Astounding Finnish Sand Battery

[SorellaLaBefana]

...The Vatajankoski power plant is home to the world's first commercial-scale sand battery. Fully enclosed in a 7m (23ft)-high steel container, the battery con-sists of 100 tonnes of low-grade builders' sand, two district heating pipes and a fan. The sand becomes a battery after it is heated up to 600C using electricity generated by wind turbines and solar panels in Finland, brought by Vatajankoski, the owners of the power plant.

The renewable energy powers a resistance heater which heats up the air inside the sand. Inside the battery, this hot air is circulated by a fan around the sand through heat exchange pipes.

Thick insulation surrounds the sand, keeping the temperature inside the battery at 600C (1,112F), even when it is freezing outside. "We don't want to lose any heat; the average winter temperature is below 0C (32F) in Kankanpää," says Ville Kivioja, lead scientist at Polar Night Energy, who monitors the battery's per-formance online...

Eronen says that with currently available technology the process of converting heat back into electricity only has an efficiency rate of 30%. But he doesn't view that as a major issue. "In a cold country like Finland we're dumping 70% of the heat that remains after conversion on the district heating networks that needs a supply of heat almost all the time," he says.

From the BBC

This is one of the few truly innovative ideas to appear on how energy can be stored with a low adverse environmental impact.

[eppur_se_muova]

1. A thermal mass, not a battery. They're storing heat, not electrical energy.

Don't know whether the builders or journos introduced the term "battery", but it's a touch misleading.

[mahatmakanejeeves]

4. I suspect that might be a term of art in Finnish that doesn't translate properly to English. NT

[I_UndergroundPanther]

2. Every home in America should

Have one of these sand batteries be totally self sufficient. No more electricity bills from burning coal.

You get the unit thats it. Service it as needed for cheap.

That would reduce our carbon footprint a lot.

We wont get these unless the R's are
made to get the fuck out of the way.

[mahatmakanejeeves]

5. Provided you have room for a 23-foot silo. NT

[OAITW r.2.0]

8. I wonder what a residential scale sand heat storage system would be, size-wise.

Concept seems pretty simple,

[NNadir]

9. Sigh...

One hears these sorts of things, and one doesn't really want to believe one is hearing them.

Nothing can make solar and wind reduce our carbon footprint. They generate more complacency than energy, and in fact, are making things worse, not better.

They are unsustainable forms of energy, and the enthusiasm for them, and for energy storage for them in particular, is reactionary, not progressive.

[mahatmakanejeeves]

3. The process "... only has an efficiency rate of 30%. But he doesn't view that as a major issue."

The battery stores 8 MWh of thermal energy when full. When energy demand rises, the battery discharges about 200 kW of power through the heat-exchange pipes: that's enough to provide heating and hot water for about 100 homes and a public swimming pool in Kankaanpää, supplementing power from the grid. The battery is charged overnight when the electricity prices are lower.

Eronen says that with currently available technology the process of converting heat back into electricity only has an efficiency rate of 30%. But he doesn't view that as a major issue.

The article elaborates:

There are of course limitations, experts note. "A sand battery stores five to 10 times less energy [per unit volume] than traditional chemical batteries," says Dan Gladwin from the department of electronic and electrical engineering at the University of Sheffield in the UK.

The Polar Night Energy team acknowledges this but argues that a sand battery is a far more cost-effective solution. The team has calculated that their battery is eight to 10 times cheaper than a lithium battery which stores the same amount of energy. To generate 8 MWh of energy using the Kankaanpää sand battery costs about $200,000 (£174,000), says Eronen. A lithium-ion battery storing 8 MWh of energy would cost at least $1,600,000 (£1,391,000), he says.

Gladwin says the sand battery is great for heating houses in countries with a cold climate, but warns that the efficiency drops off when it is used to return power to the electricity grid. ... "To make it more widely useable, they'd need to develop a way of converting the battery's heat back to electricity with 75-80% efficiency. That would make it a game changer," he says.

Eronen says that with currently available technology the process of converting heat back into electricity only has an efficiency rate of 30%. But he doesn't view that as a major issue. "In a cold country like Finland we're dumping 70% of the heat that remains after conversion on the district heating networks that needs a supply of heat almost all the time," he says.

Something that works adequately in Kankaanpää, Finland, might not be something that works adequately in Palm Springs, California.

200 kW is about 270 horsepower. Is that really enough "to provide heating and hot water for about 100 homes and a public swimming pool ..."?

https://www.bing.com/search?q=horsepower+to+kilowatts

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{snip}

They weigh less than 100 tons, and they aren't 23 feet tall.

How much would a sodium-based thermal storage system cost for the same power output?

[mitch96]

6. I wonder if this could help in Ukraine this winter? nt

[cyclonefence]

7. Isn't Iceland the perfect place for this?

Underground heat keeps Icelanders so warm they keep their windows open in winter. I was at a restaurant that bakes its bread in bubbling mud.