Intermittency is Renewable Energy’s Major Issue but there are Solutions

Intermittency

Context (IE): Gravity is emerging as the best bet in solving renewable energy’s biggest problem, intermittency.

Intermittency in renewable energy refers to the unpredictability and variability of energy production from sources like wind and solar, which depend on weather conditions and time of day.
Types of intermittency
- Diurnal Intermittency
- Seasonal Intermittency
- Weather-Dependent Intermittency
- Intra-Hour Intermittency
- Spatial Intermittency
- Resource Availability Intermittency
- Random Intermittency (due to random events like equipment malfunctions)

Grid Reliability: Intermittent energy sources can cause sudden power fluctuations that disrupt grid stability, leading to blackouts or voltage issues.
Matching Supply and Demand: Coordinating intermittent energy supply with fluctuating electricity demand is a significant challenge. It can result in overproduction or underproduction.
Energy Storage Costs: Energy storage systems often mitigate intermittency. However, these systems can be expensive to implement and maintain.
Grid Infrastructure: The existing grid infrastructure may not be well-suited to handle renewable energy sources’ variability and intermittent nature. Upgradation can be costly and time-consuming.
Resource Variability: The variability of energy can make long-term energy planning challenging.
Investment Uncertainty: Fluctuations in energy output can affect the return on investment and project profitability. This can make investors in renewable energy projects uncertain.
Backup Generation: Backup sources like fossil fuels are sometimes necessary when renewable energy is scarce, which can impede efforts to cut greenhouse gas emissions.
Technological Challenge: Creating effective technologies to address intermittency, like advanced energy storage and smart grids, can be challenging regarding R&D and deployment.

Gravity-based energy storage uses the force of gravity to store energy.
This is achieved by raising heavy objects to a high elevation when the electricity demand is low and generating electricity by lowering the heavy objects when the demand is high.

There are a number of different gravity-based energy storage technologies, but they all work on the same basic principle.
- Example 1: Pumped hydro storage uses excess electricity to pump water uphill, then releases it downhill to generate electricity when needed.
- Example 2: Compressed air energy storage compresses air when there is excess electricity and then expands it to generate electricity when needed.

About 96% of the world’s energy storage comes from pumped hydro storage.

High efficiency: These highly efficient storage systems recover most energy when discharged.
Scalability: These storage systems can store large amounts of energy, making them ideal for intermittent renewable energy.
Reliability: They are very reliable, with few moving parts and no emissions.

Cost: These systems can be expensive to build because they require a lot of land and infrastructure.
Land use: These systems require a lot of land, which can be challenging in areas where land is scarce.
Response time: These systems can be slow to respond to changes in demand.

In India, grid managers face the challenge of sustaining a monthly addition of about 1,000 megawatts (1 GW) from renewables to the grid.
Policy makers believe India needs to quickly develop energy storage options, as it is the world’s third largest producer of renewable energy, with ~40% of its electricity coming from non-fossil fuels.
India’s green initiatives led to a 24% reduction in GDP emission intensity from 2005 to 2016, but they also posed challenges for a grid powered mainly by renewables.
GoI is exploring two options: hydrogen and hybrid generation models blended with off-stream pumped storage.
The Cabinet approved a policy for increasing green hydrogen production and its use as a fuel.
The Power Ministry surveyed pumped hydro sites, and hydro PSUs are given targets for such schemes.
They are considering opencast mines for potential pumped hydro sites.