Dear Editor
Paul Homewood is right to draw attention to the limitations of Hydrogen as a means of energy storage.
The National Energy System Operator (NESO) expects grid electrical consumption to rise from around 300 to 450TWh by 2035, when 180GW of planned solar and wind along with 30GW of gas and nuclear should supply 600TWh per annum.
But the Royal Society (RS) has estimated that the grid will need around 100TWh of energy storage. If that is to come from ‘green hydrogen’ (H2), then >2TWh will be needed for every 1TWh released by the electrolysers. Then to get 100TWh from H2 Gas Turbine Generators (GTGs) – to feed back into the grid – would require around 330TWh in, implying 660TWh pa would have to be supplied to the electrolysers.
That hardly seems viable and surely a better option would be to deploy GTGs fired by natural gas – with CO2 Capture and Storage (CCS) – plus a strategically placed grid scale battery capacity of 1 or 2 hours (eg 160GW/200GWh). That should be more than enough to allow time for GTG and hydro storage startup, when wind or solar power drops off.
But since Operation and Maintenance (O&M) costs per TWh are lower for Combined Cycle Gas Turbine Generators (CCGTs) than for the planned 210GW of wind, solar and GTGs, why not abandon solar and wind and run CCGTs continuously? 90GW of CCGTs could deliver a similar TWh to what is planned and would not need so many long transmission lines.
The CCGTs wouldn’t need backup power, would have a much longer life than solar and wind farms, and would incorporate synchronous generators with rotational inertia, leading to better inherent system stability. Even better, provide 20GW of the generator capacity in the form of SMRs (Small Modular nuclear Reactors) to carry grid base load and give us some defence against international gas price escalation.
If the unproven CCS doesn’t work it wouldn’t matter, because – as demonstrated by Professor William Happer – the GHG impact of CO2 falls away logarithmically, while the UK’s human emissions only amount to around 0.0005pmm out of a 2ppm pa global emission total, ie a 1:4,000 ratio.
Also worth noting is that the UK has around 3billion trees, each of which can absorb around 1 tonne of CO2 over 100 years – ie 30Mt of CO2 pa total – that being a lot more than the UK’s human related emissions, of around 4Mt pa. So let’s stop pushing the impossible use of green H2 for grid energy storage.
Roger J Arthur, CEng, MIEE, MIET
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