1. Thermal Storage
Thermal storage can be shortly described as storing energy as heat or cold in a storage medium to be used later, either to produce power, or for heating or cooling purposes. Thermal storage is commonly used for heating buildings, cooking, generating power for electric automobiles, incinerating and more. An effective thermal energy storage system requires a chemically stable storage material with a high energy density (such as silicon), good insulation to ensure minimal heat loss and a process that is completely revisable.
2. Compressed energy
Compressed Air Energy Storage (CAES) is used to help manage the supply of electricity in the grid and is the one of the biggest forms of energy storage. CAES converts electrical energy to high-pressure compressed air, which is then stored in underground caverns. When in use, air is taken from storage, combined with natural gas and fired in a combustion turbine to generate electricity. It can work alongside technologies like wind turbines to constantly produce and store electricity. Compressed energy uses much less natural gas than conventional methods, and round-trip efficiency storage is around 70%.
3. Pumped hydroelectric storage
Hydroelectric power plants feature two reservoirs at different elevations. When energy supply exceeds demand, plants use that energy to pump water from the lower reservoir into the upper reservoir. When demand exceeds supply, however, the water is released and runs back down to the lower reservoir, passing through turbines to generate electricity.
Flywheels, in the form of kinetic rotational energy or spinning mass, are a very responsive form of energy storage. Shaped like a cylinder, the device contains a rotor inside a vacuum that accelerates to high speeds when it draws power from the grid, storing it as rotational energy. To discharge the energy, the rotor slows down and switches to generation mode and runs on inertial energy, which distributes electricity to the grid. Flywheels emit rapid response times, are low maintenance and have long life cycles.
5. Flow Batteries
Flow batteries are a type of rechargeable battery in which two chemical components are dissolved in liquids, commonly separated by a membrane. The technology is similar to both a fuel cell and a battery, where liquid energy sources are tapped to create electricity and are also able to be recharged within the same system. However, one of the big advantages of flow batteries is that simply replacing the electrolyte liquid, they can be almost instantly recharged, all while simultaneously recovering the spent material for re-energization.
Hydrogen can be produced from excess renewable energies and then be compressed or liquefied before being stored. It is a high energy density fuel and can be stored for extended periods of time. Hydrogen has played a part in the renewable energy discussion for years and is seen as the potential future for an industrial-scale energy transition. Hydrogen can be repurposed to generate electricity in fuel cells, gas turbines and engines, and eliminate harmful emissions while doing so.