Landfill gas capture turns a pollution problem into a useful energy source. As buried food scraps, paper, and other organic wastes break down without oxygen, they release methane-rich gas. Methane is a powerful greenhouse gas, so collecting it reduces climate impact and improves landfill safety.
The same gas can also fuel engines or turbines that generate electricity for homes, businesses, or the grid.
A landfill gas system works like an underground fuel collection network. Vertical wells and horizontal pipes pull gas from waste layers using a blower that creates gentle suction. The gas is cleaned to remove water vapor, particles, and corrosive compounds before it reaches a generator.
In the generator, methane burns with oxygen to produce heat, which spins machinery that converts mechanical energy into electrical energy.
Key Facts
- Landfill gas is typically about 45% to 60% methane, CH4, with much of the rest being carbon dioxide, CO2.
- Anaerobic decomposition means organic waste breaks down without oxygen and produces methane.
- Combustion of methane: CH4 + 2O2 = CO2 + 2H2O + energy.
- Electric power from a generator can be estimated by P = E/t, where P is power, E is energy, and t is time.
- Electrical energy produced over time is E = Pt.
- Capturing and burning methane lowers climate impact because methane traps much more heat per molecule than carbon dioxide.
Vocabulary
- Landfill gas
- A mixture of gases produced when buried waste decomposes, mainly methane and carbon dioxide.
- Methane
- A flammable gas with formula CH4 that can be burned as a fuel and is also a strong greenhouse gas.
- Collection well
- A vertical or horizontal pipe installed in a landfill to pull gas out of buried waste layers.
- Blower
- A machine that creates suction to move landfill gas through pipes toward treatment and power equipment.
- Generator
- A machine that converts mechanical energy from an engine or turbine into electrical energy.
Common Mistakes to Avoid
- Thinking landfill gas is pure methane. It is wrong because landfill gas is a mixture that usually contains methane, carbon dioxide, water vapor, and trace contaminants.
- Assuming methane capture eliminates all emissions. It is wrong because some gas can still escape and combustion produces carbon dioxide, though the total climate impact is usually reduced.
- Ignoring gas cleaning before the generator. It is wrong because moisture and corrosive compounds can damage engines, turbines, and pipes.
- Confusing energy and power. It is wrong because energy is the total amount produced or used, while power is the rate of energy transfer, so E = Pt connects them.
Practice Questions
- 1 A landfill gas generator produces 1.5 MW of electric power for 8 hours. How much electrical energy does it produce in MWh?
- 2 A landfill collects 2000 m3 of gas per hour, and 50% of the gas is methane by volume. How many cubic meters of methane are collected each hour?
- 3 Explain why a landfill gas system needs wells, pipes, a blower, gas treatment, and a generator instead of simply placing a generator on top of the landfill.