EP4665964A1

EP4665964A1 - Hydropower plant

Info

Publication number: EP4665964A1
Application number: EP24755777.0A
Authority: EP
Inventors: Vilo Niumeitolu
Original assignee: Individual
Current assignee: Individual
Priority date: 2023-02-17
Filing date: 2024-02-19
Publication date: 2025-12-24
Also published as: WO2024168403A1; CN120641652A; AU2024222462A1

Abstract

The invention resides in a hydro-plant systems producing electricity from gravity - potential energy of water flow from an elevated level to a lower level, converting this potential energy to electricity. The hydropower plant generating electricity compromises a vertical volume of water, a water manifold vessel, and an air supply with high volume.

Description

HYDROPOWER PLANT

THE FIELD OF THE INVENTION

The present invention is related to hydro-plant systems producing electricity from gravity - potential energy of water flow from an elevated level to a lower level, converting this potential energy to electricity.

THE BACKGROUND

The conventional hydropower plant electrical output basically relies on gravity potential energy of water. As water flows from a higher elevated reservoir to a lower elevated reservoir via a downpipe known as a penstock, to a turbine generator coupling arrangement it produces electricity. Then the water from the turbine outlet or tailrace flows out to the low elevated reservoir or river. Recently designed hydropower plants where seawater is pumped up to an elevated land reservoir then seawater flows back to the sea via a turbine to produce electricity. The cycle repeats - seawater is pumped back to the higher elevated reservoir powered by renewable power sources such as solar or wind energy to be ready for the next production. This arrangement is known as a pumped hydropower plant or pumped gravity storage battery.

In the pumped hydro power plants, the power supply capacities and the time duration of generating are limited by the available water volume at the elevated reservoir and the height differences between the higher elevated reservoir and the lower elevation, which means that the power output will be based on the flow rate and the elevation difference. Often in these pumped hydro plants the water is pumped up to fill the higher elevated reservoir water, powered by the excess power from the power grid network during low power demand or from other renewable power supplies such as solar power or wind turbine systems.

Also it is a challenge to find a suitable location for these pumped hydro power storage plants due to a large area requirement for the water reservoirs and to be near as possible to populations or to industrial areas without submerging farmlands and forest reserves and causing environmental degradation. Other various reasons including minimising the transmission line costs need to be taken into consideration.

THE SUMMARY OF THE INVENTION

One of the features of this invention is to provide a hydropower plant submerged in water in order to naturally supply a continuous flow of water up to 24 hours duration from the higher elevated water portion to turbines at lower elevation, hence eliminating the repumping of water to the higher elevated reservoir as occurs in the current pumped hydropower plant. This invention aims to combine the lower and the higher elevated reservoir into one reservoir where there is no longer a need to pump water from lower reservoir to higher reservoir but to fully usage of the water molecules are incompressible property and with the static water pressure to overcome there is no need to transport these water molecules to the top end. The water volume at the top end above the penstock inlet opening have enough gravity potential energy to push water in and down into the penstock.

Another feature of this invention is to provide a hollow watertight enclosure with a conventional hydro power plant installed within. This conventional hydro power unit can be able to operate and produce electricity, once it submerges to a sufficient water depth and withstanding its associated water pressure. The watertight enclosure consists of a water inlet opening at the upper portion to be located below the water level and with multi water outlet openings located at the lower portion of the watertight enclosure. Further openings of the watertight enclosure to atmosphere are provided for air vents and for machinery access maintenance. The watertight enclosure can be constructed and manufactured from steel, concrete and suitable plastic materials and designed to withstand corrosive sea salt water and hydraulic pressure application requirements. The anchorage of the said enclosure may be fixed into solid bottom of the seabed or the bottom and/or the sides of a lake. If it is floating on water then it can be tied and secured to fixed anchorage depending on the geographic condition of the installation site. If designed for mobility and buoyancy like ship or barge in suitable scalable form with self- propelling machinery on water within, then it promotes a secondary usage as a cargo and passengers transport vessel.

A further feature of this invention, can be in a modular construction so that it can be extended in height difference between the water inlet and the turbine for increase in power capacity. Also the lower section where the holding tanks can be arranged in a horizontal configuration to suit the installation site's available water depth and space.

Another feature of this invention is to provide a water expulsion mechanism for exhausted water from the turbine water outlet. The water flows via pipe system and automatic flow controlled valves and flow sequences as follows; the exhausted water from the turbine flows through a draft tube, then to a common manifold, a matrix of water holding tanks in pairs, and then is pneumatically pushed out to exterior water via the watertight enclosure water outlets at the lower end by high pressure air volume. The open and close of the flow valves upon this pipework are automatically control throughout the exhausted water expulsion process and it vital important the synchronization the flow so that the water flow rate to and out from the turbine keeps at the same level.

The turbine water outlet, sometimes known as a draft tube, where cross section area is enlarged, minimises the destructive water cavitation. In this new arrangement a further vessel, namely a flow adjuster vessel will be included and part of a common manifold. Inside the common manifold, a multiple of water flow vanes to minimise water flow turbulence and evenly distribute the water volume to a wider area with multi bore outputs to fill the water holding tanks below effectively. These holding tanks can be a cylindrical or rectangular shape in cross section and manufactured from steel, reinforced concrete or other materials such as plastic, fibreglass or combinations to obtain the a better structures. These water holding tanks can be arranged in rows and columns and vertical or horizontal configuration to obtain a better economical design and suitable arrangement for the installation site. It is preferable that the total water volume capacity of these water holding tanks should be more than the total water volume required to run the turbine in the designated required time duration where this time duration will contribute to overall time cycle for filling and emptying of these water holding tanks. Each of the water holding tanks is connected at relative lower level to a common manifold outlet with a control flow valve in between. On the other end of the water holding tank outlets have a controlled valve and one way flow valve which is then connected to water outlets opening at the lower end of the enclosure. A settling chamber is included at this end, to allow expulsion water to settle before totally flow out, hence preventing any erosion of the underwater surrounding. Each water holding tank will fill one at a time from the common manifold, until it is full. An open vent valve is provided for each tank to eliminate air lock during filling time, then closes once it is full. When the valve from the manifold is closed, the air supply valve will open and pressurise the said tank to a predetermined pressure level. Then the outlet valve of the said tank opens with air pressure pushing the water out to the exterior water until it's near to empty or at the predetermined water level. Then the outlet valve closes, as well as the inlet air valve and the air vent open. The empty water holding tank is then ready to be filled again for the next cycle. The compressed air volume is introduced into the water holding tanks with or without a rubber bladder, with air pressure to overcome the friction plus the exterior water static pressure. Another feature of this invention is to provide a shaped channel with partial mesh wall to be connected to the enclosure's exhausted water outlet (at the bottom of the enclosure) and run along the outside wall of the enclosure upward and then it is connected to the water inlet screen opening at the top of the said enclosure. The reason for this is so that it tends to help in maintaining the water quality at the water inlet and minimises the surrounding disturbance. A mesh portion is provided along the length, for the water to flow through in both directions and there is an atmospheric vent at the top to maintain the atmospheric pressure.

Another feature of this invention is to provide a closed hollow channel to be connected to the water outlet (at the bottom of the enclosure) of the turbine discharged water system which extends upward and then it is connected to the water inlet opening at the top of the turbine water inlet via the penstock. An atmospheric vent at the upper portion of this enclosure channel is provided. This arrangement will allow the water circulation from the turbine outlet at relatively lower level to be available at the turbine water inlet at the relatively higher elevation. The said enclosure channel is designed to receive, temporarily store and supply sufficient water volume to satisfy the required flow rate of the turbine regardless of its position and the relative elevation of the whole hydropower unit to natural ground surface.

THE BRIEF DESCRIPTION OF THE DRAWINGS To assist with the understanding of the invention, references will be made to the accompanying drawings, illustrating some of the invention features and applications. In the drawings:

Figure 1 is a flow diagram of the hydropower plant embodiment of the present invention;

Figure 2 is another flow diagram of the hydropower plant embodiment of the present invention;

Figure 3 is a longitudinal side sectional view of embodiment of the invention.

Figure 4 is a cross-sectional view AA embodiment of the invention of Figure 3;

Figure 5 is a longitudinal side sectional view embodiment of the invention;

Figure 6 is a longitudinal side sectional view embodiment of the invention;

Figure 7 is an isometric view embodiment of the invention;

Figure 8 is a longitudinal side sectional view of embodiment of the invention.

Figure 9 is another longitudinal side sectional view of embodiment of the invention.

Figure 10 is another longitudinal side sectional view of embodiment of the invention. THE DESCRIPTION DETAILS OF THE DRAWINGS AS FOLLOWS.

The drawings shown are basic profiles for the overall descriptive information of the invention in terms of water flow sequences upon the hydropower plant machinery components.

Figure 1 is a flow diagram of the hydropower plant embodiment of the present invention. The water volume 1 flows into the penstock 5 which is a combination of water flow 30 from the exterior water 32 via opening 25 and the partial return flow 18 from the bottom water outlet 17. The inlet opening 25, located in at least two places, consists of screening mesh to prevent any unwanted debris. Another function of opening 29 is to maintain the relative static pressure of water flow 18 during various load conditions. The water volume 1 enters turbine 9 via inlet 22 and exerts turbine 9 to rotate to produce the mechanical power output for the generator. Then the water volume 1 flows out via the turbine outlet 6 into a flow adjuster vessel 10. Vessel 10's main function is to redirect and adjust the water flow 1 to an even output flow into manifold 11 via multiple bores 39. Both vessel 10 and manifold 11 are designed to work together or in one vessel to minimise the time taken in the water filling process. The internal directional vanes cross sectional area of vessel 10 is to minimise the water flow rate fluctuation during the filling process if tanks are further apart. (In some cases, tanks arrangement may be 200 metres apart.) The water volume 1 then flows to water holding tank 12 via connecting pipe and valve 7 from manifold 11. The valves 7 and 13 are to automatically control the opening and shutting of the water flow as per predetermined flow sequences. The number of the water holding tanks 12 and their sizes are predetermined by factors such as the total water flow rate capacity of the turbine 9, the design running time duration per day, and other factors such as allowances for the time lagging during opening and closing of such big size valves to handle the design flowrate.

An air high pressure tank 16 is connected via automatic valve 15 to water holding tanks 12 at the upper end. The preferred air pressure should be set above the relative static water pressure at water outlet 17 so that as the water is expelled from tank 12, the working pressure still prevent back flow from outside water 32. The emptying of these tanks 12 must be synchronised with the turbine water discharge so that there is no built up back pressure which may affect the turbine 9 power output. The sequence of water filling and emptying the tanks 12 is as follows: Valve 13 closes, valve 7 opens, water is allowed to fill the tank 12 then valve 7 closes, valve 15 opens and allows air from tank 16 to pressurise water in the tanks 12 until the set pressure is reached, then the outlet valve 13 opens to allow water to be expelled to the outside settling chamber 34 and exterior water 32 via a nonreturn valve 14 through outlet 17. When water level reaches a predetermined minimum water level, then valve 13 closes and valve 15 closes. Then the air within the tank is vented out through valve 8 and is ready for the next fill sequences. Each tanks 12 emptying and filling cycles are overlapping each other to prevent any fluctuation pressure effect on turbine flowrate performance. The valves 7 and 13 are fully automatic and valve 14 is a one way flow pressure valve, set to prevent any inflow water. Also a further water discharge settling chamber 34 is provided to minimise the water flow disturbances and promote environmental reasons. All valve bores need to be kept relatively small, but large enough for the maximum design flow rate to minimise the time delay during the opening and closing process. A watertight enclosure 4 is a watertight protective housing against lake water or seawater and withstands dynamic and static water pressure for the duration of the design life. It also acts as a structural support for the hydropower plant machinery. It also provides dry working interior space 21. The said enclosure 4 can be site casted with reinforced concrete or pre-fabricated in modular sections from reinforced concrete or steel or other relatively durable material. The exhausted water flow 18 may flow upward mostly by natural and thermal current via an enclosed channel 24 toward inlet 2, combining with a supplement flow 30 from outer water 32 via predetermined multiple opening mesh windows 25 at the lower portion of enclosure 4. These openings on this enclosed channel 24 are to prevent any unnecessary negative pressure but still maintain the relative static pressure during the water flow cycle. The opening mesh window 25 is designed to let the water into channel 24 but prevent unwanted debris from entering. An opening 29 to atmosphere on channel 24 is provided for the release of any built up pressure. Then air vent 3 is a general atmospheric air vent and opening 27 provides for machinery services. Platform 28 is for loading/unloading services as well as helicopter landing space if needed. The water or sea level 19 indicates the relative mark for the water level as reference. The dimension length 21 is the relative and estimated height difference between water inflow and the turbine outflow and height 31 is an estimated height difference below the turbine outlet to the base for references. The atmosphere 20 and the external water 32 are given as a references. Internal open space 33 within the enclosure 4 is opened to outside atmosphere 20. The base 26 the watertight enclosure 4 can be anchored to the lake bed or seabed if floated or else have a solid foundation to support the massive gravity weight and dynamic load.

Figure 2 is a partial lower section flow diagram of figure 1 in a horizontal configuration embodiment of the present invention. The water holding tanks 12 may be arranged in horizontal position or at an angle to the vertical inlet water flow on penstock 5 where this arrangement may be preferable due to the installation depth which can be shallower and the available water depth is fully used to increase the hydraulic height difference between the water inlet 2 to turbine 9, hence an increase on power output. All the items from figure 1 stay the same.

Figure 3 is a partial section flow diagram of figure 1 with pictorial shape variations showing the embodiment of the present invention. The vessel 10 and common manifold 11 are shown in one body and its outlet is connected to valve 7 then to water holding tanks 12. It may be economical for these tanks to be cast from reinforced concrete on site depending on the power rating of the plant. The said tank 12 ends are to be fitted with a combination of removable precast reinforced concrete end caps and also mountings for stainless steel or cast iron pipe fittings and valves. All fittings are to be of corrosive resistant quality. A maintenance space 35 and surfaces 40, 41, 42 and 43 in various sections of the plant must have the structural strength and accessibility to allow heavy lifting equipment during installations and heavy equipment maintenance. The valve 13 and non- return valve 14 are shown connected the said tank 12 and then to the flow settling tank 34 before water exits via outlet 17. The location of flow settling tank 34 inside the enclosure 4 has benefits for maintenance reasons, since it has a dry atmosphere area.

Figure 4 is a sectional view AA of Figure 3 which is an embodiment of the present invention, showing the basic arrangement of water holding tanks 12 in matrix arrangement casting 33 in reinforced concrete. The interior profile of the said tanks 12 is shown circular but it can be any other profile such as square or other poly sided profiles. The space 35 between the wall of the watertight enclosure 4 and tank casting 33 provides clearance for lifting heavy machinery.

Figure 5 is a pictorial partial section of figure 3, the embodiment of the present invention, where water holding tanks 12 are interconnected via connection 37 and 38. The vent valve 8 needs to be installed in at least one location at the top end of the said tank 12. The filling valve 7 and emptying valve 13 can be reduced in numbers. These tanks interconnections 37 and 38 will vary the filling and emptying cycle times due to total water volume available for the cycles. This arrangement may suit other applications and economic reasons.

Figure 6 is a partial flow diagram embodiment of the present invention, water holding tank in endless loop configuration. The longitudinal lengths are in horizontal alignment. Valve 7 and valve 13 are located at the ends. The vent valve 8 is located at the top horizontal length of the said tank 12. This tank arrangement may have advantages due to lesser number of valves.

Figure 7 is a basic isometric view embodiment of the present invention. The watertight enclosure 4 shown in rectangular profile shape with section broken line 33 is for clarity. This profile shape may be used as the standard overall physical structure of this invention, due to its simplicity and full usage of natural gravitational forces. For example, on the current pumped hydropower plant, the external energy for pumping of water back to upper water reservoir is currently supplied by solar and wind farms energy external sources. Now on this invention, the returning of the water in the cycle is done naturally by water current under the principle of fluid dynamics with the assistance of pneumatic air pressure energy.

On this view, the penstock 5 runs down and is connected to turbine 9 on the interior of watertight enclosure 4. The flow adjuster vessel 10 and common manifold 11 are in a combined housing. Water holding tank 12 cavities are incorporated on reinforced concrete housing 33. Then shown below valve 13 and valve 14 are connected to settling tank 34. The other missing item labels are purposely omitted for clarity.

The simple rectangular shape structure shown was determined by practical approach and selecting a medium size hydropower plant to base the calculation of the physical shape on. The shape was selected considering the global availability of hydropower plant machinery components, the economic, the maintenance and the environmental requirements. In this case a 50MW hydropower plant on submerging in water was selected according to this invention. The theoretical calculation of the mechanical power formula (Power = mass flowrate x gravity constant x height difference x efficiency) where mass flowrate and height difference are the main two variables to determine the power rating of the plant, since the gravity and mechanical efficiency are fixed values.

Therefore for manufacturing and standardisation, machinery and structural housing can be scalable by selecting one variable or a combination to calculate the maximum power output rating according to the scope of this invention. For example, if we have 3 potential deserted empty open mine sites with the hole surface area at the natural ground area of 300 metres by 300 metres and the potential hole depth of 450 metres 550 metres and 700 metres, then according to this theoretical practical approach, we can harness 526 MW of clean energy 24 hours, 7 days duration. Therefore we have the opportunity to standardise our three proposed units, and by using standardised components which are readily available, including turbines, valves, bearings, couplings and a standard air compression system with capable mechanical rating, capital cost and running and maintenance cost should be relatively reduced and with the use of digital technology in operation of the water flow control valves (in particular the filling and emptying of water holding tanks 12) will potentially reduce the premature failures. Figure 8 is a longitudinal side sectional view of the embodiment of the invention, similar to sectional view of Figure 3 without the following components: the enclosure 4, working platform 28, vents 27 and 3. The opening mesh 25 no longer exists on enclosed channel 24 except at outlet opening 17 at the base of the unit and the water inlet into the turbine and the vent opening 29 at the top end. The water can be filled up to a predetermined level 47 above the turbine water inlet. This arrangement can be suitable for land above sea level where there is no need to dig a deeper hole for the water reservoir. Other items at Figure 3 stay the same.

Figure 9 is a longitudinal side sectional view of the embodiment of the invention, similar to sectional view of Figure 3 without the following components: the enclosure 4, working platform 28, vents 27 and 3. The opening mesh 25 no longer exists on enclosed channel 24 except at outlet opening 17 at the base of the unit and the water inlet into the turbine and the vent opening 29 at the top end. The water can be filled up to a predetermined level 47 above the turbine water inlet. This arrangement can be suitable for land above sea level where a portion of the unit can be positioned below ground level. Other items at Figure 3 stay the same. Both Figure 8 and 9 arrangements can be located and generate electricity power at industrial or city areas next to skyscraper buildings as part of the structure and its water supply and power supply, saving capital and running costs.

This is a starting point of gathering useful information about the new hydropower plant described within and may generate further opportunity for the power generation industry standardisation in structural features and equipment according to the scope of this invention.

This will increase the suitability of sites for clean energy hydropower generation, including sea ocean areas near the city population and lakes with permanent water volume on them, hence promoting and fast tracking the decarbonisation of thermal power stations at a global level.

Figure 10 is a longitudinal side sectional view of the embodiment of the invention; with arbitrary values to illustrate the Bernoulli equation. A nominal figure say 20MW power output calculation in reference to the invention (hydropower system) herein. The item 4 is the vertical enclosure wall retaining a vertical volume of water 46. Item 47 is the top water surface, and item 48 is the vertical height of the water volume above the inlet to penstock to top water surface 47 which is open 29 to atmosphere 33. The dimension 21 is the effective height difference between inlet and the turbine outlet. The item 49 is the height difference between item 47 and water outlet 17. The item 2 is the water inlet to penstock 5, feeding the turbine 9. The turbine water outlet downstream manifold and water tank combination to item 51 to simplify the calculation. The volume water 12 is contained in vessel 51 with air pressure 52 upon water surface and air volume 50. The air supply 51 is controlled with off and on air flow valve 15.

Arbitrary data and assumption values in metric measurement with the following symbols associated with the Bernoulli equation as following. Item 48 = Vertical height of water volume above the penstock water inlet.

Item 49 = Hl = 200m (height of the water level from the bottom of the vertical volume of water outlet)

Item 21 =H2 = Effective height difference of water inlet to turbine inlet.

Item 45 = Datum 1 = internal tank top water surface.

Item 52 = Pl = air pressure is applied at datum 1

P2 = static pressure on water discharge at the bottom.

VI = assume velocity of water at datum 1 = 0.5m/sec V2 = assume velocity of water at datum 2 = 2m/sec P = water density = summation

From Bernoulli equation

-> P2 = 1.96MPa

An air compressor to supply the required volume and pressure must be greater than 1.96MPa with power input of 6.8MW. Therefore the mechanical efficiency = 65.5%. According to fluid property, water is incompressible and with the law of current convection, the water supply to the top inlet and into to the penstock are fulfilled by the water molecules at the top portion of the vertical volume of water 46. The restriction from the wall item 4, encourages the water molecules to move up in a controlled predictable manner. The volume of water with sufficient height 48 and potential energy to push the water molecules into the inlet item 2 of the penstock in the required flow rate is always aim to maintain, unless cold temperatures or other water conditions affect the water flow, then external energy may be needed to adjust the water quality and condition.

Claims

THE CLAIMS ARE AS FOLLOWS:

Claim 1. A hydropower plant generating electricity compromises;

(a) a vertical volume of water which has a total height equated to cover the required height of a nominated electricity power output plus, an extra power to overcome the associated vessels and piping water flow head losses, with at least a structural waterproof wall separating the vertical volume of water from the adjacent hydropower machinery, which is installed immediately next door in a descending functional arrangement and preferably within an atmospheric dry space;

(b) a water manifold vessel acts as a temporary gravity energy storage analogous to kinetic energy storage flywheel; receiving water from the turbine exhaustion and distributing water downstream to at least two water tanks; which are parallel connected and complete with water flow controlled valves; and

(c) an air supply with high volume and high pressure introduce to the said two tanks, one tank at a time, to expel water out by synchronising and staggering the open and close the water flow valves in sequences, to secure the continuous flow of water downward from the turbine to the outlet.

Claim 2. A hydropower plant according to claim 1, the vertical volume of water can be in a fully closed to a partially open enclosure to open to a lake or ocean.

Claim 3. A hydropower plant according to claim 1, 2, the movement of the water molecules from the bottom outlet to the top of the said volume of water mainly by either natural or force convection.

Claim 4. According to claim 3, the upper portion of the vertical volume of water above the penstock water inlet has a height with enough gravity potential energy to keep the water flowing continuously to feed the turbine.

Claim 5. A hydropower plant according to claim 1, 2, 3, 4 with a scalable structural enclosure complete with hydropower unit may design to fit on ship vessel and alike, to be able to supply power for propulsion and mobility as well as supply power to the customers as needed.

Claim 6. The hydropower plant described in claim 1, 2, 3, 4, and 5 can be scaled further down into a practical version to fit on public vehicles powering their mobility and carrying load capacity, such as mining applications and or for public transportation.

Claim 7. A hydropower plant according to claim 5, 6 need to have the vertical volume of water in fully enclosed vessels to prevent water spillages, with an atmospheric air breather valve at the top portion to prevent water spillage.

Claim 8. A hydropower plant according to claims 1, 2, 3, 4, 5, 6, and 7, the physical sizes and the shapes of vessels including the internal vanes, water inlets, water outlets and water screens are designed and built to minimise the water flow turbulence and maintain the water quality, hence maximising their performance efficiency and their adaptability to each application.