The growth of renewable energy generation is a key element in reducing carbon emissions worldwide. Many countries are setting target dates for 100% renewables and Australia should do the same!
Right now, we stand at a point where solar and wind energy fit the bill for filling the demand for renewable and the potential exists in Australia to develop renewable any sources that not only meet 100% of our energy requirements but far exceed them. This has the potential to spur growth in energy-intensive industries and open the possibility for the export of renewable energy. The stumbling block for renewables as they start to make up a larger share of the energy mix is in terms of reliability. This is when Pumped Storage Hydropower comes to save the day.
What Is Pumped Storage Hydropower?
Pumped Storage Hydropower (PSH) is a hydroelectric method of generating electricity. It uses elevation to create a gravitational potential energy coupled with a turbine to produce electricity.
All well… but you must be wondering where is “pump” in all this and how is this different from conventional hydropower? A pumped-storage plant has the capacity to recirculate the water back to the upper reservoir using a pump.
As you might’ve already guessed, the system consumes some part of the produced electricity to perform pumping but the profit transcends the compromise with an efficiency of 70-80%. Pumped Storage Hydropower can operate for a very long service life, Tumut 3 Pumped Hydro was commissioned in 1973! This long asset life more than offsets the long construction duration.
PSH demands a relatively high initial investment and requires locations with specific geographical features to establish, however maintenance and operating cost is economical.
How Does It Work?
Two reservoirs are built at different altitudes – upper reservoir and lower reservoir. Both these reservoirs are connected through a tunnel.
The highlight of this system is Efficient Load Management.
During peak hours of electricity demand or during a shortage for our energy sources, water flows from upper reservoir through the tunnel into the turbine at lower reservoir. Turbine rotates and harness the gravitational potential energy to produce electricity to meet the demand of the peak hours. Water discharged through the turbines is collected in the lower reservoir.
During off peak hours (late night and early morning), the discounted energy is used to pump water back from lower reservoir to upper reservoir to refill it for the upcoming peak hours. This job is often performed by the turbine itself in case of reversible pump turbine (RPH) or by a separate pumping system.
It’s no rocket science!
Just a phenomenal use of gravity coupled with efficient use of resources and time.
Basic Elements of Pump Storage Scheme
Upper and Lower Reservoir:
Two reservoirs on different heights to enable difference in gravitational potential energies.
Intake Tunnel:
Water flows down this tunnel from upper reservoir to the turbines.
Discharge Tunnel:
Water flow through this tunnel into lower reservoir after flowing through the power station.
Turbine/Pump:
The turbines are attached at a lower elevation and during power production are rotated by the force of falling water . Turbines convert kinetic energy of the falling water in mechanical energy in the rotation of the shaft. During pumping the reserve occurs mechanical energy is used to move the water from the lower reservoir to the upper reservoir
Generator:
The generator, during power production, converts the mechanical energy from the turbine into electrical energy. During pumping everything happens in reverse, electrical energy is converted to mechanical energy to drive the turbine.
Transformers:
Transformers change the voltage of the electricity produced so that it can be distributed efficiently
What Is It Used For?
Pumped Storage Hydropower kills two birds with one stone!
It resolves two major issue of the current world – Water storage and power production.
Pumped storage technology provides a long-term and economical energy solution. The system can provide consistent power during peak demand hours and store excess energy for extended periods of time. Just like a battery!
PSH can be handy in emergency situations like fires and drought by acting as a water storage option. In fact, water stored at high elevation can be distributed for other uses without additional pumping – saving cost!
Pumped Hydro constitutes for over 95% of the worldwide active energy storage facilities and the prospect for the future is even brighter. Pumped Storage Hydropower is a primary source of clean energy worldwide and its importance is expected to grow in the future.