Anaerobic digestion (AD) is a well-established technology and is expected to play a big role in enhancing the sustainability of Irish agriculture. The process involves the breaking down of organic material such as food waste, animal waste or plant material by microorganisms in oxygen-free, heated tanks. This process results in the creation of renewable biogas and digestate.

This biogas contains methane (CH4), carbon dioxide (CO2) and a number of other gases. Once upgraded to around 99% methane purity, the gas becomes biomethane, which can displace natural gas as a fuel source.