There are several different types of hydro energy set ups used to generate electricity globally.
In this guide, we compare hydroelectric dams vs run of river vs pumped storage hydro energy projects and power plants.
We look at what each is, their differences, and examples of each being used in the world.
Summary – Hydroelectric Dam vs Run Of River vs Pumped Storage Hydro Energy
- Hydro energy is the use of running water to create electricity
- Hydropower as a whole produces the most electricity of any renewable energy source – roughly around 50% of all electricity produced by renewable energy sources globally
- There’s several different types of hydro energy – hydroelectric dams (built on rivers with an impoundment facility, dam and reservoir), run of river (may or may not have a dam – but can simply use flowing water without a dam or reservoir), and pumped storage hydro (using two reservoirs or water – one on a higher level and one on a lower level)
- Essentially, they can be divided into hydro energy power set ups that use dams and reservoirs, and those that don’t
- They can also be divided into large, medium and small sized hydro power plants, depending on the amount of electricity capacity they have (dam hydro power usually produces the most electricity)
- Hydropower is expected to expand into the future, particularly in developing economies, but growth isn’t expected to be as strong as the last 5 years to one decade (investment and expansion will mostly be in solar, wind, and bioenergy)
- Large and mega sized hydro projects can have some uncertainty regarding their funding, planning and construction – so growth and added capacity of hydro energy can be dependent on this
- According to recent studies, there is potential for many new pumped storage hydro sites worldwide – pending on-site feasibility checks. Pumped storage hydro can be a good source of stored renewable energy in the future (especially as a backup to intermittent energy like solar and wind)
What Is Hydro Energy?
- Hydro energy is the use of running water to create electricity
The Different Types Of Hydro Energy, & How Each Works
Hydro energy can be broadly categorised into two types:
- Hydro energy with dams and reservoirs,
- and, hydro energy without dams and reservoirs
Utility scale and large hydro (hydro energy produced for electricity and energy utilities) usually involves dams and reservoirs, and small or local community/village, and run of river hydro usually doesn’t.
Beyond the above broad categorisation, utility scale hydro power plants can be divided into:
- Impoundment/Dam (using an impoundment facility) – a dam stores water in a reservoir. Water is released from the reservoir through turbines, which activate a generator, and produces electricity. Dams can also serve other purposes other than just producing electricity, such as preventing flooding.
- Diversion/Run Of River – part of a river is channeled through a canal or penstock. May or may not use a dam. [It helps if a river is chosen that has a consistent flow, otherwise, without a storage reservoir, energy will be variable and not consistent]
- Pumped Storage – there is an upper and lower water reservoir. Water is stored in the lower reservoir, and when needed, is pumped up to the upper reservoir, and then released back down to the lower reservoir through turbines, which activate a generator, and produces electricity. [Pumped storage can actually store energy in the form of water, so, it can be a good backup to wind and solar energy for example]
Diversion and run of river hydro generally has less negative environmental and social impact compared to large hydroelectric dams.
Something else to note is that renewable hydro energy might be becoming a type of hydro energy in the future. Currently, pumped storage hydro uses fossil fuels to pump water up to it’s top reservoir. In the future, renewable energies like wind and solar might provide the electricity to pump and power hydro power stations.
Large vs Small Hydro (& Medium Hydro As Well)
Globally, there’s no official definition of small, medium and large hydro, but each country has a guide of what they call the different sizes of hydro plants and projects.
Size usually refers to the energy/electricity capacity or generation of the hydro plant.
All of the largest hydro projects tend to be dams as they tend to produce the most electricity (this is true when you look up the largest hydro plants in the world, like the Three Gorges Dam that produces up to 22,500 MW for example).
To give a broad idea of how hydro plants and projects might be categorised by size:
- Large – 10 GW (10,000 MW) and over
- Small – 10-30 megawatts (MW)
- Micro and Pico – in the kW range
- Pumped Storage – some of the biggest pumped storage plants have a capacity of 1000 to 3000MW. New potential pumped storage sites discovered in recent studies have potential capacity to hold 2-150 GWh of energy (sciencealert.com) [and, 2 GWh converts to roughly 2000 MWh]
Differences In The Different Types Of Hydro Energy – Cost, Efficiency, Capacity Etc.
- Overall, hydroelectricity has been one of the cheapest forms of renewable energy (although solar and wind are challenging it)
- Large Hydroelectric dams tend to be the most expensive to construct, but tend to have the greatest capacity for production (so, costs and returns can average out over the long term)
- Large hydroelectric dams tend to have the highest social and environmental impact, whereas run of river and small scale hydro that doesn’t need dams and reservoirs tends not to be as intrusive or destructive on the natural landscape
- Pumped hydro storage sites require land clearing, and once in use, may use fossil fuels to pump water up to the higher reservoir.
- Dam and reservoir hydro plants offer energy storage and can ramp up quickly in terms of energy generation in times of peak demand – this is in opposition to run of river hydro energy that requires water be flowing (depends on a river that runs year round) in order to produce electricity
Global Installed Capacity, Production & Consumption Of Hydro Energy
- At the end of 2018, made up 50% of installed capacity for renewables
- At the end of 2018, made up 15.8% of total global electricity production
- At the end of 2016, was the most consumed renewable energy source for electricity
- Between 2012 to 2018, solar PV led all renewables in annual additional installed capacity by a wide margin, followed by wind energy, hydropower, and all other renewables as a group behind that (including solar CSP/thermal)
- At the end of 2015, the leading hydropower generating countries were China, the US, Brazil, Canada, India and Russia.
Mixed Plant vs Renewable Hydropower Electricity Generation
In 2016, electricity generation from hydro power was:
- Mixed Plant – 4,048,420
- Renewable Hydropower – 0
Investment In Hydro Energy
Major hydro project investment can vary by year and can be unpredictable.
Future Of Hydro Energy
- Hydropower capacity is expected to increase 125 GW [heading up to 2023] – 40% less than [the increase] in 2012‑17
- One-fifth of overall growth (26 GW) is from pumped storage hydropower (PSH) projects
- [it is thought there could be a lot of potential in pumped storage hydro in the future as new scans and studies of the globe have found hundreds of thousands of new potentially usable sites for pumped storage hydro]
- [pumped storage hydro has the advantage of providing energy storage and baseload power as a complement to solar and wind energy]
Examples Of Hydro Energy Power Plants Globally (By Type, Capacity/Size, Country Etc.)
- Conventional Hydro Power Plants – https://en.wikipedia.org/wiki/List_of_conventional_hydroelectric_power_stations
Range from 1000 all the way up to 22,500 MW of capacity.
China features heavily, having some of the biggest hydroelectric dams in the world, including the biggest – Three Gorges Dam, which is on the Yangtze River.
- Run Of River Hydro Power Plants – https://en.wikipedia.org/wiki/Run-of-the-river_hydroelectricity
Highly variance in capacity of the major examples of run of river hydro plants globally.
Range from 16MW of capacity at a station in British Columbia, Canada, all the way up to 11,233 megawatts of capacity at Belo Monte Dam in Brazil.
- Pumped Storage Hydro Plants – https://en.wikipedia.org/wiki/List_of_pumped-storage_hydroelectric_power_stations
Range between 1000 to 3000MW of capacity.
China, the US, Japan, Australia, Spain and France has some of the plants with the largest capacity.