Harnessing Landfill Gas for Energy: Turning Waste into Power

Human beings produce a lot of waste. But what if there was an ecologically sound way of converting more of it into electricity? The good news here is that there is. A huge amount of our waste ends up in landfills and decomposes over time, releasing gases such as methane that are extremely bad for the environment. Methane can be harnessed and used to turn waste into power, creating new energy and reducing landfill emissions. So, how does this happen, and how can you benefit from it?

What is Landfill Gas, and Why Does it Matter?

Landfill gases (LFGs) are the emissions created by the landfill process, and methane alone makes up over 50%. Methane alone is responsible for more than 25% of the global warming that we are experiencing today. Due to its structure, methane traps more heat in the atmosphere per molecule than carbon dioxide (CO2), making it 80 times more harmful than CO2 for 20 years after it is released.

How is Landfill Gas Captured?

LFG is extracted from landfills using a series of wells and a vacuum system. Depending on its ultimate use, this system directs the collected gas to a central point where it can be processed and treated. From this point, the gas can be flared or beneficially used in an LFG energy project.

How to Turn Waste into Energy: The Process of Converting Landfill Gas

Methane gas is extracted from landfill sites using a network of wells and pipes. The gas is drawn from the decomposing waste and transported to a central processing facility, where it is treated to remove impurities such as moisture, particulates, and other contaminants, ensuring its suitability for energy generation. The processed gas is then used as fuel in internal combustion engines or turbines, which convert the chemical energy in the methane into mechanical energy, which is then used to generate electricity.

The mechanical energy from the engines or turbines drives generators that produce electricity. This electricity can be fed into the local power grid or used on-site. In some systems, the heat generated during the combustion process is captured and used for heating purposes, such as space heating or water heating.

Combined Heat and Power (CHP) is a highly efficient process that simultaneously generates electricity and useful heat from a single fuel source. A fuel source, such as landfill gas, is used to power an engine or turbine, which generates electricity as it runs. The heat produced during electricity generation is captured and utilised for heating purposes. This can include space heating, water heating, or industrial processes.

By capturing and using the heat that would otherwise be wasted, CHP systems can achieve efficiencies of over 80%, compared to around 50% for conventional power generation and separate heating systems. CHP systems reduce greenhouse gas emissions by making more efficient fuel use and reducing the need for separate heating systems.

Energy Production from Waste: Environmental Benefit

Landfills naturally produce methane gas as organic waste decomposes. Methane is a greenhouse gas; it’s many times more effective at trapping atmospheric heat than carbon dioxide. By capturing and converting this gas into energy, we significantly reduce the methane released into the atmosphere, helping mitigate climate change.

LFG is considered a renewable energy source because it’s derived from ongoing natural processes of waste decomposition. Unlike fossil fuels, which take millions of years to form, the organic material in landfills continuously breaks down, providing a steady gas supply. This makes LFG a sustainable and reliable alternative to non-renewable energy sources.

By converting LFG into energy, we can generate electricity and heat that would otherwise come from fossil fuels. This substitution helps reduce our dependence on coal, oil, and natural gas, all of which contribute to greenhouse gas emissions and climate change.

LFG plants typically have a smaller carbon footprint than fossil fuel plants. These plants turn a potential environmental hazard into a valuable energy resource by harnessing the gas that would otherwise escape into the atmosphere. Using waste to generate energy also helps in the overall management of waste. It provides a productive use for waste material that would otherwise contribute to environmental pollution.

Examples of Landfill Gas-to-Energy Projects

In the UK, the Mucking Landfill Gas to Electricity Power Station, operated by EDF, generates 4.8 MW of electricity, enough to power approximately 7,200 homes annually. It also avoids around 27,500 tonnes of CO2 equivalent emissions each year.

The Central Landfill at Johnston, Rhode Island, USA, produces 33.4 MW of electricity and utilises a combined cycle system to maximise its efficiency. The Luohe MSW Landfill Site, Henan Province, China, generates 2 MW of electricity and reduces approximately 416,000 tons of CO2 equivalent emissions over its crediting period. Elsewhere in Henan Province, the Luoyang Zhangluoping MSW Landfill Site generates 1.5 MW of electricity and reduces around 402,000 tons of CO2 equivalent emissions.

These projects contribute to national energy grids by providing a reliable renewable energy source, reducing reliance on fossil fuels, and lowering greenhouse gas emissions. Locally, they create jobs, reduce energy costs, and improve living conditions by managing waste more effectively and reducing unpleasant odours and other potential hazards.

What Happens to the Methane Gas from Food?

Methane from decomposing organic waste, especially food, is captured in landfills using a system of wells and pipes. These wells collect the gas, which is then transported to a central processing facility, purified and used to generate electricity or heat. This process prevents methane from escaping into the atmosphere and provides a renewable energy source.

Agricultural waste is another significant source of methane. Through anaerobic digestion, organic materials like manure and crop residues are broken down by microorganisms in an oxygen-free environment, producing biogas. This biogas, primarily composed of methane, can be used similarly to landfill gas for energy production. By capturing methane from both landfills and agricultural waste, we can reduce greenhouse gas emissions and generate sustainable energy, contributing to both a cleaner environment and energy security. 

Challenges and Future of Landfill Gas-to-Energy Technology

Landfill Gas-to-Energy (LFGTE) technology faces several challenges, including high initial investment costs, technical complexities, and regulatory frameworks. The cost to process landfill gas can be higher than natural gas prices, making it less economically viable without subsidies or incentives. Additionally, scaling up these projects requires significant infrastructure and consistent landfill gas flow, which can be challenging in smaller or less active landfills.

Future advancements in LFGTE technology focus on improving methane capture and conversion efficiency.  Innovations include enhanced gas collection systems that maximise methane extraction and advanced processing technologies that increase the purity and energy content of the gas. Integrated systems combining methane capture with other renewable energy sources, such as solar or wind, are also being explored to create more efficient and sustainable energy solutions. 

Landfill gas-to-energy technology plays a crucial role in achieving global renewable energy goals. We convert a potent greenhouse gas into a valuable energy source by capturing methane emissions from decomposing waste. This process reduces environmental impact and provides a steady supply of renewable energy, easing reliance on fossil fuels.

Supporting and learning about sustainable waste management and renewable energy efforts is vital. Consider advocating for policies that promote these projects, participating in community recycling programs, or even exploring renewable energy options for your home. Together, we can drive meaningful change towards a more sustainable energy future.