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Ramping up green gas central to net zero

In an excerpt from issue 46 of AD and Bioresources News, Keith Warburton of Wales & West Utilities, outlines an action plan to decarbonise the gas network.

Hear more on this from Keith at ADBA National Conference 2021 on 16 February in the The role of AD and Green Gas in decarbonising heat panel session.

Click here to register for the event. 

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At Wales & West Utilities we are committed to being a sustainable business. We recently became the first company to sign the Welsh Government’s Climate Change Pledge, promising to deliver a Net Zero ready gas network by 2035. This will support the decarbonisation of heat, power and transport, and in practice means that we’re preparing the gas network to be ready for green gases like biomethane and hydrogen.

As the recent Pathways to Net-Zero report, commissioned by Energy Networks Association and independently reviewed by Imperial College made clear, there is a detailed, practical plan to deliver a zero-carbon gas grid, with clear technical, operational and regulatory actions that need to take place to achieve it.

By taking a balanced approach, where we use low carbon and renewable gases along with Smart Hybrid Systems and electrification, the report’s recommendations will save around £13bn a year compared to an approach that relies on electricity alone. One of the key recommendations from that report that can be acted on immediately is increasing the volume of green gases, like biomethane, in the gas network.

In Wales and south west England we already have 19 green gas connections to our network. They inject enough green gas to supply over 120,000 homes, almost 5% of the communities that rely on our network. This could go even further were it to be combined with Smart Hybrid Heating systems, which use a gas boiler and air source heat pump together to help green gas go further.

Five key issues

The fast approaching end of RHI and associated payment reduction has reduced the number of producers wanting to connect. To address this, we’re going to be focussing on five key issues, and working closely with the biomethane and anaerobic digestion industries.

We’re going to be asking government to replace the Renewable Heat Incentive (RHI) for green gas after March 2021. RHI is an incentive that has worked, but it needs to take the next step to help us on the road to Net Zero. We’ll be working with Government to develop an incentive regime that includes decarbonised gas – but also supports market growth of Smart Hybrid Heating Systems.

We would also like there to be an incentive encouraging green gas producers to inject their green gas into the grid. Often, green gas generated through anaerobic digestion (AD) is burned in gas engines to generate energy. Often, these engines are co-located with the AD – for example at wastewater treatment works.  Except for a handful of true combined heat and power plants, this wastes lots of the potential energy in biogas as heat that is vented to atmosphere.  To maximise the whole system benefit of green gas, we strongly believe there should be an incentive that makes connecting green gas to the grid the most attractive option.

Additionally, with 19 plants connected, of different types, different feedstocks and different technology, we understand the challenges that producers face ahead of connecting to the grid, specifically dealing with periods of low demand, and the CO2 stripped from the gas after generation. We’re going to be supporting potential producers with these issues and are exploring potential funding routes to address these over the next decade.

Biomethane injection is generally at a fixed rate, and in summer or other times of low demand, networks are increasingly struggling to accommodate the amount of green gas produced. As part of the Optinet project, we’re working with Cadent, PassivSystems and Costain to review how technical solutions like smart pressure control, compression and storage can help relieve constraints on networks, and maximise the opportunity to decarbonise gas.

And, we’re going to be working with biomethane producers to explore the use of small-scale liquefaction plants at green gas plants. Liquification could provide the flexibility to overcome temporary network limitations – for example during periods of low demand in the summer. That’s a longer-term and more technically demanding solution, but one that could benefit both the whole energy system and biomethane plant investors.

Additionally, we are supporting organisations to examine the feasibility of combining green gas injection and another quickly developing technology – carbon capture and storage. CO2 is stripped from biogas before biomethane injection – and there are opportunities for that gas to be exploited too. A project we are considering includes the development of a viable CO2 supply chain from a biomethane plant, by processing the separated CO2 to food industry standard. This could make the UK CO2 industry more resilient (2018 saw shortages, to the consternation of beer and fizzy drink fans!)  while the creation of greater commercial value from biomethane could increase uptake of green gas connections, while also helping to reduce the reliance on government incentives.

An integrated response

While we’re working to address challenges our partners have, we know that we must change too. While distributed gas connections have dramatically increased in the last 10 years, functionally, we are still evolving from a network that takes gas in at high pressure and steps it down the tiers to our customers. So, this year we’re introducing a new biomethane connections process, designed to make things simpler for the wide range of potential producers that will connect to our network.

We’re also looking at other new ways of working, and how our experience, the flexibility offered by our network and the uniqueness of our geography can help maximise green gas production. This includes working with off grid green gas producers and encouraging the development of a ‘virtual pipeline’, where Compressed Natural Gas (CNG) powered vehicles store and transport green gas to an injection point. This is something already being exploited for CNG fuelling stations, and a solution that could be scalable.

The Pathways to Net-Zero report is clear: hydrogen is how we decarbonise large cities and heavy industry. In Wales and the south west, a hydrogen ‘spine’ could stretch from Bristol across the Severn to Cardiff and Swansea, allowing the conversion of the gas network in those cities to heat homes and business with hybrid hydrogen systems, but also supporting the decarbonisation of heavy industry like steel, which has a significant economic and social footprint in south Wales and needs to switch away from fossil fuel while remaining globally competitive.

But outside of that area, towns like Aberystwyth and Newtown, Exeter and Plymouth, are all going to be relying on biomethane as the decarbonised gas supply for heating, and now is the time to act. Over the next decade, we can make a series of ‘no regrets’ decisions to maximise the amount of green gas for heating homes, fuelling heavy transport and for flexible back-up power generation – and we’ll be strongly making that case to the government, Ofgem, and other stakeholders.

By Keith Warburton

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Keith Warburton has worked for over 30 years in the gas and nuclear industries, with the National Grid, Northern Gas Networks. Scottish & Southern Energy and, more recently, Lagoni Engineering Ltd. A member of the Institution of Gas Engineers and Managers and former Director of The Gas Industry Safety Group (GISG), he will lead Wales & West Utilities work on green gas, and be part of their Energy Strategy team, working to meet the UK Government’s 2050 Net Zero carbon emissions target.

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Keith will be speaking at 11.50am on 16 February at ADBA National Conference 2021. Register here to hear more from Keith.

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