Technical Feasibility of Hydrogen Boilers in Homes - A Report for ECOS
19 April 2023
The research undertaken included consideration of the technological and economic barriers to converting to hydrogen in terms of sourcing the necessary components and materials for manufacture of the boiler units themselves. [...] Within the UK, the maximum blended hydrogen share of 20% is based on previous research by the Health and Safety Executive (HSE).36 The HSE determined that this concentration of hydrogen is unlikely to increase risk from within the gas network or appliances.37 UK regulations limit the blend to a maximum of 0.1% hydrogen in public gas networks, and up to 23% hydrogen in certain special cases, such a. [...] For example, the UK heating industry is waiting for the standards and certification framework to be put in place to enable a product to be classified as hydrogen-ready.51 In terms of developing a toolkit for the conversion, it is recognised that it would be of great benefit for a standardised toolkit to work across the industry. [...] This is because 1) the higher flame speed means that the current burner does not provide enough resistance to control the flame, necessitating a resized burner design 2) the flame will sit closer to the burner face, increasing the chance of light back, possibly requiring removal of pre-mixing and alteration of the gas valve and 3) the material of current burners may not be heat resistant enough fo. [...] Interviewees advised that this is principally thanks to the Wobbe number (which is a combustion parameter related to the calorific value and density of the gas, which affects flame speed and shape and signifies the amount of energy in a given volume of gas) of hydrogen being almost identical to that of natural gas.