Landfill gas
Landfill gas is a byproduct of the decomposition of organic materials in landfills, primarily consisting of methane and carbon dioxide, along with water vapor and other organic compounds. This gas is generated by bacteria and microorganisms that break down waste, indicating that even after disposal, trash remains biologically active. Historically, landfill gas was allowed to escape into the atmosphere, leading to unpleasant odors and environmental hazards, including potential groundwater contamination and explosion risks. However, regulations from the mid-1990s mandated that landfills monitor and manage these emissions.
The management techniques for landfill gas include flaring, which burns the gas to reduce methane release, and utilizing the gas for energy production. By capturing methane, it can be converted into electricity or sold as a natural gas alternative, presenting a reliable and environmentally friendlier energy source compared to traditional fossil fuels. The use of landfill gas for energy is becoming increasingly common as landfills recognize the financial benefits, with many operational projects across the United States. This approach not only helps mitigate climate change but also promotes sustainable energy practices by repurposing waste into a usable resource.
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Landfill gas
Summary: Landfill gas, a combination of methane and other products produced through the breakdown of garbage by bacteria and other organisms in dumps, can be captured, stored, and reused by businesses and even the landfill operator itself to generate electricity.
While it is common to think of trash as being dead, once deposited in a landfill it is anything but that. Bacteria, microbes, and other microscopic organisms work in conjunction with materials in the water, soil, air, and even garbage itself to decompose our trash. As those organisms do their work, they produce significant quantities of landfill gas, which is a mixture of methane (or natural gas), carbon dioxide, water vapor, and toxic organic compounds—although principally methane and carbon dioxide. In the past, landfill gas was allowed simply to seep upward from landfills and be released into the atmosphere, causing unpleasant smells for nearby residents. Because of its natural gas components, however, landfill gas has also been responsible for a number of explosions at landfills, as well as the contamination of groundwater resources around landfill sites.
In the mid-1990s, however, the US Environmental Protection Agency ordered that all landfills meeting certain requirements monitor, collect, and manage landfill gas emissions. Monitoring can take place with equipment both near and inside the landfill itself, while collection typically takes the form of a “well” that is drilled down into the landfill, inside of which is created a slight vacuum to extract landfill gas from the site. Newer landfills might have a network of similar collection pipes built into them from the start, allowing the collection system to grow as the amount of solid waste grows.
The management of landfill gas is arguably the most important part of the process, however. It is thought that landfill gas contributes directly to climate change because of its heavy methane and carbon dioxide content. Preventing the release of landfill gas into the atmosphere might help slow climate change. There are a few ways in which landfill gas can be managed. The first is to flare the gas (simply burn it) upon extraction from the landfill. This mitigates the release of methane into the atmosphere but still releases considerable amounts of carbon dioxide as well as the potentially toxic organic materials that make up landfill gas.
The second major landfill gas management technique is to use the gas directly for another purpose. The methane content can be separated from the other material and fed through pipes to factories or other industrial operations that need natural gas to operate.
Equally promising are landfill gas management systems connected to electricity generators, whereby the methane can be combusted to produce electricity similarly to newer, combined-cycle gas turbines. Using landfill gas to generate electricity presents a number of benefits, because it prevents the release of toxic materials and gases that contribute to climate change while reducing demand for less clean sources of electricity such as coal.
Advantages
Generating electricity using landfill gas has a number of advantages over other means of producing power. The first is that, although it uses a fossil fuel (natural gas), this fossil fuel is continually being produced and is not being extracted from sensitive ecosystems such as wetlands or from deep under the ocean floor. Because the fuel is being produced in the landfill itself, there are no real costs for the fuel, as would be encountered at a typical power plant. Furthermore, because the distance the fuel must travel is fairly short (sometimes only a few hundred yards from the collection system to the gas-powered turbines), there is much less potential for disasters associated with burst pipelines and spills. Finally, because landfill gas is continually produced, the source for methane is quite reliable and the generating turbines can be operational almost 100 percent of the time, making landfill gas systems one of the most reliable and efficient means of producing electricity.
Landfill gas systems can be installed, in theory, on any landfill. In practice, however, they are typically installed either on those landfills that require landfill gas monitoring and management by state or federal regulators or on those landfills deemed large enough to produce sufficient landfill gas at least to offset the costs of installing the system. This means that some landfills, which would not necessarily come under the requirements of environmental regulations, have voluntarily installed landfill gas management systems because it has been profitable for them to do so, either by selling a clarified landfill gas to industrial users or by selling the electricity they produce to a utility company.
Using landfill gas for energy projects is becoming much more common in the United States as landfill operators come to realize that they can profit from selling methane or electricity. According to the Environmental Protection Agency (EPA), there were about 2,600 municipal solid waste landfill operating in the United States in 2024. The EPA reported that 482 of these landfills provided gas to 536 operational landfill gas projects.
Bibliography
"Basic Information about Landfill Gas." Environmental Protection Agency, 25 Apr. 2024, www.epa.gov/lmop/basic-information-about-landfill-gas. Accessed 2 Aug. 2024.
"Benefits of Landfill Gas Energy Projects." Environmental Protection Agency, 25 Apr. 2024, www.epa.gov/lmop/benefits-landfill-gas-energy-projects. Accessed 2 Aug. 2024.
"Biomass Explained." US Energy Information Administration, 15 Dec. 2023, www.eia.gov/energyexplained/biomass/landfill-gas-and-biogas.php. Accessed 2 Aug. 2024.
"Project and Landfill Data by State." Environmental Protection Agency, 22 Mar. 2024, www.epa.gov/lmop/project-and-landfill-data-state. Accessed 2 Aug. 2024.
Rajaram, Vasudevan, Faisal Zia Siddiqui, and M. Emran Khan. From Landfill Gas to Energy: Technologies and Challenges. Boca Raton, FL: CRC Press, 2011.