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'Freeze-thaw battery' stores electricity long-term for seasonal release

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Re: 'Freeze-thaw battery' stores electricity long-term for seasonal release

#61

Post by vikingerik »

alexchamberlain wrote: post #59
nikanj wrote: post #42

Earlier quoted context omitted.

Furthermore, we have a real problem with the soil storing heat: https://citymonitor.ai/transport/londons-tube-has-been-runni...

Stupid question: can we harness this 100 year old heat to power something today?

You can't exactly harness heat; what can be harnessed is a temperature differential, to convert into some form of mechanical motion or electrical potential. You'd need some apparatus that connects the hot mass and some cold sink with thermocouples. Whether that's possible or feasible on the scale of the London Tube, I don't know.

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

Instead of that, probably a more feasible way to make use of heat is just as heat, by some way of circulating it into buildings in the winter. One interesting angle of looking at this would be that it's really an artificially created geothermal source.

Re: 'Freeze-thaw battery' stores electricity long-term for seasonal release

#62

Post by llampx »

awestroke wrote: post #33
Gasp0de wrote: post #19

This doesn't seem cost efficient at all, my (medium sized) house in Germany consumes about 3000kWh of electricity during winter. This does not include heating, which consumes another 15.000kWh (of heat energy from oil, so around 5000kWh electrical energy with a heat pump). If I were to use this battery I would need to get 3000(8000)kWh of energy storage at 23$ per kWh which would amount to 69000(184000)$. There are b…

You heat you house with oil? I thought Germany was environmentally conscious

Germany is still mining coal but they are environment conscious so they sell it to Poland to burn and buy electricity from them.

Re: 'Freeze-thaw battery' stores electricity long-term for seasonal release

#63

Post by jdmichal »

ClumsyPilot wrote: post #56
snewman wrote: post #22

Earlier quoted context omitted.

Gradual heating of the ground is definitely a thing; over the decades, certain London Tube lines have drifted from pleasantly cool to sweltering: https://www.wired.co.uk/article/central-line-temperature-lon...

Yes, people are literally dying in the heat from heart attacks because city planning won't allow TFL to knoxk down a house sp they cam build a ventillation shaft

Do the tubes never cross a road? Why knock down a building instead of taking a vent to a street?

Re: 'Freeze-thaw battery' stores electricity long-term for seasonal release

#64

Post by jdmichal »

cupofpython wrote: post #36
ema wrote: post #4

Just realized that with a battery intended for seasonal storage you only get one cycle per year so for the same ROI as a battery that cycles weekly or daily it has to be much cheaper per kwh of capacity. OTOH it only needs to last for like 50 cycles.

I like to imagine a system with the different geothermal-like technologies working together in maybe a layered like structure. Extracting from the winter / summer cycle, the day / night cycle, and the consistent deep ground / surface air temp differential. Granted day / night might not have enough variation to take advantage of in a lot of places - but surely some cool tech has come out of desert areas right?

Arid locations already enjoy much cheaper cooling via swamp coolers over heat pumps. They're just enough to keep it bearable during the day, then the night comes and clears out all the latent heat.

Re: 'Freeze-thaw battery' stores electricity long-term for seasonal release

#65

Post by t0mas88 »

harg wrote: post #35
Gasp0de wrote: post #19

This doesn't seem cost efficient at all, my (medium sized) house in Germany consumes about 3000kWh of electricity during winter. This does not include heating, which consumes another 15.000kWh (of heat energy from oil, so around 5000kWh electrical energy with a heat pump). If I were to use this battery I would need to get 3000(8000)kWh of energy storage at 23$ per kWh which would amount to 69000(184000)$. There are b…

You're assuming that the battery needs to store the total energy requirements of a house for the entire year. Much of the time the energy needs can be met by conventional energy generation (wind turbines, solar, hydro, etc) and the battery is only called upon when there's a shortfall. So you'd only need a fraction of the annual consumption to make it useful. The whole idea is to make renewables more effective by stor…

If you use solar power in a climate like Germany you will get that kind of math.

Let's say you use 8000 kwh per year, and you have the solar capacity to create 8000 kwh per year. Assume you already have a normal home battery of ~14kwh so day/night is not an issue, the solar production during daytime charges the battery and all night time power comes from the battery.

Now your big problem is that 70% of the 8000 kwh solar per year is produced from May to September. You need 670 kwh per month for usage, so in those four months you have just under 3000 kwh too much. Then in April and October the panels roughly produce what you use. And November to March you have a total shortfall of 3000 kwh.

So you need seasonal storage capacity of about 3000 kwh to be able to run an 8000 kwh yearly usage on solar in this climate.

The other option is to buy much more solar panel capacity than you need, then you can use a smaller battery which in total could be cheaper since solar panels aren't that expensive anymore.

Re: 'Freeze-thaw battery' stores electricity long-term for seasonal release

#66

Post by wppick »

Is there any examples of using something like a server farm to heat a building in the winter? Removing heat from a server farm through heat exchange with a cold building seems like an efficient combination of two interests (building needs heat, servers need to get rid of heat). Of course this becomes a problem in the summer months...

Re: 'Freeze-thaw battery' stores electricity long-term for seasonal release

#67

Post by wongarsu »

wppick wrote: post #66

Is there any examples of using something like a server farm to heat a building in the winter? Removing heat from a server farm through heat exchange with a cold building seems like an efficient combination of two interests (building needs heat, servers need to get rid of heat). Of course this becomes a problem in the summer months...

Stockholm, Sweden has an open district heating network: buildings can not only buy heat from it for heating, like a normal district heating network, they can also sell surplus heat to the network. At least two data centers (Bahnhof Thule and Bahnhof Pionen) sell heat from their heat exchangers to the network.

https://celsiuscity.eu/wp-content/uploads/2020/06/Waste-heat... pages 7-9

Re: 'Freeze-thaw battery' stores electricity long-term for seasonal release

#68

Post by grenoire »

wppick wrote: post #66

Is there any examples of using something like a server farm to heat a building in the winter? Removing heat from a server farm through heat exchange with a cold building seems like an efficient combination of two interests (building needs heat, servers need to get rid of heat). Of course this becomes a problem in the summer months...

In Amsterdam, the botanical gardens and Hermitage Amsterdam exchange heat in that sort of mutually beneficial way, https://www.cultureelerfgoed.nl/onderwerpen/praktijkvoorbeel....

Re: 'Freeze-thaw battery' stores electricity long-term for seasonal release

#69

Post by PaulDavisThe1st »

t0mas88 wrote: post #65
harg wrote: post #35

Earlier quoted context omitted.

You're assuming that the battery needs to store the total energy requirements of a house for the entire year. Much of the time the energy needs can be met by conventional energy generation (wind turbines, solar, hydro, etc) and the battery is only called upon when there's a shortfall. So you'd only need a fraction of the annual consumption to make it useful. The whole idea is to make renewables more effective by stor…

If you use solar power in a climate like Germany you will get that kind of math. Let's say you use 8000 kwh per year, and you have the solar capacity to create 8000 kwh per year. Assume you already have a normal home battery of ~14kwh so day/night is not an issue, the solar production during daytime charges the battery and all night time power comes from the battery. Now your big problem is that 70% of the 8000 kwh s…

> The other option is to buy much more solar panel capacity than you need,

You need the space to install them also. I have a 6.6kW array, and would need 3x that capacity to heat my home using electrically-powered air source heat pumps during the winter months. Even with 0.75 acres / 0.30 hectares, that would be quite a lot of my property covered by panels, and way more than could ever feasibly fit on the roof (the current array is ground mount).

Re: 'Freeze-thaw battery' stores electricity long-term for seasonal release

#70

Post by PaulDavisThe1st »

KennyBlanken wrote: post #52
pjc50 wrote: post #27

Earlier quoted context omitted.

I've never really seen the advantage in going off grid per se , since it increases the amount of wasted capacity in both generation and storage, and running a few wires is cheap enough in urban environments. The most efficient arrangement might be a global grid.

Utilities around the US are working in numerous states to get favorable legislation letting them pay a fraction of what they do now for solar and wind energy fed back into the grid by residential and commercial customers. Once you even out your meter and reach net generation, any further generation into the grid you'll soon be getting bupkus for. Sorry, but I got better things to do than line the pockets of my state'…

> Battery storage systems a couple years ago were very expensive, but prices are crashing and safer tech like lithium iron phosphate are becoming more commonplace.

Unless you live in a mild climate and/or have a full Passivhaus-level construction and/or live in a very small building, there are no current batteries that will get you through a winter of heating.

I live in New Mexico, have some of the best insolation numbers around (outside of Arizona), generate around 93% of my annual electricity use, including heating (air source heat pumps) from a 6.6kW PV array. A battery system large enough to store my winter needs built with any currently available technology would be completely untenable, both in terms of cost and size.

I pay $7.71 as a monthly connection fee, and I get back my excess summer production as "free kW" during the winter, an arrangement I much prefer to being paid directly. The "free kW" are a 1:1 match for my over-production.

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