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| ▲ | bryanlarsen a day ago | parent | next [-] |
| In most practical cases, the cheapest way to provide carbon-neutral seasonal storage is to use the existing natural gas generators and feed them with carbon neutral synthetic gas. That synthetic gas is super expensive, but when you're only running it a couple times a year the gas is a tiny percentage of the cost. |
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| ▲ | crote 21 hours ago | parent [-] | | This is such a painfully obvious solution that it is almost embarrassing that it even needs to be mentioned. The "but sometimes..." crowd is obsessed with the few hours a year when it is dark, windless, battery storage is empty, hydro isn't available, and all neighbors have the same situation. Who cares, just use gas peaker plants! We already have them! Our goal is not and has never been to get a 100% solar grid. Our goal is to reduce CO2 emissions as soon as possible, and as fast as possible. If that means running gas generators for a few days every year, then that is totally fine. Want to feed it with synthetic gas, or use carbon capture on the exhaust? Even better. Running cost is irrelevant, it is more than compensated by the basically-free electricity during the summer, do whatever is cheapest to build. On top of that, you could perhaps even leave the turbines running without being fired the rest of the year. It would provide a nice source of inertia, after all - why build a standalone flywheel when you could just repurpose an emergency generator? |
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| ▲ | bluGill a day ago | parent | prev | next [-] |
| The problem with pumped storage is most of the places we can use it are already taken and have been for years. > pumped storage is still significantly cheaper for seasonal storage Only because most of the costs have been financially depreciated long ago. Try to build a brand new dam nearly anyplace and the costs will be much higher. |
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| ▲ | bryanlarsen a day ago | parent [-] | | > we can use it are already taken There are literally millions of unused locations identified that are suitable for pumped storage: https://re100.eng.anu.edu.au/global/ hydro generation sites are mostly taken. pumped storage doesn't need flow, just 2 reservoirs (one or both of which can be built) and a elevation change. > a brand new dam pumped storage facilities generally don't use dams. | | |
| ▲ | bluGill a day ago | parent [-] | | You have to have something to keep the water contained between the two. | | |
| ▲ | bryanlarsen a day ago | parent [-] | | But those aren't dams. Dams are something that stops the flow of water. And it's this stoppage that causes the environmental problems. Reservoir walls might look like dams, but they're not dams. | | |
| ▲ | crote 21 hours ago | parent | next [-] | | The main enviromental complaint is in flooding huge areas of land, which is the case with both dams and reservoir walls. | |
| ▲ | bluGill a day ago | parent | prev [-] | | Pedantically you are correct. However you are completely missing the point. |
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| ▲ | Rover222 a day ago | parent | prev | next [-] |
| I meant it's cheaper when considering building an entirely new pumped storage facility, vs battery storage. |
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| ▲ | bryanlarsen a day ago | parent [-] | | A GWh of pumped storage is $25M, a GWh of batteries is $100M. More concretely, https://en.wikipedia.org/wiki/Fengning_Pumped_Storage_Power_... was built for about $50/KWh. Which is about the same price as batteries. But that's a daily storage facility. If you undersized it's pumps so it took weeks to refill rather than ~10 hours to make it a seasonal facility, it would have been significantly cheaper. |
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| ▲ | s1artibartfast a day ago | parent | prev [-] |
| can you explain the economics of that to me, because it doesn't track my understanding. Are you just talking about total capacity dominated breakeven? The economics of both want daily cycles. Water has a more favorable power/$ scaling curve for storage if you have a site. |
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| ▲ | bryanlarsen a day ago | parent [-] | | Any sort of seasonal storage is horrendously expensive and completely infeasible using economics alone. It's really only a concern once our power grid is 98%-99% carbon-neutral and we want to get it to 100%. A battery storage facility has watts and watt-hours roughly equivalent. A typical storage battery is around "1C" -- it takes about one hour to fully charge or discharge. The limiting factor on the build price is the MWh -- if you keep the power the same but double the storage the price of the plant still roughly doubles. A typical daily storage facility wants around 4C, so that coupling between power and energy for batteries is not a significant drawback. Seasonal storage is not coupled in this way. You increase MWh by increasing the size of your reservoirs. You increase MW by increasing the number of pumps/turbines. MWh is usually a lot cheaper than MW. A typical pumped storage facility today has MWh only being 10-20X the MW which means they're tuned for daily-ish usage (see top line). One tuned for seasonal usage would have that ratio >> 100. | | |
| ▲ | s1artibartfast a day ago | parent [-] | | humm, I was thinking about it differently.
I would expect most pumped storage to have variable and diminishing cost per MWh (up to a point). Part of this is the turbines, but also other fixed project costs and economies of scale. If you hold MW fixed, the First MWh of the project is going to be more than the next until you hit diminishing returns due to specific site saturation. As an interesting side note, China has roughly 80 GW of pumped storage built or under construction. Most of the big ones I have looked at are about "10C". This is comparable to the GW output from their nuclear reactors built or under construction. Tangent: have you been following the Medog Hydropower Station?
https://en.wikipedia.org/wiki/Medog_Hydropower_Station |
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