1. Introduction
Solar and Wind power are periodically generating energy as soon as it is available instead of when it is required, henceforth demanding significant energy storage for an effective alteration to green energy. The possible manifestations of this could fluctuate importantly, including traditional lithium-based "large battery" systems, current batteries, silicon phase-change batteries, molten salt batteries, iron-air batteries, gravity batteries, carbon dioxide expansion batteries, and other unconventional notions such as buoyancy batteries.
Every possibility has its own set of pros and cons when it comes to efficiency, size, location, installation costs, operating costs, power ratings, longevity, and energy storage capacity. It's great to see that various solutions can cater to different requirements. Some solutions can support the power grid during sudden spikes in demand, while others can help balance the daily fluctuations between demand and renewable supply. Additionally, there are solutions available to address seasonal drops in supply, such as when solar energy decreases during the winter. The sand battery is an innovative storage of energy technology that employs sand as a medium for storage thermal energy. Heating the sand to high temperatures (up to 600°C or more) encompasses exploiting surplus renewable energy, like wind power and solar. Stockpiled thermal energy can generate electricity or deliver heating, when necessary, predominantly throughout minimal clean energy generation or high demand, where there is a significant need for air conditioning in hot countries. Nevertheless, the appropriateness and efficiency of using it to directly tackle electricity shortages for air conditioning requirements entail specific factors to be taken into account.
Perspective Advantages
1. Indirect Reduction Through Municipal Heating And Cooling
Sand batteries display outstanding effectiveness in storing thermal energy, rendering them appropriate for applications like municipal heating and cooling systems. In areas that already have the cooling infrastructure, therefore the stored thermal energy could be released to supply the cooling system, consequently in the reduction of the electricity demand on air conditioning systems.
2. Boosting The Grid Stability Of Reduction of Spike Electricity Demand
Sand Batteries can stabilise the grid through the storage of renewable energy that can decrease the load, given the loss of energy in the process of converting stored heat into electricity. This procedure can always function as alternative during times of high demand.
3. Enhancing Integration Of Renewable Energy Sources Into The Power Grid
Sand batteries permit the integration of renewable energy through the storage excess electricity generated during seasons of high demand. The Vatajankoski a pioneer company in Sand batteries Technology has started commercialisation in their premises in Helsinki. Moreover this company assists in ensuring the provision, stability and without interruption of energy supply by having a storage system which consists of an immense insulated steel cylinder with dimension of 7 metres high and 4 metres wide, and a heating element installed in the centre , filled with sand , once the sand is heated to proximity 500 - 600 degrees Celsius. this device is able to store 8 Mega Watt per hour of energy at minimal power capacity of 100KW. and retain the heat for later use.
Conversion Process
The Procedure of Sand Heating
Sand Batteries retain and store thermal power by heating the sand to 500-699 Celsius with effective use of the excess renewable electricity. The heat stays contained in insulated sand for late use
Heat Extraction
The conversion of heat into electricity start by extracting the thermal energy. The procedure requires the circulation of air or working / operational fluid through energy exchanger pipes buried in the sand, when the fluid gets heated resulting extricating the thermal energy away from the sand.
Steam Generation
The heated fluid is used for steam production. The potential method is by navigating the hot fluid or hot air into heat exchanger which then consequently heats the water to generate vapour. Moreover, this system has the possibilty to heat a working fluid to become vapour to power turbines.
Understanding Turbine Operations
The generated steam from working fluid flows with high pressure to a turbine which spins the turbine blades converting the thermal energy into mechanical energy.
Electricity Generation
The mechanical power from turbine gets converted into electrical power utilising a generator linked to the turbine then use it to convert rotational energy of the turbine into electrical power then to be fed to the electrical grid.
The Challenges
Conversion Effectiveness
Heat conversion of stored energy in the sand into electricity is less effective than direct electrical storage solutions such as batteries, this procedure necessitates further infrastructure like turbins, and it has build-in energy losses
Scability and Infrastructure necessities
The effectiveness of sand batteries relies on the presence of municipal heating/ cooling system and facilities required to integrate the thermal energy to the grid, in the areas that lack these infrastructures would make the implementation costly and challenging.
Primary Cooling Solutions
For direct cooling applications, other technologies, such as ice storage or advanced battery systems, may be more appropriate. These technologies store energy in forms that can be used directly for cooling, eliminating the need for efficiency-reducing conversion steps.
Conclusion
Despite the fact that sand batteries can contribute to energy stability and security of the grid, balancing renewable energy sources and decreasing the entire grid load, they are no perfect solution for electricity shortages during seasonal air conditioning consumption, they can strengthen existing energy storage solutions to generate more flexible and resilient energy system.