The most powerful tidal streams are on the surface.
Conventional propeller (or turbine) blades are great for 'delivering' power but not so great for 'collecting' power.
Bob Jones June 2022.
26th June 2022
These are seemingly un-explored concepts for generating electricity from a tidal stream and have the potential of being:-
1. more efficient, more predictable and less unsightly than offshore wind turbines.
2. more efficient and require far less depth than any underwater generating device with rotating blades (turbines).
3. less expensive, also easier to construct and maintain than current offshore generating systems.
4. less of a hazard to fish and other marine life.
Proposal No. 1. Tidal stream acting on a large vessel at anchor. See sketch below.
The vessel I have in mind is approx. 200 metres long, 50,000-ton displacement with a 6-metre draught (about the size of a cross channel ferry). Or, alternatively, a purpose built semi-submerged pontoon - see sketch below.
The vessel would be allowed to drift with the anchor line(s) driving an on-board generator(s) through a gearbox. The resistance of the generator and gearbox would self-regulate the drift speed of the vessel. I see the vessel drifting back and forth with the tidal stream between two anchor points approx. a mile apart. A simple example of this concept would be an early wood turning lathe or a bow drill.
The power generated is estimated to be 4.8MW (before losses) this is without the use of the kinetic energy which is estimated to be 225,000,000 Joules. An average drift speed of 3 m/s has been used for calculation purposes. Scaling up or down I don't see as a problem.
Alternatively, the gearbox and generator could be located at the anchor points. Provided that the anchor lines were 'locked off' on the vessel and slack taken up on the non-tensioned side. In this case getting power ashore would be easier. The anchor point installation could be similar to a wind turbine support, without the turbines.
Robert C Jones.
I am a retired engineer with some sailing experience living in Surrey UK. These proposals have been discussed with, and evaluated by a Professor of Applied Physics and Instrumentation at Kingston University, a Professor of Engineering at The University of Edinburgh, the Director of Innovation Strategy at The University of Surrey. Also positive feedback received from The Port of London Authority, Siemens Gamesa Wind Turbines and The European Marine Energy Centre Orkney.
Variable resistance generators and drive train on board vessel.
Power cable to shore attached to vessel.
In all cases the pulley drive wheel diameter to be consistent with torque required and space available.
The pulley could be in the horizontal or vertical plane.
or see below
Generally the vessels would be sited in inshore waters and not subject to extreme offshore weather.
Example of power take off for on board generators.
(Similar to Stanley hand drill gearing)
Click HERE for details of 'Microgeneration' proposal.
Alternative purpose built semi-submerged pontoon which would be less affected by wind.
(Generators at anchor points)
The keel could be adjustable, similar to a dinghy centreboard giving variable 'drag'.
Generators on board or at anchor points.
line under tension
The writer on the tidal Thames at Chiswick.
Robert C Jones
1944 Royal Kent School, Oxshott
1950 St Andrew's School, Cobham
1952 Kingston Junior Technical School
1955 Engineering Apprenticeship
Kingston Technical College H.N.C. Mech
1960 - 2004 Engineering Design and Draughting
(Drawing Board and CAD)
in the General Engineering, Electro-Mechanical,
Aircraft, Petro-Chemical and Offshore Industries.
Interests. Private Pilot's Licence UK (1967)
Private Pilot's Licence USA (1968)
RYA Yacht Day Skipper (2003)
Designer of 'The Oxshott Village Sign' (2019)
Dreaming, Creating, Writing, Walking and Working.
And Jiving occasionally!