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.

  • Is there really very much to be gained from efficiency changes to simple gas boilers ? A modern condensing boiler produces exhaust gas at about the temperature of horse breath - nothing like the old units from the 1980s where you could light a newspaper by holding it over the flue. Given that that is the only energy truly wasted, the rest staying in the building, it is not clear how much  more can be squeezed out. If the penalty is increased complexity and higher failure rates and shorter service intervals, then that all needs to be factored into the true cost. Simpler devices are generally easier to maintain.

    The 'hydrogen ready' idea is more attractive, though the same extra expenses both initial and on-going, need to be considered and further,  I am also reminded of the complexity of things like gas safe qualifications - the rules need to go in step or there will be no-one available to service the multi-fuel device - it is complex enough with separate LPG and natural gas (methane - I know propane is natural, but the HSE do not..) certifications, without introducing a new class of equipment. That is not so say do not encourage the creation of multi-fuel devices,  but perhaps not to mandate it until there are enough in use to be a majority - there may be some historical lessons from the 1970s change-over from coal gas to north sea, and that was at a time when work on gas appliances was unregulated.. At the moment most hydrogen is made from methane anyway, so the point is moot,  but presumably the idea is to use gas generated during moments of renewable over-supply.

    Similar concerns apply to combinations with heat pumps, as it is not clear who will be able to work on them - presumably refrigeration quantification as well as gas safe and electrical qualification.

    In many ways lightening the regulatory burden may actually encourage innovation, just perhaps not by big business.

  • I'm not convinced that hydrogen as an alternative to methane is ever going to happen.  There are problems with distributing it - it leaks easier than methane, and any old steel pipes still in use will be embrittled if they are used with hydrogen.  All older gas appliances would have to be converted or replaced.

    Then there's the problem of energy density.  Taking figures from,

    Methane has an energy density of 54.0 MJ/kg, whereas hydrogen is 142.2 MJ/kg.  Yay for hydrogen.

    But we measure the delivery of gas by the cubic metre.  I cubic metre of methane gives 40.34 MJ.  But a cubic metre of hydrogen is only 12.79 MJ.

    So we'd be using gas over 3 times as fast if we switched to hydrogen.  That's an awful lot of hydrogen to keep pumping into the gas mains.

  • Yes, We haven't enough electricity to spare to supply power for the electrolysis of water to produce the green hydrogen gas. Producing brown gas may be possible but CO2 is still produced then.

    Another problem is how are you going to store the hydrogen gas at low pressure as the old  gasometers would hardly be useful?

  • Producing brown gas may be possible

    Nitrogen dioxide??? Thinking

  • I am gas safe registered, methane and domestic only. I have heard that a 20% addition of hydrogen to methane supplies is being proposed, implemented before full hydrogen supplies. I presume that hydrogen unready condensing boilers should be able to cope with the increased H2O produced by combusting the mixture, and that non-condensing boilers will just rust even quicker.

    I hadn't heard of embrittlement of steel pipes, there's still loads of that around in inaccessible places.

    There should be more done to offset the carbon produced by planting trees, and possibly bamboo, instead of legislating jobs for the boys in big boiler manufacturing industries.

    Also boiler replacement schemes with grants, never work for small businesses, as entry requirements are too restrictive.

    Sorry for non cohesive reply, just getting thoughts down

  • Actually it is better than that - existing methane burning appliances with a European G number, and that has been all new ones for years, are tested with the hydrogen methane blend as part of the type approval - 'hydrogen ready' means something nearer pure hydrogen.

    At very high pressures, many atmospheres at room temperatures, hydrogen permeates into steel and has an effect similar to hardening tool steels. Cast iron is less fussed, But, those old enough to remember coal gas (the 1970s and long hair for boys as well) will note that that was a mix of CO and hydrogen, up to about 40% of it, and the old lead and cast iron pipes of the era did perfectly well at 8 inches water pressure or whatever it was. High pressure storage would  have been awkward, but the old gasometers were not really what nowadays is seen as high pressure. And they leaked a bit but folk were less worried then,


  • the 1970s and long hair for boys as well

    Who? Me? Grin

  • I presume that hydrogen unready condensing boilers should be able to cope with the increased H2O produced by combusting the mixture, and that non-condensing boilers will just rust even quicker.

    Why would more H2O be a problem? Nothing wrong with a good old-fashioned floor-standing cast-iron boiler!

  • Hi, all good a valid points.

    • You talk of 'combinations with heat pumps' would this be a CHP - combined heat and power plant?
    • What regulations would need to be addressed to lighten the regulatory burden - what about safety. presumably you don't want to increase risk?  
  • Brown gas - is this credible? if so why aren't more talking of it?