Sand Batteries: A Revolution in Renewable Energy Technology
By Adaobi Rhema Oguejiofor
Renewable energy has found greater prominence in the search for alternative source of energy, as scientists as well as researchers are actively seeking to provide efficient, reasonable and clean solutions to the challenge of storing energy. Sand batteries are one of the evolving storage options.
Sand Battery is a high temperature thermal energy storage that utilizes sand or sand-like materials as its storage medium. The main purpose of this technology, which stores energy in sand as heat, is to work as a high-power and high-capacity reservoir for excess wind and solar energy. This energy is stored as heat, and can be used for homes, or to provide hot steam and high temperature process heat to industries that are fossil-fuel dependent.
The invention, which is the world’s first fully working sand battery, was brought to life and installed by two Finnish researchers, Tommi Eronen and Markku Ylönen with the hope to support the global shift towards renewable energy. Their innovation has the ability to dispense energy for up to a year by storing it in the form of heat. With the sand battery, renewable energy production can be scaled up, ensuring that there is always enough clean energy available.
The term “sand battery,” is relatively new. It emerged when a team of young Finnish engineers in Kankaanpää, Western Finland, completed the first commercial installation of a battery made from sand, with the belief that it can solve energy storage problem in a low-cost and low impact way.
The battery is connected to a district network heating residential and commercial buildings, such as family homes and the municipal swimming pool, with the district heating network operated by an energy utility called Vatajankoski.
One might wonder how possible it is for sand to be used to save energy. Well, the heat storage of the sand battery consists of an insulated silo made of steel housing. The silo contains sand and heat transfer pipes. Additional equipment outside the storage unit includes automation components such as valves, a fan, and a heat exchanger or steam generator.
The electricity generated from the grid or from local production, as well as from fluctuating sources like wind or solar heats the sand and this charge occurs whenever clean and cheap electricity is available. When the electrical energy gets to the heat storage through a closed loop air-pipe arrangement; electrical resistance heating elements heat up the air that circulates in the heat transfer piping.
The sand reaches the maximum temperatures of about 600 degrees Celsius in Kankaanpää. Depending on different needs, it is also possible to work with a higher temperature. In theory, the maximum temperature is not limited by the properties of the sand as a storage medium, but by the heat resistance of the materials used in construction and control.
Following the effects of climate change and the rapidly increasing price of fossil fuels, a surge of investment in new renewable energy production has been born. But, while new solar panels and wind turbines can be quickly added to national grids, these extra sources also present huge challenges, one of which is the question of how the lights can keep on shining when the sun does not shine and the wind does not blow? And the answer to these problems is the reason behind the large scale batteries which can store and balance energy demands as the grid becomes greener.
Sand batteries fill an important gap in renewable energy, where storage is still the key challenge. They provide a low-maintenance system and use lower-quality sand rejected by builders to avoid contributing to the global shortage of higher quality river sand. Also, the parts that make up the sand battery do not experience wear and tear, as the only moving part is the fan, which is easy to replace. In addition to its efficiency, sand also has a very long lifetime, making it a sustainable storage for renewable energy.
These batteries stand out because they can store excess energy from solar and wind power, making renewable energy more reliable and dispatchable. They are also cost-effective compared to traditional lithium-ion batteries, making them a more feasible solution for large-scale energy storage. They are sustainable because sand is a readily available and abundant material, making sand batteries a more sustainable option than batteries using rare earth metals.
However, despite all its unique and outstanding capabilities, sand batteries are not without challenges and limitations. While they are great for storing large amounts of energy, their energy density is lower than traditional batteries. This means that they require more space to store the same amount of energy. Sand batteries also lose some heat over time, even though the heat loss rate is slow.
Although the first commercial sand battery is operational and scaling up, the technology for widespread use might require further development and infrastructure upgrades. Sand batteries are still evolving and there are ongoing research and development efforts to improve their efficiency and performance. Potentially, sand batteries play a significant role in the transition from the use of fossil fuel to a clean energy future.
