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

• 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)

Challenges from Intermittency in Renewable Energy

• 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 Storage: Solution to Intermittency

• 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.

Benefits of Gravity-based Energy 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.

Challenges of Gravity-based Energy Storage

• 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.

Intermittency Situation in India

• 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.