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GB2463100A - Low head tidal barrage with active control - Google Patents

Low head tidal barrage with active control Download PDF

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Publication number
GB2463100A
GB2463100A GB0816213A GB0816213A GB2463100A GB 2463100 A GB2463100 A GB 2463100A GB 0816213 A GB0816213 A GB 0816213A GB 0816213 A GB0816213 A GB 0816213A GB 2463100 A GB2463100 A GB 2463100A
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United Kingdom
Prior art keywords
controlling means
control
power generating
tidal range
generating station
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB0816213A
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GB0816213D0 (en
Inventor
Rupert John Armstrong Evans
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Individual
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Individual
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Priority to GB0816213A priority Critical patent/GB2463100A/en
Publication of GB0816213D0 publication Critical patent/GB0816213D0/en
Publication of GB2463100A publication Critical patent/GB2463100A/en
Withdrawn legal-status Critical Current

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03BMACHINES OR ENGINES FOR LIQUIDS
    • F03B13/00Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates
    • F03B13/12Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy
    • F03B13/26Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using tide energy
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03BMACHINES OR ENGINES FOR LIQUIDS
    • F03B13/00Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates
    • F03B13/12Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy
    • F03B13/26Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using tide energy
    • F03B13/268Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using tide energy making use of a dam
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03BMACHINES OR ENGINES FOR LIQUIDS
    • F03B15/00Controlling
    • F03B15/02Controlling by varying liquid flow
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/30Energy from the sea, e.g. using wave energy or salinity gradient

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Oceanography (AREA)
  • Other Liquid Machine Or Engine Such As Wave Power Use (AREA)

Abstract

A tidal barrage or 'reef' has a relatively light weight impounding structure that maintains a small head difference of about two metres between the sea and a lagoon, and introduces only a short delay of less than two hours to the tidal flow. This avoids many of the environmental consequences of a barrage that maximises water height differences. Sections of the barrage may be opened to allow free flow of water and ships. These may be butterfly gates e.g. 150 metres wide and 20m deep, which rotate about a central pivot. By rotating such gates by 180 degrees, the flow through the turbines will always be in the same relative direction. Active control of the turbines and gates allows the system to be altered from tide to tide to meet the needs of navigation, wading birds, salt marshes, and flood protection.

Description

DESRI PTION
Title: ACTIVE TIDE CONThOL
FIELD OF THE INVENTION
The.present invention relates generally to that of power genera- tion from tidal flows in an estuary or body of water. More spe- cifically it relates to the control of the water through the im- pounding structure to optimize the point of maximum power genera-tion and to minimize the environmental impacts caused by changes in the tidal regime caused by the construction of the structure.
BACKGROUND TO THE INVENTION
The main feature of the Reef' system is the low differential pressure/head across the barrage at any one time. In order to capture the energy but maintain oniy a small head differential the barrage must extend upwards to the maximum height of the tide. A slender structure could be used on account of the modest differential pressure (see illustration of simple fixed barrage) A bascule' or crest gate fixed to the turbine caissons could be used to achieve the same thing but with the added advantage of being able to bypass water flow over the structure. A barrage comprised of floating turbine caisson could be used, or a combi-nation of these and other features could be developed to produce the necessary head and water control.
Deepwater sections could in part be developed with very large navigation gates that can be rotated about vertical piles (the size of a lighthouse) sunk into the seabed. These gates would be of considerable size to safely accommodate large container ships.
The operating period at the rated head (of two metres) would be around eight hours and reduced head for another four hours. The longer generation period offered by this design will give a flat-ter generation curve and considerably better utilization of the plant and grid connection. It will much easier to match the gen-eration with the consumer load The flood risks associated with the Reef are low or negative, since it should reduce the risk of flooding in the low-lying ar-eas of the lagoon. The inconvenience to navigation is reduced by its position to the west and by the ability of the Butterfly gate sections' of the Reef' to open for shipping. The impact on wildlife including wading birds, sea mammals and fish should be minimal because this is the starting point for the whole endeav-our.
The water turbines can be one of several different designs and layouts and each has their own merits. The Simple fixed-flow tur- bines can be built by many more sub-contractors around the coun-try, so the price per kW will probably be the same or even lower than the large turbines that can only be built by a handful of international companies. The use of smaller and more innovative turbine designs is possible because of the modular design and more companies have the physical capability to build them. By limiting the operating head of the turbines to less than two me-tres, the differential pressure exerted on the structure in much lower than for a barrage, making the construction easier and less sophisticated so pre-cast unanchored concrete caissons similar to those used in the construction of Mulberry Harbour for the D-day landing, would allow the construction to proceed rapidly during the windows of opportunity' when the tides and weather are fa-vourable.
The reef is almost entirely made up of turbine modules, which are comprised largely of water passages and voids, so in addition to the low aspect ratio of a caisson when compared to an ernbanknient, much less material required. The height of the barrage is also reduced by not having to protect a roadway, having to counter storm surge levels or to take the higher operating head necessary for the big barrage's Kaplan turbines. Over 10 million tons of rock fill would be saved by not having to dredge a new shipping channel and further dredging would be saved by not having a rela-tively The Butterfly Gates' would have a vertical axis of rotation about a seabed implanted concrete pile. The pile itself would measure some 10 metres in diameter and extend above sea level to accommodate a platform with navigation aids and possibly a large wind turbine. The pile would extend below seabed and be grouted into the rock and possible intersect a sub-sea service tunnel. A structure in the form of a pre-cast sill would be installed be-tween adjacent piles and form a close fit with the Butterfly Gate'. The gates themselves, weighing in at around 10,000 tons, would comprise a cast concrete hull through which the turbine ducts would pass. The turbines, if installed, would be hydrauli-cally asymmetric in that the flows would always be in the same direction but the complete gate would rotate by 180° to face the water flow. While rotated to 90° ships would be free to pass through unhindered. To achieve this the clearance between a pair of pile would be over 150 metres and the depth around 20 metres.
Installation and maintenance would be achieved by floating the complete gate away from the locating pile and towing it to a suitable dry-dock. Rotation of the gate could be achieved by means of thrusters or motoring one of the turbines once the lock-ing mechanism has been released.
In the event of a storm surge, controlling the opening of the barrage could regulate the maximum upstream levels, while land drainage outfalls at a number of locations compromised by a con-ventional barrage holding' the high water for several hours, would be unaffected. With active tide control only a short dwell period at high-water could be programmed into the system to allow generation to start earlier.
Near high water when the head is no longer adequate for power generation, the butterfly gate' sections of the barrage could be opened to allow the remaining water to continue up the estuary.
The reduction in the peak tide level would thus the minimised (and even the Severn Bore might continue under certain condi-tions). Energy lost before high water can in part be recaptured by allowing generation to start earlier on the falling tide. The degree that storm surges can be attenuated by such a structure will depend on many factors and require extensive computer model-ling.
The turbines would be installed in groups of four within a ro- tatable structure. This structure can be rotated through 180 de-grees about the vertical piles so that the water flows the same way through the turbines whether the tide is ebbing or flowing.
When the gates are rotated to 90 degrees, there is a considerable gap between adjacent units allowing the water to pass through.
The ability to open the barrage and offer minimal resistance to the incoming tide is critical to the active control' of the bar-rage. This system allows the characteristics of the whole project to be altered from tide to tide giving preference to generation, navigation, the environment and even the Severn Bore, at the most appropriate times. As the time of high water advances each day it becomes more and more difficult for a conventional barrage' to match the peaks in consumer demand. Firstly the lower head tur-bines and much larger area of lagoon allows the generation period to be biased to meet the peaks. A small increase in working head caused by a delay in opening or by back pumping will allow a very significant change in the available power, without any environ-mental conflict. To obtain the same power on the smaller lagoons would almost certainly cause increased flooding upstream. Having control over the opening and closing times of the barrage as well as the turbine running times, you can tailor make the tide to the needs and modify them from tide to tide. The predictability of the tide makes it possible to increase a tide to accommodate ship movements or modify the tide height and timing to maintain salt marshes, land drainage and recreational interests. It is a very complex system to model but active tide control' will allow the many and diverse interests to preserve their unique requirements alongside the need for power generation. Active control may also be used to control silting and micro management of the marine en- vironment. Careful study of the impacts of various operating re- gimes could lead to modifications of the system to minimise prob- lems, something that is completely impossible with a fixed bar-rage.
Only limited flexibility to accommodate specific environmental changes that may occur after commissioning can be achieved with conventional barrage, but because the tidal Reef' system oper-ates on a very small head difference, it is possible to modify the operating regime to take account of the predicted height of the tide, the time of day or year. This means that if there is a particular requirement for navigation, power generation or salt marsh ecology, it would be possible to change the point at which generation, barrage opening and barrage closing take place. If an upper estuary scheme (Shoots) of a similar design were included, even more precise control would be possible.
KNOWN AND PRIOR ART
Control systems for hydro-electric installations and tidal power plants based upon water level sensing and power demand are known.
OBJECT OF AND ADVANTAGES OF THIS INVENTION
The main objective of this invention is to render the Reef' bar- rage environmentally benign but generate very significant quanti-ties of renewable energy. From the outset the requirements of wading birds, sea mammals and migratory fish have been taken into account. In addition, the need for unhindered navigation, flood alleviation and low visual impact can all been taken into account when operating this active tidal system'. It is argued that the conventional approach to design starts with the large engineering components including the water turbines and then considers the environmental impact in the form of mitigation measures after-wards.
The Reef' operating concept could potentially remove almost all the conflicts with the inter-tidal habitat, but at spring tides it may be desirable to allow the full height of the tide to wet the upper areas of salt marshes. The frequency of these events and even the preservation of the bore' will depend on many fac-tors, including the value of the power generation lost and the needs of the particular habitat. Achieving the necessary height but for a shorter duration may also be a compromise but requires a considerable amount of computer modelling.
Active Tide Control' allows the different competing interest to dovetail their activities and interests so as to minimise any ad-verse consequences, and to fine tune the operating system after construction.
Loss or altered habitat resulting from the altered tidal range is largely avoided with the Reef System' simply because the working head is so much less and the resulting changes very much smaller.
Flooding and peak tides should be reduced upstream of the reef and only marginally altered on the seaward side because the delay in the tide cycle is so short.
Difficulties with land drainage outfalls should also be reduced, simply because the deviation from the natural tidal range will fall within what is experienced naturally, even if the pattern is altered marginally.
Flooding and land drainage problems should be avoided and a de-gree of protection should be afforded to the Somerset Levels in the event of a storm surge.
THE PREFERRED OR OPTIONAL FEATURES OF THIS INVENTION
(EMBODIMENTS)
SUMMARY OF THE INVENTION
The present invention relates to a method of controlling the flow of water past an impounding marine structure subject to tidal variations by opening and closing large sections of said struc- ture and hydraulic turbines that are subject to a head differen- tial that is significantly less than the full tidal range, in or-der to achieve a predicted upstream tidal level for the purpose of maintaining an ecosystem or a desired depth of water for navi-gation or so as to protect low lying lands from inundation by flood waters.
DESCRIPTION OF THE DRAWINGS

Claims (13)

  1. CLAIMSHaving now particularly described and ascertained the nature of our said invention and in what manner the same is to be per-formed, we declare that what we claim is 1. A method of controlling the flow of water through an impound-ing marine structure subject to tidal variations by opening and closing large sections of said structure and hydraulic turbines that are subject to a head differential that is significantly less than the full tidal range, in order to achieve a predicted upstream tidal level for the purpose of maintaining an ecosystem or a desired depth of water for navigation or so as to protect low lying lands from inundation by flood waters.
  2. 2. A method of controlling the flow of water past an impounding marine structure as substantially described herein with reference to FIG.l of the accompanying drawings.R. J.Armstrong Evans Dated this day 29th August 2008AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWSApplication Number GB0816213.3CLAIMSHaving now particularly described and ascertained the nature of our said invention and in what manner the same is to be performed, we declare that what we claim is:-CLAIM 1. In a tidal range power generating station, a system of control in a combination with controlling means, that allows near natural peak tide levels within an enclosed body of water, by means of controllable turbines, and/or gates within an impounding barrage structure, such that water can flow through or freely around the turbine modules offering minimal resistance to the incoming tide on account of the said impounding structure being comprised almost entirely of turbine modules.CLAIM 2. A system of control and controlling means according to Claim 1. that is applied to a tidal range power generating station in which the differential head across the water impounding structure is significantly less than the full tidal range and typically about 2 metres.CLAIM
  3. 3. A system of control and controlling means according to Claim 1. that is applied to a tidal range power generating station in which the objective is to maintain wildlife habitat.CLAIM
  4. 4. A system of control and controlling means according to Claim 1. that is applied to a tidal range power generating station in which the objective is to maintain the depth of water for the navigation of ships.CLAIM
  5. 5. A system of control and controlling means according to Claim 1. that is applied to a tidal range power generating station in which the objective is to attenuate the effects of flooding or storm surges.CLAIM
  6. 6. A system of control and controlling means according to Claim 1. that is applied to a tidal range power generating station in which the objective is to optimize power generation.CLAIM
  7. 7. A system of control and controlling means according to Claim 1. that is applied to a tidal range power generating station in which the objective is to prevent or encourage the movement of silt CLAIM
  8. 8. A system of control and controlling means according to Claim 1. that iS applied to a tidal range power generating station in which the objective is to allow passage of migratory fish species.CLAIM
  9. 9. A system of control and controlling means according to Claim 1. that is applied to a tidal range power generating station in which the objective is to minimize the conflicts between various competing interests.CLAIM
  10. 10. A system of control and controlling means according to Claim 1. that is applied to a tidal range power generating station in which the controlling means are sluice gates.CLAIM
  11. 11. A system of control and controlling means according to Claim 1. that is applied to a tidal range power generating station in which the controlling means comprise water turbines.CLAIM
  12. 12. A system of control and controlling means according to Claim 1. that is applied to a tidal range power generating station in which the controlling means are movable sections of the impounding structure.CLAIM
  13. 13. A system of control and controlling means as substantially described herein with reference to FIG. I of the accompanying drawings.JMmstrong Evans D4tdftiis day 10th September 2009 **,*I II . e.. $ $111Iall l*S
GB0816213A 2008-09-05 2008-09-05 Low head tidal barrage with active control Withdrawn GB2463100A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
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GB2463100A true GB2463100A (en) 2010-03-10

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4039847A (en) * 1975-10-20 1977-08-02 Diggs Richard E Tidewater power plant
GB2033974A (en) * 1978-10-20 1980-05-29 Gutierrez Atencio F Tidal hydroelectric installation
DE10322941A1 (en) * 2003-05-14 2004-12-02 Gartelmann, Rainer, Dipl.-Ing. Water power unit is integrated into the gates of a flow barrier with a watertight generator housing and water fall to turbine height adjustment according to tidal condition
GB2415748A (en) * 2004-07-03 2006-01-04 Robert Cavendish Water wheel tidal barrage
GB2448669A (en) * 2007-01-09 2008-10-29 Michael Andrew Woodward Wave power generator using hinged barrier
GB2460340A (en) * 2008-05-29 2009-12-02 Rupert John Armstrong Evans Low head tidal barrage system

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4039847A (en) * 1975-10-20 1977-08-02 Diggs Richard E Tidewater power plant
GB2033974A (en) * 1978-10-20 1980-05-29 Gutierrez Atencio F Tidal hydroelectric installation
DE10322941A1 (en) * 2003-05-14 2004-12-02 Gartelmann, Rainer, Dipl.-Ing. Water power unit is integrated into the gates of a flow barrier with a watertight generator housing and water fall to turbine height adjustment according to tidal condition
GB2415748A (en) * 2004-07-03 2006-01-04 Robert Cavendish Water wheel tidal barrage
GB2448669A (en) * 2007-01-09 2008-10-29 Michael Andrew Woodward Wave power generator using hinged barrier
GB2460340A (en) * 2008-05-29 2009-12-02 Rupert John Armstrong Evans Low head tidal barrage system

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Publication number Publication date
GB0816213D0 (en) 2008-10-15

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