Pumped storage hydroelectricity (PSH) can be categorized into two primary types: open-loop and closed-loop systems. Both utilize the concept of moving water between two reservoirs at different elevations to store and generate electricity, but they differ in how the water is sourced and connected to external water bodies.
Open-Loop Systems
Key Features:
- Connection to External Water Bodies: Open-loop systems connect a reservoir to a naturally flowing water feature, such as a stream or river, via a tunnel.
- Water Flow: Water is pumped from the lower reservoir, which is connected to the external water body, to the upper reservoir during periods of low electricity demand. During high demand, water is released back into the lower reservoir, generating electricity as it passes through a turbine.
- Natural Inflows: These systems can receive water from natural inflows (e.g., rivers), which can affect the overall energy balance and capacity of the facility.
Closed-Loop Systems
Key Features:
- Isolation from External Water Bodies: Closed-loop systems are isolated from external water bodies. The water is entirely confined within the two reservoirs, with no natural inflows.
- Water Circulation: Water is circulated between the two reservoirs without external loss or gain. This minimizes environmental impacts on surrounding water sources.
- Site Requirements: These systems require a well-defined site with suitable topography, often involving artificial lakes or reservoirs constructed specifically for energy storage purposes.
Comparison Summary:
| Feature | Open-Loop Systems | Closed-Loop Systems |
|---|---|---|
| Connection to Water Bodies | Connected to natural water bodies (e.g., rivers). | Isolated from natural water bodies. |
| Natural Inflows | Can receive water from natural inflows. | No natural inflows. |
| Water Management | Water can be exchanged with external bodies. | Water is circulated internally without external exchange. |
| Environmental Impact | May impact surrounding ecosystems due to water flow changes. | Typically less impactful on the environment due to isolation. |
| Operational Flexibility | Can be influenced by natural water availability. | More consistent operations independent of external water conditions. |
Both types are essential for balancing the electricity grid and storing energy, but they serve different geographical and environmental contexts.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/what-are-the-differences-between-open-loop-and-closed-loop-pumped-hydro-storage/
