inter seasonal storage solar thermal

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Christophe
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Re: inter seasonal storage solar thermal




View Christophe » 23/12/22, 11:16

Remundo wrote:An idea that's been in my head for a few years.

Could we not consider an outdoor swimming pool
1) fairly well insulated on its side and top walls (why not a greenhouse above the pool and walls with high thermal resistance)
2) with a coil at the bottom of the pool and use it as a reversible heat pump with glycol water.

In summer, calories could be brought in, both by the sun and the cooling of the house, calories that would diffuse into the depth of the ground.

On the contrary in winter, the heating of the house would draw the calories from the bottom of the swimming pool.

The swimming pool would behave like a well from which heat would be drawn or brought in.

After a few years, a large mass of soil under the pool could be at 20-25°C, maybe more. A fairly optimal temperature, whether you want to heat or air-condition (the COPs of the machines are then at least 5)

I say that with a wet finger, this idea came to me with DLSC.ca which applies this principle much more "industrially".

I would have liked to see simulations of thermal diffusion in the ground with weather scenarios, there is enough to model in my opinion.


A "swimming pool" would not be enough (at least not where it freezes strongly in winter), with a wet finger too, I think it would take at least a pond of 150 to 200m3 so a large ground catch...and manage evaporation in summer will not be easy...

Storing and recovering in 200 m3 may cost more than the same quantity of energy stored in MCP, "all-inclusive" price since it is not the price of water that will be important...
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Remundo
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Re: inter seasonal storage solar thermal




View Remundo » 23/12/22, 11:23

MCP material might be nice.

Well trapped in a thermally insulating shell.

But what do we actually put?

paraffin oil? something else ?

You have to be careful, paraffin melts at 60°C, it makes a significant thermal gradient with the ground or the air, in short, heat losses are stimulated.

a melting temperature of 20-30°C maximum... what is the best setting? Do we use a reversible heat pump or just heat transfer circulators?

Many questions arise...
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Christophe
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Re: inter seasonal storage solar thermal




View Christophe » 23/12/22, 11:43

Ah, but I never said it was simple... If we don't see that many, it's because there are problems to solve... we're not a wokist, we can take care of it! : Mrgreen:

Basically it depends on how you want to use it.. either central or localized...

Localized is where it must act: if you put it in the walls, no insulation for the hull and lower temperature. The choice of material depends on its location: centralized 60°C is good, locally, in the walls for example, around 30°C is better...

It is absolutely necessary that the temperature plays around the melting point otherwise no interest.

For example behind a wood stove at 40°C it will be interesting to store a few kWh after the fire is out. I melted a few kg of paraffin in bowls for years on mine to see if the hold over time is sufficient... nothing has changed in 10 years...

Otherwise, do you still have 1 room to insulate at home? You could put up a sign... : roll: : roll: : roll:
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Christophe
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Re: inter seasonal storage solar thermal




View Christophe » 17/04/24, 10:09

Seen on Facebook:

Vaanta Energy, owned by Helsinki and Vaanta in Finland, plans to establish the world's largest cavern-based thermal energy storage system.

This installation, made up of three underground caverns, will store renewable energy in the form of heat, with a storage capacity of 90 gigawatt hours (GWh). It aims to meet the heating needs of a medium-sized city for up to one year.
The project addresses the issue of intermittency of renewable energy sources, providing an industrial-scale storage solution marking a significant advancement in sustainable energy infrastructure.


A link : https://eu-mayors.ec.europa.eu/fr/node/818?etrans=fr

To increase efficiency, Vantaa Energy plans to build the world's largest heat storage facility. This facility would have the capacity to store one million cubic meters of water under bedrock. The water would be heated with excess heat produced during the summer, which could then be used to produce heat more sustainably during the winter.
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sicetaitsimple
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Re: inter seasonal storage solar thermal




View sicetaitsimple » 17/04/24, 11:50

If I understood correctly, it is not a question of storing heat of solar origin, but that produced and not consumed during the summer by the incineration of local household waste. It's a little different.
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Re: inter seasonal storage solar thermal




View Christophe » 17/04/24, 12:29

This remains inter-seasonal storage...

But garbage can actually be stored "physically" because it is palpable more easily than summer solar radiation! : Mrgreen:
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Re: inter seasonal storage solar thermal




View Remundo » 17/04/24, 13:33

Remundo wrote:An idea that's been in my head for a few years.

Could we not consider an outdoor swimming pool
1) fairly well insulated on its side and top walls (why not a greenhouse above the pool and walls with high thermal resistance)
2) with a coil at the bottom of the pool and use it as a reversible heat pump with glycol water.

In summer, calories could be brought in, both by the sun and the cooling of the house, calories that would diffuse into the depth of the ground.

On the contrary in winter, the heating of the house would draw the calories from the bottom of the swimming pool.

The swimming pool would behave like a well from which heat would be drawn or brought in.

After a few years, a large mass of soil under the pool could be at 20-25°C, maybe more. A fairly optimal temperature, whether you want to heat or air-condition (the COPs of the machines are then at least 5)

I say that with a wet finger, this idea came to me with DLSC.ca which applies this principle much more "industrially".

I would have liked to see simulations of thermal diffusion in the ground with weather scenarios, there is enough to model in my opinion.

and what do you think of that?

We don't have to build a swimming pool.

We could put the brine coil, or even another service coil (e.g. to bring hot water from renewable and/or waste sources) under the foundations/ground floor of the house.

Here are the physical ideas, but nothing is encrypted

1) the thermal inertia of the ground under the house is very great, bringing or removing calories is a bit like taking a liquid (calories) or bringing it at a constant level (temperature)
2) the use of air conditioning in summer brings heat into the basement, as does possibly solar thermal collection, or the combustion of waste
3) in winter we draw from the basement to heat the house
4) it would be necessary to raise the temperature of the basement to around 20°C after a few cycles, so as to have high COPs both in air conditioning and heating, I have heard that very deep cellars were naturally at 10- 15°C in our latitudes.
5) a little photovoltaic turns the reversible heat pump.


You would have to simulate all that, with finite element software which deals with thermal diffusion with local heat supply/withdrawal
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sicetaitsimple
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Re: inter seasonal storage solar thermal




View sicetaitsimple » 17/04/24, 14:39

Remundo wrote:and what do you think of that?

Here are the physical ideas, but nothing is encrypted[/b]
1) the thermal inertia of the ground under the house is very great, bringing or removing calories is a bit like taking a liquid (calories) or bringing it at a constant level (temperature)
2) the use of air conditioning in summer brings heat into the basement, as does possibly solar thermal collection, or the combustion of waste
3) in winter we draw from the basement to heat the house
4) it would be necessary to raise the temperature of the basement to around 20°C after a few cycles, so as to have high COPs both in air conditioning and heating, I have heard that very deep cellars were naturally at 10- 15°C in our latitudes.
5) a little photovoltaic turns the reversible heat pump.


You would have to simulate all that, with finite element software which deals with thermal diffusion with local heat supply/withdrawal



Apart from the fact that there is no buried coil but a "swimming pool" equipped with exchangers, what you describe looks quite similar to Christophe's system. And I don't have the impression, or I misunderstood, that it stabilizes in temperature in the long term.
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Christophe
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Re: inter seasonal storage solar thermal




View Christophe » 17/04/24, 15:32

This year I lowered it to 14-15°C...circulator on full blast 24/20...it's a record, before I stopped using it at XNUMX°C...

I don't think it can go any lower, so there is definitely stability (caloric intake of the slab)...

A cellar is generally stabilized around 13°C...yes with a water-water heat pump it would work better, but it would consume a lot much more...than a 40W circulator...
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Re: inter seasonal storage solar thermal




View sicetaitsimple » 17/04/24, 16:56

Christophe wrote:This year I lowered it to 14-15°C...circulator on full blast 24/20...it's a record, before I stopped using it at XNUMX°C...


Do you mean that the water entering your heated floor was around 14/15° after passing through the exchangers? You have to have good knitting when you come to your house in winter! :D
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