How Pumped Storage Power Plants Work (Hydropower)

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This video explains how pumped storage hydroelectric power stations work, what their main components are and their operating characteristics.

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▶️Introduction

This type of power plant converts potential energy to electrical energy, or, electrical energy to potential energy. They achieve this by allowing water to flow from a high elevation to a lower elevation, or, by pumping water from a low elevation to a higher elevation. When water flows to a lower elevation, the power plant generates electricity. When water is pumped to a higher elevation, the power plant creates a store of potential energy. Pumped storage plants use Francis turbines because they can act as both a hydraulic pump and hydraulic turbine.

Pumped storage power plants are used to balance the frequency, voltage and power demands within the electrical grid. Pump storage plants are often utilised to add additional megawatt capacity to the grid during period of high power demand, for this reason, pumped storage plants are referred to as ‘peaking’ plants.

Because pumped storage plants can provide electrical grid operators with power ‘on-demand’, they have a high level of dispatchability (the ability to provide power to the grid as needed).

Components
Irrespective geographical location, all pumped storage plants require an upper and lower reservoir. The difference in elevation between the upper and lower reservoirs is referred to as the ‘head’ (head of pressure) and it must be significant in order for the plant to operate efficiently.

A penstock connects the upper reservoir to a Francis turbine located in the power house. A draft tube and tail race connects the Francis turbine to the lower reservoir.

Operation - Generating Power (Electricity)
Water flows from the upper reservoir, through the penstock, and to the Francis turbine. As the water passes over the Francis runner blades, a pressure differential is created that causes torque (rotary force) to be applied to the runner. The runner begins to rotate.
The turbine runner is connected on a common shaft to an electrical generator. As the runner rotates, so too does the generator rotor. As the rotor rotates through the electromagnetic field within the generator, it induces current in the stator windings and electrical current begins to flow. The electrical current is usually then dispatched to end consumers via a switchyard and electrical transformer.

Water discharged from the turbine runner enters into a draft tube where some of the kinetic energy is recovered and converted to potential energy; the water then enters the tail race and is discharged to the lower reservoir.

In this example, the potential energy of water was converted by the turbine runner into mechanical energy. The mechanical energy was transferred on a common shaft to a generator, which converted the mechanical energy to electrical energy. The entire process can be continuous until the upper reservoir is emptied.

Operation – Storing Potential Energy
Water is pumped from the lower reservoir to the upper reservoir by the Francis turbine runner. The flow path is the same as when generating electricity, except the flow direction is reversed.

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[savree-d]

Want to continue learning about engineering with videos like this one? Then visit:

Want to teach/instruct with the 3D models shown in this video? Then visit:

[wonnesahbrowne]

This video had increased my motivation into the field of hydropower development.

[williamkern]

I had no idea that this is how it all worked. Fantastic, thank you for your hard work

[RG-]

Absolutely brilliant production, thank you so much for the very informative and educational video.

[koolmyskool]

Great video, just had one open up in Tâmega Portugal in union with Iberdrola wonderful project and great for the environment.

[dr.gideonguyokideghoph.d.]

This is superb method of power generation

[meghanaambadasu]

Thank you so much. Really good explanation.

[IngVasiu]

Very interesting idea. It would be great if you would explain the efficiency of these energy reservoirs.

[angelotonielo]

Great video!!!

I have never thought about this before.

I can say that dor turbines maybe the grease is the best option even being expensive, because the time between maintenance is high.

Thank you!!!

[richsouks]

Lebanon would be absolutely perfect for this type of power, perfect terrain and an abundance of water and has plenty of sun for solar

[yogadajoshi]

this was so interesting - why did you abruptly stop? I was waiting for a nice conclusion line towards the end, although I did understand what it led up to but it stopped abruptly

[Rick-ibe]

Only thing you're missing is, which would be the actual energy losses? not translated in money, just energy used to store vs. energy stored. With that info, this would be a perfect reference for this type of storage.

[JoshBerry-jb]

Love this idea. I have been researching for some time the efficiencies claimed and they seem to be questionable. As I understand a francis turbine its very hard to be made to both generate energy efficiently an pump with similar efficiencies. I would love any information you have on people that specialise in this. From my research the energy conversion is more like 80 to 85% efficient to generate electricity but when you go to pump it back to the reservoir the efficiency can be as low as 20%. Please don't get me wrong I love the idea. I would just like more information on how efficient the system is an more importantly how to achieve it.

[jaketaraj]

Environmental protection also includes grease free bearings and bushings... these are expensive and require frequent replacement. Hydro is an expensive solution due to these maintenance challenges.

[sandunikodagoda]

Hey. Loved the video. Would it be possible to do one detailing more on the actual designing of the pumped hydro plant?

[husseinelfayoumy]

If a pumped storage plant with a total capacity of 1000MW has 4 250 MW units, would all 4 units be used to pump the water back up?

[kodavidkoko]

hi, What is the minimum height necessary for the operation of this electric plant?

[vinnyfiorella]

I know this video is old, so I'm not really expecting an answer; but if you were to rely solely on the hydro plant to both produce electricity and then use that electricity to pump the water back would it be able to do it while still being able to produce electricity for other uses. Or would it completely use up all the electricity that it generated.

[rodneyward]

I have two dams one low one high in a hill, What is the minimum head required to set up a system suitable to run a standard house with modern appliances.

[Ibrahim-ovhf]

Was wondering what the usual capacity of these plants are? Also, other than the friction in the pipes and transmission losses, are there any other major losses that should be taken into account? Lastly, is there a way to optimise these designs? You mentioned that there is usually one turbine/penstock, is there a reason for this? And can we have more than one penstock/reservoir? Thank you very much, the video was very informative.