Trash has the momentum of a freight train. How does one stop it? Abandon overflowing rubbish cans to the curbside and expect America to adopt Leave No Trace principles? No. For now, trash will flow, and America must search for the silver lining.
Enter, landfill gas. A byproduct of organic decomposition, LFG, with a little know-how, can be used to run cars, generate electricity, and even fire pottery. It may be a small benefit to a dire problem, but there’s room for growth.
What Is Landfill Gas Energy?
Nestled beneath the plastic bottles, rusty bolts, musty lawn trimmings and leftover Christmas tinsel of a landfill, billions of bacterial cells are munching away like it’s Thanksgiving meal, round one. They live without air, surviving -20 degree winters, subsisting on a yummy diet of gunk. Consequently, it is a type of biomass energy.
The bacteria produce a stew of gasses – about half carbon dioxide and half methane, with trace amounts of other hydrocarbons like propane and butane. Unfortunately, the gas also contains inorganic contaminants like mercury and chlorine. The mixture is combustible, explosive, and thanks to trace sulfides, and often smells like rotting eggs.
How Does Landfill Gas Work?
To some, that smell means money. Landfill gas can be used in a waste-to-energy thermal conversion process where the gas is burned, much like propane in a barbecue grill, and powers a heat engine.
Nature produces the gas; it’s up to mankind to capture it. Modern municipal solid waste (MSW) landfills are light-years beyond typical dump heaps. Refuse is buried beneath layers of soil and synthetic membranes to prevent pest infestations, gas permeation, and water table contamination. In closed landfills, the gas is extracted through wells drilled into the refuse and by piping the captured gas to a central location. In an open landfill, a trench-and-blower system captures the fugitive gas emissions.
Then, the fun begins:
- The gas is de-watered, filtered and pressurized.
- In many applications, the gas is simply flared to downgrade its global warming potential.
- Forward-thinking engineers, however, devised several ways to capture the energy stored in LFG. Most commonly, the gas is used as fuel in an internal combustion engine or a steam-driven turbine to create electricity. Another common application is fuel for a boiler, which only creates heat, and may be used for brick manufacturing, steel production, heating greenhouses, etc.
- Alternative uses for LFG are growing. Filtered LFG can substitute as compressed (CNG) or liquid (LNG) natural gas for residential heating and automobile fuel.
The Advantages of Landfill Gas
Generates Cheap Electricity
Landfills with LFG collection systems already operate in almost every state. In 2013, LFG produced more electricity than all domestic photovoltaic solar power, and the EPA estimates there remains growth for at least 1,000 megawatts of power, enough energy for up to 700,000 homes.
Fosters Domestic Job Creation
More than 200 American companies refine LFG for thermal and electricity generation use. The big players are Republic Services, Inc., Progressive Waste Solutions Ltd, and Orange County Waste and Recyling. Progressive Waste Solutions Ltd. alone has more than 7,500 employees – and there’s room for more!
Long-term studies of New York landfills concluded that nearby residents suffered from aggravation of asthma, throat and lung irritation, headaches, difficulty sleeping and other chronic ailments. Most of these health effects were due to hydrogen sulfides. Thankfully, LFG collection systems often capture these insidious agents as well.
Increase Residential Property Values
High-volume landfills decrease adjacent property values by 12.9 percent. Who wants the smell and the scenery? Modern LFG collection systems are quieter and more efficient than their predecessors, decreasing noise and odor pollution, and boosting nearby property values.
Boosts Landfill Safety
“When the Environmental Protection Agency finalized sweeping New Source Performance Standards (NSPS) (…) LFG recovery and control systems were (…) designed and installed to prevent subsurface LFG migration and address explosive gas concerns,” says Sonal Patel of Power Magazine.
Reduce Global Warming Agents
Methane is 25 times more potent a global warming agent than carbon dioxide. Before Pixar’s “Wall-E” becomes a documentary, America must reduce its rubbish and global warming gas emissions. Why not do both at the same time?
The Disadvantages of Landfill Gas
There is no system that can completely clean up landfill gas or capture all the dioxins from its combustion. It’s a Catch-22. Does one leave the gas untouched, a global warming hazard, or redeem the gas for fuel, generating air pollutants?
Doesn’t Address the Root Problem
The main problem with landfill gas, of course, isn’t that it’s explosive or smelly or sickening; it’s that it exists. America generates about 260 million tons municipal solid waste annually. About half is put into landfills. No landfill can generate enough energy from LFG to atone for the embodied energy and environmental impact of its existence.
Fuel Market Volatility
Everything has to pay for itself. LFG competes with traditional fossil fuels like coal and petroleum. When oil freely flows, such as in America’s current oil fracking boom, LFG becomes the more expensive option. Private investors loathe subsidizing a technology so subject to price fluctuations. For this reason, most LFG plants are financed with long-term, fixed-rate contracts.
Sensitive to Geographic Location
Landfills must either pipe compressed LFG to local power plants or deliver onsite electricity through the local grid. The farther away the power plants and distribution centers, the more costly the infrastructure.
Arguments from both sides hold weight. Kerry Kelly, senior director of federal affairs at Waste Management Inc., endorses the pragmatic middle. “We believe that not using landfill gas where it is feasible to do so would be a terrible waste of a valuable resource.” And that, perhaps, is the silver lining.