The rise of green hydrogen in a global and Irish context

The latest episode of the Redefining Energy podcast is about the future of hydrogen and includes an interview with a UK based manufacturer of electrolysers for green hydrogen production. If you're not familiar with the podcast it's hosted by two knowledgable investors in the renewable energy sector, one of which is an Irishman living in Germany.

They have both been pretty skeptical of the rise of green hydrogen for the last number of years. Though it sounds like their position softens a little by the end of the episode. Listen (29 mins): https://www.spreaker.com/user/10802082/68-greenh2?utm_campaign=episode-title&utm_medium=app&utm_source=widget

I recommend subscribing to the podcast, this is only one of many great episodes where they interview people working in the energy sector or the world of sustainable financing.

DaCor, I know you're a fan of hydrogen, but the more I learn about it the more skeptical I get.

This is basically the opposite what happened when I started looking into other de-carbonization technologies particularly wind, solar PV and li-ion BESS. From a renewables skeptic less than a decade ago, I've become the opposite - fully evangelised with the zeal that mankind is on the brink of a revolution in energy technology bigger than that caused by the emergence of oil in the 19th century.

I kinda shrugged when it came to hydrogen; I couldn't see a compelling argument/use for it except long-term (months and year scale) energy storage to complement variable renewable generation. Although even this wouldn't be a critical issue for years if not decades and we have massive scope for the de-carbonization of energy without requiring a solution in this area.

But I was under the impression that hydrogen has a key and critical advantage over methane/natural gas - which is that leaks are harmless in terms of GHG effects. But it turns out that hydrogen is terrible in this regard - as bad as methane? And of course hydrogen by its physical nature is more prone to leakage.

So why bother with hydrogen at all? We have processes whereby we can use electrolysis to produce methane from the air with almost the same efficiency as hydrogen electrolysis? We already have all the infrastructure and technology to pipe methane (natural gas) around, store huge quantities of it, ship it across oceans, turn it into electricity, heat homes with it, run vehicles, etc. All of these things can be done right now, with zero extra capital investment, and cheaply/efficiently with methane while hydrogen requires the construction of a completely new global gas infrastructure.

I just don't get the point. I'm not a conspiracy theorist at all, but it seems more and more to me that the hydrogen hype is a way for the existing fossil fuel industry to use "green arguments" to extract rent/subsidies from governments to make up for the loss of market to renewables. It reminds me of the nuclear industry in that regard. Why does it seem that all of the biggest names in hydrogen are or were previously oil and gas extraction or support companies?

In other news, it looks like "blue" hydrogen is also a bust and is worse than burning diesel 😳 in terms of overall GHG emissions according to this peer reviewed article - https://onlinelibrary.wiley.com/doi/full/10.1002/ese3.956 - even with 80% carbon capture.

The point of DeCor's paper is that the previous estimates of hydrogen's warming effect underestimated hydrogen's potential for contributing to global warming. The paper you quote from was written in 2006 and much of the references in it are papers written in the 1990s. In contrast, the latest research is prefaced by:

"While hydrogen-induced changes in methane and ozone in the troposphere [the lowest layer of the atmosphere] have been considered previously, we have also considered, for the first time, previously ignored changes in stratospheric [that is, in the second-lowest layer of the atmosphere] water vapour and stratospheric ozone in our calculations of hydrogen’s GWP,”"

And the leakage numbers are much higher than 1% - you should read the paper.

It's bad news for hydrogen - this was the the last remaining big benefit hydrogen could claim over natural gas/methane. At this stage, I can't see any rational reason for preferring hydrogen-from-water electrolysis over a methane-from-air process given both are equal in terms of life cycle net carbon. The latter can be used immediately to supplant fossil sources of methane - the former will require 10s of billions if not 100s of billions in new infrastructure, and will take decades to contribute to reducing GHG emmissions.

Of course, producing green hydrogen using electrolysis and then combusting it results in less CO2 emissions than extracting fossil fuels from the depths of the earth and burning them for energy releasing the carbon into the atmosphere.

But that's not what I was questioning. Why bother with hydrogen at all when we can use other power-to-gas processes to synthesise methane from power - this can be done without adding any (net) carbon to the atmosphere, can immediately be used to displace fossil sources of methane (natural gas) and requires NO new infrastructure?

The answer I would have given in the past is that handling and processing natural gas/methane invariably leads to leakage into the atmosphere and methane is a potent greenhouse gas while (I had believed) that this was not the case for hydrogen. But now that it seems hydrogen is at least as bad as methane in that regard, why exactly do we need to spend 100s of billions on brand new hydrogen infrastructure when we could achieve the same GHG reduction by storing excess energy in the form of methane?

I don't get it...

"On a side note, has anyone seen any grid scale proposals for hydrogen usage that involve the likes of fuel cells?"

The round-trip efficiency (electrolysis to fuel cell) is quite poor - at under 40% (I believe?) - compared to any type of battery. So I guess it could theoretically be done but it'll really struggle to make the operational finances work.

The only future for green hydrogen that makes sense to me is to displace the grey hydrogen used in industry. I'd be an enthusiastic supporter of electrolysis in this role given current production methods account for over 3% of global CO2 release. Medium sized electrolysis plants could be located on-site avoiding most of the (unsolved) difficulty and complexity involved in the storage and transport of hydrogen.

I just can't see much of a role for it in energy given the poor round trip efficiency via fuel cells. There is talk of combusting hydrogen - either mixed into natural gas or pure hydrogen turbines but the high temperature of hydrogen combustion mean there's no getting away from huge amounts of NOx generated in the process. And once you require any sort of thermal engine, you're going to take a big efficiency hit also.

I've been researching how green energy is made. The one thing I can't figure out is where the water goes after electrolysis. The oxygen is released into the air and the hydrogen is harvested. What's left? Is the water all gone after this process? If there is water left over, then I would assume it would be heated and this wouldn't be good to put back into streams/wells etc. Anybody out there have the answers?