Tackling the Methane Problem at King County’s Cedar Hills Regional Landfill
Written by Ashli Blow
Originally published by Crosscut
A compactor in the active area of the King County Cedar Hills Landfill (Photo: King County)
Cedar Hills in Maple Valley is ranked among the top 50 methane-producing landfills in the country. But new science and policy breakthroughs could help.
For decades, King County has had a landfill gas problem. While trying to fix it, the county may have contributed to several other environmental issues. And now with a key partner of King County’s Cedar Hills Regional Landfill in court, the situation has escalated. But surprisingly, so have some potential new solutions and policies.
Methane, produced in landfills by decomposing waste, is a climate super pollutant, 28 times more potent than carbon emissions when in the air. To reduce this impact, the 920-acre Maple Valley facility incinerates methane, but the process releases other dense gases that have their own climate-warming consequences.
In 2008, King County contracted with a renewable-energy company, Bio Energy of Washington, to capture methane’s byproducts and convert them into natural gas. Landfills around the country have tried to follow this model, but King County’s effort with this technology was shut down in November amid a lawsuit over pollution and the profits generated from it. Complaints against the Bio Energy project involve both air and groundwater pollution, but stopping the project is creating pollution as well.
Meanwhile, the Washington Department of Ecology has established new regulations to reduce methane emissions from landfills, part of a suite of climate policies aimed at aggressively cutting Washington’s total greenhouse-gas emissions by 2050.
“We are very conscious of and aware of the responsibilities around landfill gas management, but it is also a very challenging part of our business,” said King County Solid Waste Division Director Pat McLaughlin. “We’re in a dispute right now … and it’s a bad thing, because in the meantime, we have to flare this gas.”
Bio Energy Washington’s facility used a sophisticated refinery system that minimized the environmental impact from the conversion’s aftermath. When fully operational, the process reduces greenhouse-gas emissions by 85,000 tons, according to King County.
But by flaring gas, Cedar Hills is losing both environmental and economic benefits. Combusting methane emits carbon — a pollutant that Bio Energy Washington’s facility helped keep out of the air alongside methane.
The facility used a refinery system that processed the pollutants and sent them through a pipeline offsite for sale as natural gas. When fully operational, the process reduces greenhouse-gas emissions by 85,000 tons and generates $4.5 million worth of gas each year, according to King County. It’s enough to meet the energy needs of nearly 20,000 homes."
However, even when the gas-to-energy pipeline is running, it comes with its own challenges.
A maze of methane management
Deep within the layers of the landfills, bacteria that thrive in the absence of oxygen and light feed off buried organic waste like food and paper. During this microscopic meal, they produce methane. Letting the methane rise unchecked isn’t an option, because the gas is explosive.
The Washington Administrative Code regulates methane levels at landfills, requiring that concentrations do not exceed 25% of the lower explosive limit, the threshold at which methane can ignite when mixed with air. To control the methane, landfill operators typically choose one of three options: flaring it, converting it into energy or selling it.
The north flare station at Cedar Hills, where landfill methane gas is collected and burned off. (Photo: King County)
Over the past 10 years, Cedar Hills went with a blend of those options. Bio Energy Washington’s gas-to-energy plant was designed to help meet code and the 95.8% methane removal rate required under the landfill’s environmental permits.
To remove the methane, a network of 800 wells works like a vacuum, piping it from the landfill into the facility where a two-stage system converts it into renewable energy.
After prolonged disagreements concerning arsenic in emissions and wastewater, the system was shut down and the debate moved to the courtroom. More than 90 documents filed in the case show King County and Bio Energy Washington pointing fingers over revenue and responsibility. The case is scheduled to go to trial in February, and flaring is the “only available option” to keep Cedar Hills’ methane levels at bay, but no one seems happy with that reality.
“The county is wasting millions of dollars and the value of [renewable natural gas]
that BEW [Bio Energy of Washington] would normally produce,” said Chuck Packard, CEO of parent company Ingenco, during a public meeting in September. “The solution, we think, is that we should go back to what we were doing.”
Bio Energy Washington’s facility closure comes as Cedar Hills is experiencing an uptick in landfill gas emissions.
The latest publicly available data for Cedar Hills’ landfill gas is from 2022. According to reports filed with the Environmental Protection Agency, methane emissions have increased 18-fold, an uptick that follows increased waste, according to the Solid Waste Division. Methane emissions were 12,649 tons in 2012 and 233,019 tons in 2022.
Data availability has become a central discussion topic for landfill gas management. At the Bloomberg Green Festival in Seattle this month, scientists emphasized the need for “policy-ready” data to inform more effective pollution-reduction regulations.
Improving the state’s ability to collect such data is one of the main intentions of a new methane rule overseen by the Washington Department of Ecology. Their air-quality team doesn’t know the exact number of municipal solid waste landfills or what equipment they use to manage gas.
Under the new law, the Department of Ecology estimates that 26 landfills will be required to submit quarterly reports of their gas collection.
The Department is targeting methane because it is the second-largest greenhouse-gas contributor in Washington after carbon dioxide, with landfills being a significant source. In addition to new reporting requirements, the rules instruct municipal landfills to install equipment that captures and controls methane.
With funding from the Climate Commitment Act, the department has created a $15 million grant to help landfill owners and operators acquire technology that processes and recovers energy from methane emissions.
New ways to capture methane
A potential new way to manage methane has been discovered by researchers at the bottom of Lake Washington: bacteria that eat the materials that turn into methane. They are the microorganic opposite of the bacteria in landfills that break down waste and produce methane.
“These bacteria form a layer and they catch it,” said Mary Lidstrom, professor emeritus of chemical engineering and microbiology at the University of Washington. “What they do is they keep a significant amount of methane that’s produced on earth from going into the atmosphere.”
These bacteria are everywhere, from the ocean to glaciers worldwide. While her team got a hint from a strain in Lake Washington, Lidstrom’s breakthrough discovery came from a strain in a salty lake in Russia, which was used to develop a prototype to harness and harvest the bacteria and their energy.
She hopes to commercialize a prototype device, a bioreactor the size of a shipping container, to house the bacteria so they can feed on methane. In the process, the bacteria produce a protein-rich biomass, a renewable energy source that can be used as animal feed.
This technology excels in capturing lower levels of emissions that pipelines are too big to catch. The Environmental Protection Agency estimates that 61% of methane escapes landfills.
“Landfill gas is like the dinosaurs in Jurassic Park. Nature finds a way. It wants to leave the landfill,” said Katherine Blauvelt, circular economy director for Industrious Labs.
Her organization ranks Cedar Hills among the country’s top 50 methane-emitting landfills. While new approaches to capturing methane are promising, there must also be a system for detecting leaks, she said. That responsibility falls to new satellite and drone technology that can identify leaks through aerial imaging.
But science and technology can’t solve the landfill gas problem alone.
“We need rigorous standards that are making sure there’s vigilance and good operational practices in place,” said Blauvelt. “For Cedar Hills, and all the people around it, and for any landfill, it just couldn’t be more urgent to ensure that both the environment and human health are being taken care of.”
As Washington state kicks off its new landfill gas rules, the Environmental Protection Agency announced on Tuesday that it is proposing to update the Clean Air Act to cut methane emissions, specifically to reduce air pollution.
But compared to the pace of the climate crisis, progress is slow, as municipalities like King County navigate not only the science and policy but also the courts to resolve its landfill woes.