A mountain of rotting food, discarded clothing and cardboard boxes pile up as trucks line up the hill to dump more waste. Birds swirl in flocks above, waiting for the cranes and dump trucks to clear so they can descend upon the heap for scraps of rotting food.
With each new pile of garbage, the East Baton Rouge Parish North Landfill in Zachary grows to one of the highest points in the parish.
Some 270 garbage trucks arrive at the landfill each day, bringing with them waste from eight different parishes until an area reaches its maximum capacity. Then the garbage is permanently covered with clay so it can decompose underground.
That’s when landfill gas starts accumulating: a mixture of half methane, half carbon dioxide and some organic compounds — “a big cereal bowl of trash juice,” as one landfill maintenance worker said to describe the decay process. The amount of methane produced underground can depend on the type, age, moisture and temperature of waste buried beneath the ground, according to the EPA.
This gas has made landfills one of the nation’s largest sources of methane, a highly potent greenhouse gas that traps about 80 times more heat than carbon dioxide during a 20-year period, according to the Environmental Integrity Project, an environmental watchdog group founded by former EPA attorneys.
Finding uses for trash gas
In an effort to curb its methane production, the North Landfill has implemented a landfill gas collection system that sells off the majority of its methane to Exxon. Once garbage ferments underground for five years, wells are installed that capture the methane, transfer it to an on-site plant for cooling and send it down a pipeline four miles South to the Exxon Polyolefins Plant on Scenic Highway rather than burn it off.
The landfill currently has 97 gas wells installed on its property, which are each checked once a month, according to environmental coordinator Sarah Boudreaux.
K&L Environmental Solutions environmental technicians Brent Taylor, left, and Connor Dayton conduct a weekly pump check at the North Landfill in Zachery on Tuesday, February 7, 2024. The landfill behind them is filled with layers of garbage covered in soil and pools of methane gas underneath the surface.
Once at Exxon, the methane gas is used to fire boilers that make plastic products in lieu of natural gas.
“The project is a great example of industry and local government coming together to provide environmental benefits to the whole Baton Rouge community,” Meg Mahoney, ExxonMobil’s public and government affairs manager, said in a statement.
Exxon buys the methane from Waste Management Renewable Energy, LLC, the company that maintains the landfill gas collection system for the city, and the city-parish government collects a small portion of the revenue.
Landfills are required by the federal government to implement a landfill gas collection system after collecting a certain amount of waste, though landfills aren’t required to use that gas as an energy source. Other landfills across the country may simply burn off all of their methane into the atmosphere.
“It’s pretty much required,” said Boudreaux. “You’re not required to have a beneficial end use, but you’re pretty much required to collect it and at least burn it off.”
Gas still gets out
The landfill does not capture all of the gas that is emitted, however.
The North Landfill reported to the EPA that its collection system was about 70% efficient in capturing methane, with the rest either being burnt off on-site or leaking into the atmosphere through fugitive wells. The EPA estimates that most landfill energy projects typically capture 60-90% of methane emissions.
K&L Environmental Solutions environmental technicians Brent Taylor, left, and Connor Dayton use wrenches to loosen a nut during a pump check at the North Landfill in Zachery on Tuesday, February 7, 2024.
How much gas gets out? It's not entirely clear, because the EPA relies on calculated estimates, not comprehensive monitoring.
One EPA model, which uses the amount of waste to estimate emissions, says the North Landfill leaked out 17,482 metric tons of waste. A different EPA model, which is calculated based on how much methane a landfill captured, estimated the amount at 1,578 tons.
The Environmental Integrity Project has called on the EPA to require more direct measurements of landfill methane emissions and has found that current models for calculating methane emissions likely significantly underestimate the amount of methane going into the atmosphere.
“[These models] are estimates based on assumptions with a lot of uncertainty,” said Haley Lewis, an attorney for the Environmental Integrity Project.
Lewis added that recent evidence has shown that landfill methane is being generated sooner than previously thought because of dramatic increases in food waste nationwide, which decays more rapidly than other kinds of waste — meaning methane may be forming before landfills are required to install wells to capture the gas.
Lewis said Baton Rouge residents could help curb emissions by diverting organic waste away from the landfill. Municipalities and businesses could work together to create composting facilities and food waste production facilities, while individuals could participate in composting at home to reduce their contributions to landfills.
“When you remove the food waste from landfills by composting, it avoids taking up landfill space and can extend the life of the landfill as well,” Lewis said. “You’re not only reducing methane, but you’re making a more efficient use of the landfill space too.”