Storage of Mechanical Energy

Converting solar energy into electric energy to drive the electric pump for lifting the water from lower level to higher level can store the solar energy in a type of potential energy. Converting solar energy into thermal energy to drive the compressor also can store solar energy. Among the mechanical energy storage, flywheel storage is most notably.

Early in the 1950s, concept of utilization of flywheel in higher rotating speed to store the energy was proposed, but no breakthrough achieved. Recently, due to the emerging of high intensity carbon fiber and glass fiber, the rotating speed of flywheel manufactured by these material has increased remarkably which raised the kinetic energy storage in unit mass. Development on electromagnetic suspension and superconductor magnetic floating technologies associated with vacuum technique, dramatically mitigated the friction resistance and wind loss. New development on electric and electronic allowed the energy transfer flexible between the motor of flywheel and the system. Therefore, flywheel technology has been the worldwide research hotspot in recent years. In the US, more than 20 units conducted this research work, resulting in successful development of 20kWh flywheel and 5MWh to 100MWh superconductor flywheel being under the development. In China, small-scale pilot flywheel with the capacity of 0.3kWh was developed.

In the photovoltaic power generation system, flywheel can be used to store electricity in place of storage battery.