OK, so I need to do a brief rant on something hugely important that almost no one cares about. Humor me.

To wit: in the absence of an as-yet unidentified break through in storage tech, hydrogen is never going to be anything other than a niche player in energy mkts. Thread:
2/ Or more precisely, not unless someone finds a way to store hydrogen cheaply, at high mass & energy density and with super high round trip efficiencies. Which as of this moment Does. Not. Exist.
3/ To understand why, note that no one is advocating for natural gas-based hydrogen economy. Converting natural gas to hydrogen so we can burn it is just an inefficient way to use natural gas.
4/ The promise is from renewable hydrogen. Make electricity without CO2 from renewable resources (or off-peak nuke), then use the electricity to make zero-C hydrogen with an electrolyzer.
5/ But follow the conversion steps, assuming PV. Sunlight --> electricity --> hydrogen --> a fuel cell where we turn it back into electricity.
6/ The question is why bother with the intermediate steps? Why convert electricity to hydrogen to electricity? Why not just use the initial electricity?
7/ And the only way that it makes sense to include hydrogen is if there is hydrogen is fundamentally easier to store and distribute than electricity. But here's the rub: it isn't.
8/ Start with just first law efficiencies. A typical battery has round trip efficiencies of 70-80%. (e.g., you lose 20 - 30% of the electricity you put into the battery by the time you get it back out.)
9/ By comparison, an electrolyzer has a electricity --> hydrogen conversion efficiency of ~80%, and the fuel cell that then turns the hydrogen back into electricity has an efficiency AT BEST of 60%, more typically 30 - 40%. So max 80% x 60% = 48% round trip efficiency
10/ So all else equal, you get 70-80 MWh out of every 100 MWh you put into a battery and < 50 MWh for every 100 MWh you run through a hydrogen intermediary.
11/ That means that - before factoring in capital recovery costs - it costs 2x as much to use hydrogen as an intermediary between electricity and electricity.
12/ To be fair, that price may be worth paying for if hydrogen has some unique advantages as an energy carrier. For example, if we had a hydrogen pipeline network and didn't have an electric grid. Or if we had a really good way to cheaply store and transmit hydrogen.
13/ Trouble is, the reverse is true. We have an electric distribution grid, not a hydrogen one. We have a rising penetration of electric vehicles and charging infrastructure, but not a hydrogen one.
14/ And while battery storage has made huge technical leaps over the last 20 years, from lead acid --> metal hydride --> Li-ion, with every cheaper, lighter and longer storage batteries, H2 storage tech is frozen.
15/ 20 years ago, the state of the art for hydrogen storage was in 5000 psi compressed tanks. Today... same thing. And storing hydrogen in high pressure tanks requires even more energy use, making the efficiency even worse than the 48% max calc'd above.
16/ 20 years ago, there was talk of advanced lithium ion batteries. There was also talk of carbon nanotubes to store hydrogen. Only the former came true. But the 20 year old theories of a hydrogen economy are still batted around, as in the E&E article that started this off.
17/ (As an aside, when I was a young engineer 20 years ago, you could find analyses just like this from the Office of Technology Assessment, which Gingrich killed. We pay dearly for our legislated ignorance. Bring back the OTA!)
18/ To be sure, that's not to say there's no need for hydrogen. It's really helpful to make margarine and other unsaturated oils. Also as a rocket fuel. And perhaps as a source of thermal energy in specialized mfg processes.
19/ But in aggregate, those are niche plays. Until we have a storage breakthrough, it simply isn't going to be a major player in electricity or transportation markets. Period. Full stop.
20/ Thank you for listening. May we never have to speak of this again. /fin
Nerd postscript on this: 20 years ago, I told Joe Romm that the whole argument for H2 was based on the idea that it was the most ubiquitous element in the universe. But technically, there are more electrons than H2 molecules, so isn't that an argument for electric everything?
Joe's deadpan response: "There are even more quarks. The future is quantum."
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