Landfill Gas to Energy
WHAT IS LANDFILL GAS TO ENERGY?
LFG to E or landfill gas utilization is the collection, process, and treatment of methane emissions from decomposing waste to manufacture chemical compounds, electricity, fuels, and heat. The method of LFG to E is the third largest source of human-made methane. Being a highly combustible greenhouse gas, methane must be kept in a highly monitored and controlled environment where there is maximum utilization of the gas to produce energy, therefore, minimizing the generation of greenhouse gases ( that cause climate change) in two of the most primary sources.
According to EPA, landfill projects increased from 399 to 519 in four years after 2005 as a result of having long term benefits, including energy cost control and reduction of greenhouse gases such as methane. The projects collected the waste gas, processed it and utilized in the form of electricity, heat or directly as a revamped pipeline-grade gas. These gas treatment projects are primary energy sources for vehicles, households, and buildings.
Landfill Gas
Before understanding the process of converting landfill gases to energy, it’s vital to understand what landfill gases are. A complex composition of various greenhouse gases is produced during microbial activity in landfill which are known as landfill gases.
Methanogenesis (i.e., generation of methane), chemical reactions during decomposition of waste and evaporating of volatile organic compounds are some of the chemical processes taking place at landfills. These processes produce greenhouse gases such as carbon dioxide and methane (40%-60%). The remaining composition of the complex usually comprises of organic compounds that are volatile such as hydrocarbons.
Environmental Impact of Landfill Gases
Decomposition of tons of human garbage in landfills is a significant cause of climate change as a result of mass production of methane and carbon dioxide greenhouse gases. While carbon dioxide is more abundant in the atmosphere than methane, the latter is a more potent gas. Scientists found that methane had 25 times more effective than carbon dioxide significantly contributing to global warming even in less amount. Around 67.8 million tons of waste was recycled by landfills in 2015 to produce the gas. Around ten percent of the total production of methane is contributed by these landfills. The landfill gas collection system has a 96 percent collection efficiency, and only four to ten percent gas is lost in the atmosphere during the process. LFG to E is a green process that collects and treats green fuel source (landfill gases) simultaneously reducing methane emissions.
HOW DOES LANDFILL GAS
CONVERT INTO ENERGY?
Over several years, landfills generate a constant flow of methane that run generators to create renewable electrical energy. Anaerobic bacteria contribute immensely to the natural gas production cycle by decomposing organic garbage to generate biogas as a byproduct that comprises carbon dioxide, methane, and some hydrocarbons. This natural process begins approximately six months after the deposition of landfill waste which reaches climax in around 20 years after which it begins to decline.
Before the landfill gases can be fully utilized, they need to be treated for maximum utilization. Methane, which is created during the decomposition of organic waste in landfill, is used by landfill gas generators to generate pure, renewable energy in the form of electricity. The procedure, simultaneously, eradicates the presence of methane which is detrimental to the environment. METCO uses gas created from various landfill gas generators in the state of Texas to treat and obtain methane to convert to energy using the following process:
1: Waste is accumulated in landfills that produce the byproduct methane in abundance by decomposing of organic waste.
2: The gas is extracted and transferred through a gas collection system composed of pipelines and vertical wells to an on-site facility to a central collection header to be treated or flared. The header may be connected to a leachate collection system that collects any condensate accumulating in the pipes.
3: The treated gas is is either delivered to the energy grid to produce energy (electricity) on site or is transported off-site directly to a manufacturer nearby the area to use as natural gas. A blower pulls gas through the pipes throughout the process.
4: Some of the gas may also be flared and combusted immediately in the landfills and removed altogether without any utilization.
The setup to collect landfill gas is done by installing wells horizontally and vertically within the mass of the waste. Design experts typically suggest one vertical well should be installed for every acre of the landfill surface while horizontal should be placed every 50-200 feet away from the center of the mass waste. Both types of trenches are effective in accumulating gas. Furthermore, landfills can be closed (84% production rate) or opened (67% production rate) with the former being the more efficient one. The higher efficiency of closed landfills is a result of a higher rate of collecting as active-filling does not need to occur.
Landfill Gas Treatment
The treatment system may be primary or secondary processing. The primary processing involves gas cooling and compression, which remove particles and moisture. Whereas, the secondary processing employs a series of purifying procedures, chemical, and manual, based on the end use. Minimal treatment is required to use the gas in boilers, heaters, and kilns, while a more in-depth treatment is necessary to use it for electricity generation. Adsorping and absorbing are two primary technologies in secondary treatment of processing.
Flaring
To avoid excessive production of these harmful greenhouse gases, they may be flared occasionally. Flaring is a useful process on landfills to avoid extraction spikes of these toxic gases. The flares are either enclosed or open where the enclosed flares are more expensive as they generate higher temperatures and control light and noise pollution. Most states in the USA have made enclosed flares mandatory.
Use of Treated LFGs
Here are some sources the processed gases could be utilized on and off-site:
- Process heater, boiler, and dryer
- Leachate Evaporation
- LNG/CNG
- Artisan studios, infrared heaters, and greenhouses
- Electricity generation ( produced by running gas turbines, fuel cells, microturbines or piston engines that turn electric generators that could be on-site or off-site)
BENEFITS OF LFG TO E
Removal of
Greenhouse Gases
Landfill gas utilization or destruction helps to prevent untreated methane from escaping and ionizing radicals in the atmosphere. At the sites, METCO actively works on collecting clearing up methane to create a better environment for the community.
Offsetting Usage of
fossil fuels
Landfill gas is a green fuel also because it replaces the use of fuels like natural gas and oil that are detrimental to the environment and destroys heat-trapping gases such as methane.
Producing higher
revenues and jobs
As a result, of a cleaner environment and decreased pollution, LFG to E generates more employment, income, and higher savings.
A Sustainable and
Healthy Community
By combusting harmful greenhouse gases that would otherwise deplete the ozone and reducing fossil fuel combustion, this form or renewable energy generation allows a more sustainable and healthier environment and community to develop.
Why Choose METCO?
METCO, along with EPA, considers LFG as one of the most eco-friendly energy sources and actively participates in projects for landfill gas-to-energy as a smart solution to fulfill the community’s needs. METCO believes in providing renewable, cost-effective intelligent energy solutions with the highest profit generation for the client’s business. METCO’s team of professionals play a critical role in delivering optimal results and timely and constructive counseling to our clients. Synergistic teamwork and high performance have earned METCO immense trust and healthy relationships with its clients.
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