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PLANT

IGRS turns waste into watts


November 27, 2008
by Noelle Stapinsky

Squeezed in amongst a Future Shop, Wal-Mart and Home Depot where suburbanites carry out everyday retail transactions there’s an inconspicuous gas recovery company sucking toxic gas out of a closed Mississauga, Ont. landfill site just 800 metres away. Indeed, Integrated Gas Recovery Services (IGRS) is the height of “discretion” as its fully automated gas recovery facility converts methane gas collecting under the former Britannia dumpsite into green electrical energy that’s fed into the local power grid.

Established in 1980, the Britannia site received more than 10 million tons of waste over its 22 years of operation. In the late 1990s Peel Region closed half of the site and, through a co-operative venture with the city of Mississauga, refurbished it as the Britannia Hills Golf Course, a small nine-hole link. During this time the region was using a perimeter collection system run by a couple of low-power blowers to extract the potentially dangerous gas build-up and flare it off—a common waste management practice.

When the time came to close the rest of the dump, Peel Region wanted to find a way to collect the gas and make better use of it. That led to a relationship with IGRS—a partnership between Cambridge-based Comcor Environmental Ltd. and Integrated Municipal Services, a Walker Industries’ subsidiary—which developed and now operates a landfill gas utilization plant that produces up to five megawatts of green electricity per day.

As the rest of the landfill was being closed, the city hired a golf course architect to design and construct Brae Ben, an 18-hole Scottish-links style course. This was the first big challenge for IGRS.

“We [had to] work closely with the architect to ensure the design of the landfill gas collection infrastructure complemented the playability of the course,” says Matt Dugan, Comcor’s plant engineering manager. The piping had to be routed around the edges of the fairways and greens and the wells kept out of the way as much as possible. Once the landfill had a final cover and was brought up to a rough grade, IGRS drilled about 45 vertical wells through the garbage.

Design challenges
The wells ranged from 20- to 60-feet deep, and between each one were two to three kilometers of high-density polyethylene piping, some with a 12-inch diameter. Dugan says they used this piping because it bends. “It’s not as brittle as PVC and it’s certainly not as hard to install as steel pipe.”

The piping could not cross the fairways so for ease of maintenance, it had to be routed along the edge of the cart path. “We had to get that in before [the golf course crew] put in the irrigation pipes, drain pipes, and communication cables for the satellite watering heads,” says Dugan. “There was a lot of back and fourth on the design iterations. As the golf course tweaked its design, they made us route our pipes in different directions.”

With residential areas just half a kilometer away, IGRS’s second challenge was building a plant that was esthetically pleasing.

“We had to fit our infrastructure on this little property and liaise with the city because of this high-end commercial area,” says Dugan. “They didn’t want to see any piping equipment on the outside. And the noise was a big issue.”

The 5,000-square-foot, windowless facility is built with pre-cast concrete panels and acoustic doors to keep the noise in, plus an outdoor compound encompassed by the building so outside equipment is not visible from the street.

IGRS contracted system integrator H.S. Electric from Norwich, Ont. to design, build and install a fully automated control system using Rockwell Automation products. This system had to do everything from powering the extraction process to controlling the gas temperature, while keeping the facility operating at a maximum output.

“Our main service gear is a Rockwell MCC [main control centre]. The compressors used to suck the gas are 450 variable speed Bradley drives. Beyond that we use Alan Bradley PLCs and I/O for everything,” says Ken Stienstra, president and owner of H.S. Electric.

The two custom-built CENTRELINE 2100 Rockwell MCC is the system’s main power distributor and centre for the plant’s ancillary equipment that includes the gas compressors, chiller skid and drier skid. Inside the MCC is Alan-Bradley PowerFlex 40 and Powerflex 70 drives and Alan Bradley E3 Plus overload relays. These products work the compressor drive motors to extract landfill gas and deliver it to the generators. The gas is then conveyed using the two 450-horsepower drives that power the compressors.

There are four Allen Bradley SLC 5/50 programmable controllers that send diagnostic information about the gas temperature, motor status, engine output, pressure vibration, gas flow and vacuum information from over 100 I/O points to touch screen industrial computers running FactoryTALK View human machine interface software located throughout the plant. The operator can modify the operation and get status reports from anywhere in the plant. This interface is also accessible remotely giving personnel like Dugan access to the plant via the internet. In fact, he even receives status updates, warnings and alarms in real time on his blackberry during the day.