Sand batteries ahead? It’s no secret that sand holds heat quite well.
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Have you ever raced across a hot beach and noticed how warm the sand gets?
That simple experience hints at a powerful idea that could change how we store energy, says Knowridge.
Researchers are now looking at heated sand as a promising solution to store energy for the future.
Unlike the batteries we usually think of for storing energy, this method offers a new and potentially game-changing approach.
Batteries are great for storing energy for a short time, but we need something more for long-term storage. That’s where technologies like thermal energy storage (TES) come in.
TES isn’t limited by location like pumped storage hydropower, which needs reservoirs at different elevations. Instead, it can use materials like molten salt or even superheated rocks – and now, sand.
Sand is pretty much everywhere, making it an accessible and environmentally friendly option for storing energy.
Researchers at the National Renewable Energy Laboratory (NREL) have developed a technology that heats sand using renewable energy sources such as wind and solar power.
This hot sand is then stored in a silo and can be used later to generate electricity or provide heat for industrial processes.
Their tests have shown that this method can keep more than 95% of its heat for at least five days.
Jeffrey Gifford, a postdoctoral researcher at NREL, points out that this method doesn’t depend on rare or hard-to-get materials like some batteries do. This makes sand a more sustainable and ethical choice for storing energy.
One of the biggest advantages of using sand is the cost. It’s much cheaper than other energy storage methods.
Full article here.
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Image credit: Temperature Master
Tallbloke's Talkshop 
I think that in scotland, we call them Stone Houses, and Storage Heaters, both using compressed sand, and then we morphed into buried disposable barbecues – so we all know about them ! Dam sand holds moisture and COLD too … so the Scandinavians and Canadians ( as examples) know that too and use LOGS.
I also know how quickly they lose heat when the sun stops shining.
Try sleeping out in the Sahara
Specific Heat of common Substances Sand, quartz830 Sandstone710
Paper1336 Paraffin3260 Peat1900 Quartz, SiO2730 Snow 2090,
Wet mud2512 Wood1300 – 2400
and then there’s the Overall Heat Transfer Coefficients to get the head around
‘NREL plans to start building an electric thermal energy storage system using sand in 2025.’
Let’s see how that goes. A Finnish trial started in 2022…
Specific heat of “sand” = 830J/kg/k
Specific heat of water = 4,186J/kg/k
Which would you choose? Well obviously neither if you want to store heat in serious, compact quantity.
Latent heat of fusion of Glauber’s Salt (NaCl·Na2SO4·10H2O)
@ 32 °C = 28,600J That’s 35 times more than sand AND at a low and easily insulated temperature.
Sand batteries are a wonderful gimmick for a few “scientists” (ho ho bloody ho) to get “funding” (i.e ultimately taxpayer money) and nothing more. B.S. on stilts.
There may be some potential use but how is it better than say water which must be far easier to heat, and falls out of the sky constantly.
‘Water evaporates, sand does not.’
From this link — https://temperaturemaster.com/does-sand-hold-heat/
Caption: The sand inside the silo at Vatajankoski power plant in Kankaanpää can store heat at around 500C for several months.– Polar Night Energy
Source — https://www.euronews.com/green/2024/03/10/sand-batteries-could-be-key-breakthrough-in-storing-solar-and-wind-energy-year-round
‘The sand battery in Pornainen will be around 10 times larger than the one still in operation at Vatajankoski power plant in Kankaanpää.’ [shown above]
And exactly how are they going to convert that heat into electricity?
This was looked at during the 70s. Temperatures too low to be useful with conventional tech. Then there’s the possible corrosion problem.
In college, I was considering putting a 1K gal storage tank in the basement to pick up heat off solar collectors. The first winter in that house the area was in a temp inversion and overcast so no heat was available during Dec thru Feb. Additionally, the hydronic heating req’d a minimum of 63ºC to operate, and a maximum of 90ºC A thousand gallons of water storing heat over a delta of 30º wasn’t much total heat, and getting all that mass up to at least 63º was heat I couldn’t use.
I opted to just pull the tank and go with Natural Gas heating with a wood/coal stove + water jacket back up. Had to be careful running the stove as it easily overshot the relief valve.
Damn you skeptics. Such a beautiful idea – especially suited for April 1st – and you destroy it using numbers. Cold numbers. Shame on you!
UAE desert sand can store solar energy up to 1000°C
Date: January 4, 2016
Source: Masdar Institute of Science and Technology
Summary: Researchers have successfully demonstrated that desert sand from the UAE could be used in concentrated solar power (CSP) facilities to store thermal energy up to 1000°C. The research project called ‘Sandstock’ has been seeking to develop a sustainable and low-cost gravity-fed solar receiver and storage system, using sand particles as the heat collector, heat transfer and thermal energy storage media.
https://www.sciencedaily.com/releases/2016/01/160104164852.htm
The trail goes cold after that, on the internet at least. This 2023 article lists some advantages/disadvantages of ‘sand batteries’ for energy storage.
The Science Behind Sand Batteries: How They Store and Deliver Energy – May 2023
The sand bed transfers the heat stored within to a heat transfer fluid, such as air or water, which subsequently carries the heat to the desired destination.
Various purposes can benefit from this energy, including electricity generation, water heating, or powering industrial processes.
https://natnavi.com/science-behind-sand-batteries
A typical UK dual-fuel annual domestic energy bill is around 3,000kWh Electricity and 12,500kWh Gas. The latter is predominantly for hot water and heating i.e. thermal energy. So why store heat energy to generate electricity, in lieu of storing heat energy to use directly as heat?
Complete nonsense on a stick just to shore up the stochastic nature of poor quality electricity generators.
This hot sand is then stored in a silo and can be used later to generate electricity or provide heat for industrial processes.
or – Various purposes can benefit from this energy, including electricity generation, water heating, or powering industrial processes.
Horses for courses. All this arises because renewables are here like it or not, and can’t help overproducing power sometimes. Having to make hefty constraint payments is unsatisfactory to say the least.
Sand isn’t cited, but molten salt and bricks are.
Thermal Batteries Are the Hottest New Thing in Energy Storage – Apr 03, 2024
— Thermal batteries are the latest innovation in energy storage, offering affordability and potential for decarbonization.
— Thermal energy storage has the potential to contribute significantly to decarbonizing global heat and power and ensure an affordable, reliable, and efficient energy system.
— Lack of publicity is the key bottleneck for industrial-scale thermal energy storage deployment.
https://oilprice.com/Energy/Energy-General/Thermal-Batteries-Are-the-Hottest-New-Thing-in-Energy-Storage.html
More: “Thermal energy storage has the potential to greatly contribute to decarbonizing global heat and power, while helping to ensure the energy system operates affordably, reliably, and efficiently,” states a 2022 report from global management consulting firm McKinsey & Company. The affordability factor is huge.
Electrical engineer says this is another garbage solution for a non problem somebody made up and we don’t need to have. The whole point is electrical energy is pure enrgy and must be used as generated, not stored as some other form of energy and then regenerated, at massive cost and losses.. This is an absolutely stupid consequence of a stupid presumption and a pointless means of generation. Unnecessary if you have dispatchable power which nuclear and fossil is. FFS CEng.
Renewables can’t all be discarded overnight and more are on the way regardless of any opposition, so some forms of energy/heat storage are bound to appear. Some already have done…
https://en.wikipedia.org/wiki/Thermal_energy_storage
It is relatively easy to convert electrical energy into heat. It is altogether a different problem to convert that heat back into electricity or other form form of dispatchable energy. That pesky 2nd law of thermodynamics gets in the way. Useful energy always ultimately degenerates into useless energy i.e. heat. Entropy always increases.
This article is from 2021. The hot water could also be used for other purposes than steam for turbines, e.g. heating.
NREL Options a Modular, Cost-Effective, Build-Anywhere Particle Thermal Energy Storage Technology
Energy Storage in Sand Offers Low-Cost Pathway for Reliable Electricity and Heat Supply in Renewable Energy Era
https://www.nrel.gov/news/program/2021/nrel-options-a-modular-cost-effective-build-anywhere-particle-thermal-energy-storage-technology.html
In a new NREL-developed particle thermal energy storage system, silica particles are gravity-fed through electric resistive heating elements. The heated particles are stored in insulated concrete silos. When energy is needed, the heated particles are fed through a heat exchanger to create electricity for the grid. The system discharges during periods of high electricity demand and recharges when electricity is cheaper. Image by Patrick Davenport and Al Hicks, NREL
I shudder to think what the efficiency of such a scheme would be. And as the heat from the sand is extracted the temperature will decrease resulting in a continuous reduction in efficiency. In so far as a fossil fuel powered system struggles to exceed 40% efficiency I doubt this system will get anywhere close to that level, and at significant cost. Still it keeps the guys at NREL in comfortable employment!
They’re still at it…
DOE funds heated sand energy storage project pilot – APRIL 2, 2024
A modeled commercial-scale project storing energy in heated sand could produce 135 MW of power for five days. The U.S. Department of Energy is funding a pilot project intended to demonstrate commercial viability.
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The sand used in the thermal energy storage (TES) system could be heated to the range of 1,100 degrees Celsius using low-cost renewable power.…The NREL team’s computer modeling has shown that a commercial-scale system would retain more than 95% of its heat for at least five days, the national laboratory said in a news release.
https://pv-magazine-usa.com/2024/04/02/doe-funds-heated-sand-energy-storage-project-pilot/
Computer says yes 🤔
News release title: Solution to Energy Storage May Be Beneath Your Feet – March 28, 2024
‘Could produce’…’may be’– let’s see.