FROM WASTE TO POWER But how does landfill waste become landfill gas, and how is that gas used to power and heat the propulsion plant? The landfill itself acts as a huge anaerobic digestor, Watt explains. “You have a lot of organic waste in the landfill and no oxygen,” he says. “That naturally generates an anaerobic digestion process.” That process produces two gases, methane and CO 2 , in roughly equal quantities. In the past, Walker burned the meth-ane gas, which would otherwise be vented into the atmosphere. “But, this project affords us the opportunity to collect it, just like you would with an oil field – you have wells that drill down into the landfill and you essentially just suck out the gas,” he says. That gas is put into a large pipeline, at which point Walker cleans it up, compressing it and removing the moisture, particu-late matter and siloxanes. “Siloxanes (silicone-based compounds) are prevalent in landfill gas, and it tends to not be great if the siloxanes are burnt along with the gas in engines,” Watt explains. “Siloxanes actually oxidize onto the sides of the cylinder head and will eventually stop the engine working. So, we generally want to remove them.” Walker purchased a new state-of-the-art siloxane skid to re-move this material. Once treated, the LFG is transported to the St. Catharines plant through the 3.3-kilometre-long pipeline. At the plant, the gas goes to what the partners refer to as “energy islands.” These islands are actually four engines that generate electricity to be used on-site. The waste heat from the engines is captured and used to heat the facility. There are two streams of recovery for heating the facility. One is the waste gas coming off the engines as the methane is com-busted. The other is the heat coming off of the engine itself, which gets quite warm during the combustion process. “Typically, combustion of a fuel like this is about 35-37 per cent efficient. So, of the amount of energy that’s stored in that fuel, you’re recovering only about 37 per cent of it as power,” Watt says. “But, the heat recovery we’re getting at GM with these engines is up in the mid-50’s percentile. So, it’s quite a significant ability to recover as much as we possibly can of that landfill gas.” This type of system is often referred to as combined cycle recovery or cogeneration. “It’s worked quite well in many different places, but this is prob-ably one of the few larger-scale applications in Canada,” Watt adds. IMPACTFUL ENERGY the community,” Giroux explains. It also sends a good signal to the community of continued employment opportunities at the plant, Watt says. BARRIERS TO OVERCOME While this venture has been successful for all partners involved, there are some challenges for other industrial users that might want to embark upon a similar endeavour. “The project may not have been as successful if the landfill had been 40 kilometres away,” Giroux says when asked what factors contributed to their success. “It helped that, in the end, we only had a dedicated pipeline between the two of us that was 3.3 kilometres. “It’s a combination of finding a good industrial site that’s fair-ly close to a well-established landfill site that you can find these kinds of synergies.” “We’ve really solved an energy problem for an adjacent neigh-bour, rather than just putting green energy into the grid,” Watt adds. “So, to me, this is a much more efficient use of the system, where we have our landfill and a user immediately adjacent. But, those opportunities are not common.” For smaller landfills or landfills in remote areas that don’t have major hydro connections or gas pipelines nearby, it be-comes cost prohibitive, he explains. Consequently, for more endeavours like this to come on-line, both Giroux and Watt believe more government support is needed. There needs to be a way to “funnel” some funding to help other projects succeed, Giroux says. “The federal government is still talking about how they intend to return funds collected under their carbon policies, at least those collected from large industries under the output-based-pricing system. They say that they’re going to return it in order to help generate greenhouse gas reduction opportunities. These are the kinds of projects that they should be looking at,” she says. The Federation of Canadian Municipalities recently launched its Green Municipal Fund to help support initiatives that reduce greenhouse gas emissions, Watt notes. He hopes that subsidies from this fund can help smaller municipal landfills take initia-tive like this, turning waste into renewable fuels to help power industrial users. INVESTING IN THE ENVIRONMENT The engines generate about 6.4 megawatts of electricity for the plant, which is just over one-third of the demand for the site, Giroux says. The impact of this is huge for GM Canada. “It’s displacing what we would have bought from the Ontar-io grid. And from the recovery of the heat and distribution to the site, we’re able to reduce our greenhouse gas emissions by a really significant percentage – about 70 per cent,” Giroux says. This, in turn, has reduced the plant’s operating costs. The initiative has also created a circular economy between the plant and Walker Industries. “They’re our nearest neighbour; they had a waste that they were able to convert into a fuel that we’re able to use, to help make ourselves more sustainable, and that’s also helping Walker create a new business line, helping us to be more successful in Despite the financial barriers, both Giroux and Watt believe this is a growing market. “We’re hoping that this is a good example to others,” Giroux says. GM Canada is exploring using different types of renewable energy, such as solar and wind, to power their operations around the world. But which source of renewable electricity generation they use depends on location, Giroux notes. Renewable landfill gas is ideal for Canada, with its colder climate. “Being able to work with partners like Walker and IGRS and get reliable supply of this kind of renewable fuel for a long peri-od of time creates a real opportunity for us,” she says. “I think that GM’s at the forefront of this in terms of their overall goal with their energy use and where it’s coming from,” Watt adds. “COVID has put plans on hold in many cases, but you’re going to see many more companies making a commit-ment to invest in the environment.” • Canadian BIOMASS 19
Canadian Biomass Winter 2021: Page 19
