I think this came at me both ways as a schoolboy. Both from chemistry and physics. In our 1960s chemistry lab, Bunsen burners, flasks and array of hazardous substances were the norm. Physics seemed more cerebral. Still, the hands-on side of teaching still meant some practical experimentation. That’s the part that most engrossed me.
Electrolysis starred in two mostly harmless experiments. The colourful one was about copper sulfate[1] and the other was about splitting water into its component parts. Getting Oxygen (O2) and Hydrogen (H2) gas by electrolysis[2] is mighty simple and one of those wonders of nature.
Electrolysis is a way of producing carbon-free Hydrogen from renewable and nuclear resources. Despite the apparent straightforwardness of the process, it’s quite tricky to industrialise on a large scale. One key factor to the future use of Hydrogen is getting the cost per Kg down[3].
Let’s presume that this is a solvable problem and cheap and plentiful gas supplies will be up and running by 2030. That’s not so far off given its 2023. There will surely be a market for ample supplies given the multitude of applications for Hydrogen. Will it be a global market? It needs to be.
It’s a talking point. Hydrogen fuel is one of the viable fuels for aviation. Generating power and returning it to water in the atmosphere is an attractive idea. The process meets carbon-free ambitions even if it does have lots of complications.
On average, a Boeing 737-800 uses about 5,000 lbs (2268 kg) of conventional fuel per flight hour[4]. Cryogenic Hydrogen has lower energy density. That means much more on-board fuel storage will be needed to go as far or fly as long as a current day common commercial jet aircraft.
Designing an aircraft configuration that can accommodate these facts can be done but what of the space that remains for the payload? As it does today, on-board fuel storage will need to meet stringent safety requirements.
Adding this up, it may not be the technical issues that make this difficult. Although they are difficult the technical issues can be addressed. However, will the overall package that results be economically viable? If costs are increased by a factor of, say 5, will this provide for a commercial air transport system that is like the current one?
We may have to accept that carbon-free flying reverts to the 1960s[5]. What I mean is that, instead of low-cost flights hopping here, there, and everywhere for £100, the future maybe one where long-haul flying is a relative luxury or an expensive business need.
[1] https://www.bbc.co.uk/bitesize/guides/zgn8b82/revision/3
[2] https://www.bbc.co.uk/bitesize/guides/zv2yb82/revision/1
[3] https://www.statista.com/statistics/1220812/global-hydrogen-production-cost-forecast-by-scenario/
[4] http://www.b737.org.uk/fuel.htm
[5] https://www.skyscanner.com.au/news/airlines/the-golden-age-of-plane-travel-what-flying-was-like-in-the-1950s-and-1960s-compared-to-now
John Vincent 