Storing energy in blocks: How gravity may solve green power’s problem

Subject: Science and technology

Section: Msc

Context: As countries step up renewable energy capacity addition, there is growing urgency to develop long-duration energy storage systems

Some facts about Gravity Battery:

A Gravity battery is a type of electricity storage device that stores gravitational energy, the energy stored in an object resulting from a change in height due to gravity, also called potential energy.
A gravity battery works by using excess energy usually from sustainable sources to raise a mass to generate gravitational potential energy.
This is then lowered to convert potential energy into electricity through an electric generator.
The most common gravity battery is used in pumped-storage hydroelectricity (PSH), where water is pumped to higher elevations to store energy and released through water turbines to generate electricity.
Another form of a gravity battery lowers a mass, such as a block of concrete, to generate electricity.
As of 2019, the total world capacity for PSH is 168 GW (gigawatts). The US has 23 GW capacity from PSH, accounting for nearly 2% of the energy supply system and 95% of utility-scale energy storage in the US.
Gravity based pumped-storage electricity is currently the largest form of grid energy storage in the world.

Developments in India in the Field of Gravity Battery Storage Systems:

India’s push for deployment of large-scale renewable power makes storage a prerequisite to support this expansion.
Energy Vault is in the process of establishing a base in Bengaluru. It is in talks with NTPC Ltd i.e India’s biggest generation utility, Mumbai-based Tata Power and green energy company ReNew Power for collaborations.
NTPC had signed an MoU last year for a long-term strategic partnership for the deployment of Energy Vault’s EVx energy storage technology and software solutions.

How Energy Vault’s proprietary ‘EVx’ platform works:

Energy Vault’s proprietary ‘EVx’ platform utilises gravity and a mechanical elevator system to stack 35-tonne blocks made of a composite material at the top of a towering structure.
When the electricity demand is low, the elevator uses surplus electricity from the grid or electricity generated by renewable plants, to raise these blocks and line them up at the top of the structure.
When electricity demand picks up, the blocks are then lowered one by one, releasing kinetic energy that is used to rotate a motor and generate electricity, which can then be pumped back to the grid.