Energy-efficient automation helps generate electricity from landfill

Beneath the lush fairways of a golf course lies an underground landfill that generates large amounts of methane, carbon dioxide and other greenhouse gases. This gas has the potential to explode, kill vegetation and emit foul odors – none of which would be welcomed by the heavily populated surrounding community. The Region of Peel, which owns the Mississauga, Ontario, landfill awarded Integrated Gas Recovery Services (IGRS) the rights to collect, control and, ultimately, generate electricity from the landfill gases.

IGRS, a partnership between Comcor Environmental Limited and a Walker Industries’ subsidiary, contracted system integrator H.S. Electric in Norwich, Ontario, to design, build and install a fully automated control system using Rockwell Automation solutions. The system needed to do everything from power the gas extraction process to intelligently control the temperature. Automation also could help IGRS’ plant operators to keep the facility operating at maximum output.

“We wanted an automated system that could help collect the gases on the landfill for odor control, as well as generate electricity in a sustainable way,” said Matt Dugan, plant engineering manager at Comcor. “To do this, the equipment at the generating plant needs to run as efficiently as possible to maximize the electricity produced, while minimizing the amount of energy consumed by the plant itself.”

The generating plant‘s main MCC in the remarkably clean electrical room.

Challenge
Creating electricity from waste begins by applying a vacuum to a series of buried vertical and horizontal collection wells – some more than 30 meters deep. The collected landfill gases are then conveyed through a network of buried pipes to the IGRS generating facility 800 meters away. At the generating facility, IGRS compresses the gas up to 100 pounds per square inch (psi).

The pressurized gas is then chilled to near-freezing temperatures to remove moisture, filtered and then reheated. The treated gas fuels three internal combustion engines each direct-coupled to a generator which produces electricity. IGRS sells the power to the Ontario Power Authority, a government agency that buys the electricity from the Britannia facility and other renewable energy projects.

In addition to the challenge of preventing toxic greenhouse gases from creating an adverse effect on the surrounding community, IGRS needed a flexible solution that worked around the golf course’s playing area and irrigation systems. Regulatory requirements mandated that IGRS submit production information as well as perform noise modeling to silence the generating plant’s equipment.

IGRS wanted an efficient generating facility that could produce a constant supply of electricity for many years. “IGRS wanted an extremely reliable plant that could provide valuable information to off-site personnel for monitoring, trending and regulatory purposes,” said Ken Stienstra, professional engineer for H.S. Electric. “Rockwell Automation provided us with a system that could help meet their demands, as well as the ongoing support to address future needs.”

Solution
H.S. Electric engineers implemented an automated system to power and control nearly all aspects of the process, from collecting and treating gases to generating electricity. Intelligent Motor Control solutions from Rockwell Automation help IGRS control the process, protect its assets and maintain production levels while helping to reduce energy consumption.

Two custom-built CENTERLINE 2100 motor control centers (MCCs) with IntelliCENTER Technology from Rockwell Automation act as the main motor control source for the facility. Inside the MCCs reside networked, motor control equipment, including Allen-Bradley PowerFlex 40 and PowerFlex 700 drives and Allen-Bradley E3 Plus overload relays. These products work with the compressor drive motors to help extract landfill gas and deliver it efficiently to the generators. Two 450-horsepower motors and drives from Rockwell Automation power the compressors that convey the gas.

Four Allen-Bradley SLC 5/05 programmable controllers send diagnostic information about gas temperature, motor status, engine output, gas flow, pressure, vibration, vacuum and other data from more than a hundred I/O points to a touchscreen industrial computer running FactoryTalk View human-machine interface software. By recording, tracking and reporting this data, FactoryTalk View software from Rockwell Automation helps users manage information and control production, whether they are on-site or managing remotely. It also trends this data to help IGRS’ operators keep engines at their maximum output, detect preventive maintenance needs and troubleshoot issues more quickly.

In addition, the Web-based capabilities of FactoryTalk View software allow constant remote alarm monitoring of each I/O point. “When triggered, the controller can automatically react in a user-defined way, such as shutting down a troublesome area or sending a text message alarm via a cell phone,” said Dugan.

A well at the Braeben Golf Course, drilled more than 30 meters below the surface to capture methane gases from the underground landfill. The City of Mississauga looms just on the other side of the fairway.

Results
With an integrated automation solution that maximizes efficiency and uptime, the IGRS facility produces around 5,000 kilowatts of power per hour, enough to power an average of 5,000 homes in the Mississauga area.

“By intelligently controlling the drives and motors, we’ve experienced tremendous energy savings,” said Dugan. “For example, instead of running both 450Hp gas compressors at full speed, the drives typically run at around 75 percent of their maximum speed to provide sufficient gas supply to run the engines but minimize parasitic power costs.”

Efficiency translates to savings since motors in an industrial setting typically consume over 60 percent of a plant’s energy.

In addition to producing high volumes of net power, the facility has prevented the landfill’s greenhouse gases from causing an adverse effect on the surrounding community.

“It’s rewarding to develop a project that reduces greenhouse emissions and, in turn, generates electricity from these gases which otherwise would be vented to the atmosphere or flared off,” Dugan added. “The way the equipment seamlessly interacts has certainly helped us manage information and monitor production, even when we’re away from the facility.”

One employee works on-site during the day, although the plant generates electricity around the clock. “Although the plant pretty much runs itself, we can count on H.S. Electric and Rockwell Automation to help provide periodic, preventive maintenance,” said Dugan.

On the front end, networked control helped reduce wiring time and eliminate cumbersome hard wiring. On the back end, this networked control helps IGRS comply with regulatory requirements. IGRS can automatically record, track and report gas flow, engine output and other production data.

The minimal wiring, along with the state-of-the-art equipment and unassuming appearance, has made this a showcase facility for IGRS, which often gives tours to customers. Dugan said, “The fact that a clean facility generates electricity from something as dirty as a landfill always impresses customers.”

This case study article was written by Rockwell Automation. The results mentioned above are specific to IGRS’s use of Rockwell Automation solutions in conjunction with other products. Specific results may vary for other customers.