An alternative ‘community’ energy store

[AE-NMidlands]

Using the element out of either a storage heater or possibly a fan oven would be far better

Yes or run your own nichrome wire through the box. 500C is pretty hot so safety is an issue, Also heat loss will be related to the square of the surface area and capacity will be related to the cube of the dimensions so huge is better.
If the sand is graded to one size class then the pores will be about 30% of the volume and air will travel though that well.

I still think compressed air would be a better way to store the energy for most purposes

but not if you "only" want heat out - and that heat nearby rather than at a distance where generation and transmission losses would be less than the cost of a steam main. This is for district heating where it is built.

I would think that hoping for an airflow through sand is pretty hopeless unless it is a fluidised bed. The original article talks about a heat exchanger, so I would imagine electric elements buried in the sand (any old sand, it says, rather than special sharp sand or whatever to maintain an open structure) and a heat extraction airflow through dry tubes in the sand box.
That way there is no movement of the sand to break it down, nor erosion of your heat exchanger by sand grains in the airflow.
A

[Bugtownboy]

I still think it’s very positive that there are two new approaches to storing energy - admittedly at a fairly advanced test level. The commonality being district heating systems - something, as far as I’m aware, haven’t been used widely in the U.K.

The only one I’m aware of related to the geothermal system in Southampton city centre.

Perhaps, certainly for urban areas, it should be another option for future developments.

[AE-NMidlands]

I still think it’s very positive that there are two new approaches to storing energy - admittedly at a fairly advanced test level. The commonality being district heating systems - something, as far as I’m aware, haven’t been used widely in the U.K.

The only one I’m aware of related to the geothermal system in Southampton city centre.

Perhaps, certainly for urban areas, it should be another option for future developments.

I have long advocated new estates/suburbs at the outer end of a tram or trolleybus line heated by the exhaust from the generating station for the transport. With getting rid of gas it's probably too late now...
Trouble is we don't do "joined up thinking" in the UK any more. New development, district heating system, transport development (electrified and generation station all being done together? Not for us!
(I believe several of the London power stations like Battersea did supply district heating schemes too.)

[ALAN/ALAN D]

On a sunny summer day both my large water tanks and next doors water are at 80 deg C at the bottom of the tank by 08:30
Batteries get charged off a different system.
Lots of power going up the road.
I could have more batteries but they do fail over time.
Down side of Sand Shed. Needs to be not far from house. Lady of the house probably wont be too impressed when I try to explain size / location

[Countrypaul]

On a sunny summer day both my large water tanks and next doors water are at 80 deg C at the bottom of the tank by 08:30
Batteries get charged off a different system.
Lots of power going up the road.
I could have more batteries but they do fail over time.
Down side of Sand Shed. Needs to be not far from house. Lady of the house probably wont be too impressed when I try to explain size / location

Are you any good with a spade? The article does say they can be buried

[AE-NMidlands]

On a sunny summer day both my large water tanks and next doors water are at 80 deg C at the bottom of the tank by 08:30
Batteries get charged off a different system.
Lots of power going up the road.
I could have more batteries but they do fail over time.
Down side of Sand Shed. Needs to be not far from house. Lady of the house probably wont be too impressed when I try to explain size / location

Are you any good with a spade? The article does say they can be buried

I can't even get permission for a big rainwater tank under the patio or the top lawn!

[openspaceman]

Using the element out of either a storage heater or possibly a fan oven would be far better

Yes or run your own nichrome wire through the box. 500C is pretty hot so safety is an issue, Also heat loss will be related to the square of the surface area and capacity will be related to the cube of the dimensions so huge is better.
If the sand is graded to one size class then the pores will be about 30% of the volume and air will travel though that well.

I still think compressed air would be a better way to store the energy for most purposes

but not if you "only" want heat out - and that heat nearby rather than at a distance where generation and transmission losses would be less than the cost of a steam main. This is for district heating where it is built.

I would think that hoping for an airflow through sand is pretty hopeless unless it is a fluidised bed. The original article talks about a heat exchanger, so I would imagine electric elements buried in the sand (any old sand, it says, rather than special sharp sand or whatever to maintain an open structure) and a heat extraction airflow through dry tubes in the sand box.
That way there is no movement of the sand to break it down, nor erosion of your heat exchanger by sand grains in the airflow.
A

We don't have much district heating in UK, though there is a heating and cooling main running around the town by where I live. I still think the utility of motive power even combined with heat pumps make compressed air storage look good over turning electricity to heat and storing that, we shall see.

A fluidised bed would consume far too much power, good for rapidly freezing peas though.

Back in the days before recycling them at Machynlleth proposed collecting all the beans and soup cans and crushing them into dense blocks to circulate air past but I think that was to be solar thermal heated, they gave up on their seasonal heat stores long ago.

Good point about the possibility of sand particles getting into the flow, I have no idea how sand might degrade during numerous heating-cooling cycles.

[AE-NMidlands]

That way there is no movement of the sand to break it down, nor erosion of your heat exchanger by sand grains in the airflow.
A

We don't have much district heating in UK, though there is a heating and cooling main running around the town by where I live. I still think the utility of motive power even combined with heat pumps make compressed air storage look good over turning electricity to heat and storing that, we shall see.

it certainly does if you need electricity back out...

A fluidised bed would consume far too much power, good for rapidly freezing peas though.

Back in the days before recycling them at Machynlleth proposed collecting all the beans and soup cans and crushing them into dense blocks to circulate air past but I think that was to be solar thermal heated, they gave up on their seasonal heat stores long ago.

Good point about the possibility of sand particles getting into the flow, I have no idea how sand might degrade during numerous heating-cooling cycles.

I don't know how themal cycling up to 500C would affect sand (if at all.) I do remember being taught that wind-deposited sands could be identified because of the "millet-seed" grains, with a frosted/pecked surface. This was down to the fact that the grains impacted on each other and caused the chipping, whereas water-laid sands had shinier/smoother faces because the water lubricated and cushioned the contacts.
This doesn't show up on web search now, so maybe that theory has been superceded. I took it as evidence of the generation of much smaller particles which the body can't protect itself against if inhaled.

Anyway, moving / air-propelled or windblown sand might well generate finer dust with a silicosis risk - if it was released and available for inhalation. A bed of hot sand with electric elements and closed (air?) circuit heat extraction tubes buried in it poses no risk whatsoever - unless you are tasked with digging it back out of the silo after it has cooled down! I would hope that would be done with a vacuum suction gadget though.
A

[openspaceman]

I see Kryten has released a video today of his new boiler that appears to use just this sort of high temperature store to release it to a conventional central heating system. It weighs in at 375kg.

[Stinsy]

I see Kryten has released a video today of his new boiler that appears to use just this sort of high temperature store to release it to a conventional central heating system. It weighs in at 375kg.

Yeah, it is a storage heater that plumbs into your central heating…