Hydropower plants use three main turbine types matched to specific water conditions: Francis for medium head, Kaplan for low head high flow, Pelton for very high head. This guide explains each and where it fits.
The three main types
| Turbine | Best for | Head range |
|---|---|---|
| Francis | Medium head high flow | 10 to 300 m |
| Kaplan | Low head high flow | 2 to 30 m |
| Pelton | High head low flow | Over 100 m to over 1,800 m |
Francis turbine
Named for James Francis, an American engineer. The most widely used hydro turbine globally. Water enters radially and exits axially. Suits reservoir dams with medium head and high flow. Common in large dams globally including Three Gorges.
Kaplan turbine
Named for Viktor Kaplan. Propeller design that suits low head high flow sites. Adjustable blade pitch adapts to changing water conditions. Common in run of river and low head reservoir plants.
Pelton wheel
Named for Lester Pelton. Impulse turbine that uses jets of high pressure water striking bucket shaped blades on a wheel. Suits mountain sites with tall vertical drops. High head applications.
Choosing the right turbine
| Site type | Turbine choice |
|---|---|
| Large reservoir dam | Francis |
| Run of river low head | Kaplan |
| Mountain diversion high head | Pelton |
| Very small stream | Micro Pelton or crossflow |
| Tidal barrage | Bulb turbine (Kaplan variant) |
Efficiency
Modern hydropower turbines reach 90 to 95 percent efficiency, among the highest of any prime mover. Francis and Kaplan can operate over wide load ranges. Pelton has narrower optimal range.
Pumped storage turbines
Reversible Francis turbines dominate pumped storage. Same unit pumps water uphill during charging and generates during discharging. New designs enable variable speed operation for grid services.
Pelton design details
Water jets strike double cup shaped buckets. Bucket geometry is optimised so water rebounds sideways, transferring maximum energy to the wheel. Multiple jets can drive one wheel. Pelton wheels can be several metres in diameter.
Kaplan design details
Propeller with 3 to 8 blades. Blade pitch adjusts (unlike fixed propeller turbine). Vertical or horizontal axis configurations. Wicket gates control flow before turbine.
Francis design details
Runner has fixed curved vanes. Water enters through spiral casing and radial guide vanes. Complex three dimensional water flow through runner. Draft tube recovers residual velocity energy at exit.
Global installed base
Notable manufacturers
- Andritz Hydro (Austria).
- GE Renewable Energy (formerly Alstom Hydro).
- Voith Hydro.
- Toshiba Hydro.
- Harbin Electric (China).
- Dongfang Electric (China).
Operations
Hydro turbines are typically among the most reliable equipment in the power sector. Operational life often exceeds 40 years with maintenance. Rewinding generators, refurbishing runners, and modernising controls extend life further.
Tidal turbines
Tidal barrage installations use bulb turbines (Kaplan variant). In stream tidal uses horizontal axis turbines similar to underwater wind turbines. Both are niche but emerging.
Where hydropower turbines are going
- Modernisation of existing plants.
- Variable speed pumped storage.
- Fish friendly turbine designs.
- Small hydro deployment.
- In stream tidal commercialisation.
Frequently asked questions
Which turbine is most common?
Francis by installed capacity.
How efficient?
90 to 95 percent for modern turbines.
How long do they last?
40 years plus with maintenance.
Are Pelton wheels only in Alps?
Common wherever high head is available. Norway, Chile, Alps, Rockies.
What about tidal?
Bulb turbines (Kaplan variant) at tidal barrages.
Can turbines run at variable speed?
Modern designs yes. Grid services more feasible.
Do they affect fish?
Yes. Fish friendly designs are improving.
Is Francis or Kaplan better?
Depends on head and flow. Different tools for different sites.
Are turbines expensive?
Major cost of hydro plants. Long life amortises the cost.
Where can I read more?
Manufacturer catalogues, IEC standards, academic hydraulic engineering texts.
Summary
Three main hydropower turbine types serve different site conditions. Francis for medium head high flow reservoir plants. Kaplan for low head high flow run of river. Pelton for very high head mountain diversion. All reach 90 to 95 percent efficiency. Modern designs enable variable speed operation and grid services. Modernisation of existing plants captures significant value.
Next reading
- How hydroelectric power works
- Renewable energy complete guide
- Energy storage ranked
- Browse the UtilityRadar directory
See the assets in this article
Explore 177,000+ utility infrastructure sites
Locations, capacity, operators, and permits across 24 sectors: the same records our writers pull from.
Start browsingOperations guides from the UtilityRadar team.