Old landfill provides new electrical power

Rotting garbage beneath the rolling green hills of the old Sackville landfill is now producing enough methane gas to provide electricity to 2,000 area homes continuously for the next 15 years.

Over the course of its 20-year life, the Sackville landfill was the dumping ground for over four million tonnes of unseparated garbage, including organics such as food waste. Halifax Regional Municipality, which owns the landfill, closed the site in December 1996.

The municipality later contracted Highland Energy Inc. to collect the methane gas that is naturally produced by the decomposing organic material and turn it into a renewable energy source. That electricity - two megawatts a year - is now being sold to Nova Scotia Power Inc.

"It's a wonderful addition to what we already provide," said NSPI spokeswoman Glennie Langille. "It's making the best use of that gas, no doubt about it."

Not only is the gas providing clean, renewable energy, it's keeping harmful methane gas from going into the atmosphere, she said. Methane is a relatively potent greenhouse gas with a high global- warming potential.

Highland Energy president David McLennan said the process involves collecting the gas through a series of drilled wells and air-tight piping systems. The gas is fed into two reciprocating engines attached to generators. The engines, which run on the gas, generate one megawatt of power each. The generators are hooked up to a Nova Scotia Power transformer, which feeds into the main Sackville power grid.

"Underneath the green grass on top of the landfill is a mass of churning, disintegrating organics producing this gas," McLennan said. Landfill gas, which consists of 50 per cent methane, is essentially the same as natural gas.

McLennan said the Sackville landfill is the only dump in Nova Scotia big enough to produce enough gas needed to make such a project economically viable.

And while the Sackville landfill operation was "pretty standard practice" during its time, opportunities to collect gas from today's state-of-the art landfills - like the new facility in Otter Lake - will not exist because organics are removed from the waste stream, he said.

"We clean up the sins of the past," he said.

Langille said one advantage the landfill gas project has over other renewable energy sources is that it is constantly producing electricity.

Wind turbines, Langille said, only produce energy when the wind blows at a certain speed, and are only operational 30 to 35 per cent of the time. "So for the vast majority of the time, it's not producing electricity."

McLennan said Highland Energy already has the infrastructure in place to provide an additional megawatt of power sometime next year. They're under contract with NSPI to deliver electricity from the site for the next 15 years. The landfill, however, is expected to keep churning out gas for the another 25 to 30 years, McLennan said.

kmoar@hfxnews.ca