ABSTRACT
Energy storage becomes necessary whenever there is a mismatch between the energy available and the demand (ASHRAE 2011). Storage is especially important in solar energy applications because of the seasonal, diurnal, and intermittent nature of solar energy. Nature provides storage of solar energy in a number of ways, such as plant matter, also known as biomass, ocean thermal energy, and hydro-potential at high elevation by evaporation from water bodies and subsequent condensation (Jensen 1980). In fact, even fossil fuels are a stored form of solar energy because they are produced from biomass. Natural solar energy storage provides a longer-term buffer between supply and demand. Since solar energy availability varies by the time of the day and also by the time of the year (seasonal), and can have intermittency even during a day owing to clouds, energy storage systems can be short term or long term depending on the objective:
1. Buffering with the objective of overcoming cloudiness for short periods from a few minutes to a couple of hours.
