Most green energy plans offer 100% renewable electricity, while many suppliers are also beginning to offer a level of “green gas” by turning organic matter into biomethane. Green gas comes from a process called anaerobic digestion, where bacteria is used to break down food or farm waste to produce gas. This green gas is carbon neutral as it is produced from materials that absorb CO2 that is then released back when the gas burns. Hopefully in the future all gas can come from renewable sources but at the moment, there are not enough biomethane plants in the UK to make it a cost effective alternative to fossil fuels. This means suppliers still have to use natural gas to make sure customer demand is met. Some suppliers invest in additional carbon offset schemes to make sure the natural gas used is carbon neutral, even where green gas is not available.