Alternative battery – pumped storage.

Pumped Storage: A Homegrown Energy Solution

In the quest for sustainable and resilient energy solutions, pumped storage has emerged as a compelling alternative to traditional batteries. This technology, often associated with large-scale power plants, is now being explored for domestic applications, offering homeowners the potential to store excess renewable energy and release it when needed.

How Does Pumped Storage Work?

Pumped storage systems harness the power of gravity to store and release energy. The basic principle involves two water reservoirs: an upper reservoir and a lower reservoir.

1. Charging: During periods of excess energy generation, such as when solar panels produce more electricity than is immediately consumed, water is pumped from the lower reservoir to the upper reservoir. This process stores potential energy in the elevated water.
   
2. Discharging: When energy is required, the stored water is released from the upper reservoir, flowing through a turbine to generate electricity. This process converts the potential energy of the water into kinetic energy, which is then transformed into electrical energy.

Pumped Storage for Homeowners: A Feasible Option?

While large-scale pumped storage projects require significant infrastructure, smaller-scale systems can be implemented in residential settings. However, several factors need to be considered:

• Water Source and Storage: A reliable water source, such as a well or municipal supply, is essential. Additionally, a suitable storage tank, either above ground or underground, is required.
  
• Elevation Difference: A significant elevation difference between the upper and lower reservoirs is crucial to maximize energy generation. This can be achieved by utilizing the height of a building or constructing a dedicated water tower.
  
• Pump and Turbine Efficiency: Efficient pumps and turbines are vital to minimize energy losses during the charging and discharging cycles.
  
• Regulatory Compliance: Local regulations and permits may apply to the installation and operation of pumped storage systems.

Water Requirements for a 500W System

To determine the water volume required for a 500W pumped storage system, we need to consider several factors:

• Energy Output: 500W for 12 hours equates to 6 kWh of energy.
• Water Head: The vertical distance between the upper and lower reservoirs, which determines the potential energy of the water.
• Pump and Turbine Efficiency: The efficiency of the system, which affects the amount of energy that can be stored and retrieved.

Assuming a water head of 10 meters and a system efficiency of 80%, the required water volume can be calculated as follows:

Water Volume = Energy Output / (g * Water Head * Efficiency)

Where:

• g is the acceleration due to gravity (9.81 m/s²)

Calculating this equation yields a water volume of approximately 76,452 liters. (76.45 cubic meters.)

Example Water battery system:
To calculate the size of the system required for a 7-meter water drop, we’ll need to consider a few factors:

1. Desired Power Output: This determines the amount of energy you want to store and release.
2. Storage Duration: How long do you want the system to provide power?
3. System Efficiency: This accounts for losses in the pump, turbine, and other components.

Let’s assume we want a 500W system with 12 hours of storage and a system efficiency of 80%.

Calculating Water Volume:

We can use the following formula:

Water Volume = Energy Output / (g * Water Head * Efficiency)

Where:

• Energy Output = 500W * 12 hours = 6 kWh = 21,600,000 Joules
• g = acceleration due to gravity = 9.81 m/s²
• Water Head = 7 meters
• Efficiency = 0.8

Plugging in the values:

Water Volume = 21,600,000 J / (9.81 m/s² * 7 m * 0.8) ≈ 393,000 liters

Converting to Cubic Meters:

393,000 liters is approximately 393 cubic meters.

Tank Size:

The tank size will depend on the shape of the tank. For a cylindrical tank, you’ll need to consider the diameter and height. For a rectangular tank, you’ll need to consider the length, width, and height. As you can clearly see the 500W system would need a considerable tank size and would NOT be suitable for loft space within a home. The Average home loft space is around 27 cubic meters.
However some farms may be able to achieve the pumped storage provided that they have a suitable location.

Pump and Turbine Sizing

The size of the pump and turbine required depends on the desired power output and the available water head. For a 500W system, a relatively small pump and turbine would suffice. However, it’s essential to select components that are adequately sized to handle the load and ensure efficient operation.

Can You Put a Tank in Your Loft/Attic?

Placing a water tank in a loft or attic is a potential option, but it’s important to consider the structural load capacity of the building. The weight of the water, tank, and pump system must be carefully evaluated to avoid structural damage. Additionally, factors such as water pressure, pipe sizing, and insulation requirements need to be taken into account.
A big loft tank is around 533 litres

Scaling Down to 250W

A 250W pumped storage system would require approximately half the water volume of a 500W system, assuming similar water head and efficiency. The pump and turbine could be smaller, but the overall system design principles would remain the same.

Conclusion

While pumped storage offers a promising solution for home energy storage, it’s requirement for the volume of water make this a non starter for home projects, it may work for a farm on a hill (or cliff) in order to make the work required produce significant power. However in this scenario the power generated is small in comparison with battery storage in volume size. It is mindful to remember that you would pump the water back to the tank which would require power to do so.