Written evidence submitted by Professor William J. Nuttall (DHH0126)


  1. I am pleased to have this opportunity to submit evidence. I make this submission in a personal capacity and my comments should not be attributed to any institution with which I am affiliated. My opinions have been informed by ideas from many colleagues, collaborators, and professional contacts. I preserve their anonymity, but I express my gratitude to them. I offer my thanks to Andrew Wilson for his assistance with this submission and to the Higher Education Innovation Fund at The Open University for financial support. Those that have assisted me do not necessarily agree with what follows.


  1. I offer commentary in response to three of the eight questions posed by this inquiry.


  1. Q1: What has been the impact of past and current policies for low carbon heat, and what lessons can be learnt, including examples from devolved administrations and international comparators?



  1. A1: In recent years the dominant UK paradigm for low carbon heat has been associated with electrification, ideally associated with improved thermal insulation and with high-efficiency heat production systems, such as heat pumps. This logic led in-turn for calls, and indeed policies, to prevent the installation of natural gas boilers in new homes and natural gas infrastructure in new housing developments. Despite the conversion efficiencies achievable, this electrification paradigm will require a massive increase in generation transmission and distribution capacity. This could, in part, be offset by a breakthrough in inter-seasonal electricity storage. However, even with such developments the required increase of the UK electricity system based on low carbon sources (renewables and nuclear) will be a huge challenge indeed.
  2. More recently an alternative, or perhaps complementary, option has been proposed. The use of hydrogen gas in place of natural gas in a modified form of today’s gas production, transmission, distribution, and end-user infrastructures. This hydrogen gas could be sourced by via electrolysis using otherwise surplus renewable energy, sometimes termed ‘Green Hydrogen’ or it could be obtained from natural gas with the carbon emissions reduced via carbon capture utilization and storage (CCUS). These latter ideas, now frequently called ‘Blue Hydrogen’, are discussed in a book I published last year with Dr AT Bakenne [1].
  3. Noting the dominant and established role played by natural gas in home heating today, UK domestic heat, fuelled by Blue Hydrogen is a compelling and attractive proposition which plays into UK strengths and experience. A shift to hydrogen (both Blue and Green) would be a substantial task especially as concerns CCUS, but the challenges are to my mind less severe than in the full-electrification scenario (including electrification scenarios that include hydrogen, but with an exclusive focus on Green Hydrogen). In reality I would expect the optimal future to be a mix of electrification, and hydrogen conversion (with a significant role played by Blue Hydrogen). I suggest it would be an error to put in place any obstacles to the adoption of pipeline hydrogen as a future low-carbon fuel. For that reason, I am troubled by policies seeking to prevent gas infrastructures reaching new housing developments. I suggest that policy is not a ‘no regrets’ option.
  4. I make no comment on the devolved administrations, my comments here focus on England where I am based. I can say that as regards Blue Hydrogen I would suggest that England is in a world-leading position, but I do see serious competition emerging in the US. The fracking boom since 2000 has greatly reduced US emissions below where they might have been. It has also given the US some world-leading industrial expertise with natural gas technologies. In recent years, the US carbon sequestration credit known as ‘45Q’ has given a significant boost to US experience of CCUS. Furthermore, I note that along the US coast of the Gulf of Mexico the largest hydrogen infrastructure in the world today serves the needs of the petrochemical industry. As someone who sees the greatest potential in Blue Hydrogen, I would suggest that such industrial clusters are the key to a low-carbon future. In the UK I welcome the emergence of similar cluster-based thinking – see for example [2]. As regards international points of comparison, the US is in a strong position and is, I suggest, a key country to watch.  
  5. I have stressed a competition between electricity and hydrogen for domestic heat, but there is also a competition between these two options for low-carbon mobility. I would simply add that the US will look seriously at hydrogen in mobility and transport for particularly American reasons. First the need to get large haulage trucks across the Rocky Mountains and second the ability to fuel such trucks with enormous amounts of energy quickly at truck stops in places like Iowa. Low-carbon Hydrogen can meet those challenges relatively easily – to my understanding battery electric technologies would struggle.


  1. Q2: What key policies, priorities and timelines should be included in the Government’s forthcoming ‘Buildings and Heat Strategy’ to ensure that the UK is on track to deliver Net Zero? What are the most urgent decisions and actions that need to be taken over the course of this Parliament (by 2024)?


  1. A2: For the reasons outlined above, the government should act to ensure the continued availability of piped-gas-based heating for domestic homes, including new homes. It should, however, move to ensure that new, and renewed, gas infrastructures meet requirements for hydrogen as both a fuel blend and eventually as a pure hydrogen supply. Hydrogen has a range of potential customers aside from the proposed heating applications and this diversity of end-users could help to reduce the risk of hydrogen-compatible (or convertible) infrastructures later becoming redundant. The UK should take a ‘real option’ on hydrogen, in the sense that it should start to spend the money now to preserve the technical option of hydrogen in the future.
  2. The government should look beyond minimal costs and consider issues of technical uncertainty and risk and take also account of behavioural issues including home-owner attitudes to change and disruption. Hydrogen for heating allows for a phased approach both geographically and technologically. The phased introduction of hydrogen into new areas allows the testing of infrastructure suitability, limiting disruption. Low concentration hydrogen blends up to 20% are possible with little-to-no change to existing gas boiler equipment, allowing the gradual investment in new equipment for homeowners. For Net-Zero a shift to 100% hydrogen must come rapidly and even in that case the changes required for full hydrogen conversion are less disruptive to homeowners than the forced retro-fitting of heat-pumps, for example.



  1. Q3: Which technologies are the most viable to deliver the decarbonisation of heating, and what would be the most appropriate mix of technologies across the UK?


  1. A3: The answer to this question remains unclear, as there is no option without risk and uncertainty. In response to this reality the government should seek to preserve all options and develop technologies that provide a reasonable prospect of deliverable progress at scale. The issues are complex and there are few people or institutions with deep expertise across all dimensions of this space of policy options.
  2. Carbon capture and storage (CCS) and methane leakage minimization are key considerations for the natural-gas-based Blue Hydrogen option. When considering CCS, it is important to consider the proportion of CO2 in the gas available for CCS processing and the pressure at which it is available. Direct Air Capture may have a truly negative CO2 footprint, but ambient air represents a very poor feedstock gas for CCS. The flue gas from a fossil fuel power station would be better, but one of the best feedstocks, by far, is the gas emitted by Blue Hydrogen production processes. This feedstock could feed an economically and technically efficient application of CCS at scale.
  3. The use of low carbon external heat input in a Steam Methane Reformer could, for instance yield a very high CO2 concentration waste gas; one essentially perfect for CCUS. Nuclear energy has the potential to be such an external heat source well suited to the UK situation. In addition, looking further ahead, new high-temperature nuclear energy technologies could be an energy source for thermochemical hydrogen production from water producing low-carbon hydrogen that is neither conventional Blue Hydrogen nor Green Hydrogen.
  4. The potential role of nuclear energy in hydrogen has been considered recently by The Royal Society [3]. Looking to the future, nuclear fusion energy, with its advantages over conventional nuclear fission energy, could also be a route to low carbon hydrogen. I am an editor and contributor to an upcoming book addressing such topics [4]. The UK is world-leading in nuclear fusion research and development.
  5. In summary I suggest that it would be unwise to close the hydrogen option at this stage, and hence unwise to inhibit natural gas and nuclear energy related innovation. Britain has a world leading position in various aspects of a high-technology hydrogen future including, but not limited to, Blue Hydrogen and advanced nuclear technologies. Low-carbon hydrogen could be extremely important for UK domestic heating, for UK mobility and for global energy trade and wider industrial development (e.g. low carbon steel-making).


  1. The Committee is right to be considering hydrogen in its inquiry.



[1]  William J. Nuttall and Adetokunboh T. Bakenne, Fossil Fuel Hydrogen -Technical, Economic and Environmental Potential, Springer, 2019, ISBN 978-3-030-30907-7

[2] Equinor, H2H Saltend - The first step to a Zero Carbon Humber, available at:

https://www.zerocarbonhumber.co.uk/wp-content/uploads/2020/07/equinor-H2H-saltend-brochure-2020.pdf accessed 4 December 2020.


[3] The Royal Society, Nuclear Cogeneration: civil nuclear in a low-carbon future, Policy briefing, 07 October 2020, available at: https://royalsociety.org/topics-policy/projects/low-carbon-energy-programme/nuclear-cogeneration/ accessed 4 December 2020

[4] William Nuttall, David Webbe-Wood, Satoshi Konishi, and Shutaro Takeda (editors), Commercialising Fusion Energy - How small businesses are transforming big science, Institute of Physics Publishing (in-press, publication January 2021) ISBN 978-0750327176

December 2020