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Comment by sofixa | Hacker News Reader

> Massive battery installations plus solar are already cheaper than operating an existing natural gas peaker plant in California

Aren't natural gas prices pretty high currently ? And with many countries moving away from gas in their electricity production, or at least moving it to peak-only, the price will go down.

Furthermore, batteries with what capacity? I highly doubt they're of the size required to sustain multi-week storm/bad weather events, even for the rarity they'd be in sunny California, le alone the rest of the US.

And from a globally strategic point of view, isn't it better to focus battery capacity on decarbonising sectors such as transportation ( cars, trucks, even trains apparently ( i still think electrifying the network is a better idea overall, but i can see how it'd be cheaper upfront to just add a battery car)) instead of "wasting" TWhs of battery capacity for long term storage.

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Natural gas prices in California are dominated by transport costs, not production costs.

To survive a multi-week storm/bad weather event with a grid containing only solar and wind, you need a 3x overbuild of solar+wind in an optimal mix, along with a continental grid and 3 hours worth of batteries is all you need for 99.99% reliability: https://www.nature.com/articles/s41467-021-26355-z

> containing only solar and wind

Conveniently leaving out hydro and nuclear… [Edit: which only makes this easier.]

Nuclear isn't sustainable, extremely slow to build and astronomically expensive. It's not an option.

Hydropower is sustainable but has a very limited potential,and its impact on the environment is much, much higher than comparable wind/solar installations.

Nuclear is very sustainable. With enrichment, the world's known uranium supplies (5.5 million tons) would last about 30,000 years at present usage rates, if used with fast breeder reactors. The NEA estimates that's a sixth of what's out there. Obviously this doesn't go as far if you scale it up 10-100x, but in addition, there's about 4.5 billion tons dissolved in seawater.

This is just the uranium, not even touching the thorium. And once we get to this point, there is uranium on the Moon and Mars. The waste-management problem is harder in the political sense than the engineering sense.

> With enrichment, the world's known uranium supplies (5.5 million tons) would last about 30,000 years at present usage rates

How does it matter if you enrich or you use a natural uranium reactor? The amount of fissile material is exactly the same.

> if used with fast breeder reactors

But that's breeding, not enrichment.

> but in addition, there's about 4.5 billion tons dissolved in seawater.

...aaaand there goes your requirement for a breeder. Breeders may very well turn out not to be worth the bother.

Burning down the existing nuclear waste is a nice ability of breeders.

There's not a lot of waste to be burned anyway. If you separate U238 from the spent fuel, you don't have lot of mass left.

The big advantage of nuclear is that it is reliable. However, the paper I linked above says wind and solar can be reliable, so nuclear no longer has any redeeming qualities.

A reliable grid of nuclear + renewables is significantly cheaper than without the nuclear, according to the EU study that has been circulated here a couple months back.

The abstract for the paper (thanks for that link!) says:

> Yet even in systems which meet >90% of demand, hundreds of hours of unmet demand may occur annually.

... and the low end of the range is 72%, which leaves many more hours unaccounted for. Some amount of reliable, clean power is needed on top of the renewables.

Yes, the abstract sucks. Those are the numbers without batteries or over-building. To get to 99.99% you have to add all the mitigations: 3x overbuild, 3 hours of batteries and a continent wide grid.

A continent wide grid is easier said than done.

There’s already a lot of nuclear and hydro built!

It's a paper, not a plan. It's not saying you should switch to only wind and solar, it's that you can.

This is a proper plan: https://mitpress.mit.edu/books/electrify

It has a role for existing hydro and nuclear.

Oh sorry, I misread your original comment as saying that plan wouldn't work because it required too much overbuilding, when actually you were saying that it would work! Yes, our existing hydro and nuclear just makes it even easier to switch.

> And with many countries moving away from gas in their electricity production, or at least moving it to peak-only, the price will go down.

If there is less consumption I would imagine the price would rather go up.

Normally if nothing else changed you'd expect prices to go down since the most expensive providers (= those with highest costs of doing their business) pulling the price up leave the market.

That would happen if supply goes down even more. Is this the case here ?

This was my thought too. I hope OP responds with why they think lessened demand would lead to lower prices. That doesn’t make any sense.

It's a consequence of a demand curve: https://en.wikipedia.org/wiki/Demand_curve, an established concept in economics

It’s unclear to me if that accounts for second order effects? For example, lower demand leads to lower prices, sure. But then those lower prices lead to higher demand. This should quickly reach equilibrium if buying and selling were spur of the moment decisions with no long term consequence. But in the energy market that’s not the case. Building a power plant is a commitment to buying that product, which locks in that demand regardless of price. And so continued low prices could lead to more construction of gas plants, which leads to an increase in demand.

Basically what I’m saying is that the demand curve models a simple market with a fungible good, which can be bought and sold easily. We have to recognise that it’s like studying spherical, frictionless projectiles in physics. A good starting point, but not how the real world works.

>For example, lower demand leads to lower prices, sure. But then those lower prices lead to higher demand.

Supply curve is missing in these statements.

> Building a power plant is a commitment to buying that product, which locks in that demand regardless of price.

What? Is there some sort of law that requires buyers to buy all of the electricity a power plant can produces?

> And so continued low prices could lead to more construction of gas plants, which leads to an increase in demand.

This is backwards. An increase in demand for electricity might lead to construction of new gas plants, with a bet that even with the increased supply, electricity buyers are willing to pay at least x price for electricity for y duration sufficient to earn a z return on investment for building the new gas plant.

I hear a lot about replacing gas with hydrogen (completely doable with the existing infrastructure).

Any particular sources? From a quick web search, it sounds like hydrogen has a very different energy density (Joules/cu. m., or BTU/cu. ft., or whatever), very different combustion and leak safety characteristics, and can either leak through or embrittle many parts of the existing (natural gas) distribution infrastructure.

If that's anything resembling correct...then the change-over would be more like replacing all-diesel fuel & engine infrastructure with gasoline.

This is the oil/gas industry trying to keep themselves relevant. Thats why we keep hearing abouti it.

Hydrogen can be cheap (extracted from natural gas) or green (electrolysis). It can't be both.

Hydrogen is also a monumental PITA to store.

Electrolytic hydrogen can be cheap as long as 1) electricity for electrolysis is cheap and 2) electrolyzers are cheap. 1) is reasonably easily assured by shaving off overgeneration of electricity from renewable power plants. 2) is a matter of electrolyzer R&D, although it's true that it's slightly complicated by the former solution of 1) by decreasing their duty cycle. Nevertheless, 1) is the dominant problem.

As for storage, it's true that storing hydrogen is problematic but once I calculated that even existing facilities for natural gas in, say, Germany would be sufficient for a whole month of the whole country's grid running off of hydrogen. This is less than the several months provided by using the same storage for natural gas, but since in the following decades, the demand for this gas is going to shrink severely as German buildings are going to be replaced by low-energy buildings (pursuant to the 2010/31/EU Energy Performance of Buildings Directive and the 2012/27/EU Energy Efficiency Directive, as well as presumably future regulations), this capacity might be freed up, and in any case it's a much larger capacity than is predicted to be required (https://www.sciencedirect.com/science/article/pii/S001429211...) for a 100% renewable grid in Germany.

One interesting idea I don't know the feasibility of but is tempting anyway is ultra-large-scale liquid hydrogen storage. Considering the square-cube law and low density of liquid hydrogen stressing the structure (just 70 kg per cubic metre of liquid hydrogen tank, as opposed to 1000 kg per cubic metre of a water tank, for example), ultra-large-scale storage of hydrogen could be feasible in principle -- certainly much more than for example liquid hydrogen storage for a car, and in industrial settings to boot (as opposed to cars handled by ordinary citizens).

>even existing facilities for natural gas in, say, Germany would be sufficient for a whole month of the whole country's grid running off of hydrogen.

As I understood it natgas storage facilities wouldnt keep hydrogen. It'd leak.

Gas infrastructure used to deal with coal gas which contained ~50% of hydrogen. Somehow it worked back then. Doesn't seem like an unsolvable problem to me.

Green hydrogen can be cheap if electricity is cheap. With the falling prices of renewables, that is quite likely to happen soon.

But green hydrogen is only useful if electricity is cheap but batteries are expensive. The original article indicates why batteries aren't expensive and are likely to get dramatically cheaper over the next decade. That's why hydrogen is likely to stay irrelevant except for niche use cases.

Green Hydrogen is also good if you absolutely need Hydrogen. In this case, Green Hydrogen at twice the cost of getting it from Natural Gas is still a win.

e.g. steel manufacturing can use Green Hydrogen for the Reduction reaction, as part of the alternate pathway without coal.

Oh certainly. I added the "niche use case" modifier. Compared to transportation and power generation, steel manufacturing is a "niche use case". It's a massive use case, but compared to the transportation and power generation use cases people usually hype hydrogen for...

> But green hydrogen is only useful if electricity is cheap but batteries are expensive

That is absolutely not true. How exactly will cheap batteries for example allow you to make ammonia for agriculture, the chemical industry, etc.? Current global ammonia production alone is worth something like two hundred gigawatts of power continuously pumped into electrolyzers. That's like ten percent of global electric generation at the moment.

Compared to the cost of large-scale hydrogen storage batteries will always be expensive. This is why grids will use hydrogen for long-duration energy storage instead of batteries.

Which is effectively a battery! Hydrogen production is energy intensive, but if you produce it with excess energy capacity and then use it when it's needed, it's a decent energy storage method. Though mobile applications (air travel, trains, etc) are more likely to dominate in the shorter terms as it's lighter than batteries in high power applications

The only feasible way to do that is to use the hydrogen at the source of production to make methane, using direct air capture and reduction of CO2 (Sabatier process) as the carbon source. This is because existing methane pipelines would be embrittled by hydrogen and would soon fail, with disastrous consequences.

Hydrogen from electrolysis is best viewed as an intermediate feedstock for further chemical synthesis, as with ammonia production, methane production, jet fuel production, etc. There is perhaps potential for dumping excess grid electricity into hydrogen storage tanks at power plants as a temporary storage system, i.e. converting the hydrogen back to electricity via fuels cells (not turbines!) to meet electrical demand later.

Hydrogen storage requires special alloys to avoid steel embrittlement however, so it's fairly expensive.

What is the efficiency of the hydrogen, air capture, methane, burn cycle?

34-44% for hydrogen and 30-38% for methane [0].

[0]: https://en.wikipedia.org/wiki/Power-to-gas#Efficiency

Ah, great. So the incremental loss of going from crazy-talk to actually-reusable-infrastructure is not groundbreaking.

" I highly doubt they're of the size required to sustain multi-week storm/bad weather events"

Those bad weather events come usually with lots of wind - which you can harvest, too. So the solution might just be the often propagated energy mix.

And you can build batteries without any rare elements(natrium instead of lithium), so if you build enough of them and enough solar and co. then who cares if some of that energy gets lost, as long as the grid remains stable?

> Those bad weather events come usually with lots of wind - which you can harvest, too. So the solution might just be the often propagated energy mix.

As i have said a few times around here, there's a meteorological phenomenon across Europe now ( since September, and projected to go well into the winter), with bad weather ( clouds, low sunlight), low temperatures, and low wind speeds. Traditional hydro and tidal energy generation are still OK, but solar and wind are at historical lows. And again, this is ongoing for months.

Furthermore, a bad weather event like storms can have winds that are too fast for a wind generator to operate safely.

At least for Germany, that's just not the case. Wind is going quite strong this quarter, so strong that it easily offsets the lower-than-average solar generation. And that's mostly due to the weather – expansion was massively stalled by conservative administrations in the last few years.

Well, I know that, because I have to sustain that lack of sun and wind here, too.

But the south(west) of europe still has lots of sun, like it almost always has. And a bit further south, there is always sun in the desert.

So yes, I would not deconstruct all the conventional power plants, just yet. And I think having some backup gas plants is not a bad idea, either.

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