Seasonal thermal energy storage

[NailBiter]

Has anyone managed to pull this off? How did you do it?

"Seasonal thermal energy storage (STES), also known as inter-seasonal thermal energy storage, is the storage of heat or cold for periods of up to several months. The thermal energy can be collected whenever it is available and be used whenever needed, such as in the opposing season."

https://en.wikipedia.org/wiki/Seasonal_thermal_energy_storage
 

[JohnMo]

16 minutes ago, NailBiter said:

managed to pull this off

Anyone with a GSHP does it every day.

[NailBiter]

Just now, JohnMo said:

Anyone with a GSHP does it every day.

I'd be very interested in hearing from anyone with a GSHP that charges it with heat in the summer for use in the winter. I know that happens naturally but you need a massive array which cannot be built over in any way (nor can it be fouled by tree roots etc). 

[Redbeard]

Centre for Alternative Technology in Machynlleth did. The basis was experimental (and cheap, I guess!), so it (water-trickle solar roof over black-painted crinkly tin feeding  a 100,000 litre - IIRC -thermal store which ultimately leaked) proved the concept very well. The store was a big hole lined with huge EPS blocks and lined with pond-liner. I believe the issue was that the liner used to extrude into gaps between blocks and pop! I believe the short-lived Earth Centre at Conisborough had an inter-seasonal heat store too, but I am not sure how well that worked.

[Redbeard]

Tony Cowling also has ISHS, I think. He described it in a recent AECB webinar. http://tonyshouse.readinguk.org/

[Redbeard]

I realise these 2 are not using GSHP, but I was answering your 1st post, not your 2nd. Both these use(d) solar thermal. Simple trickle at CAT and, I think, evac tubes in Tony's House. I think he is a member here so he might pop in to the discussion.

[NailBiter]

Thanks for taking the time to reply.
 

1 hour ago, Redbeard said:

The store was a big hole lined with huge EPS blocks and lined with pond-liner. I believe the issue was that the liner used to extrude into gaps between blocks and pop!

Maybe ICF with a membrane would solve this issue: https://www.nudura.com/products/tremco-nudura-products/below-grade-waterproofing/ 

 

1 hour ago, Redbeard said:

Centre for Alternative Technology in Machynlleth did

Looks like a very interesting place cheers. Nothing on their website about it though.  I'll try emailing them if not but do you know where you read / saw this?


There is another project detailed here (Howe Dell Primary School) : https://earthbound.report/2024/01/10/what-is-inter-seasonal-heat-storage/

 

1 hour ago, Redbeard said:

Tony Cowling also has ISHS, I think. He described it in a recent AECB webinar. http://tonyshouse.readinguk.org/

 

I will check this out thanks a lot. 

Edited April 4 by NailBiter

[Mike]

There are a number in Switzerland, including some small apartments blocks -

 

[SteamyTea]

30 minutes ago, Mike said:

Switzerland

London has around 1410 hours of sunshine a year, Zurich 1566.  Sunshine hours are a measure of clear sky, not intensity.

Quite a different weather regime, and is 4° further south than London, so better intensity.

London is the 4^th cloudiest city in Europe.  Glasgow is the cloudiest, then Birmingham, then Reykjavík.

https://www.currentresults.com/Weather/index.php

 

If interseasonal thermal stores worked, all our houses would have them, not as if it is a new concept and never been looked at before, or the world was waiting for some new materials like Hopium and Unobtainium.

 

As a general point, it is worth reading up about Entropy, which explains, in a round about way, why it is so hard to get from a high entropy to a low entropy without putting in lower entropy.

Entropy will be the death of us all, but it will not stop dreamers thinking they can beat nature.

 

 

[DamonHD]

I think that for much of the UK it could be made to work.  MacKay did the sums to indicate that only at fairly high urban densities do you need to actively push heat back into the ground in winter.

 

Also see for example:

 

Geothermal pavements: A city-scale investigation on providing sustainable heating for the city of Cardiff, IK

Makasis, Nikolas and Gu, Xiaoying and Kreitmair, Monika J. and Narsilio, Guillermo A. and Choudhary, Ruchi

https://www.sciencedirect.com/science/article/pii/S0960148123011631

DOI:10.1016/j.renene.2023.119248

 

Quote: "Depending on ground conditions, 184–345 kWh annually/m road of heat can be provided.  Geothermal pavements can reduce anthropogenic heat flux into the ground by 390 MWh/a.  In low population density areas 100% residential demand can be fulfilled, overall 23%.  Replacing traditional systems can reduce carbon emission by 75%."

 

Basically much of Cardiff's home heating could be provided by shallow geothermal.

 

And this mob looked at Cardiff because the geology is very very well studied.

 

Rgds

 

Damon

 

[Mike]

3 hours ago, SteamyTea said:

 

If interseasonal thermal stores worked, all our houses would have them

Probably something to do with economics and available space too...

[SteamyTea]

I use about 300 kWh/month in the winter to keep my house warm.

So approximately 10 kWh/day.

Initially I shall assume that there is no added input in December and January, so I need to store 600 kWh.

Water would be the most cost effective medium to store energy in as it is cheap and easily transportable.

Water stores about 0.00116 kWh.kg^-1.K^-1.

So I would need, if I could get a ΔT of 40K (40°C up to 80°C as anything below 40°C would not really be useful) to store approximately 6,500 litres.

If they were stored in rectangular vessels, I would need 7 m³, so quite a big hole.

That is before adding insulation.

Realistically PIR with a k-value 0.025 W.m^-1K^-1 is the most practical.

So how much would I need.

Assuming that my ground is at 10°C once deeper than 1 meter, the vessel is 7 metres long, by 1 metre wide and 1 metre tall, I would have a surface area of 30m² to insulate.

If I added 1 metre of insulation onto each side, then that is 9m by 3m by 3m hole I would need to dig, 81m³, the surface area would be 126m², that is about half the volume of my house and nearly the same surface area (house is 184m²).

So what would the heat losses be.

 

R-Value = 1 [m] / 0.025 [k-value] = 40

 

U-Value = 1 / 40 [R-Value] = 0.025 W.m^-2.K^-1

 

Power [W] = 0.025 [W.m^-2.K^-1] x 126 [m²] x 70 [ΔT] = 220 W or 5.3 kWh/day.

 

Knocking up a quick mathematical model, the losses, before any usage, look like this:

 

 

So that is 254 kWh of useful energy lost.

 

So what to do.

Two options really (well 3).

Add more insulation, which is expensive. Doubling the thickness will give a surface area of 270 m² and a volume of 275m³.

That is now much larger than my house, but no matter, lets work out the losses as I am full of hope.

2 metre thickness of insulation works out as a U-Value of 0.0125 W.m^-2.K^-1.

Now this throws up a strange result, the losses are actually greater, 272 kWh total, because the total surface area has increased by 144 m².

Now there is some dispute as to where the thermal losses should me measured.  I always use the outside area as this is larger.

 

 

Just for a laugh, and I had a good snooze this afternoon, let us see what the losses are when using the surface area of just the water container, the 7m x 1m x 1m, 30m².

At a U-Value of 0.025, it is 60 kWh total, and at 0.0125 30 kWh.

Now the truth is it will be somewhere between the two and without a much more detailed model, which allows for the corner affects i.e. effectively thicker insulation.

So shall we settle on 155 kWh total losses.

 

The second way is to increase the volume of storage by an extra cubic meter, that would store an extra 45 kWh but loose some of that to losses, about 7 kWh total.

So we would actually have to add another 4m³, so a total storage of 11m³ of water.

 

Now we could change the geometry to get the smallest surface area to insulate.  This may need a custom container that is cube 2.25m on each side.

Adding a metre thickness of insulation would expand that to 4.25m on each side, so a volume of 77m³ and an area of 108m².

The losses would now be 208 kWh total out of the original capacity of 510 kWh.

Still not enough.

Let us for a cube 3m on each side, that is easy as you can buy 1m by 1m by 1m vessels easy enough, and stack them in a cube.

So that would have a storage capacity of 1254 kWh initially (at Δ40) and losses with 1m of insulation of 301 kWh, leaving a possible useful amount of 950 kWh.

Big hole in the ground though, 5m on each side, 125m³ which is only 35m³ less than my house volume.

 

Now I have only worked this out for a laugh, but I did it a few years back when @DamonHD and myself discussed it before, I think I came to the same conclusion, which is my third option, don't (expletive deleted)ing bother.

 

 

 

[SteamyTea]

29 minutes ago, Mike said:

Probably something to do with economics and available space to

See above

[DamonHD]

On 04/04/2024 at 21:20, DamonHD said:

I think that for much of the UK it could be made to work.  MacKay did the sums to indicate that only at fairly high urban densities do you need to actively push heat back into the ground in winter.

 

Ahem ... in summer!

[Iceverge]

There was a project in Drakes Landing in Canada.

https://www.dlsc.ca/

 

Scanhome did one in Galway with an EPS insulted water store.

 

https://www.scanhome.ie/pdf/Storing-Sunshine.pdf

 

I think there was one near the Watford gap of the M25 to defrost the road in winter. 

 

 

The deep tube lines in London are probably the only successful (if accidentally) examples. They're heating up every year. 

 

 

 

 

 

 

Moral of the story, 

 

Build your house 50m underground. 

 

 

 

[SteamyTea]

2 minutes ago, Iceverge said:

The deep tube lines in London are probably the only successful (if accidentally) examples. They're heating up every year

How much is caused by all the electric motors, and brakes, on the trains?

Also, if the average OAT goes up, the thermal losses will go down. That should be easy enough to check.

5 minutes ago, Iceverge said:

Drakes Landing

One of the few towns that is a similar latitude as London.

But.

https://www.cbc.ca/news/canada/calgary/okotoks-drake-landing-solar-energy-repairs-future-1.7148389

[Iceverge]

3 minutes ago, SteamyTea said:

How much is caused by all the electric motors, and brakes, on the trains?

 

A huge chunk of it I imagine. I suppose if you were able to install a subway train in your house that would account for a significant amount of the annual heat demand. 

 

It'd be irritating though. 

[SteamyTea]

45 minutes ago, Iceverge said:

It'd be irritating though. 

Depends, the posters used to be good.