After about a year, decomposed matter emits methane-rich gas that can be used as a cheap energy source. To capture gas for use as heat or power, landfill sites must first be prepared with an impervious lining. Gas is extracted from vertical wells in the waste and is filtered before it is used to generate energy.
Using the highly toxic methane gas prevents it from entering the atmosphere. It's 20 times more potent a greenhouse gas than CO2. Unfortunately, not all the biogas produced on landfill sites is used. In 2005 landfill leakage made up 40% of total UK methane emissions.
Landfill gas production is flourishing. There are over 174 landfill projects in the UK providing electricity for at least 660,000 homes.
Around 40 million tonnes of waste are dumped on landfill sites every year. This could generate around 6.75 TWh (cf. kWh) of electricity: enough for 1.6 million homes!
But the answer isn't to convert our rubbish into energy. We need to reduce the amount of waste we produce. Try NOT to buy products that are wrapped in excess packaging. Minimise your rubbish and recycle as much as you can.