In Ada County, food waste and other trash might be heating your home in 2025. A new facility at the Ada County Landfill will soon be processing methane emissions into natural gas for commercial use.
Much of what we throw away is little more than greenhouse gas emissions in waiting. Trash from our homes, businesses and especially the organic waste from our kitchens quickly break down into the potent greenhouse gas methane.
“The net effect is about 25 times that of CO2. You absolutely don't want methane going into the environment,” said James Tomlinson, Chief Operating and Technical Officer of Texas-Based BioGas Development. He leads the gas capture project at the Ada County Landfill.
Federal regulation requires landfills to mitigate methane emissions. For nearly 20 years, Ada County has burned some captured methane to generate electricity. Most of it is just flared off; burned to release the less-damaging greenhouse gas carbon dioxide.
“Nobody wants to flare gas,” Tomlinson said. “We're trying to take a quote-unquote waste product and turn it into something really positive.”
The promise of trash-to-energy has been fleeting in Ada County. In 2010, the County partnered with Eagle-based Dynamis Energy with a plan to transform tons of physical waste into renewable energy.
"This is the second of what we hope will be many renewable energy projects located at the County's new renewable energy industrial park," said then-Ada County Commission Chairman Fred Tilman in a press release at the time.
But the public pushed back with pollution concerns, the company missed deadlines, and Ada County Commission candidates of both parties in the following election promised to reverse the deal.
“The county commissioners in 2010 as they processed this, they cut the public out of the process, the didn’t involve other elected officials, they didn’t involve the current waste contractor, they didn’t do a third party evaluation to see if the technology even works, they didn’t vet it properly,” said former District One Commissioner Jim Tibbs, speaking with Boise State Public Radio as a Republican candidate in 2012.
The deal with Dynamis ultimately collapsed in 2013, costing Ada County the $2 million it invested in the project, and a $2.2 million settlement three years later with Fortistar, the company already using trash emissions to generate electricity. Fortistar sued, alleging it already had a deal for landfill gas the county was then promising to Dynamis for its project.
BioGas ultimately bought the power generating operation from Fortistar in 2018, known as Hidden Hollow Energy LLC, and runs it today. The operation is producing about three megawatts of energy a day, enough to power about 3,000 homes.
The new natural gas conversion facility expects to put the approximately two-thirds of collected landfill gas currently being flared to work right away.
“The amount of gas we're going to be producing here to start is enough to do about 20,000 homes, Tomlinson said. He thinks that output could double in 10 to12 years.
Here’s how it works: Miles of tubing dug into the landfill collects methane and other gasses from decomposing trash, under a vacuum. Each well is monitored, many in real time by electronic sensors, explained Ada County Landfill environmental compliance manager Dylan Potter, during a tour of the site.
“We'll adjust that at the wellheads depending on the gas quality and other considerations like Surface emissions,” Potter explained.
Methane volume and quality degrade over time, and each well is throttled to maintain quality for the whole system.
Once collected, temperature and pressure changes help separate the water vapor, gases and volatile organic compounds, and deadly hydrogen sulfide - which is captured and retained in special containers to be trucked off for disposal elsewhere.
To this point, the process is about the same as cleaning up the gas to burn for electricity. Tomlinson compared the next steps needed to make deliverable natural gas to reverse osmosis; filtration at a molecular level.
Gas is pushed through “dozens and dozens of these membrane modules until it reaches about a period of about 94% methane,” he explained. “We also unfortunately concentrate the nitrogen and the oxygen in the process, and so we have to go through a secondary process called a nitrogen rejection unit - which removes really everything, not just nitrogen. We basically absorb our product, which is methane, into activated carbon, activated charcoal. And then we put a vacuum on that activated carbon to remove all the gas out. By that point, we're now at about 98.5% pure methane. We’re now at pipeline quality”
The gas is then transferred several hundred feet to a nearby Intermountain Gas substation, where it’s carefully monitored and injected with an artificial odor before heading about 7,000 feet to Intermountain's supply pipeline along Highway 55.
“If at any time the quality of that gas does not meet our specs, sensors will note that and immediately close the valve to prevent any more gas getting into the system,” utility spokesperson Mark Snider told Boise State Public Radio.
The "Hidden Hollow project" will be the sixth renewable gas connection on the Intermountain Gas network, Snider said. Five similar systems in the Magic Valley are fueled by methane from agriculture waste. Utility customers won’t see a difference in gas performance or cost, Snider said.
“Under Idaho law and PUC rules, Intermountain Gas is not allowed to use ratepayer dollars for a project like this. So the producer of the gas or the developer of the methane recovery program and system is responsible for fronting all of the costs.”
About $50 million for Hidden Hollow Energy, according to Tomlinson. Last year, the operation qualified for a $25 million dollar loan through the US Department of Agriculture’s rural energy for America Program. BioGas will pay Intermountain Gas an annual maintenance fee, too.
Converting methane to natural gas is a far more expensive process than making electricity, but it’s more lucrative too; about three times more, according to Tomlinson. His company has similar projects underway in Texas, And he’s talked with Canyon County about opportunities at Pickles Butte Landfill - though that site’s distance from a gas pipeline likely limits its potential to electricity generation.
Tomlinson proudly said his company is small and privately-funded, with no outside investors.
“This is not all about making money,” he said while guiding a site tour. “It's certainly nice that we're getting paid to do this. But I hate seeing a wasted resource just being flared. I mean, that just galls me.”
The first gas from Hidden Hollow should make its way to Intermountain’s pipeline by the middle of this month. Tomlinson had hoped to be up and running by late December, but the final steps slowed through the holiday season.
Ada County Commission chairman Rod Beck called the project a win-win for the county, starting with about $1 million each year they expect in gas royalty revenue.
“Not only do we get royalty, we produce clean energy credits,” he said. “And then we sell those clean energy credits to Europe. because, well, they pay more for them.”
The income helps keep landfill fees low, according to Landfill Director Herb Cantu. And all our trash will continue to generate usable methane into the next century. Cantu says changing the way they lay down trash and cover it means better compaction, which leads to greater and more reliable emissions.
“As the site grows, we are installing additional landfill gas collection pipes, and that would be something we would have to do anyway,” Cantu explained.
Because all that gas has to go somewhere, and it might as well heat our homes, our water and our stovetops.
Editor's note: Boise resident Kristi Allen contributed to this story.
