Is it a good idea to spend time focusing on making carbon creating boilers more efficient?

Perhaps as after all they will possibly be around for another few decades. Is hydrogen a viable solution is a slim possibility for large scale heat in buildings?

I’m preparing a response to government  on their Improving boiler standards and efficiency and I wondered whether anyone in the community has technical or operational experience to share. The consultation is asking for feedback on 53 questions which relate to one of the three following topics.

  1. proposals to improve boiler and heating system efficiency through improvements to minimum standards
  2. proposals to mandate that from 2026 all newly-installed gas boilers are ‘hydrogen-ready’
  3. the potential role of gas boiler-electric heat pump hybrids in heat decarbonisation in the 2020s and 2030s

If you have ideas that you think should be included based on your experience, I’d be interested in considering them.

If you prefer not to respond publicly you are welcome to private message me.

  • thanks ... the 20% hydrogen is being demonstrated. not clear if viable option

  • We are in the fortunate position in the UK of having undergone a significant distribution system upgrade over the last 12 years. More than a decade ago, the UK gas networks supported by OFGEM embarked upon a programme of work known as the Mains Replacement Programme (MRP), whose intention was to replace cast iron and steel distribution mains with polyethylene pipe (the yellow pipes you may see being installed in roadworks).  Since that time, 85% of the UK distribution network has been replaced with PE which is 100% hydrogen compatible.  The remaining MRP is planned to have completed this programme before 2030.  Independent research and testing on representative gas distribution pipework was commissioned by BEIS and OFGEM in 2020.  This work was conducted by the UK HSE and DNV under the H21 and Hy4Heat programmes and concluded that if existing distribution pipework was leak free with methane, it would also be leak free with hydrogen.    The National Gas Transmission Network is steel, but mainly low strength steels, that do not suffer hydrogen embrittlement.  Nevertheless, a current research programme called FutureGrid for National Grid (as was) is building a large testing facility with decommissioned sections of the National Transmission System (NTS) at the DNV Spadeadam Research site.  That facility will test a number of hydrogen blends, plus 100% hydrogen to determine the suitability of the NTS for hydrogen.  That work is being monitored by the UK HSE.

    The differences in energy density are an issue which is currently being addressed through significant network modelling to establish if the changes in pressures and flowrates will cause any issues.  It should always be borne in mind that the gas networks are "overdesigned" in that they are designed to carry the amount of energy needed for a 1 in 20 year extreme weather event.  The introduction of condensing boilers in the UK have also significantly reduced existing gas demand so there is significant flow headroom in the system today.  

  • Currently, apart from a lack of supply, and the need to change the Gas Safety Management Regulations, there is no reason why a 20% blend of hydrogen could not be introduced into domestic heating today.  Gas boilers, cookers and fires can all use a 20% blend, without any modification.  Large gas consumers such as power stations are more sensitive to hydrogen blends, and would probably not be happy with more than 8% blend without burner modifications, but they are connected to the NTS, and not the distribution system.

  • Hi Rick!

    I'm not in the boiler industry, but I am an R&D person in the hydrogen industry (trained in the UK but working in Germany).

    I've read the proposal and I hope these comments (below) will be helpful; if not and I've got the wrong end of the stick as it were, do please ignore.

    Thanks for your time responding to this proposal to do with the hydrogen industry - we don't really have time to get this one wrong so I'm glad to know there are experts such as yourself responding to the proposal to help get these important decisions made by a very well informed government.



    Specific training for working with hydrogen (question 38 on page 45 of the proposal)

    I would definitely encourage there to be some specific training for technicians before they undertake work to 'finish off' a 'hydrogen-ready' boiler when 100% hydrogen is available to a consumer - so it's a 'yes' from me for consultation question 38 on page 45. It's not too tricky to work with but it would be negligent for me to tell a technician that its no different to natural gas based on my experience with hydrogen.

    Nitrous oxide emissions from hydrogen boilers (question 32 on page 41)

    Boilers burning hydrogen produce fewer air pollutants than boilers burning natural gas because they cannot produce pollutants such as particulate carbon (soot). If the consensus is that hydrogen boilers could also produce fewer nitrous oxides, then I would be in favour of requiring them to do so. Everyone stands to benefit from cleaner air in their neighbourhood and does not have to sacrifice having a comfortable home to live in!

    By comparison heat-pumps do not produce these air pollutants. If clean-air targets are more widely implemented (and more effectively enforced!) choosing not to install a boiler (whether 'hydrogen ready' or not) totally locks out local emissions of unpleasant air pollutants, which may be attractive to consumers.

    This is relevant to the discussion regarding the policy towards hydrogen boilers because if the future popularity of this technology is being over-estimated, there may be additional risk with respect to the price-parity promise from manufacturers (page 10, final paragraph: "Based on a price promise made by industry, the government expects the upfront costs of hydrogen-ready boilers to reach price parity with those of existing natural gas boilers once they match the current levels of production") which may not be accounted for in the analysis.

    Indeed with the current proposal production of 'hydrogen-ready' boilers never grows to the point where the price-promise becomes relevant, those those with these boilers may end up paying a premium, despite best intentions. To protect individual consumers the government may choose to subsidise the scheme leading to the taxpayer boiler companies to install a less flexible and future-proof technology than the heat-pump alternative, which this may not be the intended outcome of this proposal.

    Accounting for the ability of heat pumps to also cool homes in hot weather on the economic case for 'hydrogen-ready' boilers (question 53 on page 60)

    Heat-pumps can be run in reverse to cool, rather than to heat. A boiler (regardless of the fuel) cannot do the same.

    Given the increasing frequency and severity of extremely warm and dry summers in Northern Europe, perhaps consumers will find the idea of installing a heat-pump even more attractive than is being accounted for in the proposal at present, given that they need not also purchase, find room for and run (as much) air conditioning equipment to stay comfortable and healthy all year round.

    I see this as another factor which could jeopardise the 'price parity promise' from manufacturers dependent on the voilumes of boilers produced and sold, or at least the pace with which this transition is expected to occur.

    It may be that these aspects has been included in the analysis upon which the predictions in the report have been made, indeed I hope so. If someone in the know could reassure me of this I would be grateful!

    Until then the scientist in me would prefer to see some evidence, such as these aspects being mentioned in the detailed comparison between boilers, combination/hybrid systems and heat pumps in the proposal.

    To be open and transparent, I have not read each of the 105 sources directly referenced by the proposal. It may be that my concerns stated here are irrelevant because these aspects have been well considered in the work which informs the predictions in the proposal, but these details are only to be found in the referenced sources. If so, I would be reassured to hear from those in the know that I need not be concerned. Incase not I thought it would be worth mentioning, perhaps others are thinking something similar - I'd rather mention it and be wrong than this aspect be overlooked.


  • Hello Joe. Just to respond to a couple of your comments.  NOX production is a feature of combustion, not a chemical characteristic of hydrogen vs methane.  Therefore the solution to minimise NOX is correct burner design, which is why the upgrade kit for 100% hydrogen boilers includes a new burner, specifically designed to ensure that a hydrogen boiler meets the same NOX standards as a methane boiler does today. 

    As a heat pump owner myself, the statement that a heat pump can also be used to cool as well as heat, is theoretically correct, but it depends on the nature of the system it is connected to.  In warm air systems, a heat pump could be configured  to produce cool air as well.  However, in wet systems (which is nearly all of the UK systems), running chilled water through underfloor pipework or radiators is likely to result in undesirable condensation formation, perhaps hidden within structures where damage cannot be detected until it is too late.

    Your observation on training is correct and crucial (as are concerns over the supply chain).  Whatever solution is chosen for domestic heat, we will need to replace 24 million natural gas boilers in a little over 24 years (by 2050 for net zero).  Given that you cannot take consumers off heat for conversion over winter, you effectively have 8 months a year in which to do the conversion.  Roughly speaking, this is then around 35,000 properties per week being converted!