Gravity battery: How gravity may solve green power’s problem

What’s in Today’s Article?

• Why in News?
• What is a Gravity Battery?
• Development of Long-duration Energy Storage Systems
• Advantages of the ‘EVx’ Platform
• Gravity Batteries vs Lithium-ion Batteries
• India’s Renewable Energy Push and Challenges
• Developments in India in the Field of Gravity Battery Storage Systems

Why in News?

• As countries step up renewable energy capacity addition, there is growing urgency to develop long-duration energy storage systems.
• Gravity batteries are emerging as the best bet in solving renewable energy’s biggest problem - intermittency.

What is a 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.

Development of Long-duration Energy Storage Systems:

• As countries step up renewable energy capacity addition, there is growing urgency to develop long-duration energy storage systems.
  • These systems could be installed alongside green power generation to balance out the variability in renewable power, given that green generation is not always in sync with the electricity demand cycle.
• Energy Vault (a Swiss company founded in 2017), a developer of utility-scale storage technology, is offering a proprietary gravity-based storage, to plug this gap.
  • 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.

Advantages of the ‘EVx’ Platform:

• This type of energy storage could be an innovative solution for countries (including India).
• It can solve the biggest impediments to wider deployment of renewable generation - the ability for power companies to store energy for use by consumers when the sun is not shining or the wind is not blowing.
• This could also facilitate the shift to a circular economy while ensuring clean energy transition.

Gravity Batteries vs Lithium-ion Batteries:

• Gravity batteries are not the only way renewable energy can be stored, lithium-ion batteries dominate the market and some experts favour green hydrogen.
• But gravity is free, clean and easily accessible, without the complications of producing hydrogen or the environmental and human rights concerns linked to some lithium mining.
• While lithium-ion batteries lose capacity after they have been charged and recharged over years, the gravity systems are made of robust components which will last much longer.

India’s Renewable Energy Push and Challenges:

• The country is the world’s third largest producer of renewable energy and nearly 40% of installed electricity capacity comes from non-fossil fuel sources.
• This green push has resulted in a 24% reduction in emission intensity of GDP between 2005 and 2016, but it has also thrown up challenges of a grid being increasingly powered by renewables.
• Also, grid managers are already grappling with the challenge of operationally sustaining a massive monthly addition of an average 1,000 megawatt from renewables to the electricity grid.
• Policy makers are of the view that New Delhi needs to expeditiously work on developing viable energy storage options.
• There are two alternatives being considered by the government for now: hydrogen and hybrid generation models blended with off-stream pumped storage. 

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 (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.

Q1) Why is India pushing for renewable energy resources?

India aims to achieve net zero emissions by 2070, and renewable energy is key to achieving this goal. Solar energy accounts for a significant share of India's renewable energy portfolio.

Q2) What is floating photovoltaics (FPV)?

FPV are solar panels mounted on a structure that floats on a body of water. The systems have advantages over PV on land as water surfaces may be less expensive than the cost of land, and there are fewer rules and regulations.

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