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Grid energy storage, popularly known as large-scale energy storage refers to a collection of techniques for storing energy on a large scale within an electrical power grid. When electricity is abundant and cheap especially from intermittent power plants like renewable electricity sources like wind, tidal, and solar power or demand is low, electrical energy is stored and later returned to the grid when demand is high and electricity prices are higher.
Grid Energy Storage: The Concept
Networked energy storage systems are rapidly being deployed by utilities and grid operators. This pattern is similar to what is happening in the IT industry, where data centers separate processing and storage clusters. Faster virtualization technologies and lower storage costs have propelled production. Smart grids are beginning to morph into network-attached storage in a similar way. Self-balancing, self-healing networks would be new types of power grids that use demand–response algorithms and sophisticated prediction models to smooth and optimize energy output. Smart grids and connected grid-energy storage would enable electricity producers to send excess supply to temporary storage sites, which will then become energy producers when demand for electricity is higher, allowing producers to optimize output by storing off-peak power for use during peak times. Intermittent energy producers would not need any local storage devices because they would be directly connected to the grid, which would function as a giant battery. Solar energy could be stored for use at night, while wind energy could be stored for use during calmer periods.
Types of Grid Energy Storage
- Pumped Hydroelectric
Pumped hydroelectric plants generate electricity by harnessing the power of falling water. On peak demand days, pumped hydroelectric stations around the world produce between 200 and 2,000 megawatts of electricity. They produce no emissions and, once charged, are ready to use in 15 minutes, making them both faster and greener than a peaker plant.
- Compressed Air Energy Storage
Compressed air energy storage (CAES) is used in natural gas power plants. Normally, natural gas is used to heat air, which drives a turbine in a generator. CAES may be used when natural gas plants are near an underground pit, such as a cavern or an old mine.
Flywheels spin to store electricity. The quickest ones have a motor, a levitating magnet, a vacuum to eliminate friction, and a protective shell. When there is excess energy on the grid, it can be used to power the motor that spins the magnet. When electricity is needed, the flywheels can generate it in minutes to hours, depending on the situation.
Supercapacitors store energy by splitting charges at a faster rate than flywheels. They are called “super” capacitors because they hold more energy than conventional capacitors while still functioning in the same way. Extra electricity can be used to drive charges off of some metal plates and onto others, leaving some plates positively charged and others negatively charged. When electricity is needed, the plates neutralize and the charge flows through the circuit, forming a current.
For the grid, batteries are similar to Lego sets. They come in a variety of shapes and sizes, can be stacked or expanded to store more capacity, and can power a generator for seconds to hours. Trailer-sized flow batteries like vanadium redox and zinc-bromide, as well as high-temperature batteries like sodium-sulfur, are available. These can provide up to 20 megawatts of power for many hours at a time. Lead-acid batteries are widely used in today’s burst-power applications. Metal-air, lithium-ion, nickel-cadmium, and lead-carbon batteries are some of the other types of batteries. Chemical reactions are used and released by all batteries.
Importance of Storage
The role of an electricity utility provider is to ensure that the supply of electricity meets consumer demand at all times, and in most countries, their output is governed by legislation. The voltage, frequency, and continuity of the supply as calculated at the customers’ premises are all subject to strict safety requirements and very tight tolerance limits. Compliance with these requirements is one of the problems facing generation and distribution companies, as they must meet a fluctuating consumer demand over which they have little leverage, with resources that fluctuate in unpredictable and unrelated ways.
With the need for uninterrupted demand for energy, storing it seems to be the only way out. The above-mentioned types of storages are effective and efficient which will help in balancing demand and supply of the energy.