University of Saskatchewan

September 23, 2014   

How I Spent My Summer Vacation

(From left) U of S students Patrick Schmidt, Derek Stevens, and Manoj Singh work with their specialized probe at the Saskatoon Spadina Landfill. {Photo courtesy of James Zheng}
October 22, 2007

One man’s trash is another man’s… power source?

October 20, 2007
Seventeenth in Series
For The StarPhoenix
By Wendy Gillis

Of all of the places Derek Stevens imagined he would do research for his master’s degree, the Saskatoon landfill was not one of them.

“I never thought I’d ever be doing a master’s degree in garbage,” says the University of Saskatchewan civil engineering student. “A lot of people have a strange reaction when they hear that I’m studying a dump!”

Stevens is part of a team of U of S engineering researchers who have launched an innovative project at Saskatoon’s Spadina landfill. With funding from the Federation of Canadian Municipalities and the City of Saskatoon, the team wants to find out how best to use garbage dumps as a source of green energy.

Landfills emit methane while they decompose. The team is testing to see if the methane can be captured easily and economically, conceivably to be hooked into Saskatoon’s power grid.

New “bioreactor” technology is revolutionizing the design and operation of newer landfill sites, making gas collection projects possible in many cities across Canada. But the age of the Spadina landfill makes capturing methane a challenge because there are significant difficulties with retrofitting the 50-year-old landfill.

Finding ways to overcome these difficulties is the main thrust of the team’s research, work which could pave the way for similar retrofits in other older landfills.

To capture the gas, the team has to suction out the gas through a series of pipes and wells, much like how a vacuum cleaner functions. But to produce enough methane to make the project economic, they must first speed up the rotting process.

To do this, the team has to add water to the garbage, to accelerate decomposition by bacteria. To get the water down into the garbage, they have cut trenches in to the landfill.

But they’re not exactly drilling through typical ground.

“We’re not just drilling through soil, we’re drilling through stoves and tires and engine blocks – it’s very slow,” says Stevens.

Once the water gets down to the garbage, there’s another concern. When the water is added to the waste, it is important to know where it is moving and to what degree the moisture content of the waste has been increased.

That’s where geological engineering master’s student Patrick Schmidt comes in. Schmidt is developing a method to measure the moisture content in the landfill—using devices previously only used in agriculture.

Schmidt says it’s possible to add water to the landfill, but it must be done with caution. Part of his research will be figuring out how much can carefully be added to the upper driest part of the waste before there is a chance of contamination moving downward.

Adding water to the landfill affects its stability. PhD student Manoj Singh is studying the structural effects of adding water to the landfill and hopes to better understand structural problems of landfills around the world.

Singh worked in the waste industry in Dehli, India for over 15 years and came all the way to the U of S to work with the project supervisor Prof. Ian Fleming. He wants to find out why some landfills fail and collapse—such as a recent collapse in the Philippines that killed almost 200 people.

“My work is exciting because this research has not really been done. Nobody knows why [landfills] fail,” he says.

Along with the prospect of reducing greenhouse gas emissions and the potential for a new source of energy, the results of the project could include a cleaner, more beautiful world for the next generation.

“If a landfill stabilizes within 30 years rather than 300, it can be turned into a recreational area, or a ski hill,” says Stevens.

Schmidt says he’s happy to be using his degree towards something so positive. “I’ve seen this thing from conception: from paper, to the drilling of the first wells, to the installation of all of the instrumentation, and now we’re almost at the point where there’s the potential for power. It’s just a very, very fulfilling feeling.”

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Wendy Gillis is a student intern with the U of S Research Communications office.

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