Biogas

The beauty of biogas

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Biogas is a direct, zero carbon replacement for natural gas and is produced by anaerobic digestion of organic waste (food waste, food processing waste, sewage – anything you can compost).

A direct, zero carbon replacement for natural gas

When it’s produced, biogas is about 50% methane and 50% CO2, so it doesn’t burn as cleanly as natural gas – which is 95% methane. However, we can we treat it (using equipment that comes pre-packaged in a shipping container!) and turn it into biomethane: a clean burning, zero carbon gas that’s pipeline ready and can be used in any gas appliance currently available on the market.

The past two decades have seen huge growth in the production and use of biogas globally, particularly in the UK, Germany and Denmark. In fact, biogas now makes up 20% of Denmark’s natural gas – and this is expected to increase to 30% by 202319. The technologies used to produce, upgrade and inject biogas into gas networks are improving all the time, which means it’s getting cheaper too.

Biogas in New Zealand

Biogas is already produced at 20 landfills and wastewater treatment plants in Aoteoroa, where it’s burned to provide heat and power for the sites. We actually produce enough to provide around half of the country’s residential gas needs! It’s currently not injected into the gas grid; but that’s what we want to change.   

Firstgas Group has partnered with Beca Engineering, Fonterra, Lion and EECA to carry out a technical study of the potential of biogas. Together we’re investigating how we can unlock the opportunity of injecting biomethane (cleaned biogas) into our existing gas network. Not only would this maximise the value of suitable compostable waste streams, but it would begin to decarbonise the gas network. And, as the volume of biogas in the grid increases, it means gas users could move to zero carbon without having to change their appliances.

This study is well underway with results due in April 2021.

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Did you know?

Anaerobic digestion

‘Anaerobic digestion’ is a process very similar to composting, but the difference is that it takes place with no air/oxygen present.

There’s also a valuable CO2 by-product created during biogas production, which can be used in industrial processes, to make fizzy drinks, or fed into a greenhouse to enhance plant growth.

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Hydrogen trial results

The Hydrogen Feasibility Study

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For Firstgas Group, the Hydrogen Pipeline Trial Study set the foundation for our ongoing delivery work on hydrogen. The results show we have sufficient network capacity and a viable strategy for converting our networks to hydrogen: painting the picture of what a zero carbon gas future could look like for Aotearoa.

Read the full report