Many years ago, when we had engine room breakdowns in good weather it was always good to have a break from below to lean on the rails of the ship and just look at the ocean. One sensation was the ship moving with no power caused by whatever tides were prevailing in the area, but following the clearly marked ‘paths’ on the oceans it was possible to have an idea of the tremendous power within the tides of the oceans. According to one of the Mates who was also into Oceanography, if man could harness the tidal-flow he would amass a wealth of natural force. Looking back some 60 years it is only now that the possibilities become clearer with the design of many forms of water turbine that can be adapted to suit the environment at any time.
Watching a programme on TV about the maintenance of offshore wind farms it became abundantly clear there is no need to build up 300 m diameter blades for increasing considerable the useful energy output of such of area. The output would increase considerably if only the support bases of these monster wind turbines would be used to arrange tidal turbines with free rotation to suit the tides and utilise the known tides to have water flow through a rotating element to generate power.
The rotating element will suit tide movement and generate power. In this way the energy production field won’t rely only on wind to rotate an element to generate power but it will have the constant flow of tidal current to use.
Assumption has always been with Wind Farms that the Propeller will have fewer problems in air than in tide flow, however the Wind system is always going to be dependent upon wind speed and direction… and ultimate wind presence. Looking back some 60 years it is only now that the possibilities become clearer with the design of many forms of water turbine that can be adapted to suit the environment at any time and with tide the system should flow for 24 hours during a full tide change and flow, with something similar to the Archimedes flow.
Archimedes Spiral is the basic water turbine but figured here are the common types of water turbine rotors. However something like an Archimedes Spiral would possibly be more effective and least likely to become blocked but the rotation of element of all types should stay clear therefore filter screens or deflectors may be necessary.
Probably the biggest problem to overcome for the use of ‘Tidal Water Turbines’ is the content of sea water ie: fish, fishermen’s nets, junk from passing ships and detritus floating in the seas.
The arrangement would need some form of filter protection to prevent unit fill up from a fish shoal and also prevention of detritus in the seas around a ‘Lagoon’.
These may not be enough for some tidal solutions, for these solutions maintaining the ‘Lagoon Ship Free’ could be essential as well. A free-standing tidal power system would still need warning markers or buoys to prevent accidental destruction of freestanding tidal units.
It is obvious that the location of units has to match the tidal movement but on top of the “water issues”, the tidal units shall also be a reasonable match for the onshore locations for transmission to top up grid or battery systems.
Few apparent solutions occur today as preeminent: the self-supporting unit, the circulating tunnels system (possible integrated into other shore based complex), the standalone ‘Tidal Unit’ compact unit and the coexistence of wind and tidal on same foundation.
The self-supporting unit could be embedded into ocean floor or can be supported by the Wind Mills support bases. Practically these units are the wind mills above the sea level but submerged and actuated by the tidal flow or by any steady subsea current in area.
For this solution it is desirable to follow the tide and in this way not only the flow of energy would be steadier but also the chances are that less stress would be placed on unit.
Of course, servicing could be a problem but, my 2 cents is that quick release mechanism could be designed for turbine allowing bringing it at surface and servicing it. If the engineering is done properly the repositioning for operation should be only a matter of pulling and self-locking.
Protection from storms and heavy seas should be again designed in for area of installation and reason to make system tight for operation.
A good question is if the large blades could be replaced by Archimedes spiral what would be possible to have the outer edge capable of a cutting edge to maintain free rotation.
The circulating tunnels system is another form of Tidal Current flow.
Despite the fact that no grids or protection deflectors are shown in this concept sketch and even with what appears to be ample clearance it would still be possible to jam the rotor. It is not clear what is the precise significance of the water pump in this instance, if it is used purely as another method of generating electricity with purely water turbines (maybe something like the Archimedes Screw with direct connection to the battery storage/ power grid) or the real intention here is to pump water up to shore through the high pressure pipe where is converted in energy and returned after into the sea via the low pressure (in this case why the “pumps” are connected to both pipes…).
Same as for the self-supporting unit it is also important to protect the system by either marking as a
‘Lagoon’ or restriction towers along the length of the operation.
This is another form of the standalone ‘Tidal Unit’, a compact unit, which would be underslung for operation in a tidal situation. The compact unit as shown here could prove to be far more versatile. Thinking of Marine Application, this would also be able to be mounted into the sea water circulating / cooling so not necessarily in relation with tide. This would reduce the on board generators use and allow fuel saving. In a different housing this would also be a useful system in industrial water systems generating during water flow, say from water utilities and in large industrial units where water is in use. Let’s not forget the nuclear complexes where large flows of water are circulated for cooling down the units. Shrink it down; it could possibly to be used in a recirculation fashion in domestic use circuits.
The wind and tidal are not excluding each other and can easily coexist on the same foundation. The submerged part of the jacket type structures used for wind mills could easily accommodate also Tidal Turbines so tidal turbine could be installed on existing wind turbine support structures or a re-enforced structures no longer supporting wind turbines. The tidal turbines would need upper deck protection and each unit staggered into an array. As always, the end open to tide will be covered with a filter-grid cap to allow free water flow and prevent blockage. If a rotor support can be used then tidal rotation will allow full generation on tidal flow and ebb.
The Archimedes Spiral shown on the figure above is just a basic suggestion but other technical solutions already available could prove to be more effective. Kaplan Water Turbine is another design that could be adapted for an array of water turbines under-slung on a wind turbine support structure, understand these can also be mounted with a ‘Fish Friendly’ rotor B.
I can’t stress more that whatever rotates in the sea needs a very effective sealing system and prevention of damage to the parts immersed in sea water, bit like a tail-shaft on a large ship.
It will be important for any ‘Tidal Unit’ to be tight to prevent water and detritus from entering into rotating elements and trigger rust and/or foul (see picture). If the seal system does not function over a life-time then costs become very high.
The prevention must be in place to ensure maximum life of the Under-Slung units, so a form of Grid Cover has to be designed to cover the Outside Diameter of the unit and fit like a double-cap which is removable and maintains a clean flow to the tidal unit.
However, the grid or filtration cover is not sufficient, the sealing of the shafts is essential as well and here MarSealSer experience could help plenty.
Last but not the least it worth a lot to inform about the site presenting in great detail the project of a tidal energy generation lagoon in the Bristol Channel in the UK: https://aberthawtidalps.co.uk
Unfortunately this project was controversial for various UK Governments and the UK environmentalist. Practically all was done until now to prevent tidal power installation in the Bristol Channel in the UK.
However tides are far more reliable than sun or wind for producing the necessary power any nation now requires therefore I found encouraging the recent news released in the press regarding the reconsideration of the Severn Estuary Tidal Energy project (see the link below). https://www.cnbc.com/2022/03/11/severn-estuary-britain-resurfaces-huge-tidal-energy-plan-amid-ukraine-crisis.html
My background, Grammar School Education, served apprenticeship with C A Parsons Newcastle on Tyne, during which worked at the Farnborough National Gas Turbine research facility, myself and two senior apprentices rebuilt a Parsons Patent of Coal dust fired Gas Turbine which worked very effectively 1956, inserted heat exchangers in exhaust system and final filtration at stack end, spent 10 years Engineer Officer on Oil Tankers, became involved with Fluid Sealing Technology and became European Tech Manager for A W Chesterton Boston Mass, presented seminars on FST from the Russian Border to the Med, also spell as European Technical Manager for Magnus Maritec, wrote articles on use of floatation chemicals in Ballast Tanks presented to all ,major shipping companies, Series of illnesses and dropped from Op Table in hospital, started Marine Sealing Services Ltd after long period illness. Written number of articles on two stroke seal failure and how to save system oil, now putting together Web Site to sell training in Fluid Sealing Tech/Pumps
The front picture was provided by Futureoftheocean team (tanks to Ramona Popa alias Mony Wee Bony)
All the other pictures have been provided by the author of the text, Mr. Ernie Terry of MarSealSer.
As per the author of the text, part of the pictures belongs to MarSealSer and the remaining have obtained mainly when marked as Royalty free and not having any noted originator.
Copyright © 2018 Future of the ocean - All Rights Reserved.