Green energy, also known as renewable energy, can be stored using various methods to ensure its availability and reliability when the renewable source is not actively generating power. Here are some common methods for storing green energy:
Battery Storage: Energy can be stored in batteries, such as lithium-ion batteries, which are commonly used for small-scale energy storage. Battery storage systems can store excess energy generated from renewable sources like solar or wind during periods of low demand or high generation and release it when needed.
Pumped Hydro Storage: This method involves using two reservoirs at different elevations. During times of excess renewable energy generation, the energy is used to pump water from the lower reservoir to the upper reservoir. When electricity demand is high, the stored water is released, flowing downhill through turbines to generate electricity.
Compressed Air Energy Storage (CAES): This technique involves compressing air using excess renewable energy and storing it in underground caverns or large tanks. When energy demand is high, the compressed air is released and expands through turbines to generate electricity.
Thermal Energy Storage: Thermal energy can be stored by using mediums such as molten salts or heated fluids. Excess renewable energy is used to heat the medium, which can then be stored and later used to generate electricity by passing it through a heat exchanger to produce steam for a turbine.
Hydrogen Storage: Renewable electricity can be used to produce hydrogen through a process called electrolysis, which splits water molecules into hydrogen and oxygen. The hydrogen gas can be stored and later used as a fuel for power generation, heating, or transportation.
Flywheels: Flywheel systems store energy by converting excess electricity into kinetic energy, spinning a rotor at high speeds. When electricity demand increases, the rotor's kinetic energy is converted back into electricity.
Thermal Storage: Thermal energy can also be stored in the form of heat or cold using materials with high heat capacity. This stored energy can be utilized for heating or cooling purposes when required.
The choice of energy storage method depends on factors such as scale, cost, efficiency, and the specific requirements of the renewable energy system. Different storage technologies are employed to accommodate the unique characteristics and needs of various renewable energy sources.