What is green gas?

Several energy companies now sell green gas alongside renewable electricity. 

Green gas is biomethane and accounts for a very small proportion of the gas in our grid. The rest is natural gas. 

The proportion of biomethane is set to increase as the government plans to help fund enough new anaerobic digestion to produce gas for around 200,000 homes.

How is green gas made?

Organic materials, such as food waste and farm waste, are broken down by bacteria in huge tanks, or digesters. The breakdown happens without oxygen, so it’s called anaerobic digestion. This process produces biogas.

Biogas is then purified and the CO2 is removed, turning it into biomethane. Biomethane has similar characteristics to natural gas, so it can then be added into the gas grid and used in homes. It can also be produced from landfill gas and the gasification of biomass. 

Find out more: how we make renewable energy in the UK

Like with renewable electricity, green gas is not piped directly to your home if you have a tariff that supports its generation. We all have the same gas pipes as everyone else on the gas grid. The difference with a green gas tariff is that you're paying extra towards the green gas that is added into the grid mix.

Is green gas renewable?

Yes, green gas comes from a renewable source, such as food waste or farm waste. 

In contrast, natural gas is formed when decomposing plant and animal matter are put under heat and pressure under millions of years. So it’s not easily replaceable in our lifetimes, and there’s a limited amount of it.

Biomethane is carbon neutral. It releases emissions when we burn it to heat our homes but is made from organic materials that absorbed carbon dioxide when they grew. Burning it releases the same amount of carbon dioxide so, overall, it doesn’t add more CO2 to the atmosphere.

Which companies sell green gas?

Fewer companies sell green gas tariffs than green electricity. They include:

Some companies make additional claims for their green gas. For example, Ecotricity says its green gas is vegan (made from grass cuttings rather than byproducts of animal farming, such as manure) and 100Green says that all its biogas is UK based.

What is carbon offsetting?

Carbon offsetting is reducing carbon dioxide (or other greenhouse gas) emissions to compensate for emissions released elsewhere. Some energy companies offset the carbon emissions of gas customers in order to state that their gas is carbon neutral.

British Gas, Co-operative Energy, Ecotricity, Octopus Energy, Ovo Energy and Shell Energy are among companies that offset the carbon emissions of some or all of their gas.

Carbon offsetting usually involves supporting projects that reduce emissions and fight climate change. They can be around the world. Examples include:

• Tree planting
• Supporting biomass power plants in India and Chile
• Supporting a hydropower plant in Bhutan
• Building wind farms in India
• Reducing deforestation in Brazil

Look for firms which use verified emission reduction schemes too.

How much does green gas cost?

Green gas is more expensive than renewable electricity and there is less of it around. 

Like renewable electricity, there are also certificates to show where green gas was produced. These are called Renewable Gas Guarantee of Origin (RGGO) and Biomethane Certificates.

These are more expensive than certificates for electricity. RGGOs cost £9.39-£12.77 per megawatt hour in 2022, according to energy consultancy Cornwall Insight.

Some suppliers offer green gas as an ‘add-on’ that you can pay extra for, rather than including it in their tariffs as standard.

If you’re looking to cut the carbon footprint of your heating, find out more about heat pumps.