How to Produce Green Hydrogen for $1/kg (2023) | Hacker News Reader

How to Produce Green Hydrogen for $1/kg (2023)

caseyhandmer.wordpress.com

49 pointsbschne43 comments

When doing back of the envelope calculations like this, it is helpful to look at the raw materials cost that goes into the capex figures.

For example, in transformers there is a lot of steel and copper. You likely won't reduce their costs much unless you figure out how to build them with less steel and copper.

But in electrical inverters, there is only a little steel and copper, and the rest of the cost is in fairly specialized silicon, software, and high design costs. There big cost reductions are probably possible at scale - perhaps to just 1% of today's inverter costs.

Now remember that whatever you're building needs to compete not with today's system, but in a hypothetical future with those optimized inverters.

Your 60Hz inverters will use about as much copper (or aluminum) and steel as a 60Hz transformer, or a 60Hz generator. How much of it you need is mostly determined by the frequency, voltage, and current it will handle.

What is another advantage for the people in the article, because they still need DC/DC converters, but they have complete liberty to pick its frequency.

Inverters do not operate transformers at 60 Hz. Many of them don't have even have isolation transformers at all. Their magnetic components are comparatively tiny. Those that do have isolation transformers will run them at high frequencies to keep the core size down.

I don't think any solar projects use 60Hz inverters. ~10kHz seems to be the industry standard, although I believe some micro inverters go right up to 1Mhz (saves on capacitors, copper, and steel, but you have to buy much more expensive silicon)

If you put the energy into the grid, you do it with 50Hz or 60Hz.

According to the article, they are feeding the DC current straight from the solar panels to the electrolyzers. They don't need transformers.

Some transformers use aluminum instead of copper.

That isn't as big a win as you imagine, since while the copper is more expensive, the aluminium is less compact (needs to be thicker to get the same resistance), which in turn means the wires need to be longer for the same number of coils, which means they need to be even thicker to keep the same resistance.

That in turn makes the coils much bigger, which also means the steel core needs to be bigger to accommodate the coils, and thicker to keep the magnetic resistance (reluctance) low. Making it thicker again makes it longer means it needs to be even thicker.

Basically, one property being a bit worse (electrical resistance of the coil material), makes everything else much worse.

Some use GPUs, math, and attention.

I believe we were explicitly told that attention is all you need.

Transcription error, it should have been all ewe need.

And some use living metal and energon.

Presumably this also applies to desalination and other energy intensive applications.

Basically, cheap solar combined with cheap capex equipment running 25% of the time can beat trying to run expensive capex equipment 24/7 once energy costs dominate the equation.

Note that this future, as well as requiring insane amounts of super cheap electricity, also requires someone to figure out cheap direct air capture of CO2. Nobody is even remotely close to that yet.

For what it's worth, I think they (as in Terraform) intend to also tackle that part of the problem.

I think one advantage they have over current DAC approaches is that since they're going straight from their capture material into their methane reactor, they are both creating a valuable output from their carbon capture (where as most current systems need to add sequestration costs).

There's a lot we can do with hydrogen alone. But yep, carbon capture from the air is very important.

> Cheap direct air capture of CO2.

What is wrong with trees or algaes? Seems to me it doesn't get much cheaper than that.

That is literally what Casey Handmer, author of the post, has a company working on, because he’s accurately projecting the exponential solar energy increases coming.

One thing which frequently seems to be overlooked it that clean, preferable distilled, water is needed to fuel a hydrogen electrolyzer (the less clean the more issues when trying to electrolyze it).

Which has it's own monetary, energetic, and potential social cost. A potentially not so small cost, too. Depending on location and climate change.

On the contrary, distilled water is not conductive enough. You do need some ions in it. Inexpensive chemicals like sodium hydroxide/ bicarbonate also prevent limescale, avoid producing chlorine, etc...but then you end up with salty/alkaline brine. Which might be the true issue here, how to dispose of industrial quantities of that.

This is a whole heck of a lot of assumptions and hurdles they’ve described to get anywhere close to that $1/kg price… I wish them well, but 2027 isn’t too far away here.

They are quite mundane assumptions. As they said, an electrolizer is a very simple thing. I wouldn't be surprised if they already are testing something that gets close to those numbers.

The real hard part for the H2 generation is scaling it. And the real hard part of their goal is the CO2 capture.

An electrolyzer is conceptually simple.

The process that results in a novel commercially-viable electrolyzer that exists in quantity that operates on cheap materials and achieves their described output over many years of unattended operation is not simple.

The title of this article is correct but seems to be misleading some readers. Their goal is not to produce hydrogen, but to produce synthetic natural gas. Using solar to produce hydrogen as a precursor is just the particular approach they've chosen:

We’re developing a scalable electrolyzer to deliver the cheapest possible green hydrogen, which we use as a precursor chemical to make cheap synthetic carbon neutral natural gas in our Terraformer.

As a result, some of the comments so far that correctly point out the difficulties of establishing a hydrogen infrastructure are missing the point. They aren't planning to distribute hydrogen, and don't need such infrastructure. Instead, they're planning process the hydrogen immediately and internally and then piggy-back on the existing natural gas infrastructure.

Note that large amounts of natural gas distribution networks are hydrogen-capable, and adding decarbonization reactors to the supply allows CO2-free operation of formerly natural gas appliances.

IIRC the process is thermal cracking of the methane, which can use solar energy.

Most "hydrogen-capable" networks cannot pipe pure hydrogen, only natural gas "sweetened" with hydrogen.

"Green" hydrogen is anything but. Electrolysis is a fundamentally inefficient technique. Scale it all you want, but you will hit diminishing returns faster than with water desalination. Natural hydrogen is the way to go, and I hope hydrogen wells will become as ubiquitous as gas wells in 50 years' time.

> Electrolysis is a fundamentally inefficient technique

Yes, but if we’re seeing huge overproduction times on renewables that might not be a showstopper. Hydrogen is a poor choice for powering things like cars compared to the alternatives but if you have industrial processes which need a flame on the order of 2,000°C it could make sense to have peak capacity wind/solar splitting hydrogen & oxygen for those.

To add to that, there are already a number of energy intensive processes that already use hydrogen. Manufacturing fertilizers for example. Currently the hydrogen for these Processes is produced from natural gass but it's a matter of time before production using green energy becomes cheaper.

According to some reports, there are enormous amounts of "gold hydrogen," that is hydrogen in underground deposits, that's just waiting to be extracted:

https://www.newscientist.com/article/mg26134760-500-the-gold... ( https://archive.is/4g6dw )

How this enormous non-polluting energy source went unnoticed for decades is mystifying to me. That Toyota and other big auto manufacturers are investing in hydrogen fuel cell and even hydrogen combustion engines means that many people who know what they're doing are betting on this future. The math doesn't really work that well for a "green hydrogen" future, but it may work for a "gold hydrogen" future.

I was under assumption that, to reach $1/kg, hydrogen should be byproduct of electrolysis of sea water with additional products such as chlorine, calcium carbonate ( precursor of cement ? ), other precious metals, etc combined to reduce price of the hydrogen.

To extract 1kg of hydrogen with electrolysis you need ~50 kWh with inefficiencies (39.4 with no losses)[0], while one kilo of hydrogen only has 33.6 kWh[1]-roughly 1.17kWh to produce 1 kWh worth of hydrogen (no losses). For diesel, it seems to be quite similar-roughly 1.18 kWh per 1 kWh, however in reality at current efficiencies for hydrogen it is more like 1.5 kWh/1kWh. It seems companies need more incentive to switch to hydrolysis based solutions to cancel out the much higher costs of hydrogen storage

[0] https://www.weforum.org/agenda/2023/09/seawater-electrolysis...

[1] https://rmi.org/run-on-less-with-hydrogen-fuel-cells/

How far does an average car go on 1kg of Hydrogen?

“One kg of hydrogen contains about the same energy as a gallon of gasoline. Today a fuel-cell electric vehicle with 1 kg of hydrogen can drive approximately 60 miles, compared to conventional vehicles, which get about 25 miles on a gallon of gasoline.”

Source: https://www.energy.gov/eere/vehicles/articles/hydrogens-role...

60 vs 25 shows the ridiculous inefficiency in ICEs: a huge amount of the power in gasoline is wasted as heat- and then some of the rest is wasted again because you can’t reclaim it via regenerative braking. Hybrid fuel-cell vehicles are a great alternative to BEVs, but only if we can get the production, storage and transport of hydrogen solved.

> Hybrid fuel-cell vehicles are a great alternative to BEVs, but only if we can get the production, storage and transport of hydrogen solved.

There’re fuel cells which oxidize propane instead of hydrogen, here’s an overview https://www.sciencedirect.com/science/article/abs/pii/S00162...

We have already solved storage and transport of propane. Production is harder because natural gas is so cheap, but there’s some promising R&D https://news.ycombinator.com/item?id=37218727

Thanks, that's not bad at all!

The bigger problem is transportation and storage, not comparative energy density. Still, my hunch is that shipping goods through trucking, planes, and ships is more likely to use hydrogen in a 0-emissions world than anything else.

I'd take the other side, if that was a bet.

Trucking is almost certainly going to be primarily batteries. Electricity is always going to be cheaper than hydrogen made from electricity. Trucking is a low margin business, so cost is the primary consideration.

Batteries can be used for short distance flight, but they don't work for long distance flight. There hydrogen will be competing against synthetic kerosene. Green hydrogen is cheaper than synthetic kerosene but the big problem is certification. I figure it'd take 20 years, and that clock hasn't started yet. Synthetic kerosene can be used in existing designs.

Shipping is volume sensitive, not weight. My prediction is that they will more likely switch to ammonia. Given how easy it is for ships to jurisdiction shop, I imagine it will be a long time before they switch.

Batteries take a long time to charge and I believe time on road is a bigger cost factor. Hydrogen can do ~1000 KM (prototype from Daimler) vs 3300 KM for diesel trucks. Refill time is ~30 min to full compared to 5 minutes for diesel. The Tesla semi claims to do ~800 KM and can get back 560 miles after 30 minutes. So the EV semi is ~40-50% the efficiency of a hydrogen one. Now of course, there may be ancillary reasons why EV might still win (e.g. batteries continue to scale better because they have so many more uses & thus get better economies of scale).

Ultimately though, I’m not 100% sure battery production can keep up. Lithium production is growing by ~20% YoY and that’s just from transitioning a small portion of our automotive fleet to EV. Getting to 100% consumer automotive EV may bump by 2035 which is a common target may bump that up as would using it for grid scale storage. It’ll be interesting to see how the price of lithium keeps up with that increased demand as we exhaust the easily accessible deposits and have to start mining more expensive deposits.

You’re probably right about e-kerosene for aviation and ammonia for shipping although neither of those is actually net 0 in practice (+ emit all sorts of noxious other gasses). Hydrogen would probably be the cleanest although it has larger logistical challenges.

Truckers are required to stop for 30 minutes every 4 hours. That's enough time to add another 4 hours of range to a battery.

If we had a lithium shortage the price would be spiking. Instead it's crashing. There are only a few kilograms of lithium in each vehicle battery, so the expanded supply is able to keep up.

https://www.dailymetalprice.com/metalpricecharts.php?c=li&u=...

P.S. A diesel semi either has extra tanks so it can go 3000km or it doesn't and can fill in 5 minutes, but not both. Not that it affects your point.

> The current decline in lithium prices can be primarily attributed to the slowing growth of electric vehicle sales in China. This is coupled with the broader slowdown in the Chinese economy.

https://carboncredits.com/why-lithium-prices-are-plunging-an...

> California and the federal government had different rules related to the number of hours truckers may drive without a break. Under California law, truckers must take a 30-minute off-duty rest break for every five hours worked and a 10-minute off-duty break for every four-hour period.

> Federal law, on the other hand, required fewer breaks, less often. In the court case IBT v. FMCSA, the Ninth Circuit Court of Appeals upheld the FMCSA’s decision to preempt California’s meal and rest break rules. The court upheld that interstate drivers are exempt from California’s meal and rest break rules because they are “incompatible” with federal regulations.

> Barring an unexpected reversal by the U.S. Supreme Court, truckers in California will satisfy their meal and break obligations under federal regulations without the need to abide by California’s laws in this matter.

> Specifically, these federal rules mandate a break of at least 30 consecutive minutes after 8 cumulative hours of driving time.

It’s 30 minutes of break time every 8 hours not every 4 and the only time it was close to that was temporarily while California had regs that were in effect until SCOTUS overturned.

https://www.gbw.law/blog/2021/march/what-are-california-s-re...

I think you’re right though about long haul trucking in the near term though - I think EVs will probably move first if Tesla scales up production this year & capture the market and mind share and hydrogen will not be able to compete and you’re right about aviation in the short term. Shipping though is ambiguous because it’s still too early to tell who’s winning and aviation may switch long term as part of a decarbonization and anti-pollution push if that ever happens.

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