It has always been a complex to balance power demand and supply with the large amounts of renewable sources of energy like tidal, wind and solar PV energy which are all dependent on weather changes. And once they are included in the grid, the balancing process gets more complicated. In 2008, the power industry's most critical were faced in Texas, USA when the huge wind portfolio died down which resulted in a 1200-MW drop making the electric Council body declare a state of emergency. Of course, this 3-hour shortfall caused overloads and blackouts.

There are technologies that are well-established which provide important energy storage capacity but need certain infrastructure and geographical features while there are others that are deployed instantly whenever they are required but have limited capacity. However, there is a new technology gaining ground – power storage batteries.

 Large-scale Power Storage Batteries

 There are special batteries that are used for large-scale energy storage made by energy storage companies. These power storage batteries comprise of electrochemical cells although there is no single type of cell suited for all applications.

 1. Lead-acid batteries

These batteries make use of a liquid electrolyte and are still being used today. Small volumes of energy are stored by this battery but it is very reliable and cheap. DCLA (deep-cycle lead acid) batteries are used in renewable energy systems which provide steady current for a long time.

2. Lithium ion batteries

These kinds of batteries are known to be dry cell batteries which have electrolyte contained in a low-moisture paste. Over the years, li ion batteries have been a subject of interest because of their high energy density and with the emerging electric vehicles manufacturing, the production of these batteries has gone on a larger scale. The prices will significantly fall.

3. Vanadium Redox Batteries (VRBs)

These power storage batteries are known for their clean technology having a long lifespan and high availability. They have a low energy density of about 40 Wh per kg, although there are indications that they have modified it by a 70 percent improvement. The prices of these special batteries are volatile with an increase in their demand.

 4. Molten salt batteries (liquid sodium batteries)

These power storage batteries offer both high power density and high energy density, which operate at temperatures between 400-700 degrees centigrade. However, there is cause for concern about safety and management issues which have resulted in stringent requirements placed on the components.

5. Ultracapacitors

Also known as supercapacitors, polarize an electrolyte to store energy instead of storing it chemically like a battery. They have a lower energy density but a higher power density than regular batteries. Although they have been in existence for long since the 1960s, they are expensive and are manufactured in limited quantities making them cost-competitive.

 Comparisons and predictions

According to the Electric Energy Storage Technology Options, a paper of the US Electric Power Research Institute, the sodium-sulphur batteries which are a variety of molten salt battery, are the third most used energy storage solution having 316MW installed.

Li Ion batteries made by storage energy manufacturers have grown in revenue from $795 million to $2.2 billion between the years 2011 to 2016 and with its improved cycle life and energy density over the lead-acid batteries. This has enabled li ion batteries to gain much penetration into the data center market and if the costs of these batteries can be trimmed by around 33 percent, as well as possessing improved lifetimes, this technology can gain full control of the energy storage market.