7.2B Energy storage systems Notes

Energy Storage Solutions: Pumped Hydroelectric Storage (PHS)

1. Intermittent energy production from renewable sources such as wind and solar creates challenges in balancing supply and demand.
2. These renewable sources produce energy only when conditions are favorable (e.g., wind blowing or sunlight shining), which may not align with peak demand times.
3. Energy storage systems are crucial to ensure a reliable and continuous energy supply.

One of the most effective storage solutions is Pumped Hydroelectric Storage (PHS).

Pumped Hydroelectric Storage (PHS)

1. It is the most widely used form of large-scale energy storage and has been in operation for decades.
2. It plays a key role in balancing energy supply and demand, particularly in systems that rely on intermittent renewable sources.

How Pumped Hydroelectric Storage Works:

1. Energy Generation (Discharge Mode):
   1. During periods of high electricity demand or when renewable energy generation is low, water from the upper reservoir is released.
   2. The water flows downhill through turbines, generating electricity as it passes through the turbines connected to generators.
2. Energy Storage (Pump Mode):
   1. During periods of low electricity demand or when excess renewable energy is generated (e.g., high wind or solar power), surplus electricity is used to pump water from the lower reservoir to the upper reservoir.
   2. This process stores potential energy in the form of water at a higher elevation, which can later be released when demand is high.

Advantages of Pumped Hydroelectric Storage (PHS):

1. Large-Scale Energy Storage:
   1. PHS provides a large-scale, reliable energy storage solution.
   2. It can store significant amounts of energy for long durations (hours to days), making it well-suited for stabilizing the grid during peak demand times.
2. Efficiency:
   1. PHS systems typically have an efficiency rate of around 70-80%, meaning that a substantial portion of the energy used to pump water is recovered during electricity generation.
   2. Although this is not as efficient as some other energy storage solutions like batteries, it remains highly effective for large-scale energy storage.
3. Grid Stabilization:
   1. PHS helps maintain grid stability by providing frequency regulation, voltage control, and load balancing.
   2. It is especially useful in regions with a high penetration of renewable energy sources, such as wind and solar, which can be variable.
4. Long Lifespan:
   1. PHS systems are durable and can last for several decades, providing long-term storage without significant degradation over time.
5. Low Operating Costs:
   1. Once the initial infrastructure (reservoirs, turbines, and pumps) is in place, the operating and maintenance costs are relatively low.

Challenges of Pumped Hydroelectric Storage:

1. Geographic Constraints:
   1. PHS requires specific geographic conditions, such as locations with significant elevation differences (mountainous regions or steep terrain) and proximity to water sources.
   2. Not all regions have the appropriate geography to support PHS projects.
2. Environmental Impact:
   1. The construction of PHS plants can have environmental impacts, such as habitat disruption, changes in river ecosystems, and the flooding of land to create reservoirs.
   2. These concerns must be carefully managed through environmental assessments.
3. High Initial Capital Cost:
   1. While operating costs are low, the initial capital investment required to build PHS facilities (especially the construction of reservoirs, dams, and associated infrastructure) can be very high.
4. Water Availability:
   1. PHS systems depend on a reliable water source, which may not be available in all regions or could be impacted by climate change and water scarcity.