The generation of cheap, reliable energy while reducing the associated carbon footprint remains one of the big challenges of the 21st century.

Ocean currents could be used as a cheap renewable energy source that is suitable for covering base load demand. Currently mostly axial flow turbine are considered which have several drawbacks:

• dangerous to marine live due to rotating blades
• difficult to scale up due to mechanical stress and cavitation
• expensive materials needed

Similar ideas

To my knowledge, this is the first design without any electric components below the waterline and without the need for a rigid structure under water. Similar concepts are implemented at Seaqurrent or at Minesto, however they still use a rigid, expensive structure under the waterline.

Main idea

The system consists of the following components, as depicted in diagram 1:

• a vessel, moored or anchored to the ocean floor
• a generator installed onboard of the vessel
• two umbrellas that are connected via the generator to each other.

The system generates energy while one of the umbrellas is open and pulling, while the other is pulled in in a closed state. By switching the states and the end of the rope, quasi-continuous power output is possible. A possible mechanism for opening and closing the umbrellas is depicted in diagram 2.

The concept has the following strengths:

• Adaptable to many possible sites by changing umbrella size and adding several umbrellas behind each other. Could be also used for river-flow power station or tidal power stations.
• use of low cost technology: electrial generator with easy access, use of old ships, use some form of plastic fabric for the umbrellas, steel rope)
• immense power output: A 2006 report from United States Department of the Interior estimates that capturing just 1/1,000th of the available energy from the Gulf Stream, would supply Florida with 35% of its electrical needs. [pdf download]

Possible downsides

• power generation: varying power output as there is a dead point between two cycles. This implies the need for buffer (battery, capacitor)
• need for grid connection, or use of energy onboard

Direct energy usage onboard

The electrical energy could be also directly used on the ship to avoid the need for batteries or grid connection. Possible usage scenarios could be:

• Water desalination ( very large water tanks required, maybe large plastic bags in the ocean that could be dragged back to the coast)
• Cryptocurrency mining. An energy-intensive task typically done using coal energy.
• Hydrogen generation