Types of Energy Storage Systems
Energy storage systems offer a wide range of technical approaches to managing power generation to create a more flexible energy infrastructure and bring efficiency and cost savings to consumers.
Different Types of Energy Storage Systems
1. Battery Energy Storage Systems
2. Thermal Energy Storage Systems
3. Mechanical Energy Storage Systems
4. Hydrogen Energy Storage Systems
1. Battery Energy Storage Systems
There are various types of batteries, including lithium-ion, flow, lead-acid, sodium, and others designed to meet specific power and duration requirements.
Lithium-ion batteries were initially used in consumer products, but are now used in small residential systems and large systems that can store several megawatt-hours (MWh) and support the entire grid. , Used for various purposes. These systems typically combine a monitoring and management unit to house a large number of batteries in a rack. These systems have a small footprint in the amount of energy they store. For example, a small refrigerator-sized system can power an average home for several days. A 100 MWh utility-scale system can fit on less than 0.5 acres.
Lithium-ion batteries have received a lot of press because of the rapid drop in cost due to the increasing popularity of electric vehicles.
Another type of battery is a flow battery in which energy is stored and provided by two chemicals that are dissolved in a liquid and stored in a tank. These are suitable for longer-term storage.
2. Thermal Energy Storage Systems
Thermal energy storage systems convert energy into heat that can be reused later. The basic process is relatively simple compared to the complex chemical processes that make up a battery, but large solutions can require large construction projects.
Sensible Heat Storage System
This is the most commonly used form of thermal energy storage systems and is (relatively) easy to implement. Sensible heat systems use energy to heat or cool solid or liquid substances such as water, salt, sand, and rocks. For example, in solar power systems, solar energy is used to heat water and salt in insulated containers. Hot water or salt can be held for several hours until needed and can generate steam that drives a turbine and converts that energy into electricity.
One of the biggest examples of this is the Nevada-based Crescent Dunes Solar Energy Project. You need a 10,000 signboard-sized mirror that reflects sunlight into the central receiver at the top of the 640-foot tower. This sunlight heats the molten salt directly to a temperature of 1050 ° F, at which point it is transferred to a hot tank. Then you can gradually feed the steam generator. In July 2016, operators operated the plant for 120 hours continuously, supplying 24 hours of solar power to the grid.
Latent Heat Storage System
This less commonly used method relies on changing storage media. Solid to liquid. This allows applications such as air conditioning and refrigerator technology to freeze water at night and slowly melt and cool building ice during the day to balance peak energy demand. Latent heat storage is a more expensive approach, but it produces three times more energy density than sensible heat storage. In other words, proper design in a grid-scale system can be beneficial.
Thermochemical Storage System
This approach is the most energy-efficient and the thermochemical reaction provides the highest storage capacity. Chemicals used include silica gel/water, magnesium sulfate/water, lithium bromide/water, lithium chloride/water, NaOH / water. In this process, heat is used to evaporate water, causing an endothermic reaction. When water is added again, an exothermic reaction occurs and heat is generated and can be used for power generation.
3. Mechanical Energy Storage Systems
Mechanical energy storage systems use kinetic or gravity to store energy. Since the generator uses the motion of the turbine to generate electricity, these systems harness the potential power to drive the turbine at a later date.
Like thermal energy storage, it is based on a relatively simple theory but produces some complex and imaginative results. In its simplest form, it can take the form of weight and a pulley, and the energy required to lift the weight is stored as a gravitational potential until gravity is released again. However, storing grid-scale energy requires more ambitious ideas.
Pumped hydro is one of the main forms used since the 1980s. The largest pumped storage is currently in Bath County, Virginia. Like all hydroelectric dams, it uses the force of water to spin a turbine to generate electricity. Dams control the flow of water to optimize power generation.
This differs from standard hydroelectric dams in that electricity is used to “store” energy when demand is low, pumping water from a lower reservoir to an upper reservoir. When demand increases, this water is re-emitted from the turbine.
4. Hydrogen Energy Storage Systems
Energy is stored through the electrolysis of water, which separates hydrogen and oxygen molecules. Hydrogen is stored and used in power generation in much the same way as fossil fuels but without emissions. It is also effectively used in fuel cells in the automobile sector.
For small-scale use, hydrogen can be stored in pressurized vessels. However, for large projects, it is stored at up to 500,000 cubic meters in underground salt caverns at a pressure of 2,900 psi. A cave of this size and pressure supplies about 100 GWh of stored power.
With the spread of renewable energy, the need for efficient, scalable, and cost-effective energy storage is also increasing. However, finding the best solution for all situations is still difficult. Further development of each method of energy storage may continue, with various facilities being developed alongside renewable energy projects around the world.