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Keith Owen, Head of Systems Development and Energy Strategy, took part in a Delta-EE Podcast about the possible use of the gas network to transport hydrogen blends and 100% hydrogen in the future


About H21

In 2016, Northern Gas Networks, the gas distributer for the North of England, produced the H21 Leeds City Gate feasibility study.

Based on a blueprint of the city of Leeds, this pioneering industry first 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.

Leeds City Gate also demonstrated that this could be achieved at an acceptable cost to the customer.

Before the vision of a hydrogen gas network can be fully realised, the critical safety-based evidence for such a conversion, upstream and downstream of the meter, must be provided. Without it, a credible government policy decision on decarbonisation of heat cannot be made.

On behalf of the UK gas networks (Northern Gas Networks, Cadent, SGN and Wales & West Utilities), a Network Innovation Competition bid was successfully submitted to OFGEM in 2017, as a first step towards providing this evidence.

After securing £9 million Ofgem funding, with a further £1 million contributed by the UK networks, H21 NIC is working to present the quantified safety evidence between natural gas and 100% hydrogen used within the existing GB as distribution networks.


The H21 NIC will be delivered in 2020, followed by field trials. Phase One of the NIC project is being carried out in two parts: 

Phase 1a – Background testing at the Health and Safety Laboratories, Buxton. These tests, on a huge variety of network assets including pipes, valves and joints, will confirm potential changes in background leakage levels.

Phase 1b – Consequence testing at the DNV-GL facility at RAF Spadeadam in Cumbria. This phase will involve tests to confirm any changes to safety risk under background conditions, failure and operational repair on a hydrogen gas network.

Following on from the evidence found in Phase 1a and 1b the project will move forward into Phase 2. Phase 2 will involve testing of operational procedures.

To enable the field trials to commence once Phase 1 is completed the project has secured Network Innovation Allowance funding to locate suitable test sites and develop the conceptual design, now underway. In line with BEIS’ Hy4Heat project, once the field trials have proven that it is safe to move forward there will be a live trial in 2021/2022.


Conversion of the North of England

Underpinning the safety case is the H21 North of England, a strategic report presenting a conceptual design for converting the gas networks of the North of England to hydrogen between 2028 and 2035.

This report builds on the original Leeds City Gate study, as a solution for deep decarbonisation of heat.

This includes 3.7 million meter points (circa 85 TWh per annum, 12.5% of net UK population) across the major urban conurbations of Leeds, Bradford, Wakefield, Huddersfield, Hull, Liverpool, Manchester, Teesside, Tyneside and York. The design incorporates a 12.15GW hydrogen production facility, 8TWh of inter-seasonal storage, all associated onshore infrastructure and the requirements of the associated carbon capture and storage scheme, scaling to 20 million tonnes per annum by 2035.

H21 North of England represents one scenario for hydrogen gas grid conversion, a credible engineering solution following completion of the last pieces of critical safety evidence, which will be provided by the Hy4Heat and H21 NIC programmes by 2023. The H21 programme is supported by a range of strategic Network Innovation Allowance projects, which feed into both the NIC and North of England.

Meet the H21 team

Our dedicated team of experienced industry professionals are delivering a suite of projects providing compelling evidence for a UK gas grid conversion to hydrogen.



  • Tim Harwood

    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 Captial 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.

  • Mark Danter

    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.

  • Russ Oxley

    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.

  • Neil Travers

    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’

  • Ryan Mallinder

    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.

  • David Tomkin

    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.

  • Stella Matthews

    Stella has had a varied career that has seen her undertake many professional roles, the vast majority of these have been within the heritage sector. She previously set-up and developed a social enterprise that provided training and education through heritage based experiences. In addition to this she has worked as a tutor for the University of Hull and within the adult community education sector, completed a traineeship with the National Archives and undertaken roles at Pricewaterhouse Coopers and the NSW Ombudsman.

    Stella has worked within the gas industry for the past two years, undertaking roles at Northern Gas Networks. Her current role is as Assistant Project Manager on the H21 suite of projects.

  • Mick Smith

    Mick began his career in the gas industry back in 2002 as an apprentice Mainlayer/Craftsman.

    Having spent the first 10 years of his career building up a robust knowledge and understanding of several core operational work streams including Emergency & Repair, Connections and Mains Replacement, Mick has spent the last 8 years as a TOTEX Site Manager managing the safe delivery of North Tyne’s REPEX programme.

    As the H21 Site Manager, Mick is responsible for maintaining the test sites for the H21 NIC Phase 2 project.

  • Matthew Kluwe

    Project Coordinator

    Matthew is new to the gas industry after working at a facilities management firm Mitie for the previous two years as a project assistant, he graduated from the University of Hull with a First-Class degree in Sport and Exercise Science in 2018, his current role within Northern Gas Networks is Project Coordinator of the H21 suite of projects.

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.

NGN’s mains replacement programme will see 3,800 km of old metal gas main replaced with modern plastic equivalents by 2021, with work carried out by local contractors to ensure that investment stays in our region. The distributer is championing gas as a clean, renewable and cost effective energy source and actively exploring how the network can be adapted to transport alternative forms of gas, keeping infrastructure costs and customer bills down.



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



SGN is the gas distributer 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, WWU look after 7.5 million domestic and business customers, safely transporting gas across 35,000 km of pipes.


Health & Safety Laboratories

HSL is a world-leading provider of health and safety solutions to industry and government. Combining scientific, medical and technical expertise, the HSL manages risk and protects the workforce from illness and injury.



DNV GL is 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. Its large-scale Spadeadam Testing and Research centre delivers unique multiphase flow testing facilities, harnessing technologies and expertise required to investigate and address customers’ most challenging technical needs.