What is it ???
An Underwater windmill like a device that extracts power from the tides. Renewable energy technologies are becoming
an increasingly favourable alternative to conventional energy sources
to assuage fossil fuel related issues. Tidal energy offers a vast and
reliable energy source. This technology is similar to wind energy
technology, with the rotor blades driven not by wind power but by tidal
currents. The gravitational pull of the moon produces a swift tidal
current, which spins the long blades of the turbine . Which in turn
produces electricity via different parts of underwater windmill .
This Energy derived from the moon that now helps to power a small arctic


Why it is called as “underwater windmill” ? 
“Basically it’s like putting a windmill in the water,” said Bjorn Bekken, a project manager for Hammerfest Strom. Or as it’s looking like a wind mill & are installed on the ocean
floor and large river bed , that means these are under the water.


  1. In simple a underwater windmill consists of a number of blades mounted
    on a hub (together known as the rotor), a gearbox, and a generator.
  2. The hydrodynamic effect of the flowing water past the blades causes the
    rotor to rotate, thus turning the generator to which the rotor is
    connected via a gearbox.
  3. The gearbox is used to convert the rotational speed of the rotor shaft to the desired output speed of the generator shaft.
  4. The electricity generated is transmitted to land through cables.
Underwater Windmill
Fig. Underwater Windmill


There are two types of underwater windmill
  1. Horizontal axis

  2. Vertical axis
In horizontal axis underwater windmill , the rotor shaft is parallel to the direction of the flow of water.
In vertical axis underwater windmill , the rotor shaft is perpendicular to the direction of the flow of water.

  1. The turbines can convert kinetic hydro energy into power ranging from 25 kW to 250 kW, depending on turbine size and current.
  2. Kinetic energy is converted to mechanical power in a nacelle within the turbine.

  • Underwater ( tidal) turbines are a fairly straightforward concept, as far as cutting-edge energy technology goes.
  • They are essentially windmills installed onto an ocean floor or river bed.
  • The underwater current produced by the tides spins blades arranged like an airplane propeller.
  • These turbines are attached to a gear box, which is connected to an electrical generator.
  • This produces the electricity that is carried by cable to shore.
  • Once it’s plugged into an electrical grid, the electricity can be distributed.
The advantages of under water windmill is much more  than the disadvantages:-
  • Uses Tidal energy ,which is a clean and renewable source of energy
  • Have lesser impact on the environment
  • Low running cost
  • Long lifetime with little maintenance
  • Reduces the dependence upon fossil fuels


Tides play a very important role in the formation of global climate as
well as the ecosystems for ocean habitants. At the same time, tides are a
substantial potential source of clean renewable energy for future human
generations. Depleting oil reserves, the emission of greenhouse gases
by burning coal, oil and other fossil fuels, as well as the accumulation
of nuclear waste from nuclear reactors will inevitably force people to
replace most of our traditional energy sources with renewable energy in
the future . Tidal energy is one of the best candidates for this
approaching revolution. Development of new, efficient, low-cost and
environmentally friendly hydraulic energy converters suited to free-flow
waters. This type of machine, moreover ,can be used not only for
multi-megawatt tidal power farms but also for mini-power stations with
turbines generating a few kilowatts. Such power stations can provide
clean energy to small communities or even individual households located
near continental shorelines, straits or on remote islands with strong
tidal currents.

Factor Of Safety Used in Machine Design | Significance | Importance
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