Harnessing Energy From Trash: Landfill Methane Gas For Fuel And Power Generation

The recent fire outbreak at Olososun dumpsite Ojota-Lagos, Nigeria, caused environmental pollution. The incident emitted clouds of thick smoke which posed dangers to health of the residents. However, the Lagos State Commissioner of Environment dispelled the perception that the fire was set by individuals or officials of the government. He explained that the fire was naturally caused by gases produced by decomposing waste. These gases can cause combustion in dumpsites.

_{Fire incident at Olososun Dumpsite: Twitter}

The government has earlier marked this dumpsite and two others (Ewu in Elepe and Solus in Igando) for closure. Since they weren’t sustainable for solid waste management, the authority has conceded to construct more landfills at Badagry and Ikorodu. This project will promote the sustainable system of solid waste management in the state.

Considering the population of Lagos, an enormous quantity of trash is deposited at the various dumpsites and landfills across the city. Despite the campaign to reuse and recycle used materials, waste continue to accumulate. It is worthy to note that not all trash can be recycled or reused. This category of solid waste ends up in dumpsites and landfills.

In addition to the proper management of the waste, the gas emitted by the decomposing trash can be captured. This gas can be used for heating or to produce electricity. Harnessing the gas will not only eliminate fire outbreaks in dumpsites, it will also minimize the adverse effects of climate change.

Bacteria that can thrive in the absence of free oxygen (anaerobic bacteria) can decompose solid waste in landfills to produce biogas. This gas consists mostly of methane, a major component of natural gas. Methane is used for cooking, heating, and generation of electricity. The biogas also contains carbon (iv) oxide, CO2 and minute quantities of other gases.

Solid waste can be beneficial if biogas from landfills is converted into an energy source. To actualize this purpose, the gas from the decaying trash will be captured before it gets into the atmosphere. Once the gas is emitted, it rises above the landfill. It is then collected through pipes. However, pockets of it may be trapped among the waste in dumpsites. The trapped gas can cause combustion. The collected biogas is treated to separate the methane, which is burned to generate electricity or produce heat.

The diagram below shows a system for harnessing methane from the landfill.

_{Landfill Methane Capture}

Construction of such systems at the numerous landfills in Lagos will promote electricity production in the city. Besides, an increased supply of electricity will improve the life of the residents ant the economy of the metropolis. The waste generated in Lagos state will be put to good use if the landfills become part of the city’s energy project.

Methane emitted from decomposing trash has been used as an energy resource in various parts of the world. In Sweden, a biogas-powered train has been in operation since 2005. This train transports people between two cities, a distance of 75 miles apart. The United States also use energy generated from landfills, with power from landfill methane exceeding solar power in New Jersey and New York. The use of Germany has also used electricity generated from biogas to power millions of homes.

There is a need for sustainable management of commercial and industrial wastes and municipal solid wastes. The biogas emitted by the rotten trash is highly flammable due to its high content of methane. Besides, methane is a greenhouse gas that is over twenty times more powerful than carbon (iv) oxide when it rises into the atmosphere. When not properly managed, the biogas becomes a health hazard to people. It is also dangerous to the environment.

Flaring of the methane gas or burning, which is carried out in some landfill can reduce the emission of biogas. These methods keep methane away from the atmosphere. They also eliminate the harmful odor emanating from the decomposing waste. However, the energy potential of the gas is lost.

_{Electricity Generated From Landfill Methane}
The generation of electricity from landfill methane will go a long way to support power supply in Lagos. Besides preventing the escape of the gas into the atmosphere, capturing methane from trash will also prevent odors. However, methane is odorless. Landfill methane can also be converted to liquefied natural gas for powering vehicles. The compressed gas can serve as fuel for garbage trucks.

Besides the production of biogas, a poisonous liquid also oozes from decomposing waste. It can contaminate groundwater if it isn’t collected and treated. To avoid pollution and emission of greenhouse gas, biogas collection from landfills is important.

Landfills should be constructed with linings to prevent the harmful liquid seeping from the waste from contaminating the groundwater. Systems for the liquid collection, groundwater monitoring and venting of gases should be provided.

References
Methane Capture and Use | A Student's Guide to Global Climate ...
https://archive.epa.gov/climatechange/kids/solutions/technologies/methane.html

Landfill gas | Landfill gas generator | Dump site power - Clarke Energy
https://www.clarke-energy.com/landfill-gas

Lagos Shuts Down Olusosun Dumpsite After Fire Outbreak | Sahara ...
saharareporters.com/2018/03/.../lagos-shuts-down-olusosun-dumpsite-after-fire-outbr.