Landfill gas is a type of biogas produced when biodegradable waste, such as food, paper and green waste, decomposes without oxygen inside a landfill. As the waste breaks down, naturally occurring microorganisms convert organic material into a mixture of gases. This process continues for many years after waste is placed, which means even closed landfills can continue to generate gas.
Typical landfill gas is mainly methane and carbon dioxide, with smaller amounts of nitrogen, oxygen, water vapour and a wide range of trace gases. Some of these trace components, such as hydrogen sulphide and certain volatile organic compounds (VOCs), can be odorous or harmful at sufficient concentrations, which is why modern landfills are engineered to control and collect gas.
Why landfill gas matters
Methane, the main energy component of landfill gas, is a powerful greenhouse gas. Over the short term it traps much more heat in the atmosphere than the same amount of carbon dioxide. If landfill gas is allowed to escape, it can therefore make a significant contribution to climate change.
At the same time, methane is a valuable fuel. When landfill gas is captured and used instead of fossil fuels, it can provide useful energy while also reducing overall greenhouse‑gas emissions. This dual role—as both a risk and a resource—underpins current policy and engineering practice in the UK and many other countries.
How landfill gas is generated
Landfill gas generation follows a series of stages that begin soon after waste is deposited:
- In the initial aerobic stage, any oxygen trapped in the waste is quickly used up.
- As conditions become anaerobic (without oxygen), bacteria convert complex organic materials into simpler organic acids.
- In the methanogenic stage, specialist microorganisms convert these acids into methane and carbon dioxide.
Gas production usually increases to a peak within a few years after a landfill cell is filled, then gradually declines over decades. The total amount of gas produced depends on factors such as waste composition, moisture content, temperature and how the site is engineered and operated.
How landfill gas is managed in modern landfills
Modern engineered landfills use dedicated systems to capture and control landfill gas. Vertical or horizontal wells are installed within the waste body and connected by a network of pipes to a central gas compound at the edge of the site. A slight vacuum is applied so that gas is drawn into the system rather than migrating off site.
Once collected, the gas is either:
- Burned in an enclosed flare, which converts methane into carbon dioxide and water vapour, or
- Used as a fuel in engines, turbines, boilers or combined heat and power (CHP) units to generate electricity and sometimes useful heat.
In some cases, landfill gas is upgraded to biomethane by removing carbon dioxide and trace contaminants. The upgraded gas can then be injected into the natural gas grid or compressed for use as vehicle fuel.
The UK context: regulation and good practice
In the UK, landfill gas management is a regulatory requirement as well as good environmental practice. Landfill permits set conditions for gas containment, collection and treatment throughout the operational and aftercare life of the site. Operators are expected to:
- Design and install gas collection systems appropriate to the scale and risk of the landfill.
- Monitor gas flows, composition and emissions on and around the site.
- Use suitable measures, such as enclosed flares or energy‑recovery plant, to minimise emissions and manage safety and odour.
National climate commitments also emphasise the need to reduce methane emissions from waste. This encourages early installation of gas systems, optimisation of existing infrastructure and progressive diversion of biodegradable waste away from landfill.
Potential and opportunities in the UAE
In the United Arab Emirates, waste‑management strategies are moving towards greater energy recovery and reduced reliance on traditional landfilling. Large‑scale waste‑to‑energy projects are being developed to process municipal solid waste that would otherwise go to landfill, cutting future landfill gas generation and associated methane emissions.
However, many existing and legacy landfills in the UAE will continue to generate landfill gas for decades. These sites represent both a liability and an opportunity. By applying modern landfill gas collection and utilisation techniques—adapted for local climatic and regulatory conditions—UAE authorities and operators can:
- Reduce uncontrolled methane emissions from older sites.
- Improve local air quality and control odour and safety risks.
- Recover additional renewable energy in the form of electricity, heat or vehicle fuel.
For clients in the region, understanding landfill gas fundamentals and the experience built up in more mature markets such as the UK provides a useful foundation for planning, design and investment decisions.