What is an Underwater Windmill : Working & Its Applications

Generally, windmills only produce mechanical power of their tasks like plumbing or granting of water. Windmills are connected to a generator for electricity generation. The first underwater windmill was invented by Charles F Brush to generate electric energy.

There are different kinds of renewable energy sources available like solar, tidal, wind, hydro & geothermal. Ocean energy refers to a range of technologies that use the ocean like wave energy converters, offshore wind, tidal or current, and OTEC (ocean thermal energy conversion). As the name suggests, a windmill is arranged under the ocean. This article discusses an overview of the underwater windmill and their working

What is Underwater Windmill?

Generally, windmills remove power from the energy of wind. Similarly, underwater windmills or tidal stream turbines extract energy from the ocean water flow. Windmill uses kinetic energy (KE) of the flowing water while wind blades utilize moving air.

As compared to a normal windmill, the working principle of the underwater windmill is similar. A set of blades will create electrical energy & changed from mechanical energy moved with the help of an aqueous flowing of water.

Underwater Windmill
Underwater Windmill

Tides are mainly used to push the water from slanting blades to make them turn. At different depths of the ocean has a different current. This kind of windmills includes slow revolution due to the significant amount of water strength on air. Windmills are arranged within an ocean and coated with slippery materials or Teflon.

Underwater Windmill Operation Principle

The essential parts of an underwater windmill include turbines, gearbox, generator, cables, and support. When water flows, the rotor rotates to make the generator turned ON. The gearbox is used to change the rotary speed of the rotor shaft to the preferred output speed of the shaft of the generator.


The generated electricity can be transmitted toward the land through the cables. The turbines can change kinetic hydro energy into power. Underwater windmill includes a number of blades that are arranged on a hub, a generator & a gearbox.

The effect of hydrodynamic for the water flow can cause the rotor to spin, therefore turning the generator where the rotor is allied through a gearbox. The gearbox is mainly used to change the rotating speed of the rotor shaft to the preferred output speed of the generator shaft. The electricity produced can be transmitted toward land using cables.

  • In an underwater windmill, the following factors will affect the entire system
  • Cavitation Avoidance or bubble formation
  • Avoidance of marine growth buildup
  • Corrosion resistance

Underwater Windmill Types

Underwater windmills are classified into two types like the following.

  • Horizontal Axis
  • Vertical Axis

In horizontal axis type underwater windmills, the arrangement of rotor shaft can be done parallel toward the water flow direction. The different windmill projects are available in different countries all over the world which include the following.

  • The MCT or Marine Current Turbine project
  • The Hydro Helix Energies Project in France
  • Norway or E-Tide Project Hammerfest
  • The Lunar Energy Project in the UK
  • The Tidal Stream Energy Project in the UK.
  • The SMD Hydro Vision TiDEL Project in the UK

In a vertical axis type underwater windmill, the arrangement of rotor shaft can be done perpendicular toward the flow of water direction.

  • The Enermax Project in Italy
  • Oscillating Hydrofoil
  • The Blue Energy Project in Canada
  • The Gorlov Helical Turbine in the USA

Comparison between Different Types of Power Sources

The comparison between different kinds of power sources mainly includes different parameters like power, cost estimation and maintenance.

Source of Energy

Power Cost Estimation


Solar Energy In single unit, the power is 200kwh 1.2lakh to1.8 for

only unit

Wind Turbine 2.5Mw to 3 Mw 1.3M$ to 2.2M$ for each mega watt High
Hydro Power Plant Based on dam size 25kw to16900 Euro Extremely High
OTEC 88000Twh\yr 3 to 8Million High
Underwater Windmill 700K KW hrs one single turbine 10 Million Medium

Types of Ocean Technologies

Ocean technology uses different resources for generating electricity. Several ocean technologies are also adaptable which can be divided into three major categories.

Wave Energy Converters

These systems remove the ocean wave’s power to change it into electricity. Usually, these systems utilize either a water column otherwise some kind of surface to capture the power of the wave. As compared to oceans, some lakes may provide enough wave movement to hold the energy of wave converter technology.


Tidal or current systems mainly capture the ocean wave energy under the surface of waves & after that convert them into electricity. Usually, these systems mainly depend on underwater windmills either vertical/ horizontal, which turn in the ocean current otherwise altering tide similar to an underwater windmill. This technology can be adapted to oceans.

Ocean Thermal Energy Conversion or OTEC

OTEC stands for Ocean Thermal Energy Conversion generates electricity through the temperature differential within the warmer surface of the water & colder deep water. OTEC includes the most restricted applicability within the US country as it needs 40 degrees of differential temperature that is normally available in different locations such as Hawaii & other more hot climates.

Offshore Wind

Offshore wind projects acquire benefits from the huge wind resources accessible across oceans & large water bodies. At the outside of an ocean, winds freely blow. In addition, winds on oceans are very strong as compared to most onshore, so allowing for wind projects through capacity factors of as much as 65 %, quite the opposite to the 35-40 percent attained onto land.


The advantages of an underwater windmill include the following.

  • Less maintenance and gives more lifetime
  • The underwater windmill uses Tidal energy and this is a clean & renewable energy source
  • Decreases the dependence on fossil fuels
  • It has less impact on the environmental impact
  • Running cost is less
  • Tidal energy is totally renewable & it doesn’t generate emission
  • It is placed under the water
  • No fuel cost
  • It is an emission-free power source
  • It replaces other electricity-generating techniques which depend on fossil fuel burning like coal, so the greenhouse effect can be caused.
  • Tidal energy provides fewer benefits because transportation corridors can be built on tidal generators.
  • These can support water mains, roadways, rail lines, otherwise communication lines, which again can balance
  • The expenditure of installing the tidal device.
  • Not like renewable resources, the ebb & the ocean tides flow are completely conventional & reliable. They don’t affect external forces like the weather.
  • This kind of energy will decrease the dependence on oil reserves from different countries.
  • Once the tides go out gravity sucks the water through the turbines to generate electricity
  • Windmills’ predictability can make it simple to incorporate into accessible power grids.


The disadvantages of underwater windmills include the following.

  • The initial cost is very high
  • Installation underwater is very difficult
  • To avoid the corrosion of the blade, it must be coated
  • Damages habitat up to 500m away
  • Difficult to maintain


The applications of underwater windmills include the following.

  • Windmills are used to remove power from the energy of wind.
  • These are used to remove energy from the flow of water in oceans and these are also known as Tidal stream turbines.

Thus, this is all about an overview of the underwater windmill. Windmills play an essential role in global climate development & the ecology of ocean habitats. Simultaneously, tides are a considerable potential source of clean renewable energy for future human generations. These power stations provide very clear energy to tiny communities, individual households positioned near continental seashores, on remote islands, or straits through strong tidal currents. Here is a question for you, what is an alternate name for an underwater windmill?