Green Energy Statement
ENERGY STORAGE FOR ELECTRICAL GRIDS: CURRENT STATUS AND TECHNOLOGY PROSPECTS?
School of Engineering, University of Edinburgh
King’s Buildings, Edinburgh, EH9 3JL, Scotland, UK
A green electricity grid which will be able to meet the growing energy demand, and fulfil the network’s requirements, is one of the main goals of the energy industry, and along with renewable energy sources, electricity storage will be the main pathway to it. The variety of different technologies, their applications, and the obstacles they face are presented, along with a set of future scenarios. Finally, it is concluded that the growth of storage capacity will be substantial …show more content…
The most common one is the Pumped Hydroelectric Storage (PHS), which uses two water reservoirs at different heights, and transforms electricity to potential energy. When demand is low it pumps water to the higher reservoir, and when energy is needed, water flows back through a turbine to produce electricity (IEC, 2011). Another way to store energy is the Compressed Air Energy Storage (CAES), which compresses and stores the high pressure air when there is excess power, and using it to drive an expansion turbine when power is needed (Energystorage.org, 2015). Isothermal and Advances Adiabatic CAES are both emerging technologies with the same principle. A really important set of storage technologies, is the Battery Energy Storage (BES) which can be divided into Solid State and Flow batteries. Batteries take advantage of electrochemical reactions, to transform energy from electricity to chemical and vice versa, through the electrochemical cells (Luo et al., 2014). The classification of batteries is a huge subject which is out of the scope of the current report and the numbers on tables 1 and 2 are just an indication. Flywheels are mechanical devices which can rotate using excess energy, and produce electricity by slowing the rate of rotation connecting them to a generator (Arup, 2013). Energy storage can be also achieved using Supercapacitors, which are normal capacitors with high capacitance but small size. The difference with BES is that the storage does not relies on electrochemical processes but on static charge (Hadjipaschalis et al., 2009). Superconducting magnetic energy storage (SMES) is another storage technology which uses DC current to create a magnetic field and store energy (Arup, 2013). A wide technology which can be divided in a variety of sub-categories is the Thermal Energy Storage (TES) which uses a storage medium and a cooling