FLEXIBLE POWER EXPORT CABLE
TO BE UPDATED SEE BELOW
TO BE UPDATED SEE BELOW
Unrestrained, any vessel will be carried with the tidal stream approximately 20km during one (approximately 6 hour) tide, assuming an average tidal stream speed of 1m/s. (Water particles can travel up to 70km on one tide).
Using the resistance of energy storage flywheels while in a controlled drift for 2km and then the energy harvested using KERS for 2km. This force could be called 'Dynamic Drag' or 'Horizontal Gravity'.
The energy harvested can be calculated from the area presented to the tidal stream, the speed of the tidal stream, distance of drift and to a lesser extent the kinetic energy of the vessel.
This proposal is designed to create energy from a drifting, but at the same time restrained, vessel on the surface of a tidal stream. Multiple vessels 'ebbing and flowing' (similar to double-acting pistons) in tidal streams around the globe would give continuous output.
How can we harness this energy?
The following design layout is suggested as a starting point for trials purposes.
Two parallel 4km long anchor lines/cables are laid on the sea bed in line with the tidal stream. They are to be located in estuaries or inshore waters and not subject to extreme offshore conditions also well away from navigation channels or shipping lanes. They are securely anchored at both ends. Around the UK there would be many suitable locations in most estuaries or tidal streams.
The cables pass through robust guides 1435mm apart, (the same as as a standard UK rail track) on the bow and stern of the vessel and over support rollers. The cables are not attached to the vessel. The vessel is allowed to drift freely along the anchor line/cables.
As the tide begins to ebb or flow the vessel will begin to drift with the tide, the anchored cables passing along the deck.
Standard friction drive 4 wheel train bogies attached to the deck are driven by the moving cables causing 'resistance' from the drive motors which have been converted into generators.
Using MPPT ( Maximum Power Point Tracking ) or a ‘speed governor’ the speed of the drifting vessel is to be held to a constant speed of 0.5m/s. At this speed the vessel would take approximately 2 hours (1 hour either side of high tide) to travel 4km. Also, at this speed power could be generated during spring or neap tides.
MPPT will allow all design parameters to be explored, including the area presented to the tidal stream (power input), the speed of the drifting vessel, the number of lines/cables/generators required and the distance of drift for all given tidal stream speeds. On average, maximum tidal stream speeds around the UK are 3-4m/s (6 knots).
An estimated power output from an average sized cross channel ferry drifting 'beam on' to a tidal stream of 3m/s would be 4.8mW without using KERS (Kinetic Energy Recovery System). Or, 4 Thames barges 30m long with a draught of 2m would produce 1Mw (plus the kinetic energy). Suitable locations would include the Carrick Roads near Falmouth for instance. This is an anchorage for a number of vessels which could easily be converted into ‘power stations’.
Adjustable ‘drag’ inducing surfaces in order to increase (or decrease) 'power', improve efficiency, control pitch, roll and yaw similar to ships stabilisers or any aircraft, can be deployed. These surfaces would be controlled automatically providing a more stable platform and also help hold the vessel to a predetermined 'track' during tidal ebb and flow.
Anchor loads at the anchor points will be minimized, if not completely eliminated, due to the weight/length of cable/chain resting on the sea floor.
'Vessels', ideally, would be semi-submerged pontoons which would provide a lower 'platform' suitable for generators and ancillary equipment. They are also readily available and would be less affected by wind.
This proposal would be less of a hazard to fish and other marine life than many other offshore generating systems.
This is a relatively simple, but seemingly un-explored, concept for generating energy from the tidal stream and has the potential of adding significantly to the mix in our quest for clean, pollution free and entirely predictable energy.
Possible 'issues' as a result of turbulence caused by the restrained vessel would need to be investigated during trials or modelling.
Multiple surface 'drag' units would be far less expensive to develop, far less restricted in location, do not require significant depth, far easier for access and maintenance, and most importantly, far more reliable than many current offshore generating devices.
Any comments, constructive criticism or suggestions welcome. Patents or intellectual property rights have not been sought.
Robert (Bob) Jones.
Retired Engineer. Surrey, UK.
Engineering Apprenticeship. 1955 - 1960.
O.N.C. Mechanical Engineering. Kingston Technical College. 1957.
UK PPL 1967.
US PPL 1969.
RYA Day Skipper 2004.
60+ years Engineering Design.
Designer of the Oxshott Village Sign. 2018.
grab the ocean
To get an idea of the power of the tidal stream on a small buoy click
Feedback received – names supplied.
November 2021. Professor of Applied Physics and Instrumentation, Kingston University. Ongoing help and encouragement.
February 2022. Interest from KBR Leatherhead.
February 2022. Interest and helpful comments from EMEC (European Marine Energy Centre).
April 2022. Port of London Authority (PLA) keen to develop this proposal as part of their 'going greener' policy.
Offer of trials facility downstream of the Thames Barrier.
August 2022. 'An interesting concept for sure'. Professor of Energy, Power and Intelligent Control, Queens University, Belfast.
October 2022. Helpful comments and contacts from The UK Hydrographic Office Taunton. Admin.
November 2022. Helpful comments and contacts from ORE Catapult.
December 2022. Interest from the 'Coast Lab' at Plymouth University.
December 2022. 'Thanks for sharing your interesting concept'. 'I consider that these (predictability and reliability) could be very positive attributes of the concept given competent engineering design and manufacture'. Professor of Offshore Engineering, Strathclyde University.
January 2023. Interest and encouraging comments. Winchester University.
February 2023. Encouraging comments from Bath and London South Bank University. Admin.
February 2023. 'We conclude that much of the preliminary research has already been done by yourself and so a student would be unlikely to add anything meaningful to the concept already developed'. Nottingham University Research Department.
February 2023. 'An interesting feasibility model, we wish you every success with your project going forward'. Vital Energi.
February 2023. Interest and helpful contacts from The Institution of Mechanical Engineers. Admin.
February 2023. Invited to submit this proposal to The Royal Society for publication and peer review.
February 2023. Interest from OXTO Energy, developer of flywheel energy storage systems.
March 2023. ' good luck to you in your endeavours'. Professor of Nearshore Processes, Plymouth University.
March 2023. Feedback from The Royal Society - 'The submission is essentially a proposal for a new engineering design to harness tidal energy. Unfortunately Proceedings A does not publish this type of submission'
March 2023. ‘I think it’s an interesting – dare I say ingenious – proposal’. Editor, New Energy World, Energy Institute.
April 2023. ‘An interesting idea’. BBC Environment Correspondent.
April 2023. Helpful suggestions re- funding. Associate Professor of Renewable Energy, Southampton University.
April 2023. ‘Good luck with your endeavour’. Professor of Mechanical Engineering. Swansea University.
May 2023. Helpful comments and contacts from Warwick University Engineering Team. Admin.
May 2023. ‘The idea sounds interesting, good luck with your research and your project’ Professor of Fluid Dynamics. Warwick University.
September 2023. Interest, information and helpful comments from Dr of Mechanical Engineering. NREL (National Renewable Energy Laboratory) Denver, Colorado.
September 2023. Interest, helpful comments and analysis from Professor of Engineering Science. University of Oxford.
October 2023. 'The concept is very well explained'. Professor of Marine Renewable Energy, University College Cork.
October 2023. 'your technology looks extremely interesting'. Head of Business Development. ORE Catapult.
October 2023. 'Your idea looks interesting'. Corporate Innovations Manager, Bekaert. Manufacturer of subsea anchor lines/cables.
CONCEPT & WEB DESIGN © 1995-2023 Robert C Jones