Curious, can this be used in reverse, to keep sand cool and use it to cool down houses? Would bring down a lot of AC usage in tropical countries.
Normally they just pump sea water since that's usually below 20 C anyway.
Large-scale ‘sand battery’ goes online in Finland
241–250 of 307 posts
Re: Large-scale ‘sand battery’ goes online in Finland
#242Earlier quoted context omitted.
As a German living in a city with mandatory district heating... the end result is to be that people seem pay more for heating than they would with a decentralised system. I think that's mostly due to the high upkeep costs of the system, though, the transmission loss is quite manageable, I think. Of course there are arguments to be made that when accounting for the cost of installing a heating system, and the space it…
Yeah I'd hate having District heating. A friend had this in the past and she couldn't even regulate it. The house was way too hot for her. It would not work for me as I usually have the house around 16 degrees C in winter. Needless to say my energy bill is very low :)
> Yeah I'd hate having District heating. A friend had this in the past and she couldn't even regulate it.
Interesting because I could regulate mine after all the radiators were replaced around 20 years ago.
And I kind of had to because the workers installing them made a mistake and I got the radiator meant for the living room, so it was grossly oversized for the space it heated.
That being said it's usually mandatory to keep them at least half-open considering that the heat is shared with other apartments.
I now live in a building from the early 90s and the knobs are all functional but I don't use them because the city pumps heat according to the weather outside.
Re: Large-scale ‘sand battery’ goes online in Finland
#243What's the round trip efficiency of something like this, and what's the rate of loss to the environment? There's been a couple of these posted in the last few days and I have no feel for these numbers.
The concept seems to be similar to the "Gridscale Storage"[0] system sold by Stiesdal technologies[0], which claims a round-trip efficiency of 55-60%.
The important insight here is that per Carnot's law[1], the higher the storage temperature the higher the theoretical max efficiency for thermal storage. Stiesdal had an initial concept that stored at even higher temperatures (1000C) and used a standard power plant steam turbine for converting back to electricity. But these turn-key solutions are probably more realistic.
If you are interested in realistic renewable energy, do browse the Stiesdal pages: Henrik Stiesdal [2] was pretty much the inventor of the modern wind turbine (sold the upwind 3-blade design to Vestas, CTO at Siemens Wind Power): He seems to have a superb intuition for industrializing heavy machinery. I am keenly following his advances into electrolysis and floating offshore wind power.
[0]: https://www.stiesdal.com/storage/the-gridscale-technology-ex... [1]: https://en.wikipedia.org/wiki/Carnot_cycle#Carnot's_theorem [2]: https://en.wikipedia.org/wiki/Henrik_Stiesdal
Re: Large-scale ‘sand battery’ goes online in Finland
#244The ‘sand battery’ explained: Insulate a lot of sand and heat it with an electrical element (300-500°C). When you need the energy back, pump air into it and you get hot air to power generators and heat buildings.
It's important to remember with most of these thermal batteries is that they are limited in efficiency by the laws of thermodynamics, both when putting the energy in and then again pulling it back out.
The net round trip total power loss is usually well above 50%.
Re: Large-scale ‘sand battery’ goes online in Finland
#245Earlier quoted context omitted.
> gas supplies in question were not covered by sanctions, but Russia tried to unilaterally switch to being paid in roubles I don’t think this is a very honest characterization: Russia demanded payment on their terms only after they were kicked out of SWIFT and their reserves frozen by foreign banks. I don’t think I’d describe that change in payment terms in response to bank sanctions as “unilateral” or unrelated to s…
Russia's invasion of Ukraine was the unilateral issue here, everything else was a response to that. But either way I'd characterise this as a 'payment dispute' because the issue was how Russia wanted to be paid, not that Finland was barred from paying them at all.
There is nothing unilateral in two imperialist powers fighting. Just like there was nothing unilateral in WW1 or WW2.
Re: Large-scale ‘sand battery’ goes online in Finland
#246Earlier quoted context omitted.
Where I come from in Europe, things look even more suicidal. Electric power futures for mid-2023 are currently traded at ten-fold the price of electric power one year ago. The end seems uncomfortably nigh.
Yeah, well Europe becoming more dependent on US crude which is 5x more expensive than cheap Russian crude (which more of would have flowed into Europe if Nordstream 2 had been completed) is exactly what the US petroleum companies want. Biden and those who support his administration are using this as an opportunity to push their green energy agenda here in the US, and most of the equipment manufactured for solar comes…
Nordstream 2 was a gas pipeline.
Also Ural crude was always priced roughly on par with Brent:
https://www.neste.com/investors/market-data/urals-brent-pric...
You're probably referring to marginal cost, but that's only partly related to market price.
Re: Large-scale ‘sand battery’ goes online in Finland
#247As an American it completely breaks my expectations that district heating not only works can be more efficient that decentralized heating. The amount of heat lost just moving water from the water heater on one side of the house to the shower on the other is ridiculously high in houses here. The idea that you can insulate well enough to efficiently move heat across a city is amazing to me.
I wonder how far out one can scale a cooling, rather than heating, system. Probably not worth it making it city-wide, but then - who knows? If it works for heating...
Re: Large-scale ‘sand battery’ goes online in Finland
#248The ‘sand battery’ explained: Insulate a lot of sand and heat it with an electrical element (300-500°C). When you need the energy back, pump air into it and you get hot air to power generators and heat buildings.
It's important to remember with most of these thermal batteries is that they are limited in efficiency by the laws of thermodynamics, both when putting the energy in and then again pulling it back out. The net round trip total power loss is usually well above 50%.
I'm no thermodynamicist, so I can only take you at your word about the power loss. But still:
* Suppose you can effectively and consistently get 40% of the energy you put into this kind of battery.
* Suppose you can make enough sand batteries to cover your overall power consumption (this is a big ask, but for the sake of discussion let's assume we can achieve this).
* Suppose that you have an energy source that's non-uniform across the day. For simplicity suppose that it produces 2N MegaWatts for 12 hours and 0 MegaWatts for 12 hours, i.e. N MegaWatts on average.
* Assume that electric power consumption, not including the batteries, is uniform across day and night (It isn't; it would actually be lower when power is generated if we're talking about solar).
* suppose we want a uniform power source when considering the batteries.
------
Now, let delta be the fraction of our power output which we divert towards batteries, which are only charging during the 12 hours in which that is possible. Solving for uniformity,
fraction not diverted to batteries = fraction recovered from batteries
(1 - delta) = 40% \* delta
1 = 1.4 \* delta
delta = 1/1.4 = 5/7 ~= 0.7143
1-delta ~= 0.285
That's not great, but it's pretty damn good!
Re: Large-scale ‘sand battery’ goes online in Finland
#249Earlier quoted context omitted.
> Russia demanded payment on their terms only after they were kicked out of SWIFT and their reserves frozen by foreign banks. If only there was something Russia could do to stay in SWIFT and not be hit by sanctions....
Why stay in SWIFT when it's been demonstrated that they can be cut off from global supply on the whims of the US administration? That one decision did more for the death of the American empire than any other.
It was a joint decision, taken by the US administration, the EU council, the UK and Canada in response to the Russian invasion of Ukraine -- not just something the Americans came up with.
Re: Large-scale ‘sand battery’ goes online in Finland
#250As an American it completely breaks my expectations that district heating not only works can be more efficient that decentralized heating. The amount of heat lost just moving water from the water heater on one side of the house to the shower on the other is ridiculously high in houses here. The idea that you can insulate well enough to efficiently move heat across a city is amazing to me.
As a German living in a city with mandatory district heating... the end result is to be that people seem pay more for heating than they would with a decentralised system. I think that's mostly due to the high upkeep costs of the system, though, the transmission loss is quite manageable, I think. Of course there are arguments to be made that when accounting for the cost of installing a heating system, and the space it…
District heating is a regional monopoly in Germany.