With the enhanced deployment of Wind & Solar energy systems, the need for exploring & adopting some efficient & effective storage systems to operate the electric grid efficiently has become a necessity.
Energy storage systems must be developed to include two levels Namely:
- Storage at “generation level”. This would help create an “operating reserve”, enable “load leveling” & instill “black start capability” in micro-grid networks.
- Storage at Transmission & Distribution Levels. At this level, the system would address “Power Quality”, “Transmission line stability” & “Power oscillation damping”
There are a host of storage systems, which are under active consideration, and there is a need to examine all possible systems before adoption. The selection process of a suitable storage system, must take into consideration the following:
- Economic Viability &
- Technological fitment
Most prominent amongst those being researched upon are the SMES (Super-conducting Magnetic Energy Storage) & Hydrogen Storage Systems, which hold a great promise for the future. Numerous teething problems need to be resolved before large-scale adoption.
Extensive R&D efforts are underway for realizing the idea of “Hydrogen Economy” to be a successor of the fossil-fuel era. The greatest advantage of using hydrogen gas as a storage system emerges from the fact that it has the largest energy content of any fuel, making it a very good ‘vehicle’ for holding and distributing energy. It can hold up to 120MJ/kg, and therefore a relatively small amount of hydrogen is needed to store significant amounts of energy. The stable chemistry of hydrogen also means you can store energy longer than any other medium.
On the other hand, “Superconducting Magnetic Energy Storage” (SMES) is another viable method of energy storage based on the fact that a current will continue to flow in a superconductor even after the voltage across it has been removed. When the superconductor coil is cooled below its superconducting critical temperature it has negligible resistance, permitting the current to flow even after a voltage source is disconnected.
The energy is stored in the form of a magnetic field generated by the current in the superconducting coil. It can be released by discharging the coil.
Due to its very high cycling capacity and high efficiency over short time periods SMES is very well suited to high power short duration applications. They are used in many voltage stability and power quality applications. On-site SMES is suitable to mitigate the negative impacts of renewable energy in power quality related issues, especially with power converters – needed for solar photovoltaic and some wind farms – and wind power oscillations and flicker.