Читать книгу Energy - Группа авторов - Страница 54

Continuous increase of variable renewable energy (solar and wind) in electrical power system (EPS) leads to advances in the field of energy storage. For energy storage, pumped‐storage power plant (PSPP) is a well‐developed technology with continuous improvements taking place in PSPP (Kougias et al. 2019) in order to reduce response time for transition mode i.e. from pump to turbine and vice versa. Recently, two technologies are evolving under PSPP which can play an important role in fast energy storage systems, namely flywheels and supercapacitors (Sarasúa et al. 2016; Gevorgian et al. 2017). Synergy between fast energy storage systems and hydropower operation permits an improved frequency control in EPS. Integration of these technologies into the operational hydro plants can be easily done in a span of a few months which can provide advantages in voltage control in the proximity of the hydro plant. Coordinated operation of fast energy storage systems and hydropower plants is also possible for one or set of hydro plants which are connected to the transmission power system in other geographical locations. As an example, globally, by the end of 2017, total installed hydropower capacity including pumped storage was 1267 GW (IHA 2018) as evaluated by International Hydropower Association. Now, assume that every operational hydro plant and PSPP are connected by fast energy storage systems with 5% (assumption) of the installed capacity, then new 65 GW fast energy storage systems are needed to be manufactured and installed across the world.

A new concept in pumped energy storage is emerging, known as underwater pumped hydro energy storage (UPHES) owing to advance research in the energy storage area. Its technical feasibility was investigated between 2008 and 2011 (Kougias et al. 2019). In contrast to the PSPP, it is not restricted to specific geographical locations. In UPHES, sea acts as the upper reservoir while a hollow deposit situated at the seabed is the lower reservoir. Seawater enters the deposit, which in turn drives the turbine and leads to electricity production.