Things are Starting to Warm Up. 21

[dik]

https://www.reuters.com/world/asia-...mothers-bear-brunt-climate-change-2022-06-14/

a sign of things to come... hold on to your hats, folks.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Do you feel any better?

-Dik

 

[Tomfh]

For this to work there has to be some way to circulate the sand

The water would circulate, not the sand.

 

[TugboatEng]

The problem is the thermal conductivity of the sand. Running tubes through the unit would only be able to remove hea immediately adjacent to the tube. I think it would be much more efficient to take the hot sand out via conveyor and blow air through it.

 

[Tomfh]

Running tubes through the unit would only be able to remove hea immediately adjacent to the tube

The same as any heat exchanger.

 

[dik]

I don't know how Iceland takes advantage of their geothermal heat... maybe something similar. I know that if it could be harnassed, it would have a real impact on Canada's carbon footprint.

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Tomfh]

I know that if it could be harnassed, it would have a real impact on Canada's carbon footprint.

If it worked it could have an impact everywhere.

 

[dik]

concur, tom... but Canada is up near the top when it comes to carbon footprint per capita... our climate is a big cause. We do not need it for generating electricity; he have ample hydro power, I think.


So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Tomfh]

Yeah it seems an especially good idea when heat itself is such a valuable resource.

 

[TugboatEng]

Tom, heat exchangers, if they don't have pumped flow have convection. With sand there is no convection. There must be pumped flow.

 

[Tomfh]

Tug, heat exchangers are a basic technology that are used everywhere to suck heat from a mass of hot material. I don't understand this objection that you need conveyor belts to ferry hot sand back and forth when a long winding pipe thru the mass would achieve the same end.

 

[TugboatEng]

Heat exchangers work by conduction, convection, and radiation. Sand is a poor conductor. Solids don't convect. 500C doesn't produce enough radiation. For this to work there needs to be some work done to get the heat where it needs to be.

Look at the structure. It's not shaped like a typical heat exchanger. It has a sloped side. I'd assume that's the conveyor that returns the sand to the top. That structure also contains the heat exchangers as they're not likely in the sand silo itself.

 

[IanCA]

No capacity specifications or estimates for the existing sand battery. I'm going to assume this is another fantasy at this point

"Vatajankoski and Polar Night Energy are building a heat storage facility where electrical energy is stored as heat in the sand. The warehouse, which has a heating power of 100 kW and a storage capacity of 8 MWh, will provide heat to Kankaanpää's district heating network." ... "The actual heat storage is a steel tank about four meters wide and seven meters high, inside which Polar Night Energy's patented automatic heat transfer system is installed."

On their web site: Link

 

[Pud]

Looks like the US is working on sand batteries too:

https://www.nrel.gov/news/program/2...rticle-thermal-energy-storage-technology.html

Politicians like to panic, they need activity. It is their substitute for achievement.

 

[TugboatEng]

Good find, I didn't think to search in Finnish. Those numbers are in fact impressive.

 

[dik]

... and the good news, "Construction will begin immediately." No waiting for 10 years to study the problem.

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[rb1957]

hummm, I wonder if another "gravity energy storage system" ?
ie a scam

another day in paradise, or is paradise one day closer ?

 

[dik]

There will be a lot of snakeoil salesmen coming out of the woodwork.

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[rb1957]

so we're heating sand using surplus electricity. Ok, what's the efficiency of this process ? I thought resistance heating was woefully inefficient ?

then we store this hot sand, with presumably zero loss ?

then we extract the heat from the sand (with some efficiency) and convert that to electricity (with some efficiency).
I appreciate that part of the story is that we're using energy that would've otherwise gone to waste so getting anything back is better than nothing ?

oh, and somewhere we have to pay for transporting the sand to the top of the silos.

I have trouble seeing the sand flow "effortlessly" past the heat exchanger ...

another day in paradise, or is paradise one day closer ?

 

[stevenal]

Resistance heating is highly efficient. The efficiency losses from other processes escape as heat, but if heat is your goal conservation of energy means you get all of it as heat.

Now going back to electricity is another story entirely.

 

[TugboatEng]

I would assume these use direct contact heat exchange.

Yes, there is loss from transporting the sand around.

Even moving 100 tonnes of sand to the site uses a non-trivial mount of energy.

But, 8MWh is a decent amount of energy and rivals all but the largest battery installations.

For heating this is great. At 500C, only expect about 20% of capacity if used for steam cycle electricity generation.

A better use for power generation would be to augment the energy for the intake air heater or as a feedwater pre-heater of a conventional power plant.

Of course, this idea would get none of that sweet taxpayer funding or venture capital.

 

[Tomfh]

Resistive heating is 100% efficient. It is be very easy to turn energy into heat. It’s generally what we try to avoid doing!