Energy storage systems have proliferated in the last decade and continue to rise in importance in our power network. Battery energy storage systems (BESSs) have become an integral part of renewable energy and the key to address the intermittency of solar and wind power. In recent years, there has been significant deployment of BESSs in the power system; for example, the total BESS capacity installed globally of 11 GWh in 2017 is expected to grow to 100-167 GWh by 2030. Applications for energy storage are endless. In this blog, we will discuss the role it plays in advancing our power grid.
Energy systems have experienced a dramatic change in the last few decades, including a rapid decrease in the cost of wind and solar power generation and an even steeper decline in the cost of electricity storage. As the price of the energy storage falls, deployment in new areas is increasingly attractive. Commercial battery pack cost has dropped from $1,100/kWh to an astounding $156/kWh. The nosedive in battery cost allows greater grid flexibility as distributors can buy electricity during off-peak time when energy is cheap and sell it to the grid when it’s in greater demand.
There are various types of batteries integrated in the power grid worldwide. Each type can utilize the system in different ways. Battery selection is focused mainly on the application of BESS (such as power or energy) and the cost efficiency due to a high cost ratio of battery to total project cost (roughly around 50% to 60%). Battery options include:
Lead-Acid Battery
Lead-acid batteries are mainly used in the electrical substation. It is the main source of the backup energy in the substation. Lead-acid battery has the lowest cost (perkWh), low self-discharge and a wide range of operating temperatures.
Sodium Sulfur Battery
Sodium sulfur batteries (NaS) are a molten-salt type battery. Its solid electrolyte needs to be melted into liquid requiring the temperature to be raised and kept around 300°C. Its advantages are its high-energy density with moderate cost (per kWh) and its long lifecycle (up to 4,500 cycles). However, for power application, it’s considered to be highly price (per kW), causing it to be unsuitable for high power, short duration applications.
Li-ion Battery
Lithium-ion batteries are increasing the efficiency and effectiveness of transmission and distribution networks. With its various chemical formulas, Li-ion batteries are flexible to fit most BESS applications. It also has a long lifecycle.
Hybrid BESS
In order to combine the advantages of multiple types of batteries, BESS may consist of more than one type of battery. For example, the high-power Li-ion battery can be combined with the lower cost lead-acid battery to decrease the project cost while providing the same application as a pure Li-ion battery BESS.
