Energy Storage Using Next Generation Batteries Helps In Integration Of Renewables

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Batteries, as we know, are electricity/energy storing devices. Rechargeable batteries or secondary batteries such as Lead acid batteries can be charged and discharged throughout their lifetime.

The world is witnessing a rapid increase in the addition of renewable energy capacity especially solar and wind power. India has set an ambitious target to achieve installed capacity addition of 100 GW of solar power generation and 60 GW of wind power generation by 2022. Though these systems are free of fuel costs and carbon emissions, they have their own limitations. The renewable energy sources are intermittent in nature. Solar energy is generated only during bright sunshine hours which are approximately only 5 hours per day. Wind energy can be generated only during wind season which is approximately 5 months in a year. If the grid is not available, the energy generated goes waste. And even if the grid is available, dispatch of electricity must be managed. India is also suffering from a constrained transmission and distribution capacity. Thus a renewable energy system is to be backed up with an energy storage system.

On the other hand, there are hundreds of villages in our country which don’t have access to electricity as they don’t have grid connectivity. There are many villages in mountains, deserts and islands where providing the grid connectivity is impossible. In these villages, electricity can be provided through solar or wind power generation systems combined with a battery backup. Apart from rural areas, batteries are gaining demand in urban areas in the field of smart homes, smart grids, electrical vehicles, etc.

Conventionally used batteries are lead acid, nickel cadmium and lithium ion batteries. Generally, for solar standalone power generation systems, lead-acid batteries are used. Batteries alone cost about 50% of the total cost of a solar system and their life span is just five years. So, every five years, the owner has to change the batteries and make a substantial amount of fresh investment. The other major problem is that batteries are bulky and hence require a lot of space. For bigger systems, apart from space, personnel have to be employed in order to maintain the system. Ni-cd batteries have been banned in many nations owning to toxic nature of cadmium. Research on next-generation batteries is going on across the globe to overcome these limitations.

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In the last few years, new kinds of batteries have been demonstrated that deliver high enough capacity to serve as much as a factory, towns or even ‘mini-grids’. These batteries are based on Sodium, Aluminium or Zinc. Caustic chemicals and heavy metals are avoided in their fabrication. They are more affordable, more scalable and safer than the common lithium ion battery. The newer batteries are better suited to support transmission systems that rely heavily on solar or wind power.

A battery is usually made up of an anode on one side, a cathode on the other, and an electrolyte in between. For a lithium-ion battery, lithium ions move from the anode to the cathode (and back) through the electrolyte during charging and discharging. A start-up called Fluidic energy has powered hundreds of villages in Madagascar using its zinc- air batteries which are lighter, energy denser and cheaper. Zinc-air batteries use zinc articles as the anode, air as the cathode and potassium hydroxide as the electrolyte.

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The Ministry of New and Renewable Energy is planning to introduce National Energy Storage Mission in order to enhance electricity storage capacity in the nation. This mission along with National Smart Grid Mission and National Electric Mobility Mission is set to promote the use of batteries across our country. Solar Energy Corporation of India is planning to set up a 750MW solar power plant along with a 100MW installed storage capacity at Ananthapuramu village in Kadapa district in Andhra Pradesh.

The technology is still not mature and has plenty of room for improvement. The ideal battery is yet to be invented. But looking at the pace at which the research work is going on, the ideal battery is not far from invention and commercialization.