2024-01-12 05:00:00
Stones that are hundreds of degrees hot can store heat very efficiently for long periods of time
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Stones can be used to store electricity and heat cheaply and for a long time. The method is gaining momentum thanks to renewables.
Renewable energy sources are very volatile, meaning they sometimes provide more, sometimes less energy. If you want to replace coal, oil or gas power plants to an increasing extent, you need Storage, and big ones at that. Electrochemical batteries are expensive and require a lot of resources. Other forms of storage are therefore required to meet the requirements of entire power grids. Pumped storage power plants and hydrogen, for example, or else Stones. They exist everywherethey are cheap and they can store heat very well.
Good at more than 600 degrees
What use is that if you want to store electricity? You can have a so-called Carnot-Battery build from it. The stones are heated with the electricity and store the heat for days or weeks. If necessary, the saved one can be used thermal energy back into electricity can be converted, for example by using the heat to evaporate water and drive a turbine with a generator attached to it.
Carnot batteries can be used with all kinds of substances, such as water, liquid salt, ceramic, graphite, Concretein short: all materials that have one high specific heat capacity exhibit. The special thing about stones and other solids is that you can… heat up particularly strongly can, explains Christoph Hochenauer, the head of the Institute for Thermal Engineering at TU Graz. “Bis 100 Grad Water has by far the best properties as a heat store; molten salt can be used up to around 600 Degrees Celsius heat up, for everything above that only solid-state storage is an option.”
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Also a Carnot battery, but with liquid salt: solar thermal power plants concentrate sunlight onto a tank that can release heat to generate electricity even in the dark
Lots of activity around TES
The higher temperatures you reach, the longer you can last. Apart from converting it into electricity, the heat can of course also be used directly, for example to supply certain industrial processes or district heating systems. Because stones are so cheap and widely available in recent years more and more companies and research projects have emerged that want to use their potential as heat storage.
Thermal energy storage (TES) stones are supplied by, among others, the Israeli company Brenmiller offered or by Stiesdal Storage Technologies from Denmark. The Finnish company Polar Night Energy stores heat in sand.
A large project was carried out by Siemens Gamesa realized in Hamburg. However, this has now been discontinued again. As the company tells futurezone, the technical feasibility demonstratedbut there is There is still no commercial market for large-scale storage. Die Situation is changing but right now, says Thomas Riegler, project manager at AEE INTEC. The Austrian research institute leads an international group of experts on behalf of the International Energy Agency with the aim of assessing the potential of heat storage and bringing it closer to decision-makers.
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Toggle Infobox
- Advantages of thermal energy storage with stones: do not require rare materials, do not lose performance over time, have no negative impact on the environment, are cost-effective
- The positioning near cities is advantageous. There is a higher demand for heat there. Using waste heat increases efficiency
- 2,500 degrees Celsius should achieve heat storage that works with graphite. The US start-ups Antora Energy and Forth Power promise the industry enough heat to melt steel itself
Seasonal postponement possible
There is currently a lot of research and development in stone storage, and many different variants are being developed. It is important that each locally occurring rock used to avoid complex transport. Even if some types of stone, such as soapstone or basalt, are more suitable, there are no major differences in heat capacity.
According to Hochenauer, you can store electricity in heat storage with one Efficiency of around 30 percent calculate. So if you store electricity as thermal energy and use it to generate electricity again, only a third is left. So TES played in one similar league to hydrogen. With stone storage, energy storage over several months is conceivable. In this respect, they would also be suitable for seasonal shifts, for example Sommer abundant solar power generated only in the Winter to consume.
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