[tgtweak]

In theory you can use any power source - hydroelectric, geothermal, nuclear, wind - but the benefit to solar is that you can fully utilize it when the sun is shining and store the output (compressed natural gas) for storage, transportation and use off-hours.

You could also technically use this as a grid-battery, taking in excess grid energy when it is cheap and converting it into natural gas that can be run back through a gas peaking plant that spins up to meet peak demand. You could also look into SOFC fuel cell plants [1] to convert the stored natural gas into electricity at 60% and heat at 30% (the heat is high temperature which is good for cogeneration or as a direct heat source). There would need to be some very large spreads in margin on those to make up for the fact you're likely double-dipping on inefficiencies when going from electricity in -> natgas production -> storage -> generation -> electricity out.

On that same note though - in some free and open energy markets it is not unheard of to buy at <$10/MWh during excess production periods and sell at >$200/MWh at peak on-demand - plenty of margin for arbitrage there - as the tesla megapack facilities have demonstrated in Australia. In comparison a 4MWh megapack facility (2MW in/2MW out) is priced at $1.9M before installation [2]

[1]https://assets.bosch.com/media/en/global/stories/sofc/solid-...

[2]https://twitter.com/SawyerMerritt/status/1643488856946122754...

(updated for M/Mega - thanks)

[martinald]

Yes exactly. In the UK power is becoming increasingly negative in pricing when there is high wind + solar output. This is actually increasingly alarmingly rapidly (and there is 3-5GW of offshore wind, plus loads of utility scale solar coming online).

Prices are then very high when wind and solar is low - which happens to be when demand is the highest (cold weather snaps in winter which tend to result in very low windspeeds).

National Grid is already paying £1bn/yr to turn off wind farms when supply is too high (plus paying a fortune for new nat gas peakers, which are limited by law to run for 10 days a year max). It's projected that curtailment payments to wind farms will reach £4bn/yr.

While some of this will be rectified with more transmission capacity (there is a 4GW offshore HVDC link being built between scotland and england), if the claims of terraform are true and hold up at scale, I think this is the actual breakthrough people have been looking for.

These could be connected to substations near wind farms (which also happen to be near major gas interconnectors from the north sea) and generate when power prices were low or negative, which will be a large amount of the time. They'd then get paid not only for the arbitrage in gas prices but also they would be able to take (most/all) of the curtailment payments national grid is paying the wind farms.

To be clear batteries do not work particularly well for a market like the UK. Batteries work well for overnight storage of solar, they do not work well for northern climates like the UK that require weeks of storage of power to cover low renewable output in winter. That's not to say there isn't loads of batteries being constructed right now, there is, but it's to cover very short term movements in supply and demand - the much harder problem is covering days or weeks of low output.

[arrowsmith]

I don't get it, why does it cost billions to turn the wind farms off? Why isn't it free?

[japanuspus]

Because some of the windfarms still run on legacy contracts where they were incentivized by a guaranteed selling price for the power they produce. They are reimbursed for the loss of income they suffer due to curtailment.

[throwaway2562]

Correct. The UK regulator (Ofgem) and thus UK consumers are being taken for a ride by windfarmers, who made these deals a precondition of building farms.

We will be paying them £2.5bn a year to not generate electricity by 2030

https://www.nsenergybusiness.com/features/examining-challeng...

‘A wholly unsatisfactory state of affairs’ indeed

https://www.ref.org.uk/ref-blog/372-why-are-unsubsidised-win...

[mschuster91]

> You could also technically use this as a grid-battery, taking in excess grid energy when it is cheap and converting it into natural gas that can be run back through a gas peaking plant that spins up to meet peak demand.

The loss in such a cycle is abysmal, alone from thermal loss (not to mention the loss during compression and decompression) - even straight fuel cells are at 60% round-trip, compared to batteries with >>90% efficiency.

[pydry]

Batteries are good at smoothing out daily or even weekly variations but do not make any sense whatsoever for seasonal power storage.

It's ridiculously cost ineffective to charge a battery in July only to discharge it in December.

60% roundtrip is cost effective if you're synthesizing when the sun is blazing and the wind is blowing hard and burning it when wind, solar and batteries have all tapped out.

Thats especially so if the equipment has low capex which it seems like this does. Unlike batteries that makes it cost effective to overbuild and idle it most of the year.

[ben_w]

> It's ridiculously cost ineffective to charge a battery in July only to discharge it in December

Indeed.

This is why the cheapest solutions in most places are a mix of a mere few days off storage plus a target production level that is a little higher than you need on an average day in winter.

While this doesn't work above the arctic circle (you could do it with a power line somewhere sunnier or a synthetic fuel, and possibly also geothermal or nuclear etc., devil is in the details for all options) overproduction + 35-90 hours of batteries is sufficient for most people and places:

https://tonyseba.com/wp-content/uploads/2020/11/RethinkingEn...

[cbsmith]

Is that more effective than the traditional, "store the energy as kinetic potential energy by pushing water uphill, so you can let it go down the hill later" approach.

[pydry]

For storing energy cheaply for months at a time and transporting it across large distances, yes.

Pumped storage has ~90% roundtrip efficiency, good at storing energy for days or weeks but maxes out easily. The energy density of water pushed uphill is very low.

I think we should be pushing a lot more water uphill, but I see it as an alternative to or competitor to grid-scale batteries and a complement to syngas.

Syngas production will probably be most useful if built next door to a wind or solar farm and used to siphon off energy which is currently curtailed when the grid is maxed out.

It can then be easily stored in enormous quantities and easily transported by ship to anywhere in the world that needs it.

[danmaz74]

It's not more effective where you have the right conditions for pumped storage, but those conditions aren't very common around the world.

[pydry]

I'm curious about where you read this. I see this idea that pumped storage geography is rare pop up a lot on Hacker News but I don't know where it's coming from and it rarely seems to come with citations.

If you look at this map, you'll see that unlike, say, dam-appropriate geography, it's actually extremely common:

https://www.energytransitionpartnership.org/uploads/2023/05/...

[mschuster91]

The problem is, the potential for buildouts of pumped hydro isn't that large any more. In Europe, most usable areas have been built out, and new projects are likely to be denied because anything involving creating dams or bodies of water with rapid differences in water level is incredibly devastating on nature and wildlife.

[danmaz74]

I'll admit that I wasn't talking about potential green-field sites not linked to rivers or existing reservoirs, as described in your link. How many of the sites they identified as viable with their algorithm would actually be economically, socially and environmentally viable is a big question though. Not saying some of these sites can come to fruition, but for sure the capex and lead time for this kind of projects is huge.

[genman]

Figure 2 doesn't agree with you. It's common but not geographically equally distributed.

[_Microft]

> On that same note though - in some free and open energy markets it is not unheard of to buy at <$10/mWh during excess production periods and sell at >$200/mWh at peak on-demand - plenty of margin for arbitrage there - as the tesla megapack facilities have demonstrated in Australia. In comparison a 4mWh megapack facility (2MW in/2MW out) is priced at $1.9M before installation [2]

m means milli, M is mega.