Solid Waste & Recycling

Feature

Landfill Gas-to-Energy

Like many other municipalities, Waterloo Region has eliminated most recyclables, organics, electronics, tires, bricks and even drywall from the residual waste stream but waste management staff is always looking for an opportunity to do more. To...


Like many other municipalities, Waterloo Region has eliminated most recyclables, organics, electronics, tires, bricks and even drywall from the residual waste stream but waste management staff is always looking for an opportunity to do more. To date, the region’s 72-hectare landfill has accepted millions of tonnes of waste and is expected to reach its 15 million-tonne capacity in the next 20 to 25 years.

“The challenge,” says Waste Management Supervisor Paul Rabb, “is finding cost effective programs to increase our landfill’s longevity and minimize its environmental footprint.”

In 1995, the region recognized the opportunity to recycle landfill gas and invited four local businesses to provide proposals for the construction, operation, maintenance and financing of a landfill gas-to-energy (LFGE) facility. Gerdau Courtice Steel, a local steel recycler now referred to as Gerdau, was awarded the project.

In 1999 – landfill gas, typically comprised of methane, carbon dioxide, water vapor and other chemicals – was collected at the region’s Cambridge, Ontario landfill and used to supplement the natural gas that supplies a steel re-heat furnace owned and operated by Gerdau.

“After the contract was awarded, studies indicated that the quantity of methane may be greater than expected,” says Bob Downie, corporate environmental manager at Gerdau. As a result, Gerdau funded additional wells at the Cambridge landfill and supplied equipment to further clean the gas and pump it into the steel mill. Modifications were also made to the furnace.

“The furnace consists of 36 gas-fired burners arranged in five zones,” explains Bob Downie, corporate environmental manager at Gerdau. These zones include preheat and heat zones as well as three soak zones. The furnace is controlled by a computer and has a rated capacity of 129 BTUs per hour, enough energy to heat approximately 75 tonnes of steel billets from room temperature to 2,100°F in one hour. Even though the Cambridge landfill no longer accepts refuse, the waste inside the hill continues to generate gas and will continue to do so for many years, notes Cari Rastas Howard, project manager waste management.

In addition to environmental benefits, revenue generated from the sale of the gas to Gerdau is used to offset plant operation costs. Between August 2003 when the region began charging royalty charges and December, 2010, Gerdau Amertisteel used over 200 billion Kcal of landfill gas, says Rastas Howard.

For Gerdau, the partnership with the region has resulted in a reduction in natural gas consumption, lower fuel costs, and a decline in greenhouse-gas emissions from the steel mill. Since 1999, landfill gas has supplied about 30 per cent of the energy required to operate the re-heat furnace, says Downie, “eliminating approximately 118,000 tonnes of CO2 emissions each year. It’s a beneficial use of a resource that otherwise may have been wasted and a win-win opportunity for the company and community.

In 1995, 50 wells were created at the Waterloo landfill to collect landfill gas. In addition to flaring gas to eliminate odour, the region recognized methane as valuable commodity that could be used to generate power. A request for proposal (RFP) from Waterloo’s waste management services lead to another waste-to-energy partnership with Toromont Power Systems.

Toromont builds, supplies and operates high-efficiency power plants that produce up to 50 megawatts. In the last fifteen years, Toromont Power Systems has built 15 power plants fuelled by natural gas, landfill gas, bio-gas or diesel fuel. Landfill projects generating between 3 to 8 megawatts (MW) are in place in Waterloo, Guelph, Toronto, Sudbury, Thunder Bay and Hamilton.

“These communities,” says Ron Cocking, business development, Toromont, “have recognized that a well field is an excellent way to control odours troubling neighbours and provide an outstanding environmental benefit in the destruction of methane – one of the worst greenhouse gases.”

At the Waterloo landfill, a similar pipe system to that used at the Cambridge landfill was constructed to draw landfill gas into a generating station owned and operated by Toromont. The field pipe used is mainly high-density polyethylene pipe (HDPE); pipe inside the blower and power generation facilities is stainless steel, according to Rastas Howard. In total, there is 11 km of HDPE header, lateral and collector piping ranging in size from 25 mm to 400 mm depending on the location. In 1998, 23 more wells were added, ensuring a constant supply of gas until at least 2050.

When landfill gas enters the station, it’s pre-treated and used to run engines that produce electricity. A fuel conditioning system removes moisture and a filter conditions the fuel by removing particles and remaining moisture.

“Toromont and Caterpillar keep the process very simple,” says Cocking. “The water drops out and back into the leachate system at the landfill containing it in the facility built to manage it.” Blowers raise the gas pressure to the required 5 psi, adds Cocking.

In 2000, the electricity generating station went into full operation with four Cat G3516 gas-fueled 925 killowatt generator sets. A fifth generator set was added in 2002 bringing capacity to 4.6 megawatts. In 2009, a G3520, rated at 1600 kW, was added bringing the capacity to 6.2 MW. The station currently generates 6.25 MW of “green” power which is delivered back to the grid through an arrangement with Ontario Power Generation.

Toromont Power Systems received a national award for Innovation and Excellence from the Canadian Council for Public-Private Partnerships for the project and the Region of Waterloo earned a Sustainable Community award from the Federation of Canadian Municipalities. In 2003, the region received an Award of Excellence for the partnership with Gerdau from Ontario’s Ministry of the Environment for outstanding achievement in the fight against smog and climate change.

Deborah Everest-Hill is a freelance writer in Stoney Creek, Ontario. Contact Deborah at deboraheverest-hill@sympatico.ca (Note, Deborah is available for freelance corporate and other writing assignments. Connect with her on LinkedIn.)

Sidebar: Solar flare provides localized odour control

In addition to using soil and a tarp system to eliminate odours, Waste Management Services at the Region of Waterloo is testing the effectiveness of a solar flare to burn excess landfill gas. In an older section of the landfill, a CF-5 flare manufactured by LSC Environmental Products is positioned on a manhole or access chamber where it uses conventional solar panels and an ignition system to ignite and burn methane.

“Solar flares have been in use for some time,” says Cari Rastas Howard, project manager waste management. “We are experimenting with moving it (the flare) wherever required for short-term, localized control.”

Landfill gas is typically comprised of methane, carbon dioxide, water vapour and other chemical compounds. The CF-5 flare sparks every 1.5 seconds and is generally distributed one unit per acre. The CF-10 model is essentially the same flare but has a larger gas pipe enabling it to manage a larger gas flow.

“Most customers have a rough idea of the flow at their site,” says Luke Cody, technician at LSC. “The CF-5 is adequate for 90 per cent of applications.”

“In addition to eliminating unwanted odour, the flare prevents methane from entering the atmosphere thereby reducing greenhouse gas emissions,” says Jon Arsenault, director of waste management. According to Environment Canada, methane develops when matter decays in an oxygen-free environment. Sources of methane include: wetlands, rice paddies, animal digestive processes, fossil fuel extraction and decaying garbage. Because methane is effective at trapping heat, it is a powerful greenhouse gas.


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