Mar. 06, 2013 - Issue #907: Garbage Goes Green
Garbage Goes Green
New biofuels facility will further divert waste from the landfill
Edmonton will soon be producing a new source of fuel, and it's probably not what you'd expect from a city in the middle of oil country.
"Right now we're achieving about a 60-percent recovery of the waste stream that we get here at the Waste Management Centre," Waste Management Services public education specialist Neil Burkard says. "When this whole biofuels and shredding operation is in the works, we'll have 90 percent diversion, and that will be one of the highest recovery rates of any city on the planet."
Most of the 40 percent of municipal waste that is currently trucked to a landfill outside of the city will be turned into biofuel when the facility is ready to go—likely by the end of this year—at the city's Waste Management Centre. The operation will take garbage that cannot be composted or recycled and put it through a process to turn it into potato chip-sized material called feedstock or RDF (refuse-derived fuel). Burkard is excited about this since the feedstock that is created from garbage will then be used as a fuel source to create more feedstock.
"It's going to get two purposes: it's going to become the feedstock for creating energy to heat the material up which is being turned into the gasified material," he says, adding, "It's bloody awesome because you're not having to consume another source of energy."
The feedstock will then be heated to over 700 degrees C inside a biochamber where the bonds of the material will be cracked to form a synthetic gas (syngas) made of hydrogen and carbon monoxide. Then it will be turned into 36 million litres of methanol and, in a few years' time, ethanol.
"More than likely you won't see a lot of methanol in vehicles other than in windshield washer fluid. It's the additive so it doesn't freeze. But there's lots of options to use methanol in the Edmonton area," says Jim Schubert, general supervisor of conversion technologies for EWMS. He points out that methanol can be used to make specialty chemicals for the pulp and paper industry or in the production of formaldehyde.
The biofuel itself will come from ethanol. "They can add the process train to take it from methanol to ethanol and then more than likely you'll see it in gasoline blends because it is mandated in the province now to have five-percent ethanol in all gasoline blends. It's not happening everywhere, but slowly it will," Schubert adds.
Dr David Stuart, associate professor in the University of Alberta's biochemistry department, explains a bit further how ethanol is used as a fuel source. "Ethanol is one of the most commonly used biofuels; that's in large part because it's really easy to make. As a culture, we've been doing that since the Egyptians, and that is simply getting sugar or starch and feeding it to yeast, and as part of their natural metabolism, they create ethanol. But ethanol is not a really great biofuel in part because it mixes with water and you don't want water getting into your engine, and also, the energy from fuel comes from breaking carbon bonds. Ethanol has only two carbons whereas gasoline, for example, or diesel fuel are very long chains of carbon, so they're much more energy dense."
Stuart says when ethanol is blended with gasoline it adds a biological component that reduces the amount of fossil fuel used, but it still has a somewhat lower energy content.
"One thing that people don't always understand about biofuels is that we want to use biofuels because it's green and less polluting so [there is] less greenhouse gas, but when you burn a biofuel it releases carbon dioxide the same as if you burn gasoline," Stuart says. "But the great thing about a biofuel approach is that the CO2 that's released by burning the biofuel is then used by plants to grow because that's where they get their carbon and then you take the plants, make the fuel and you burn it. So it becomes a fairly rapid cycle and in that sense it's sustainable."
Methanol from refuse. When the facility is completed, 36 million litres of methanol will be produced. // Eden Munro
While there may still be a lot of oil in the ground, Stuart says the burning of fossil fuels is only a one-way movement of carbon since nothing is returned to the ground. "All that oil in the ground comes from plants originally, but it takes a few hundred thousand years to make the oil," he explains. "So we don't really have the time to wait a few hundred thousand years to make that cyclic process. So that's one of the great advantages of biofuel."
Enerkem is the company the City has teamed up with to convert the garbage that cannot be recycled or composted into biofuel. However, there will still be about 10 percent of waste left over that will not work as a fuel and will end up in the landfill. But Schubert says that after the biofuel centre is up and running, perhaps down the road they'll be able to look at how to convert that remaining 10 percent of waste into fuel. In fact, the department he works for is already testing out different forms of waste to see if they could be turned into biofuel.
Not all materials can easily be turned into methanol or ethanol, such as hazardous waste or even large amounts of PVC plastic used in window frames.
"PVC plastic is 45-percent chlorine, so when you gasify PVC plastic you produce high concentrations of chlorine that you then have to scrub out," Schubert explains. But when PVC is mixed in with other garbage, it becomes easier for the syngas conditioning process to remove contaminants then if it was just a load of PVC by itself. The contaminants will be turned into wastewater or a solid that has a reagent added to neutralize them so that no gases are emitted into the open air. The wastewater will be sent to the treatment facility in Gold Bar and the solid material will go to the landfill.
Compost the most. This facility creates 50 000 tonnes of compost annually. Wood chips from old Christmas trees help to keep the odour at bay. // Eden Munro
Edmonton's Clover Bar landfill closed in 2009, but the City had a plan underway well before then to manage the massive amounts of waste that are produced here every year. A recycling program began in 1999, followed by a composting program in 2000. And Schubert says by 2002 they were talking about how to minimize the rest of the waste that was just piling up in the landfill.
"We found that what's remaining has good heating value and good calorific value, but it's not really suitable for more composting or more recycling," he notes. "We've taken all of the good waste out, so to speak, but the material that's remaining would be suitable for some kind of thermal treatment."
The project is costly, but Schubert says that even if the city had decided to travel the traditional path of waste incineration, it would still have been just as high an investment. Enerkem will invest $105 million into the biofuels facility and the city will invest $35 million to $40 million to prepare the feedstock. The project should cost $140 million overall, with some provincial grants being provided.
"Right off the bat, the province is contributing $29 million towards that; $20 million of the $29 million is going back to Enerkem," Schubert says. "We're giving that in different milestone payments as part of construction, so right now they've received a portion of it and when it's fully constructed they'll get the full $20 million. The other $9 million went towards the research facility and that's what I'm in, which is a pilot system to test different waste feedstocks that could be suitable for gasification in the future."
The city is responsible for operating the equipment to turn garbage into feedstock, and Enerkem will look after turning that into methanol.
"We're paying them a fee to process it, so it's still costing us money, but then they're also selling the methanol—and in the future ethanol—and that will pay for the overall operation," Schubert explains. "So in nice round numbers, it's about $50 a tonne that we're paying them to process the material and around $25 to $30 to turn it into a feedstock that's suitable."
Despite operating the first garbage-to-biofuels facility in the world—Schubert points out that other facilities that process waste wood are much different—it's still crucial for residents to sort their waste appropriately. Any garbage that should not be going through the system can slow everything down.
Michael Robertson works as a waste leader at the Integrated Processing and Transfer Facility—where your household garbage ends up and is sorted—and has seen a lot of questionable garbage since the IPTF opened in 2009 (before that whatever wasn't recycled or composted ended up in the landfill).
So long winter. At least in this gasifier where temperatures of 700 degrees Celsius will turn garbage into feedstock. // Eden Munro
"Every once in a while we get a mattress or maybe a bathtub or a dishwasher goes through the system, and when one of those goes through, it's a pretty good bet that it's going to clog up somewhere," Robertson says, adding that metal, electronics, batteries and even newspaper are all things that need to be recycled properly.
"One of the strangest things that I saw just before Christmas was a live rabbit. It was found in the sort room, which meant it had been thrown in a garbage truck, dumped on the floor, pushed by a loader, picked up by the excavator, dumped on the line, went up the line and they found it in the sort room still alive and well; terrified and shaking like you wouldn't believe. We brought it into the control room, put it in a basket, gave it some food and called the SPCA and they came down and picked it up. It looked like a domestic rabbit; it was a cute little black bunny."
The IPTF is an integral part of the biofuels operation, as this is where material will be separated to use in the production of methanol, and Robertson says the primary goal of the facility is to be a leader in the industry for waste reduction and reuse.
"I think it's an interesting time in our society as a whole that we're really evolving the way we look at waste and what we can do with it," Robertson says. "And the city has taken a lot of effort to try and be at the forefront of that new technology and I think it's really exciting to be one of the few places in the world to do that."
Burkard calls it all a symphony. "We have all these little pieces which make up this very massive, beautiful opus," he says. "We have garbage, we have recycling, we have electronics, we have paper, we have biosolids, we have landfill gas, we have leachate. All these different things that are associated with waste are really in one location here in Edmonton.
"Go to other municipalities around the world and they could be spread out over vast distances, so it makes their systems not that efficient. But here, this is kind of like a one-stop shop for waste. All of these facilities work together in concert with one another. And individually it doesn't seem all that impressive, but when you start to think of how they interrelate, it's amazing how much waste we are starting to divert from the landfill."
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