis more than 20 years ago.

However, Asimakis says deep-lake water cooling is complex and expensive and requires big up-front investors who don't demand an immediate return.

With the City of Toronto and the Ontario Municipal Employees Retirement System on board, Enwave landed enough seed funding to begin construction.

A three-year, $1.6-million investment by Toronto Hydro in the form of incentives for customers helped Enwave land some big-name buildings, including the provincial legislature, the Air Canada Centre, Royal Bank Plaza and the Toronto Dominion Centre.

Asimakis says rising electricity costs, coupled with surging demand for environmental protection, fuelled interest. Toronto Hydro was looking to reduce peak energy consumption by up to 250 megawatts and embarked on a mix of conservation and demand management programs.

Deep-lake water cooling currently provides a regular supply of 75,000 tonnes of refrigerant capacity.

A 500,000- to 700,000-sq.-ft. building uses an estimated 1,000 tonnes, while the largest skyscrapers use 3,000 to 7,000 tonnes. Enwave and Toronto Hydro began by switching the properties to cheaper, energy-efficient air-conditioning systems before converting them to deep-lake water cooling.

"Their air conditioning is completely off the (traditional power) grid," Asimakis says.

Deep-lake water cooling isn't viable for every community. "You need a large body of water right next to a densely populated urban core," Asimakis says. "I've heard of cottages in Muskoka that take water from lakes for air conditioning, and there are smaller systems in Halifax and elsewhere, but these are much more limited in scale. " At Energy Probe, a Toronto-based energy policy think-tank, executive director Tom Adams says he considers deep-lake water cooling and landfill methane capture to be particularly viable economically and technologically, though with a somewhat limited overall impact.

"Deep-lake water cooling is credible, cost-effective and highly reliable, but its opportunity for expansion is modest because the number of communities that can access this kind of thing are pretty limited," Adams says.

"It's the same with landfill gas capture - its use for power generation is critical because it reduces the smell and the greenhouse gases. It's relatively expensive power, but I think this is acceptable when you look at it from the point of view of overall environmental impact."

Adams says that, while he expects farmers will face increasing pressure to reduce pollution, particularly from animal wastes, and composting thus presents a viable solution, he isn't convinced a compost-based heat-transfer system is a significant player in a fairly diverse alternative energy market.

"You're looking mainly at customers like greenhouses and other farm operations with significant thermal energy needs, such as poultry producers and hatcheries, but it's relatively small potatoes," he explains.

Ultimately, Adams says, options to conventional sources of power are needed, and the path to the future will include a variety of alternative energy sources, such as wind generation and bio-fuels, as well as deeper conservation measures.

(Saul Chernos can be reached at chernos@businessedge.ca)