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Radius Systems has been testing procedure to stop gas flow for gas operations under 100% hydrogen conditions


About H21

H21 is a suite of gas industry projects, carrying out vital work to prove that the gas network can safely transport hydrogen in the future.

Over a third of the UK’s carbon emissions are generated by the 83% of domestic homes currently using natural gas for heating and cooking. The UK is committed to reaching net zero emissions by 2050, so the gas we use needs to change. Hydrogen can play a vital role because it produces no carbon at the point of use.

Reusing the existing gas network to transport hydrogen could lead to the least disruptive and most cost effective route to carbon free heating for the majority of homes. It would also make use of a vast asset with the ability to deliver a reliable and flexible supply of gas.

Boris Johnson’s 10 point plan included a commitment to hydrogen production with the aim of heating a neighbourhood with hydrogen gas by 2023 and then an entire town, with tens of thousands of homes, by the end of the decade. The Climate Change Committees’ sixth carbon budget and the government’s Energy White Paper also both committed to a role for hydrogen to tackle decarbonisation and create jobs in an emerging green economy.

The H21 programme is funded by Ofgem and led by Northern Gas Networks in partnership with Cadent Gas, West and West Utilities, SGN, National Grid, Leeds Beckett University, DNV and the Health and Safety Executive. This means the work is undertaken on behalf of the gas networks so there is no duplication of effort and the projects bring together the very best expertise. H21’s first project examined the gas network in Leeds and produced the Leeds City Gate feasibility study. The report concluded it was technically possible and economically viable to decarbonise the UK’s gas distribution networks by converting them from natural gas to 100% hydrogen at an acceptable cost to the customer.

H21 now comprises multiple projects to tackle the many different challenges of a hydrogen gas conversion and you can read more about them here.

Current status

Since the Leeds City Gate report proved that a hydrogen gas conversion was technically possible and economically viable, the scope of H21 has expanded to include multiple projects which tackle the many different challenges of a hydrogen gas conversion.

Phase one of the work is now complete and phase two is nearing completion. In recent projects we have tested hydrogen on a purpose built micro-grid, which represented a typical UK distribution network at Spadeadam. The microgrid, which is believed to be a world-first was used to review, test and make recommendations to amend the operational and maintenance procedures required to operate a network on 100% hydrogen.

The project team also completed 100% hydrogen trials on a section of existing gas network in the South Bank area of Middlesbrough. The network was disused and disconnected. For several months, gas operations and maintenance activities were rigorously tested under 100% hydrogen conditions to understand how the network would be operated in a hydrogen world. At this site, the hydrogen was odourised with the same smell as natural gas for the first time.

Meet the team

    Tim Harwood

    Head of Programme Management at Northern Gas Networks (NGN) with responsibility for the H21 project

    Tim has 39 years experience in the UK gas industry covering a wide range of operational and project roles across all pressure ranges and assets types within distribution and transmission. Previously working for 8 years in National Grid Transmission (NGT) he held a number of senior roles as pipeline engineer, project delivery engineer and engineering manager. Tim’s previous roles at Northern Gas Networks (NGN) include Head of Capital Projects, Head of Maintenance and Programme Manager Major Projects.

    Tim’s current role is Head of Programme Management at Northern Gas Networks (NGN) with responsibility for the H21 project.

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    Mark Danter

    Senior Project Manager for the H21 suite of projects

    A highly experienced chartered engineer, Mark has a proven track record of delivering multi-disciplinary project programmes including water, LPG, bio-diesel, ethanol and white fuels, as well as methane.

    Mark has worked on several innovation and pilot projects within the gas industry and took on the role of Project Director for conversion from LPG to natural gas in Douglas, Isle of Man. Mark is now Senior Project Manager for the H21 suite of projects.

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    Russ Oxley

    H21 Senior Project Manager

    Russ has spent his entire career working in the gas distribution industry ensuring major mains replacement, diversion and CAPEX projects are delivered to the highest levels of safety performance, efficiency and customer satisfaction.

    As H21 Senior Project Manager, Russ is responsible for ensuring that critical safety evidence is gathered from a programme of strategic tests undertaken at a number of H21 test sites. The outcome of these tests will also allow any commercial or operational impact to be considered.

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    Neil Travers

    Project Manager of Phase 2b Unoccupied Trials of the H21 NIC Phase 2

    Neil started his career in the gas industry as an apprentice engineer in 2001.

    He spent 12 years as an Emergency Service Engineer before progressing to Site Manager working within several operational work streams including Purge & Relights, Mains Replacement and Emergency Repairs. Neil moved up to Operations Manager and has managed previous NIA funded innovation projects.

    Neil joined the H21 team in October 2019 and is currently managing the Phase 2 unoccupied trials in the South Bank area of Middlesbrough’

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    Ryan Mallinder

    Project Manager of Phase 2a Network Operations of the H21 NIC Phase 2 project

    Ryan joined NGN 8 years ago as a Gas Operative within the Emergency and Repair team. Following this he took on the role of Team Leader, where he was responsible for safeguarding life and property, replacing mains and services and carrying out specialist repairs on the gas network.

    Ryan then moved into the Capital Projects team as a Site Assurance Officer overseeing high risk work including the demolition of our redundant gas holders. Recently he undertook the role of Project Manager within the Capital Projects team where he was required to oversee the design, tender and build of above ground installations on the high pressure network.

    Ryan has now joined the H21 team as Project Manager and will be managing Phase 2a Network Operations of the H21 NIC Phase 2 project.

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    David Tomkin

    H21 System Modeller

    David began his career in the gas industry 20 years ago as an apprentice engineer with Transco. He has since worked in the Gas Distribution National Control Centre (DNCC), as an engineer for British Gas and as the National Technical Manager for Gas Safe Register.  David is a Fellow of Institution of Gas Engineers and Managers (IGEM) and a qualified gas incident investigator. He was awarded IGEMs first ever Engineering Technician of the Year award in 2018. Additionally, he has contributed to and sits on numerous industry standard committees, panels and working groups as well as the Council of IGEM.

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    Stella Matthews

    Hydrogen Development Manager

    Stella has worked in the gas industry for 5 years, starting as a Document Controller before undertaking Project Coordinator and Assistant Project Manager roles. For 3 of those years she has worked on the H21 project gaining skills and knowledge about how hydrogen could be used as a solution for decarbonising the energy industry. In 2019 she was successfully awarded the Ralph Halkett Travelling Fellowship, which saw her travel to New Zealand to undertake a work placement with Powerco and First Gas. She has recently started a Business Development role which sees her developing and implementing NGNs hydrogen strategy with a view to bringing other stakeholders along on the journey.
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    Chris Bates

    H21 Project Engineer

    Chris started his career in the gas industry as a System Control Strategy Analyst in 2015, working to increase efficiency in the operation of high pressure infrastructure and offtake capacity management.

    He then moved into the Programme Management and Capital Projects team as an Investment Team Leader and Project Manager, responsible for the development and implementation of CAPEX investment strategy for transmission pipelines throughout RIIO-1 and as part of NGNs RIIO-2 submission. In addition to his role, Chris is also undertaking a degree in mechanical engineering.

    Chris joined the H21 team in March 2021 as a Project Engineer and will be managing a suite of NIA projects to further the H21 research and development portfolio.

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    Jarred Knott

    H21 Project Engineer

    Jarred has spent five years as a part of the Innovation team, leading the charge on changes for the business and customers. He has delivered a variety of projects from Gas Detection Dogs to ground-breaking robotic platforms for the network.

    Jarred has previously been an Assistant Manager, Auditor, Photographer and full time Artist. He graduated from the University of Huddersfield with a BA Hons in Contemporary Arts and Contextual Studies.

    Jarred brings creativity to the H21 team along with portfolio and project management skills, plus the ethos of innovation needed to realise a hydrogen gas future


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    Liam Parling

    Energy Futures Engineer

    Liam joined NGN in 2013 and started in the REPEX team doing Network analysis before moving to a Principle designer role looking after the REPEX project designs for Yorkshire. Liam worked on the H21 Strategic modelling of major urban areas modelling the conversion and sectorisation of Hydrogen. In 2019 he moved to the Asset Strategy team as an Asset Risk and Strategy Analyst working on the development of C55 and the GD2 strategy. Joined the H21 team in 2021.

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Project partners

Northern Gas Networks

Northern Gas Networks (NGN) is the gas distributer for the North East, most of Yorkshire and northern Cumbria, transporting gas to 2.7 million homes and businesses.NGN’s network consists of 37,000 km of gas mains, enough to stretch from Leeds to Sydney, Australia and back. The business generates £300 million each year for the region’s economy by stimulating employment and consumer spending.


    A global quality assurance and risk management company, providing classification, technical assurance, software and independent expert advisory services to the maritime, oil & gas, power and renewables industries.


    Owner and operator of the largest gas distribution network in the UK, safely transporting gas to 11 million homes and businesses across West Midlands, North West England, East of England and North London.


    The gas distributor managing the network that safely distributes natural and green gas to 5.9 million homes and businesses across Scotland and the south of England, operating more than 71,000 km of pipes.

    Wales & West Utilities

    Operating the gas distribution networks across Wales and the South West of England, for 7.5 million domestic and business customers, safely transporting gas across 35,000 km of pipes.


    Using scientific expertise and regulatory insight to address health and safety risks, for organisations or as part of a shared research programme.

    National Grid

    Owner and operator of the UK’s gas transmission grid which includes 4,740 miles (7,630 kilometres) of high-pressure gas pipes and also the UK’s electricity transmission system.

    Leeds Beckett University

    A team of academics and practitioners, including psychologists, data scientists, environmental scientists, architects, design specialists, construction managers and building performance researchers, with over 20 years’ experience of research and consultancy in sustainable energy use.

Partners of H21