[Edit] after realizing that currents are faster therefor
stronger close to the surface, at the end of this idea I
propose a new simplification.
Typical sea current energy recovery is done with heavy and
gigantic structures holding turbines. see link (to be posted).
Enter the halfSail system.
The halfSail base, suspended
directly beneath the boat/ship/platform, controls a folding
sail, opening and closing it in turn.
When open the sail pulls a cable which transfers the power
upwards via a pulley to the floating platform, pulling a
transmission system for generating electricity. (See details
below and illustration attached)
All electric generation is done at the surface above water,
with existing electric generator technology and well known
Thrown into the sea from any size ship, boat or floating
platform, it can be easily configured to work with any sail
and thus can be configured to produce any required quantity
of electricity available for recovery at the desired location.
There is no need for a permanent installation, and the
can be easily moved and redeployed at another location
the need arises. It is also extremely safe for marine life,
no fast moving parts in the water.
Here's how it works: (See illustration).
Two square half-sails overlap each other creating a
When the sail reaches the end of its rope, two "connecting
cables" are let to slide out from the sail connection,
the two halves to "fold out", and the sail to be easily pulled
Once reaching back to the base, the connecting cables are
pulled tight again and locked in place so that now the sail is
one large sail again, pulling on the current.
The ropes and the sail can be polycarbonates or plastics
(Kevlar ropes and carbon fiber sailcloth) making the system
cheap, foldable and lightweight.
That's all, folks! Stay tuned!
[Edit] simplification: The sail, floating with top on the water
surface pulls directly at a cable powering the generator on