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New Sand Battery

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A new way of storing renewable energy is providing clean heat through the long Nordic nights.

Sky Building Composite material Engineering Gas



It's a low-maintenance system, says Kivioja. The company uses cheap, low-quality sand that's been rejected by builders instead of high quality river-sand which is used in vast quantities for construction, leading to a global shortage.

"There's no wear and tear involved with the [heat exchange] pipes and the sand. The fan is the only moving part and it's easy to replace if necessary," says Kivioja.

Sand is a very effective medium for retaining heat over a long period, storing power for months at a time. And there are other benefits too. "The sand has a very long lifetime: it can heat up and cool off any number of times," says Kivioja. "It will get denser after a while so needs less space. At that point we can add more sand."
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I've read the whole article and still can't get it: they claim it can store power "for months", but then it's said this thing is heated every day by solar and wind generators.

While serving as a huge capacitor to rectify the lack of sun or excess heating of some tech process suspended for a night, I doubt it can warm houses all-over the winter, storing the energy, saved in summer. That'd be a too huge amount of energy needed to be stored.

It's like a gravity generator with a benefit of absence of moving parts, but that benefit comes for it's suited only for the cold climate, as it's hard to efficiently convert heat back to electricity.
 

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During the Carter administration I took advantage of the energy tax credit for solar by installing a Four Seasons greenhouse room onto my previous farm house (I had a natural gas well also...boy do I miss that). The glass installation was similar to what Arbys used to have at their restaurants. An old handyman I worked with helped me with the concrete and block work. We built a block wall up to match the 1st floor of the house and I lined the outside walls and the ground with 4" of blue Styrofoam board then had pea gravel poured in with 1' of concrete over that up to the house main floor level. The glass also had inside motorized insulated shades that I could lower during the night to keep in heat. The floor was painted dark brown to collect infrared from the sun. The room has two doors that open to the house...a single to the kitchen and a double to the living room. After a bright sunny winter day the amount of furnace support often went down to zero. With snow on the ground it was even better. Two sunny days in a row and the floor would stay nice and warm for 1-2 cloudy days after. It saved a lot as the gas well usually gave out Dec thru Mar.

The big solar farms with mirrors do something similar by using phase change of salt. They cook birds however just like wind generators are bird Cuisinart's as they build them in the bird migration paths where the winds are reliable.

A neighbor up the street has vertical geothermal. I'm jealous but don't want to fork out the big up front cost. The wood stove serves me pretty good with the cost of wood for the heating season at $400 when I don't have any available from my property (we had a multi-year supply of ash from the beetle infestation ravage).
 

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Discussion Starter · #5 ·
I wonder if a water well used for lawn irrigation could be converted to geothermal?
 

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If I follow the article discussion correctly, this is how the sand battery works. The output is "clean" heat, not electricity. Such "clean" heat reduces the need for heat created from "dirty" sources.

Solar and wind power generate electricity, which flows through a resistance heater in the sand to convert this "green" electrical energy into thermal energy. Fans blow to distribute the heat throughout the sand, where the temperature rises to 600C (1,112F). Good insulation keeps it there within the "battery." When energy demand rises (e.g., evenings/nights/cold winter days), rather than draw "dirty" energy from coal-fired electric plants or use fossil fuel products for heating water or homes, heat from the "battery" is sent through heat exchange pipes and directed to the target use: water heaters and home heating. Any heating derived from this "green" source reduces the need for similar water/home heating sourced from "dirtier" power. During the night, when electric rates are low, grid power can be used to keep the "battery" full of heat. I suppose this taints the claims of "clean" heat if the power comes from coal-fired generators. During the day (or on windy nights?), renewable power is used. Sounds to me like the sand battery is a local town’s equivalent of a large apartment house’s boiler room, sending heat, rather than steam, to the individual residences.
 

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Discussion Starter · #8 ·
The output is "clean" heat, not electricity.
Yes. "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". "Nordic countries which have long hours of darkness and an increased need for heat in the winter, but extended hours of sunlight in the summer."

Instead of chopping wood, store summer heat for winter use. Probably not a solution for Florida. :) That's OK. it's a simple, easily maintained, non-polluting solution geared for the local conditions in Nordic countries.
 

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200 kW for use by 100 homes is 2 kW per home. That's barely enough to heat up some water to wash your hands. Not saying storing summer heat for winter days...
 

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Yes. "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". "Nordic countries which have long hours of darkness and an increased need for heat in the winter, but extended hours of sunlight in the summer."

Instead of chopping wood, store summer heat for winter use. Probably not a solution for Florida. :) That's OK. it's a simple, easily maintained, non-polluting solution geared for the local conditions in Nordic countries.
Seems to me the sand battery is designed to allow large amounts of renewable energy (solar/wind energy) to be converted into thermal energy. This is more than just preserving summer heat. The thermal energy can then be used directly for heating (water and homes), or the thermal energy could be used, for example, to boil water for a steam engine to convert thermal energy into propulsion energy or electricity. Not necessarily an efficient process, but it allows time-shifting from energy creation (sunny/windy) to energy use.

What about a present-day version of the Stanley Steamer, using sand battery heat for the car’s propulsion steam engine, and where the vehicle’s smaller version of a sand battery is easily and quickly "re-heated" by a quick visit to the much larger sand batteries located at the "Fast Reheating Sand Battery" stations located everywhere?

What is missing is the "gallon equivalence" of thermal energy that translates the 8 MWh capacity of this "sand battery" and the 200 kW discharge rate into more familiar terms. The Wikipedia article on British thermal unit says, "While units of heat are often supplanted by energy units in scientific work, they are still used in some fields. For example, in the United States the price of natural gas is quoted in dollars per the amount of natural gas that would give 1 million BTUs of heat energy if burned [The modern SI unit for heat energy is the joule (J); one BTU equals about 1055 J]." If we had a familiar conversion rate, we could better understand, for example, how much natural gas it would take to supply homes and water heaters with 200 kW of heat.
 

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200 kW for use by 100 homes is 2 kW per home. That's barely enough to heat up some water to wash your hands. Not saying storing summer heat for winter days...
A steady 2kW of power is easily enough power to heat our house through winter (in Minnesota).
It may not be enough in less efficient homes. Most homes in Europe are smaller and much more efficient than the average home in the USA.
I suspect 2kW will be very helpful in that region.
 

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..but fairly cheap, low tech and robust components.
I have a1950s slab-on-grade ranch in northern Ohio that keeps itself warm all day long in the winter, thanks to its south-facing windows and great insulation -- even on moderately cloudy days -- until the temps dip to well below freezing. That's with 30-year-old windows. And the wide eaves keep the sun out in the summer, making the place easy to cool.

Too much is made of technology. Simple, common-sense measures are more important.
 

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Is it enough to heat the water for your shower/(dish)washer too?
It would seem that for domestic hot water needs, a "water battery" might be the better choice. It would use daytime solar energy to heat your water which would be stored locally at the point of use, and could be supplemented with [wind generated] electricity when there are several cloudy days in a row.. This hot water heater technology obviously already exists, and would seem to be more efficient than incurring the losses in photovoltaic generation, and hot air distribution.

I wonder how the output of the sand battery scales down as the sand cools, say to 550F?
 

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A steady 2kW of power is easily enough power to heat our house through winter (in Minnesota).
Not possible unless you have a 300 ft^2 home with suberb insulation.

Is it enough to heat the water for your shower/(dish)washer too?
possibly...

Time to get the maths out! (and a partial energy industry rant...)

In the summer, my family of three uses about 17 CCF of natural gas for hot water, clothes dryer and the cooktop. No use for space heating in summer. 17 CCF (hundred cubic feet) at ~1,000 Btu/cf = 1,700,000 Btu of energy over the course of the month. This is equal to about 500 kW-h of electrical energy. Assuming the gas water heater uses most of this (teenager showers!) and is about 80% efficient, that means you could get by with about 400 kW-h of electrical energy to heat the water (electric water heaters are essentially 100% efficient). Divide 400 kW-h per month by 720 hours per month, and you would need about 0.56 kW of continuous heating to supply the hot water (and an incredibly large tank). So, is 2kW of power enough to heat hot water for your home? Likely yes, just don't use it very fast or buy a really big tank.

However, to heat your home? In the winter we use 10 - 15 times more gas, so you would need 6 - 10 kW continuously to provide the same energy. (relatively mild at 6,900' in Colorado) In reality, you would draw 40 - 50 kW intermittently for space heating. How big is the electrical service coming into your home? 200A service x 240V = 48kW. Better turn out the lights and shut down the fridge, TV, computer, hairdryer, and, and, and .... ) Do you have a 100A service? Older home with 60A service? It's going to get cold pretty fast!

Heat your house with 2kW??? Think about it... a small electrical space heater is generally maximum 1500 watts (1.5 kW). Do you really think you could heat your entire home with one and a half small space heaters? Not possible.

Good thing some of our beloved governors think we can de-carbon the energy industry by switching to electricity! Time to invest in copper mining! We're all going to need 400A services to our houses soon!
 

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Time to get the maths out! (and a partial energy industry rant...)

In the summer, my family of three uses about 17 CCF of natural gas for hot water, clothes dryer and the cooktop. No use for space heating in summer. 17 CCF (hundred cubic feet) at ~1,000 Btu/cf = 1,700,000 Btu of energy over the course of the month. This is equal to about 500 kW-h of electrical energy. Assuming the gas water heater uses most of this (teenager showers!) and is about 80% efficient, that means you could get by with about 400 kW-h of electrical energy to heat the water (electric water heaters are essentially 100% efficient). Divide 400 kW-h per month by 720 hours per month, and you would need about 0.56 kW of continuous heating to supply the hot water (and an incredibly large tank). So, is 2kW of power enough to heat hot water for your home? Likely yes, just don't use it very fast or buy a really big tank.

However, to heat your home? In the winter we use 10 - 15 times more gas, so you would need 6 - 10 kW continuously to provide the same energy. (relatively mild at 6,900' in Colorado) In reality, you would draw 40 - 50 kW intermittently for space heating. How big is the electrical service coming into your home? 200A service x 240V = 48kW. Better turn out the lights and shut down the fridge, TV, computer, hairdryer, and, and, and .... ) Do you have a 100A service? Older home with 60A service? It's going to get cold pretty fast!

Heat your house with 2kW??? Think about it... a small electrical space heater is generally maximum 1500 watts (1.5 kW). Do you really think you could heat your entire home with one and a half small space heaters? Not possible.

Good thing some of our beloved governors think we can de-carbon the energy industry by switching to electricity! Time to invest in copper mining! We're all going to need 400A services to our houses soon!
The article says, "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." I interpret that to mean the sand battery discharges about 200 kW of thermal energy, not electrical energy. The solar and wind energy that was converted into thermal energy for storage in this "battery" is not being converted back into electrical energy, and then back into thermal energy again.

I wrote earlier that "Gallon-equivalent" terms are needed here. To restate the numbers you have provided, if 17 CCF of natural gas, the amount your home uses each summer month, is the thermal power equivalent of 500 kWh of electrical power, then:

energy content of 17 CCF of natural gas = energy content of 500 kWh of electricity = energy content of (500/33.7 =) 14.8 gallons of gas

The stated full capacity of the sand battery is 8 MWh, or the energy content equivalent of (8,000K/500K x 17 =) 272 CCF of natural gas, and the discharge rate is 200 kWh, or approximately the energy content equivalent of 6.8 CCF of natural gas per hour. Your home’s daily summer monthly usage, around 0.6 CCF, is equivalent to about 5 minutes’ worth of sand battery discharge. Daily heating in winter (10-15 times as much gas, you write) may use the equivalent of an hour or so of output, so perhaps enough heat to meet the daily needs of 20 or so homes per fully charged sand battery output in winter...

To provide additional support for your rant, I’ll add that yesterday I read in the Kalamazoo Gazette an article written by Washington Post writer Shannon Osaka. The article includes: "Over the past several years, the mantra of energy experts has been that we need to electrify everything... But installing all of that electrical stuff... will require something that the United States doesn’t have: lots and lots of electricians... According to the nonprofit group Rewiring America, which focuses on electrification, shifting the economy away from fossil fuels will require no fewer than 1 billion new electrical appliances, cars and other items in American households alone... The problem is that many in the industry say the country already has an electrician shortage — one that could get worse as clean energy ramps up... Part of the issue is that more people are leaving the profession than entering it."
 

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bring back fossil fuel or maybe in 10 years it'll be so warm we won't need heat.
how many of you actually have all electric houses.I do,,in the winter you can have 1$500-2500 /month bill.sucky part for me,,no nat. gas on my street.so,oil propane or wood.I get wood for free.now in the next month solar,it can't be big enough to supply for electric heat w/o putting a bunch of panels in my front or side yard.both visible from the street.my neighbors would flip out.
 

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Discussion Starter · #20 ·
There are skilled trade labor shortages everywhere.
Concrete masons top the list with 904% growth in demand compared to pre-pandemic numbers.
Electricians have risen 130%.
Plumbers are up 129%.
And carpenters are up 121%.

And of course trucking. There is also a shortage of skilled auto mechanics.

This seems like a fairly broad issue of increased demand for skilled trades coupled with not enough people and a low unemployment rate.

Plus, many don't want to do manual labor. They are going to be a tiktok influencer or video game star.

Seems like we need to get more people who don't mind manual labor, train them, pay an attractive wage. Where will we get these people?
 
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