Introduction of Sand Battery
If technology to effectively produce energy is important in the current society, technology to effectively store energy will be important in future society. This is because fossil fuels, which led to the development of modern society, are gradually being depleted, and environmental pollution problems are becoming more serious due to excessive carbon dioxide emissions.
Energy Storage System
Ultimately, in the future, renewable energy such as solar/wind power will replace fossil fuels. However, the energy production of new and renewable energy is discontinuous and heterogeneous compared to existing energy production technologies. Therefore, a large-capacity energy storage technology that stores energy and uses it whenever needed is absolutely necessary. There are a variety of technology candidates that can store energy in large quantities, including lithium secondary batteries, pumped storage power generation, redox flow batteries, and CO2 batteries. Today, let’s take a look at ‘sand battery’ technology, the latest large-capacity energy storage technology.
Russia Ukraine War and Energy
Due to the recent impact of the Russia-Ukraine war, Europe can no longer expect a stable supply of natural gas from Russia. Many media outlets are saying that Europe will experience its coldest winter due to Russia’s unilateral gas supply cutoff. To this extent, humans are heavily dependent on the energy supplied by natural gas to live in modern times. So, is there no suitable alternative energy to replace natural gas? Among European countries, Finland sought to find an alternative in ‘renewable energy + sand batteries’. Recently, Finland is said to have installed a demonstration model of a sand battery. Sand batteries are a type of energy storage device that can effectively store heat energy for several months.
How it Works
The operating principle of the sand battery is as follows.
- Produce electricity using renewable energy.
- Some of the energy produced is used directly in homes or businesses (used as electrical energy).
- The remaining energy is converted into heat. (Use an electric heater)
- Use the heat to indirectly or directly heat the sand. (heats sand up to 500 degrees)
- Sand storage stores store heat for a long time because they are well insulated.
- The stored heat can be taken out and used whenever needed.
The sand storage tank contains sand and a heat exchanger. Through this heat exchanger, sand can be heated and, conversely, heat can be obtained from the heated sand. As such, the structure and operating principle of the sand battery are simple. Nevertheless, due to the characteristics of sand, it has the advantage of being able to effectively store heat. Currently, both Europe and Korea are expanding the installation of new and renewable energy. However, the biggest problem with renewable energy is that energy production cannot be actively changed according to changes in energy demand. In other words, solar power generation can only be generated when the sun is present, and wind power generation can only be generated when the wind blows. In this way, when using renewable energy, energy production fluctuates, so the energy must be stored somewhere.
Why Sand?
So why store heat in sand? In fact, other materials other than sand, such as phase change material (PCM) or water, can be used. However, sand is attracting attention as a medium that can store heat due to the following characteristics.
- You can get it cheaply.
- The state does not change when heated to a high temperature. (Water changes state.)
- High specific heat (can store a lot of heat)
Conclusions
[Advantages of sand batteries]
- The structure and principle are simple.
- Low manufacturing cost (using cheap materials)
- Easy to install
- Scale-up / scale-down is easy
- Safe
[Disadvantages of sand batteries]
- Expensive electricity generated from renewable energy must be converted back into heat.
- There is loss during the energy conversion process.
- It is effective when installed right next to a renewable energy power plant. However, homes and factories that need heat are far from power plants.
- The heat transfer rate of sand is low.
