I don't know what the efficiency of the process described in TFA, but from Wikipedia I see that Electricity->Gas->Electricity has an efficiency of 30-40%. There are other alternatives like pumped hydro stations that are way more efficient.
Chemical energy is dense, easy to store, and you need methane for stuff like fertilizer.
Solar energy is basically free ($30/MWh and falling rapidly). The solutions we'lp use are the ones which scale and the ones which are cheapest for storage as it will be much more expensive than the energy.
For storing for a day, that's probably sodium batteries as the cost per MWh through is lowest.
For storing for a year, you want to minimize cost per MWh stored. Right now this looks like methane, maybe hydrogen or for heating, thermochemical batteries.
This is always claimed, and is always false. Please do not repeat falsehoods.
Existing hydro generation needs a watershed. Pumped hydro does not. All it needs is a disused hilltop and earthen dike, and not always the dike.
It doesn't always need the hill: underground cavities work to pump water up out of, and to drain into.
Batteries will always be the most expensive alternative. They will be used in limited amounts, mainly for very short-term (overnight) storage.
Do you have any good numbers on real world projects? I'm very happy to be wrong here, but all the numbers I can find are either lies from nuclear shills or using existing watersheds. Most also only focus on the cost per kW which is higher than batteries and not the relevant metric (as batteries can drain in a few minutes) for season-long storage.
Also a quick back of the envelope seems to suggest emptying and filling lake Baikal could store as much energy as about a billion tonnes of chemical storage. This seems like a reasonable upper bound which would indicate pumped hydro is about an order of magnitude short of solving the problem. Current battery production is nowhere near (total cumulative seems to be about a megatonne chemical equivalent even if it is more than doubling annually it'll take over a decade to catch up), but this is expected because batteries are optimal for short term.
Overall by gut feel it seems a more feasible to make and store ten cubic kilometers of chemical fuel worldwide than move 200,000km^3 of water around.
Dedicated pumped hydro storage is typically quite shallow, with an earthen dike (if needed at all), and the only place with high pressure is at the bottom end of a penstock. It does not need to store years of water; just a day's worth is useful.
To make it impossible to mine more fossil fuels even for a mixture of slave-driving sociopaths unrestrained by law and theocrats actively seeking apocalypse we need to be able to use a MWh at night in mid winter that was produced at 2pm in summer for less than around $40 and then do it another billion times without hitting some resource limit. Hydrogen with storage is shockingly close, and if synthetic ammonia/methane or metal hydride get over the line, noone will look at fossil fuels again.
You seem to be telling me that pumped hydro is already there, but I can't find a decent source agreeing with you (or any numbers dealing with this use case for that matter).
There are actually dozens of shallow reservoirs behind earthen dams way high up in California's Sierra Nevada mountain range, many almost a century old, constructed with bulldozers that used pulleys instead of hydraulics, hauled up there on fantastically bad cart-track roads. The reservoirs feed penstocks down to Pelton wheels thousands of feet below. For storage, they just attached pumps to the penstocks to push water back up.
And I can attach a washing machine motor to my water tank. If it produces basically nothing and costs double the alternative, it's not relevant to the discussion.
> There are actually dozens of shallow reservoirs behind earthen dams way high up in California's Sierra Nevada mountain range, many almost a century old, constructed with bulldozers that used pulleys instead of hydraulics, hauled up there on fantastically bad cart-track roads. The reservoirs feed penstocks down to Pelton wheels thousands of feet below. For storage, they just attached pumps to the penstocks to push water back up.
So there are no new projects which not destroying an ecosystem that are on cost parity with batteries then?
Also as an aside, how pathetic is capitalism as an organizational system that we can't achieve the types of things that were done with horses and carts and pulley bulldozers in the past?
This makes it better than existing batteries for ~1 day time scales and roughly on par with the upcoming generation of things like sodium batteries.
It's not a clear indicator as it's obviously optimized for power, but these all seem to be big advantages specific to the site which would indicate that an artificial reservoir would have trouble competing even against batteries.
Different sources have figures that differ by a bit (presumably projections vs actual) and most seem to have some mistakes. Here's one. https://www.nsenergybusiness.com/projects/fengning-pumped-st...
I could believe that you might improve storage/cost by a factor of 10 if you found a suitable reservoir by reducing power, but that seems to back up my initial assertion that you need specific geography and to significantly change the ecosystem fairly well.
As such it seems like it is not much better than a battery for displacing fracked methane, oil, or nuclear for mediating seasonal variability (which is what synthetic denser-than-hydrogen fuel is for as it is optimized for approximately zero cost per capacity at the expense of the highest cost per joule with competitive cost per watt).
Plus batteries still have a 10-20% efficiency benefit.
We also have underground compressed air using existing deep cavities, and undersea compressed air. And underwater buoyancy, drawing floats down toward seafloor-mounted pulleys, using a winch and motor-generator on shore. Demand will not exceed our capacity to make cables and floats.
But the real answer is that there is nowhere even close to as great a need for long-term storage as you imagine, just as there is not much petroleum stored today. Petroleum is extracted and delivered continuously and reliably. Myriad tropical solar farms will synthesize ammonia year-round, shipping anywhere needed on demand, so storage is needed only until the next shipment arrives.
And HVDC transmission lines will move power from where it is being produced to where it is not, over 1000s of km, at a wholly tolerable loss rate. Much of this will move power eastward from afternoon production and westward from morning production, but also generally fill in for local production and storage shortfalls everywhere.
So Finland can have ammonia shipped in continuously all winter long, just as they ship in petroleum and NG today. Transmission lines will compete for that business.
These are more technologies that compete with batteries, not fuels. And poorly at that. CAES in ideal sites might compete with batteries for a while yet, but the others do not. Even a single truck full of ammmonia can store the equivalent to tens of thousands of cubic metres worth of displacement storage. A cubic metre float in a 500m deep body of water can store 5MJ, or about the same as a battery you can lift with one hand and buy for a few hundred dollars.
> But the real answer is that there is nowhere even close to as great a need for long-term storage as you imagine, just as there is not much petroleum stored today. Petroleum is extracted and delivered continuously and reliably. Myriad tropical solar farms will synthesize ammonia year-round, shipping anywhere needed on demand, so storage is needed only until the next shipment arrives.
Moving energy 2000-4000km as not-electricity is strictly a harder problem than storing it for 6 months and is solved with a subset of the same solutions. The main upside is energy input is cheaper and there is less idle time. This is definitely part of the solution but comes under the same heading.
HVDC systems are a solution for most of the issues, but distant solar isn't completely uncorrelated. Also no country is going to stake their survival on a system with cascading failure modes that can be triggered by anything from war, to a heat wave, to a blizzard, to a cyclone, to a forest fire, to political games. Thus capacity for months of backup is still required.
All of this is moot anyway because your other comment led me to find sources stating green ammonia is already within 50% of cost parity with fossil fuels for the cheapest solar energy sources and ammonia fuel cells are now viable as well with the same technology. Between that and thermochemical storage, fission is obsolete immediately and fossil fuels only need one more price shock for the transition to start.
Also none of this supports your original assertion that pumped hydro meaningfully exists in a non-ecosystem-altering way.
You are always free to invent falsehoods about pumped hydro, as about anything else.
PVs solve net energy needs. Perovskites might even make them do so without needing strategic mineral reserves. But they don't really provide energy security, and keeping fossil fuel infrastructure working for 1 month in 30 is extremely costly.
> You are always free to invent falsehoods about pumped hydro, as about anything else.
Then show the real numbers. I did. Demonstrate it being viable as a significant portion of primary energy in a typical country as a new project.
Better than fuels at present, but inherently fragile so not a complete solution. Also those are just claimed building costs not including operation (and assuming it lasts about as long as the pv), and the natural monopoly spawned always winds up being a massive tax money sink, so it's not clear that building thousands of hvdc lines is going to work out.
AFAIU it is even less fragile because it's usually 'point-to-point', which means to integrate it into the grid you need very modern substations with the ability to 'transform' the DC into the AC of whichever pre-existing grid by means of mass cascaded https://en.wikipedia.org/wiki/Insulated-gate_bipolar_transis...
Which in turn makes the grid around these substations smart, the more, the smarter. Because you have much better ability to switch and regulate(diversion from same frequency in AC-grid due to dynamic load or failure) much faster.
Think of the difference between the large external 'power-brick' for older laptops vs. the small switching power-supplies for contemporary notebooks. Just in reverse.
Nothing? The point is transmission is extremely fragile. To physical conditions (weather, accidents, faults). To market effects (massive price gouging during those failures due to lack of buffer). And to market failures (harmful monopolies always form around private utilities and neoliberals always privatize utilities).
Then if the oceans are involved, cost becomes a non-starter.
That remains to be seen. Some people seem to think different.
https://electrek.co/2022/04/21/the-worlds-longest-subsea-cab...
&
https://xlinks.co/morocco-uk-power-project/ is just the latest of those ideas/projects. I think it was on HN too.
People like to equivocate this with making entire countries uninhabitable or ongoing destruction.
It also requires vast quantities of concrete (and thus has high one time emissions)
We should still avoid it where we can now that we know better.
Hydro power dams use up a watershed, but those are not being built for storage systems. Pumped hydro storage does not consume a watershed or harm wildlife or fisheries. Pumped hydro does not need concrete for construction.
Please do not repeat this falsehood.
- Is at a site of a type that is available with over 100x the capacity of fenging (ie. a hill with a dirt berm would count if there are 4000GWh of hills that could be plausibly used somewhere). If it does this it will help, but is still several orders of magnitude shy of replacing fossil fuels.
- Fulfils your criteria about not destroying an ecosystem.
- Is not built on top of a past project unless there are enough of whatever the past project is to fulfll criterion 1 (ie. a quarry or mine is fine if there are many similar mines or a handful of immense ones) or the cost of repeating the project elsewhere is included.
- Can empty its reserves in 2 months
- Doesn't take up a prohibitive amount of surface area (is at least 20kWh/m^2 or at most 10x the size of a solar array to fill it).
- Has an operating cost under $30/MWh of stored and produced energy
Otherwise pumped hydro does not meaningfully exist as it cannot beat batteries (the thing that is a long way from being good enough to replace fuels) or must destroy a watershed or other ecosystem.
There is no shortage of land to use for elevated reservoirs, and (again) no implied threat to watersheds in building them. There is no need for "at least 20 kWh/m^2". Reservoirs have many uses that all add value. They may store energy and water, provide recreation, habitat, irrigation, and a site for solar, all at once. There is no need for them to store 2 months' power. There is very little economy of scale: a dozen reservoirs are as good as one. Construction cost is not proportional to capacity. At worst, it goes as the square root, to build the perimeter dike.
Extraction rate is a question of how big and how many Pelton wheels attached to generation equipment you care to install.
And, as always, immediate and local cost will dictate choice. There is no need for universal numbers or a single answer for everybody.
Further intntional misrepr#sentation. Batteries solve the short term storage problem (especially sodium ion batteries). You're proposing a much worse solution to the short term storage problem as if it is relevant to the remaining unsolved problem (long term storage). Solving the long term (in space or time) storage problem yields solar supremacy -- conditions in which it becomes untenable to open a new fossil fuel facility or even keep existing ones open in 10 years even with trillions in ongoing subsidies.
> Construction cost is not proportional to capacity. At worst, it goes as the square root, to build the perimeter dike.
You need to make it deeper, or use more land. And when the largest project in the world is at cost parity with batteries in spite of using an existing project and river, that's a damning indictment of anything smaller.
The "largest project in the world" is, by definition, not representative.
There is, because it is the main impedement to the universality of renewable energy.
> The "largest project in the world" is, by definition, not representative.
Yes. Extremely large, recent infrastructure projects by the CCP tend to have vastly lowe stated costs than anything smaller or in another place. If it's unusual\y expensive, show me one which is representitive. Show me a breakdown of a small project (or any project) which uses a typical hill and costs less than projected battery costs at time of completion.
It’s not that great for river fish, either.
But pumped hydro is a completely different proposition.
Meanwhile, each dollar diverted to nukes from building out solar+wind+storage brings climate catastrophe nearer. The immediate cause for catastrophe will be global thermonuclear war triggered by ... more subtle ... effects of the change.