Green Hydrogen: Could It Be Key to a Carbon-Free Economy? | Hacker News Reader

Green Hydrogen: Could It Be Key to a Carbon-Free Economy?

e360.yale.edu

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One thing the article misses is that green hydrogen may in many cases be better used as the feedstock for other products such as green ammonia. Other than its use in fertilizer, ammonia can also be burned as a fuel. Using green ammonia as a fuel is one of our best bets for decarbonizing shipping, for example. And it has the additional advantage that we already have a fairly large scale distribution infrastructure for ammonia, so there's less of a chicken-and-egg bootstrap problem for early adopters. This Royal Society report is a pretty good introduction to the subject: https://royalsociety.org/-/media/policy/projects/green-ammon...

A significant problem with ammonia-as-fuel is that it combusts to produce NOx, already a major pollutant and public health issue in many parts of the world. As with diesel engines, the exhaust can be scrubbed with AdBlue selective catalytic reduction, but this adds to the cost and complexity.

These issues are discussed in the report - see pages 28/29 for example. Another approach discussed in the context of transport fuels is to use ammonia as an effective storage medium for hydrogen - cracking ammonia back to hydrogen before feeding it to a PEM fuel cell. That also has some challenges, notably in minimizing ammonia in the hydrogen, which isn't good for fuel cells. In the end, I do think we'll end up with liquid synthetic fuels being essential for decarbonization - the question is not if, but which?

This is exactly wrong. Ammonia and its precursor urea are the chemicals used in SCR to reduce NOx.

4 NH3 + 5 O2 → 4 NO + 6 H2O

A subsequent reaction leads to NO2:

2 NO + O2 → 2 NO2

Per wikipedia [0], the combustion equation is:

4 NH3 + 3 O2 → 2 N2 + 6 H2O

That's nitrogen and water. Apparently, your scary equation requires the presence of appropriate catalysts, which catalysts could certainly be excluded from any particular engine.

[0] https://en.wikipedia.org/wiki/Ammonia#Combustion

Yes, but if you read just a little further in that article: “The combustion of ammonia in air is very difficult in the absence of a catalyst”

Practically speaking, NOx formation is difficult to avoid in combustion applications and would require safeguards/mitigations just as it is in Diesel engines.

Another issue is that the whole concept of green ammonia relies on having sufficient green hydrogen feedstock to produce it with in the first place.

I do recommend reading the Royal Society policy paper linked in the parent post!

That looks interesting, now I wonder how dangerous/polluting a tank leak can be for ammonia compared to diesel and hydrogen

Well, hydrogen tanks are kept at crazy crazy pressures, so if you stand next to an active leak it will literally cut you in half - high pressure tanks are pretty scary stuff. On the other hand, pure ammonia will kill you straight away if you breathe it in. Diesel is not great, but short of drinking it it won't kill you, and it doesn't really like exploding either. I'm not really trying to make an argument against hydrogen/ammonia, I just find this stuff interesting.

Search on "Green Hydrogen" yields an impressive list of articles on this subject. The science and economics do not appear to weigh substantially in favor of hydrogen as fuel. This article, amongst others, argues an interesting opposing view: https://www.thenewatlantis.com/publications/the-hydrogen-hoa...

That viewpoint is comically out of date. It's unaware of 10,000 psi carbon fiber tanks for one thing. There are many other things wrong with it.

Not too many of those arguments have become invalid since the article was written. Still incredibly hard to make Hydrogen work economically. No real breakthrough in terms of how we store it, creating huge problems for any type of Hydrogen infrastructure.

The trouble with solar -> electricity -> hydrogen -> electricity and the like is that normal lithium ion batteries seem to do the job cheaper and better for most applications.

Batteries (except flow batteries) must be scaled linearly with the desired storage capacity. Hydrogen storage on the other hand only requires a container to be scaled with the desired capacity (square-cube law) while the conversion machinery, i.e. the power rating of the storage, can be scaled independently.

Building batteries for seasonal energy storage would require huge amounts of raw materials. Building hydrogen storage requires nothing because you can reuse salt dome caverns previously used for natural gas.

> "Building hydrogen storage requires nothing because you can reuse salt dome caverns previously used for natural gas."

Note that at atmospheric (or any) pressure, the volumetric energy density of hydrogen gas is less than 1/3 that of natural gas. You would need 3.2X more salt cavern space to store the same amount of energy.

Yes - often, if you're starting from scratch. But for replacing natural gas (for example in domestic piped domestic heating) or coal (steel production) in the short term, hydrogen may be more cost effective.

To replace natural gas you're probably much better off using that hydrogen along with some CO2 and electricity to produce methane.

They'd probably have to convert it into methane or something for domestic gas heating. It's not really safe to have in houses.

The plan in the UK IIRC is to mix hydrogen (10-20% I think) into the existing mains gas supply to lower the carbon intensity somewhat, in the long term though we're trying to replace boilers with heat pumps for domestic housing.

Hydrogen starts to make sense when we have 200% overproduction of solar/wind energy.

Assuming energy is essentially free Methane synthesis would be a more viable option IMHO.

I was shocked to learn that natural gas pipelines are more efficient than high tension power lines. Near natural gas infrastructure you may well be right.

Conductive metals have resistance, so they must lose a portion of their energy as heat. A pipeline only has to overcome friction on the inner surface of the pipe, which is easily reduced by having a wider pipe. So this isn't a surprise.

Hydrogen pipes will have the same benefits, albeit you will want a wider pipe due to the lower density.

Hydrogen has problems of leaking out, and damaging materials, in both cases because very small molecules can easily insert themselves where they don't belong.

Every couple of years everyone forgets what a pain in the butt it is to control pure hydrogen. There should be a write up somewhere that people can link to instead of having to explain it all again to a new crowd. You could even link all of the research and research opportunities into ways of mitigating those problems, which would just make the point all the better.

When you solve those n problems we can talk about whether you can solve them at a price point that makes commercial hydrogen viable. Until then we can use it for space ships, which by design spend their entire life outdoors and far away from any structure or worker that isn’t there to directly or indirectly support the fuel delivery system, and is nowhere near civilians.

This is close to becoming a FUD argument. Hydrogen does not leak out of properly designed pipes and containers in appreciable quantities. Embrittlement doesn't not happen either except for specific cases or where an incorrect alloy was used. These are mostly solved problems in modern times.

Last time I was at university we stored hydrogen in pure lead bottles(70kg bottle for just 1L of hydrogen!) and it would leak all of it naturally over about 4-6 weeks. And the bottles had to be replaced every now and then because hydrogen makes them brittle while permeating through them.

Has that changed? Do we now have some exotic materials that can hold it better than pure lead?

Carbon fiber? That's what cars like the Toyota Mirai are storing it in.

The NASA planned replacement for the space shuttle had a bunch of setbacks, but what killed it was the carbon fiber cryo tanks delaminating. They couldn’t solve the problem fast enough and it all got shitcanned. Has that been solved now?

The Mirai can have a low pressure tank, fed from a much larger, higher pressure tank at the fuel station. That tank and the delivery systems for it are separate problems that also have to be solved at scale.

“At scale” is the problem that public policy has to wrestle with. Just because you can do something doesn’t mean you can do it for everybody.

That was in the 1990s. Not to mention they were trying to build a non-cylindrical tank which made things significantly harder.

I don’t know about such things, so have a well-intentioned question: are these problems solvable at scale at reasonable cost? One hears about pipeline leaks frequently, and hundred+ mile long pipelines seem like a hard thing to construct with rigorous precision.

https://en.wikipedia.org/wiki/Hydrogen_pipeline_transport

Hydrogen pipelines exist and for the most part work as intended. There are straightforward ways of avoiding the main problems. AFAIK, these are cost effective solutions.

If you have hundreds or thousands of miles of pipes installed by third-party contractors, the existence of improperly designed pipes, incorrect alloys, and corner cutting becomes virtually inevitable.

However super conducting pipelines don't. Crack cheap superconducting materials and you've got 20% more electricity back.

Outside of peak times, that might be a reality sooner than expected.

Wind doesn't stop blowing and it might be argued that it is stronger at night.

Solar peak does not match the consumption peak neither.

People used to think that productivity advances would lead to a 10 hour work week. I worry that overproduction of energy will be effectively impossible. Without some profit motive, extra energy would be likely be diverted to cryptocurrency schemes and the like.

Methane is a far worse greenhouse gas than CO2, and a major part of emissions from existing gas turbines is small amounts of methane leaking before it's burnt.

So, even if the methane is derived from captured atmospheric carbon, it still wouldn't be carbon neutral.

More like 300% as electricity -> hydrogen -> electricity is around 35% efficient IIRC

I can see Hydrogen as having uses for industrial chemistry. I can also see it having uses for jet fuel, and for vehicles that must travel a long way away from charging points, assuming batteries never reach the same energy density as gasoline.

But for civilian cars, it's a bad battery. It's hard to store and hard to use, and it explodes. The only reason fuel companies love it is that it keeps people coming to the pumps, rather than plugging in any damn place like with battery-electric.

Anywhere with water and electric can produce it. It's why Japan has long favoured it with the their (now previous) abundance of nuclear.

Anywhere with electricity can charge a battery.

You only need H2 if you need to go where batteries can't, or if you're doing actual chemistry.

AFAICT Japan favours hydrogen as a replacement for LNG.

> wind and solar energy can provide the electricity to power homes and electric cars, green hydrogen could be an ideal power source for energy-intensive industries like concrete and steel manufacturing

It's not a power source. It's a different battery. The sun is still the source in these cases.

Nothing works as well as reducing consumption and demand. While we'll always need power, we should always at least mention the higher goal of reducing demand.

>It's not a power source. It's a different battery.

It's also (sort of) equivalent to exporting oil, in a sense. Some country recieves it by ship, pumps it into a tank, and uses it as a source of energy.

Obviously it's generated from cheap electricity rather than pumping geological deposits, but I suspect that hydrogen will displace LNG.

I don't think any government has reducing demand on its radar. They all promise a green future without consumers having to change their behaviour one iota.

The british government has had many energy saving initiatives by increasing home insulation, energy saving light bulbs and their ilk, which have been pushed for at least 20 years.

That's energy efficiency, which is not the same as reducing demand - it's Jevon's paradox all over again. Decreasing the cost of various energy uses results in people being less worried about using them, and using them more as a result. Plus, saving money and improving the economy increases energy use in general (not to imply that improving the economy is in itself a bad that).

https://en.wikipedia.org/wiki/Jevons_paradox

> The energy density of green hydrogen is three times that of jet fuel, making it a promising zero-emissions technology for aircraft

I assume this is on a per-mass (as opposed to per volume) basis, which is misleading due to the storage challenges associated with hydrogen. The practical reason we calculate energy density is because weight matters for transportation purposes. I think at this point in the discussion, we should be including the mass of the storage medium (tank) in the denominator of the energy density calculation, particularly given that cutting-edge solutions involve capturing hydrogen in metal hydrides or porous materials.

Also, given that the discussion is centered specifically around energy storage for long-haul transportation, shouldn’t the investment be evaluated relative to the potential cost of fully electrifying long-haul trucking, shipping and air transport (ie developing next gen batteries and electric motors for these apps)?

That's a fair reminder but it's also worth noting that there are on-going research in the field of improving storage density for hydrogen. https://pubs.rsc.org/en/content/articlelanding/2019/ee/c8ee0...

I've seen some interesting Hydrogen generation using aluminium and gallium, the alloy they make oxidisers so well that it will pull the O2 out of water and release hydrogen. Now how much energy is used to reclaim the aluminium/gallium alloy and rid of the extra oxygen is something I'm not sure of. But certainly pulling hydrogen from water efficiently is one area of interest.

No.

Green hydrogen might have some application, specially in creating some other greenly produced chemicals.

But in terms of transportation, heating and grid storage its not the right solution.

The price is still incredibly high so far we have seen no consistent cost curve on hydrogen production. While we have batteries declining in cost like crazy and lots of new battery approaches being developed as well.

Maybe? But unlikely. Hydrogen energy density is pretty poor considering the alternatives [1].

[1] https://en.wikipedia.org/wiki/Energy_density

Having to compress it to 10,000psi to get a useful amount of energy, hydrogen embrittlement of steel, very wide upper and lower explosive limits, burns with a clear flame. I can't imagine hydrogen ever being used by consumers, it's just a complete liability.

Modern direct fuel injection systems today can compress fuel at almost 30,000psi (https://en.wikipedia.org/wiki/Common_rail), so 10,000psi is nothing. Hydrogen is much safer than batteries, this is a fact.

That's just plain false.

Any significant amount of Hydrogen gas is crazy dangerous to work with because it has such a wide explosive range.

Reading through the Saturn V manual (as you do), the design aspect that surprised me the most was just how much of the hardware was dedicated to hydrogen gas leak detection! It was everywhere. Even the skin of the thing was a two layer affair in places, deliberately designed with channels and helium pressurisation in a complicated way to flush even the tiniest leak through long channels to the nearest sensor.

It sounds crazy until you realise that even a pinhole leak would release gas that rises up and concentrates in spaces between bulkheads and tanks where it can rapidly reach an explosive mixture ratio.

Hydrogen is not safe at all.

So explain the never ending cases of batteries catching fire. This is actually a big scandal, shows that the NHTSA has an agenda and no credibility at all.

Energy-dense storage is always inherently energetic, that's the definition of what energy storage is!

Flywheels explode.

Dams burst.

Fuels burst into flame.

Batteries catch fire.

Hydrogen explodes.

The difference is the relative rate. Batteries are very safe! You probably have one in your pocket on a daily basis and you don't stress about it.

Hydrogen needs special handling by professionals using constantly monitored specialised containment vessels or it explodes.

Those "well publicised scandals" you reference? Something like 90% of them are being promulgated by traders with a short position in TSLA. As you can imagine, they're not exactly unbiased.

To quote an actual analysis, not frothing-at-the-mouth ranting from day-traders losing their shirt because Tesla is doing well:

"Regarding the risk of electrochemical failure, [this] report concludes that the propensity and severity of fires and explosions from the accidental ignition of flammable electrolytic solvents used in Li-ion battery systems are anticipated to be somewhat comparable to or perhaps slightly less than those for gasoline or diesel vehicular fuels. The overall consequences for Li-ion batteries are expected to be less because of the much smaller amounts of flammable solvent released and burning in a catastrophic failure situation."

Ref: https://en.wikipedia.org/wiki/Plug-in_electric_vehicle_fire_...

I'm not saying batteries are safer than liquid fuels, by the way, because both are much safer than hydrogen.

Compressing a liquid to 30,000psi is nothing like compressing a gas. It's why hydrodynamic testing is done with water rather than air.

They measure energy density by unit volume though. So a gas is always going to look poor by that measure.

I think hydrogen fuel will really become viable when it can be safely and easily stored in solid or liquid form, when I suspect it's energy density will look a lot better.

More than 90% of hydrogen produced today comes from fossil fuels. If your intent is to reduce CO2, hydrogen is not the path you want to go.

Also quite hilarious that to produce hydrogen(inefficiently)you must first produce electricity.

You know what you could have done instead? Skip the hydrogen step and just use the electricity.

I think you can have both technologies used for different things, you know the best tool for the job. Maybe you have a ton of electricity that you just have to throw it away or pay people to take it because batteries are still not as good, if you have too much electricity you could attempt to transform it in chemical energy and store that.

I am not sure why some people think there is a Hydrogen conspiracy that is attempting to sabotage electric energy, the issue is with batteries and storage.

The issue with storage is being addressed and being fixed rapidly with battery and other technologies while hydrogen has been promised and invested in by governments for 50 years with very little results.

Some technologies with far more promise see almost no investment because the continues dream of hydrogen is always being hyped up and then governments give money to the fossil fuel or car industry to work on hydrogen.

Its far more sensible along every dimension invest money into battery and other grid storage system compared to making the highly inefficient transformation to hydrogen and back.

Not only is in inefficient, its also inherently expensive and inherently dangerous. Hydrogen sucks as a storage system and the only reason we pursue it so much is that it has been the intellectual darling since 'the hydrogen economy' came out.

Liquid Air, Liquid Metal, Redux Flow Batteries, LFP, traditional Li-Ion, Compressed air are all better technologies to invest in.

Governments put also a lot of money in green energy too so it makes sense to for them to put money in more "green" storage.

>Not only is in inefficient, its also inherently expensive and inherently dangerous.

Use best tool for the job. The natural gas I use to heat my home is dangerous too so I had to use approved professionals to install it, and I have to have approved professional come and check my installation every 2 years. When electricity would be better for my job I will use it.

Isn't a failure in logic to believe that batteries will get better and greener over time but for some reason hydrogen related stuff won't get better as well? Maybe chemists will find some efficient way to make a denser liquid fuel if we would invest enough in research.

Yes, just the best tool for the job and its not hydrogen.

Yes, hydrogen production can potentially improve. Of course, it can, if we invest infinity money into it everything can improve.

The question is with limited resources make choices about what the best couple of things are that we can invest in. In terms of basic research, some study on hydrogen is appropriate. But it is nowhere close to be the right system for grid storage, in the next 1-2 decade.

The problem is this, hydrogen is the older technology compared to these battery systems it has shown a far, far slower improvement curve. And an top of that, the cost improvement curve is even worse. Where should investment go, in places where we are making massive leaps on both the fundamentals and the cost, or to the system that is mostly stagnant.

We literally have totally new battery systems go from research to mass deployment while hydrogen with more overall investment has only improved a tiny amount.

>I am not sure why some people think there is a Hydrogen conspiracy that is attempting to sabotage electric energy, the issue is with batteries and storage.

You need to be on guard and skeptical about anyone critical of renewables, because there's been a coordinated and large-scale campaign by oil companies to push climate denialism and to pour FUD on any alternatives. And after 50 years, we're both out of time for the slow-and-steady approach and we also have technology that has major real-world adoption.

Good-faith actors are hurt by this, but there's no real alternative short of A) letting corporate campaigns control the agenda, or B) fixing our political system so corporate money isn't so effective at influencing politics. It's an unhappy situation with no easy solutions.

I agree with critical thinking, but the comment I replied was about using electricity generated probably by renewable that is stored as hydrogen. So the hydrogen cabal would use the renewable camp tech, the only people worried by that would be the batteries people(mining, creating, selling, recycling this batteries).

IMO electricity will be the better tool for most of the jobs but not all and we can't transition to electric over night.

>You need to be on guard and skeptical about anyone critical of renewables, because there's been a coordinated and large-scale campaign by oil companies to push climate denialism

So my argument that hydrogen is sourced vastly from fossil fuels is disregarded because I'm critical of renewables?

>I think you can have both technologies used for different things, you know the best tool for the job

Hydrogen industry is already a mature industry. Nobody is saying don't use hydrogen. The challenge is that people are proposing hydrogen in replacement of electricity and it's a needless extra step.

>Maybe you have a ton of electricity that you just have to throw it away or pay people to take it because batteries are still not as good, if you have too much electricity you could attempt to transform it in chemical energy and store that.

Certainly. The better use for said energy would be say desalination or many many other options.

>I am not sure why some people think there is a Hydrogen conspiracy that is attempting to sabotage electric energy, the issue is with batteries and storage.

I think you misunderstand. I care about climate change and people who think they are getting into 'green energy' via hydrogen will be wrong. The vast majority of hydrogen production is from fossil fuels.

I'm not suggesting 'green hydrogen' is a conspiracy in the sense that fossil fuel folks know hydrogen is still fossil fuels and are pretending it's green.

I'm saying there's a very huge chance that it won't be green and even if it is. It's no where near as efficient as other options.

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