an autodidact meets a dilettante…

‘Rise above yourself and grasp the world’ Archimedes – attribution

Posts Tagged ‘green energy

some more on hydrogen and fuel cells

leave a comment »

an electrolyser facility somewhere in the world, methinks

Canto: Our recent post on democracy and public broadcasting has made me turn to PBS, in order to be more democratic, and I watched a piece from their News Hour on clean hydrogen. Being always in need of scientific education, I’ve made this yet another starting point for my understanding of how hydrogen works as an energy source, what fuel cells are, and perhaps also about why so many people are so skeptical about its viability. 

Jacinta: Fuel cells are the essential components of hydrogen vehicles, just as batteries are for electric vehicles, and infernal combustion engines are for the evil vehicles clogging the roads of today, right?

Canto: Yes, and Jack Brouwer, of the National Fuel Cell Research Centre in California, claims that fuel cells can be designed to be just as fast as battery engine. Now according to the brief, illustrated explanation, diatomic hydrogen molecules enter the fuel cell (hydrogen occurs naturally in diatomic form, as does oxygen). As Miles O’Brien, the reporter, puts it: ‘A fuel cell generates electricity by relying on the natural attraction between hydrogen and oxygen molecules. Inside the cell, a membrane allows positive hydrogen particles [basically protons] to pass through to oxygen supplied from ambient air. The negative particles [electrons] are split off and sent on a detour, creating a flow of electrons – electricity to power the motor. After their work is done, all those particles reunite to make water, which is the only tailpipe emission on these vehicles.’  

Jacinta: He tells us that the oxygen is supplied by ambient air, but where does the hydrogen come from? No free hydrogen. That’s presumably where electrolysis comes in. Also, membranes allows protons to pass but not electrons? Shouldn’t that be the other way round? Electrons are much tinier than protons.  

Canto: Very smart. Maybe we’ll get to that. Brouwer talks of the benefits of fuel cells, saying ‘you can go farther’, whatever that means. Presumably, going farther with less fuel, or rather, you can have a lot of fuel on board, because hydrogen’s the lightest element in the universe. Clearly, it’s not so simple. O’Brien then takes us on a brief history of hydrogen fuel, starting with the conception back in 1839, and real-world application in the sixties for the Apollo missions. The Bush administration pledged a billion dollars for the development of hydrogen fuel cell cars in the 2000s, but – here’s the problem – they were producing hydrogen from methane, that infamous greenhouse gas. Ultimately the cars would be emission free and great for our cities and their currently dirty air, but the hydrogen production would be a problem unless they could find new clean methods. And that’s of course where electrolysis comes in – powered by green electricity. 

Jacinta: The splitting of water molecules, a process I still haven’t quite got my head around…. 

Canto: Well the PBS segment next focuses on the sectors in which, according to Brouwer, hydrogen fuel will make a difference, namely air transport and shipping. Rail and heavy vehicle transport too – where the lightness of hydrogen will make it the go-to fuel. It’s energy-dense but it must be compressed or liquefied for distribution. This makes the distribution element a lot more expensive than it is for petrol. So naturally Brouwer and others are looking at economies of scale – infrastructure. The more of these compressors you have, the more places you have them in, the cheaper it will all be, presumably. 

Jacinta: Right, as presumably happened with wind turbines and solar panels, and the more people working on them, the more people coming up with improvements… But how do they liquefy hydrogen?

Canto: Hmmm, time for some further research. You have to cool it to horribly low temps (lower than −253°C), and it’s horribly expensive. There was a bipartisan infrastructure bill passed recently which will fund the building of hydrogen distribution hubs around the USA through their Department of Energy. That’s where the action will be. The plan, according to mechanical engineer Keith Wipke of the National Renewable Energy Laboratory, is to do in ten years what it took solar and wind 3 or 4 decades to achieve. That is, to bring hydrogen production costs right down. He’s talking $1 per kilogram. 

Jacinta: Okay, remember that in 2032. 

Canto: Yeah, I won’t. They’re talking about improving every aspect of the process of course, including electrolysers, a big focus, as we’ve already reported. They’re connecting these electrolysers with renewable energy from wind and solar, and, in the bonobo-science world of caring and sharing, any new breakthroughs will quickly become globalised. 

Jacinta: Yeah, and Mr Pudding will win the Nobel Peace Prize…

References

Could hydrogen be the clean fuel of the future? (PBS News Hour video)

green hydrogen? it has its place, apparently

Written by stewart henderson

April 25, 2022 at 5:37 pm