Context:
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.
Relevance:
GS III: Science and Technology
Dimensions of the Article:
- What is a Gravity Battery?
- Development of Long-duration Energy Storage Systems
- Gravity Batteries vs Lithium-ion Batteries
- India’s Renewable Energy Push and Challenges
What is a Gravity Battery?
A gravity battery is a type of electricity storage device that operates on the principle of gravitational potential energy.
Working Principle:
- Gravity batteries store energy in the form of gravitational potential energy, which is the energy an object possesses due to its height relative to the Earth’s surface.
- These batteries work by using excess energy, typically generated from sustainable sources, to raise a mass, such as water or a heavy object, to a higher elevation. This process converts electrical energy into gravitational potential energy.
- When electricity is needed, the elevated mass is lowered, and as it descends, the stored potential energy is converted back into electrical energy using an electric generator.
Common Types:
- The most common type of gravity battery is used in pumped-storage hydroelectricity (PSH). In PSH systems, water is pumped to higher elevations during times of excess energy production and released through water turbines to generate electricity when demand is high.
- Another form of a gravity battery involves lowering a mass, such as a concrete block, to generate electricity.
Global Capacity and Significance:
- As of 2019, the total global capacity for pumped-storage hydroelectricity (PSH) was 168 GW (gigawatts).
- The United States alone had a PSH capacity of 23 GW, accounting for nearly 2% of the country’s energy supply system and representing 95% of utility-scale energy storage in the US.
- Gravity-based pumped-storage electricity is currently the largest form of grid energy storage worldwide, playing a crucial role in stabilizing electrical grids and managing energy fluctuations.
Development of Long-duration Energy Storage Systems
As countries expand their renewable energy capacity, the need for long-duration energy storage systems becomes increasingly crucial. These systems help balance the variability in renewable power generation, which may not always align with electricity demand. Energy Vault, a Swiss company founded in 2017, offers a proprietary gravity-based storage solution called the ‘EVx’ platform.
How the ‘EVx’ Platform Works:
- The ‘EVx’ platform utilizes gravity and a mechanical elevator system to stack 35-tonne blocks made of a composite material at the top of a towering structure.
- During periods of low electricity demand, surplus electricity from the grid or renewable plants is used to raise these blocks and stack them at the top of the structure.
- When electricity demand increases, the blocks are lowered one by one, releasing kinetic energy that powers a generator to produce electricity, which can then be fed back into the grid.
Advantages of the ‘EVx’ Platform:
The ‘EVx’ platform offers several advantages, including its potential to address challenges in countries like India:
- Grid Balancing: It helps balance the variability of renewable energy generation, ensuring a more reliable power supply.
- Storage for Non-Sunny or Windy Periods: It provides a solution for storing energy generated during sunny or windy periods for use when these resources are not available.
- Circular Economy: The platform supports the transition to a circular economy by efficiently storing and utilizing energy resources.
- Clean Energy Transition: It facilitates the shift towards clean energy sources by ensuring that renewable energy can be effectively stored and utilized.
Energy Vault’s ‘EVx’ platform represents an innovative approach to long-duration energy storage, addressing one of the key challenges in the broader adoption of renewable energy.
Gravity Batteries vs. Lithium-ion Batteries
While gravity batteries offer a promising solution for renewable energy storage, lithium-ion batteries dominate the market. Some experts also advocate for green hydrogen. Let’s compare gravity batteries with lithium-ion batteries:
Gravity Batteries:
Advantages:
- Free and Clean: Gravity is a free and clean energy source, easily accessible without the complexities of hydrogen production or environmental concerns related to lithium mining.
- Durability: Gravity systems consist of robust components that have a longer lifespan compared to lithium-ion batteries.
Challenges:
- Scale and Efficiency: Gravity batteries may require larger installations for the same energy storage capacity as lithium-ion batteries, impacting their scalability.
Lithium-ion Batteries:
Advantages:
- Market Dominance: Lithium-ion batteries are widely used and readily available, making them the current market standard for energy storage.
- Efficiency: They are known for their high energy density and efficiency, suitable for various applications.
Challenges:
- Capacity Degradation: Lithium-ion batteries tend to lose capacity over time with repeated charging and discharging.
India’s Renewable Energy Challenges:
- India is a significant producer of renewable energy, with nearly 40% of electricity capacity coming from non-fossil fuel sources.
- However, the rapid growth of renewables presents grid management challenges, including operational sustainability.
- Policymakers are exploring viable energy storage options, including hydrogen and hybrid generation models with off-stream pumped storage.
- Developments in Gravity Battery Storage in India:
- India’s push for large-scale renewable power necessitates energy storage solutions.
- Energy Vault, a gravity-based storage technology company, is in discussions with major Indian energy companies, including NTPC, Tata Power, and ReNew Power, to collaborate on deploying its EVx energy storage technology.
- NTPC has signed an MoU for a strategic partnership with Energy Vault, highlighting the growing interest in gravity battery storage systems in India.
-Source: The Hindu
