GB2517678A

GB2517678A - Lock Form Reversible Tidal/River Energy Extraction Device

Info

Publication number: GB2517678A
Application number: GB1311266.9A
Authority: GB
Inventors: Christopher Anthony Budd
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-06-25
Filing date: 2013-06-25
Publication date: 2015-03-04
Anticipated expiration: 2033-06-25
Also published as: GB201311266D0; GB2517678B

Abstract

A means of extracting power from tidal or river flows is provided consisting of two or three gate type sluice valves 2,3, and 4 mounted one behind the other along the length of a flume channel 1 where the water level is higher at one end of the flume to the other. Each gate can stop or allow the flow of water through the channel. Two of the gates 2,3 are mounted a fixed distance apart and the third 4 is mounted onto a carriage that travels backwards and forwards between them. The outer gates open in sequence whilst the centre gate closes allowing water through from the higher level to drive the carriage along the flume whilst extracting energy by means of a hydraulic pump or similar. Return of the opened carriage gate enables repositioning of the carriage and the commencement of a further cycle.

Description

Lock Form Reversible Tidal/River Energy Extraction Device Power has been extracted from tidal and river flows for hundreds of years and the technologies employed have become firmly established. In recent times however the need to extract energy efficiently from all known natural sources has greatly increased leading to investigations and a re-think of different and more efficient ways of using these traditional resources.

Static head waterwheels use a dam to create a flow of water over paddles. A similar principle has been employed to extract tidal energy but in these applications the reverse flow normally requires separate or reverse flow wheels and reservoirs which are expensive and of low opera.ting efficiency. More recent designs employ turbines rather than wheels but require deep water or some type of means to convert the static energy contained in the water into kinetic energy before operation of the device. The installations require considerable fixed assemblies and infrastructure with disruption to the natural flow of the river or tidal system which may be unachievable or unacceptable in sensitive ecological areas.

The present invention relates to a unique method of extracting energy from the flow of a. river, the ebb and flow of a tidal estuary or any mixed combination of the two flows at the same time. Moreover this invention provides for a system that requires minimal local infrastructure, is less costly, is considerably more efficient and causes minimal visual impact.

A means of extracting power from tidal or river flows is provided consisting of two or three "gate" type sluice valves mounted one behind the other along the length of a flume channel (Ref Fig 1) where the wa.ter level is higher a.t one end of the flume to the other. Each gate can stop or allow the flow of water through the channel. Two of the gates are mounted a fixed distance apart and the third is mounted onto a carnage that travels backwards aiid forwards between them.

The outer gates open in sequence whilst the centre gate closes allowing water through from the higher level to drive the carriage along the flume whilst extracting energy by means of a hydraulic pump or similar. Return of the opened carriage gate enables repositioning of the carriage and the commencement of a further cycle.

The energy extraction sequence operates in two stages. During the first sta.ge the gate on the higher water level side is opened and the carriage, with the centre gate closed, is driven along part of the flume length by the inflow of water, generating energy as it moves down the channel. At a certain distance along the channel, the higher level gate is closed stopping the inflow of water whilst the carriage, with the centre gate still closed, continues to travel along the flume generating a further quantity of energy. Because the trapped water between the gates has a fixed volume, the head lowers as the carriage continues along the channel and when the head has reduced to close to that of the "downstream" lower water level the gate opens releasing any residual water to the downstream side. To complete the cycle the carriage remains open and returns to the start position to commence the next operating cycle. In this way both the dynamic and static head energy contained within the water is extracted.

The third (downstream) gate remains open and unused whilst the flow is in one direction so when the device is employed in a river, for example, this gate is surplus to requirements. Adding the third gate however enables the device to work equally well in either direction, in an ebb and flow tidal situation for example, by simply changing the sequence of opening and closing of the gates.

Because a river estuary flow merely adjusts the period length and perhaps partially the head achieved during each tidal cycle the device can automatically adapt to extract the maximum amount of energy available regardless of the change of balance of inflow and outflow period length or tidal height.

In a further application the system can be used to pump water upstream by applying power to the carriage and adjusting the sequence of the gate operations.

The gate design is similar to but not the same a.s a. sluice or canal lock gate and in one arrangement can be curved along the length and mounted onto a shaft which is aligned parallel to the blade and concentric with the curved radial shape. With this configuration the water forces can only a.ct through the centre of rotation of the gate and therefore cannot apply a resisting torque so all actuations are achieved with the minimum amount of wasted energy expenditure.

The invention will now be described solely by way of example and with reference to the accompanying drawing (Ref Fig 2). Three sluice type gate valves (2), (4) and (3) are mounted one behind the other along the length of a flume channel (1). Gates (2) and (3) are mounted a fixed distance apart and the third gate (4) is mounted onto a carriage (8) that can travel backwards and forwards between them. The gates are similar to but not the same as sluices or canal lock gates and are principally arranged to open and close quickly with the minimum amount of opera.ting force. In one arrangement the ga.te profile (9) can be curved along the length and mounted onto a shaft (10) which is aligned parallel to the blade and concentric with the curved radial shape. In this configuration opening and closing of the valve is quick and easy rotating the assembly about shaft (10) 90° to any one of three positions, closed to the left, closed to the right or fully open upright in the centre. The water forces can only act through the centre of rotation of the gate and cannot apply a resisting force to the operation so all actuations are achieved quickly and with the minimum amount of wasted energy expenditure. A further beneficial effect of the configuration is the considerable increase in the bending strength given to the lock gate section across the flume width.

The device works through a sequence of operating motions. At the commencement of the operating cycle Fig (2A) the carriage mounted gate (4)is considered to be closed as is gate (2) with gate (3) open. Opening gate (2) (Fig 2B) allows water to act onto gate (4) pushing the carriage (8) along the flume whilst energy is extracted via hydraulic or electrical means (not shown). At an intermediate position between gates (2) and (3), gate (2) closes (Fig 2C) whilst gate (4), still closed, continues to travel along the flume as the height of the now trapped volume of water (5) falls and the quantity of energy generated gradually reduces. When the height of the trapped water (5) reaches close to that of the lower water level (6) Fig (2D), gate (4) opens releasing any remaining head to the "downstream" level (6) and returns to the position at Fig (2A) then closes in preparation for the commencement of the next opera.ting cycle.

During this first sequence of opera.tions and whilst the flow of water is in the direction of arrow (7), gate (3) remains open. With a tidal ebb and flow situation however the direction of the flow will reverse every half tidal period and when this occurs the operational sequence of gates (3) & (2) will be reversed. Gate (2) now sta.ys open during the sequence and gate (3) performs the functions tha.t were being performed by gate (2) providing the required intermittent supply of water now from direction of arrow (11) to the centre gate (4). To complete the changeover centre gate (4) closes to the "left" rather than to the "right" and energy is extracted from the opposite direction of motion of the carriage (8). When one fixed and one moving gate is employed, as with a river installation for example, the water flow and energy extraction occurs in the one single direction. In this situation only gates (2) and (3) would be required as gate (3) always remains in the open position.

Most hydro river systems require overflow means to release extra flow in flood wa.ter situa.tions. This system does not require additional flood measures a.s both or all three gates can be raised together to the fully open position to provide the necessaty full bore flow flood relief measure.

Because of the flexibility of the system the device can also be used as a pump to pump water upstream. Gate (4) can be closed to trap a quantity of water at the lower level (6) and by applying power to the centre carriage (8) the head of the trapped water can be raised by driving it towards the gate (2) until the water level matches that of the higher side. Gate (2) can then be opened and the water delivered to the higher level of the stream by further motion of the carriage (8).

Claims

Claims 1) A method of extracting energy from the flow of a river, the ebb and flow of a tidal estuary or any mixed combination of the two flows a.t the same time.
2) A device as claimed in claim I consisting of two or three gate type sluice valves mounted one behind the other along the length of a flume or channel in which the water level ma.y be higher at one end than the other.
3) A device as claimed in claim 2 in which each gate can stop or allow the flow of wa.ter in either direction through the channel.
4) A device as claimed in claim 2 in which two of the gates are mounted a fixed distance apart along the flume and the third is mounted onto a carriage that is arranged to travel backwards and forwards between them.
5) A device a.s claimed in claim 4 where the carriage mounted gate is connected to a hydraulic pump or other means to extract energy when the carriage assembly is driven along the flume in either direction.
6) A device as claimed in claim 5 in which the outer gates are opened intermittently in sequence allowing water to flow from the higher to the lower level to act against the third gate when closed to drive the carriage.
7) A device as claimed in claim 6 where, when the gates at both the higher and lower water level ends are open and the centre carriage mounted gate is closed, energy is extracted by the motion of the carriage driven by the head difference across the closed centre gate.
8) A device as claimed in claim 7 where, at an intermediate point along the travel of the closed carriage gate, the higher water level gate is also closed stopping the inflow of water whilst the carriage, with the centre gate still closed, continues to travel along the channel.
9) A device as claimed in claim 8 where the continued travel of the carriage mounted ga.te after the closure of the upper gate, causes the level of the now trapped in-between volume of water to descend from the upper level to close to that of the lower level.
10) A device as claimed in claim 9 where, when the level of the in-between volume of water approaches that of the lower level, the centre carriage mounted gate opens and releases the previously trapped volume of water to the lower level.
11) A device as claimed in claim 10 where, after the centre gate has opened and released the tra.pped water to the lower level, the carriage, with the centre gate remaining open, reverses and returns to a position next to the upper level gate.
12) A device as claimed in claim ii where, after the centre carriage gate has returned to a position next to the upper level gate, it closes and the upper level ga.te opens so a.s to transfer the upper water level head difference to the carriage mounted gate to commence another traverse whilst generating energy.
13) A device as claimed in claim 12 where the upper water level becomes the lower level and vice-versa the lower level becomes the higher and the functions and timings of all the gates is mirror imaged so tha.t the device works in the same way but in the reverse direction.
14) A device as claimed in claim 13 where only the sequenced opening and closing of the centre gate is reversed so that the device works as a pump rather than an energy generating device by the driving of the carriage mounted ga.te to increase rather than reduce the level of the in-between water level.
15) A means to extract power or use as a pump from tidal or river flows substantially as described herein with reference to Fig I & Figs 2A,B&C of the accompanying Drawings