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green hydrogen? it has its place, apparently

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easy-peasy? don’t be guiled

Canto: So now that Labor has won government in South Australia it’ll be implementing its hydrogen plan pronto, I presume. But so many people seem iffy about hydrogen, I thought we might do another shallow dive on the topic.

Jacinta: Yes, we jointly wrote a piece last June on SA’s hydrogen plan (linked below), and a brief interview today with Andrew ‘Twiggy’ Forrest caught my attention – time to revisit and further our education on the subject.

Canto: Yes, a recent ABC article described Forrest’s ‘green hydrogen hub’ in Gladstone in central Queensland. He’s building the world’s largest electrolyser facility there. We’re talking gigawatts rather than megawatts. He expects – by which he means hopes – that the facility will have the capacity to produce 2 gigawatts (that’s 2000 megawatts) of electrolysers per annum, just for starters.

Jacinta: I’m not sure whether to trust Forrest’s hype, but I like his enthusiasm. He reckons he already has buyers for his electrolysers and that ‘the order list is growing rapidly’

Canto: Interesting – Forrest says that the lack of electrolysers has been a problem for a while, and apparently Australian researchers at the University of Wollongong, associated with a company called Hysata, have achieved a ‘giant leap for the electrolysis industry’, with its ‘capillary-fed electrolysis cells’, which have attained 95% efficiency, up from the previous 75%. This was published in the peer-reviewed journal Nature Communications, so it’s not just hot air.

Jacinta: Apparently electrolysers have been around for quite some time, with very few improvements, so this seems important. The researchers describe their approach thus:

The central challenge was to reduce the electrical resistance within the electrolysis cell. Much like a smart phone battery warming as it charges, resistance wasted energy in a regular cell as well as often requiring additional energy for cooling.

“What we did differently was just to start completely over and to think about it from a very high level,” Swiegers said. “Everyone else was looking at improving materials or an existing design.”

Canto: Reducing electrical resistance – that’s always the key to cheaper and more effective electricity, it seems to me. That was at the heart of the AC versus DC battle, and it’s what has made LED lighting such a vital development.

Jacinta: I still don’t understand LED lighting. Photons instead of electrons, yet still connected to an electric circuit driven by electrons in wires…

Canto: Anyway, returning to hydrogen, there’s a presumably new organisation called the Australian Hydrogen Council, whose website has a frequently asked questions section. The key thing about green hydrogen, or otherwise, is where the electricity comes from to produce electrolysis. To be green, obviously, it needs to be from solar or wind, or hydro. The FAQ section also mentions that the electricity can come from carbon capture and storage, resulting in ‘low to zero carbon emissions’.

Jacinta: Hmmm. We’ll have to do a shallow dive on carbon capture and storage soon. I know that ‘greenies’ are generally highly skeptical, but sometimes I feel a bit skeptical of greenies. Am I allowed to say that?

Canto: A generalised skepticism means looking critically at any scientific claims. But I’ve been thinking about electrolysis, particularly the electrolysis of water, which is key to this clean green hydrogen-producing process, presumably. It’s about ‘lysis’ – splitting, or separating – by means of an electrical current. But to paraphrase Woody Allen, ‘I’m two with science’. Or to put it another way, science is to me like a lover I’m passionate about but can never fully, or even partially, understand…

Jacinta: Well I’ve watched a wee citizen science video about doing electrolysis of water at home. You need, according to these guys, distilled  water, nice and pure, and ‘kosher’, non-iodised salt. Mix it together in a heat-resistant beaker, about nine parts water to one part salt, until the salt dissolves, and insert a couple of spoons attached to a nine volt battery into the mix. The salt increases the conductivity of the solution, as pure water isn’t conductive, much. You’ll need an acid, such as vinegar, to neutralise the alkaline solution that results from the experiment. That alkaline solution is essentially sodium hydroxide, NaOH, aka caustic soda or lye, which can cause burns, so home experimenters need to protect themselves accordingly. Then you insert the spoons, each connected to one of the two terminals of the battery, into the beaker. Bubbles of hydrogen and chlorine gas will form, as long as the two spoons are kept separate. Note that inhaling chlorine gas is a v bad idea, so, again, protection. And best to do the experiment outside. So what is happening here? Salt is an electrolyte, an ionically-bonded compound. The ions are what facilitates the transfer of electrical energy. So what we have in the solution are molecules of H, O, Na and Cl, the molecular bonds having been broken by the electrical current. In this home experiment, the hydrogen and chlorine gases escape into the air, but of course the hydrogen will be captured for energy use in the system being developed by Forrest and others.

Canto: Yes the salt water is used as an electrolyte, but different electrolysers will use different electrolytes. The US website energy.gov describes three types of electrolysers being used or considered at the commercial level – polymer electrolyte membrane (PEM), alkaline, and solid oxide. The problems with all these types is cost-effectiveness. For example the solid oxide membranes in that type of electrolyser need to operate at very high temperatures – between 700 and 800°C – to function effectively, though promising work is being done to lower the temperature. From what I can gather, the PEM electrolysers are showing the most promise. This uses a solid plastic electrolyte, and for what it’s worth I’ll quote something about how it works:

  • Water reacts at the anode to form oxygen and positively charged hydrogen ions (protons).
  • The electrons flow through an external circuit and the hydrogen ions selectively move across the PEM to the cathode.
  • At the cathode, hydrogen ions combine with electrons from the external circuit to form hydrogen gas.
  • Anode Reaction: 2H2O → O2 + 4H+ + 4e Cathode Reaction: 4H+ + 4e → 2H2

Jacinta: As you’ve said, the cost of electrolysers is a major barrier, and I’ve been unable to find out the type of electrolysers Forrest’s company (Green Energy Manufacturing) is going with. I did find out that Twiggy likes to be called Dr Forrest now, having completed a doctorate in Marine science recently. Also, there’s quite a lot of skepticism about his green hydrogen project.

Canto: Yeah, like there was with SA’s big battery… Stop Press –

The electrolysers produced at the GEM facility will partner FFI’s advanced manufacturing capabilities with cutting-edge Polymer Electrolysis Membrane (PEM) technology developed by NASDAQ-listed company Plug Power to deliver a high-purity, efficient and reliable end product.

That’s advertising blurb from the Queensland government, so we’ll have to wait and see. But getting back to the skepticism about hydrogen as an energy source – what gives? Well, according to Rosie Barnes, Australia’s engineering Wonderwoman, the process of creating hydrogen by electrolysis and then burnng it in a full cell is very energy-inefficient compared to direct or battery electrical energy. That’s three compared to one wind turbine, for example. Also hydrogen takes up a lot of space – remember those massive zeppelins?

Jacinta: Not personally.

Canto: Well, another problem with hydrogen is its flammability. The Hindenburg wasn’t the only hydrogen airship that went up in flames. They can replace hydrogen with helium apparently, but that presents another set of problems. In any case, it looks like hydrogen isn’t going to be the silver bullet for green energy, but it will surely be a part of the energy mix, and with technologies for storage and transport being developed and improved all the time, it’ll be interesting to see how and where green hydrogen finds its place.

Jacinta: Yes I’ll certainly be keeping an eye on the projects happening here in Australia, and how the likely change of government at the federal level makes a difference. My feeling is that they’re keeping mum about their energy plans until after the election, but maybe I’m being overly optimistic.

 

References

a hydrogen energy industry in South Australia?

https://www.abc.net.au/news/2022-02-28/andrew-forrest-begins-work-on-green-hydrogen-hub-in-gladstone/100865988

https://www.nature.com/articles/s41467-022-28953-x

The Sci Guys: Science at home – electrolysis of water (video)

https://www.energy.gov/eere/fuelcells/hydrogen-production-electrolysis

https://www.sciencedirect.com/science/article/pii/S2589299119300035

https://www.statedevelopment.qld.gov.au/news/people-projects-places/breaking-ground-how-aldoga-is-leading-queenslands-renewable-energy-charge

https://skepticalscience.com/hydrogen-fuel.html

Hydrogen and Helium in Rigid Airship Operations

 

Written by stewart henderson

April 18, 2022 at 5:57 pm