WO2009111861A1

WO2009111861A1 - Submerged generation and storage system (subgenstor)

Info

Publication number: WO2009111861A1
Application number: PCT/CA2009/000250
Authority: WO
Inventors: V. Martin Parker
Original assignee: Parker V Martin
Priority date: 2008-03-13
Filing date: 2009-03-03
Publication date: 2009-09-17

Abstract

A Submerged Generation and Storage system (SubGenStor) composed of multi- megawatt turbines or pump/turbines that are capable of storing and generating renewable energy. The goal of this invention is to create a virtually invisible and environmentally friendly renewable energy storage and generating station package composed in major part of commercially available components or components that are currently far along in development (i.e. modular undersea components and construction). This invention uses man made submerged lower storage reservoirs mounted on the floor of the body of water that are at the same pressure as and vented to the air directly above the upper water level of the body of water in which it is located. Energy capacity and duration is limited only by the operating depth and the size of the lower storage reservoir. These plants could be located close to load centers, such as cities, along coastal areas. An additional benefit can be gained when located in a tidal area. As a method of tidal generation energy can be generated when the tide is high and less energy used if the reservoir is cleared/pumped out when the tide is low. Cycle efficiency can then be maximized based upon the tidal range. The lower reservoir and associated underwater structures could also be used to anchor or support offshore wind turbines to supply additional renewable energy in the form of high pressure air or electricity.

Description

Submerged Generation and

Storage System (SubGenStor)

BACKGROUND OF INVENTION

[0001] A pumped storage plant is currently the only practical method for large-scale storage of electrical energy. A reversible pump/turbine is used to pump water up during off peak hours and then the same unit is used to generate energy during peak hours.

[0002] Pumped storage is a proven, economical form of energy storage that makes better use of existing capacity. Facilities can be built at moderate costs as a peaking or intermediate capacity plant. Using available off peak energy from renewable sources or from must-run base-load plants, pumped storage provides low-cost peak energy. It has superior operating characteristics used for load-levelling and load-following duties, and provides excellent response times for automatic generation control purposes. These characteristics reduce the cycling and load-following demands on base-load plants and provide overall improvements in system reliability and operating economy.

[0003] The amount of power from the potential energy in water that a water turbine can generate is directly proportional to the flow (volume) of water and to the head. It requires more energy to pump a volume of water up a set head than that volume of water can generate for the same head.

[0004] It has been long known that for a set water flow the power output of a water turbine continues to increase or decrease directly with the elevation (water pressure due

i to gravity) difference between upper water level and lower water level. Current high head turbines and pump/turbines operate with heads (elevation differences) of up to some thousands of feet. Pump/turbines today have cycle efficiencies (energy used compared to energy supplied) in the range of 82 to 85 %.

[0005] An example of the prior art which is similar to this invention is patent US7188471 B2. This prior art does not allow for the storage volume required by this current invention, or the separate operation modes of generating and pumping. This prior art relies on "a pump for evacuating water from said enclosure, said pump calibrated to evacuate from said primary chamber approximately the same volume of water admitted into said enclosure by said intake valve." This prior art also details the pump as being operated by wave motion and being in continuous operation. Another example of prior art which comes close (but with many differences) to the novel ideas in this present invention is detailed in patent US6347910 Bl. Said prior art is a sealed unit and does not utilize the present invention required water pressure difference between the top of the body of water elevation (generally close to or at atmospheric pressure) and the elevation of the top of the water in the lower reservoir which is submerged at the bottom of the body of water, but also at the same basic air pressure as the atmosphere above the body of water. This prior art relies on some kind of two stage pump system in order to operate. Patent application US20030059292 is similar but used with moving water currents. This disclosure also is "pressurized at a pre-determined internal pressure sufficient to offset the external pressure of the body of water in which the energy converting module is submerged" so it is doubtful it would operate efficiently since there would be little to no pressure difference. The relatively shallow water depth of the SubGenStor system (not more than ~500m), separate generation and pumping/clearing modes nor the possible large output generator units along with multihour storage volume are also novel aspects of this present disclosed invention.

[0006] The available other reviewed and searched similar prior art patents and commercial devices/techniques disclosed in the public domain do not utilize the novel combination of elements arranged and configured as disclosed and claimed herein.

[0007] Accordingly, the primary object of this invention is to provide a Submerged Generation and Storage system (SubGenStor) composed of multi-megawatt turbine or pump/turbines that are capable of generating power and energy. To create an underwater renewable energy generating and storage station composed of commercially available components or components that are far along in development.

SUMMARY OF INVENTION

[0008] A power-generating pump/turbine energy storage system is disclosed which offers the advantage that the pump/generating units are located underwater out of visual range and can be located in close proximity to the load center.

[0009] This system allows multiple, modular units to be used. By the novel idea of mounting these at the bottom of a lake or ocean (any body of water) the units do not require water channels (penstocks or tailrace) of any great length.

[0010] Prior art allows for pump/ turbines similar to these units to enable the capture and storage of energy, but all previous have been located at or near or under the ground and do not utilize the novel idea of being submerged in what is basically its own upper reservoir. Prior art also allows for various pump/turbine plants to be located around or utilize existing lakes, but none envision the arrangement of this invention.

[0011] Using a novel idea the turbine or pump/turbine units are mounted in a watertight structure beneath a body of water and with the use of air vents the lower storage reservoir is kept at normal atmospheric pressure while the storage reservoir fills during generation. At the end of a period of generation or when the lower storage reservoir is filled the lower reservoir is pumped clear or forced clear of water by mechanical or pressure means. Vent tubes floating at the surface and/or access caissons will be equipped with all necessary warning devices for marine traffic.

[0012] Underwater cables will carry the generated energy to inverters, converters, transformers, switchgear etc. as required located on the shore and then into the electricity grid.

[0013] The underwater structure is designed such that it can also assist with the inlet and outlet of the water flow to and from the pump/turbine.

DETAILED DESCRIPTION

[0014] A specific object is to provide a water pump/turbine for generating power which is characterized by a modular construction and provides a high cycle efficiency at relatively low cost and without sacrifice of structural integrity.

[0015] The power generated could be variable frequency AC transmitted to the shore where it is converted to DC then via power electronics to pure waveform AC voltage. Power generated could also be high voltage AC or DC. [0016] Still another object is the ability to provide a battery of mutually supporting power generating pump/turbines that are disposed in parallel to one another.

[0017] These objects are achieved by providing a turbine or pump/turbine that essentially comprises multi-vane input and output stator (the water distributor); a rotating turbine/impeller unit and a multi-pole rotor in a motor/generator stator. Some or all of the units may include direct or gear drive from the turbine/impeller to a variable (or constant) speed electrical rotor. It is possible that a torque converter could take the place of or assist the gearbox.

[0018] These turbines or pump/turbines are mounted in a water tight structure beneath the water and discharge into a vented lower storage reservoir also located beneath the water anchored onto the bottom of the body of water and typically including a "dead storage" water area used as ballast.

[0019] The body of water will usually be large enough such that operation of the system will not lower or increase the upper water level any substantial amount.

[0020] This invention could generate at high voltage, low ampere variable frequency AC for transmission to the shore. Energy is then converted to DC, then back to a pure AC waveform to match the power grid using existing commercially available power electronics.

[0021] Alternately, the generators can be high voltage DC for transmission to the shore and then converted to pure waveform AC to match the power grid. They could also be synchronous high voltage AC then transformed at the shore to match the power grid. [0022] Described briefly the turbine or pump/turbine system above functions in the Generation mode as follows: directed by the inlet shape 103 in figures water enters past the valve and into the scroll case where pressure is equalized around the distributor assembly. The water flow is controlled and made laminar (or at least substantially less turbulent) as it passes between the wicket gates of the turbine onto the turbine rotor (runner). The water pressure (head difference from upper water level 108 to lower water level 115) causes the turbine rotor to rotate at a speed proportional to the flow and pressure of the water due to gravity. As the rotor is driven the output shaft torque acts to drive the associated generator 101 (or gearbox then generator) thereby producing power which is transmitted to the transformer 102 then to the desired point of use by a power cable 104. As the water passes through the discharge the area enlarges and flow is directed into the draft tube section where it expands gradually and leaves the turbine unit to enter the lower storage reservoir 109. The water level of the lower storage reservoir 115 will vary based on flow and operation. In generation mode it will fill with water while air is vented to the surface either through the access shaft and air vent 106 or air equalization tubes 118 or both depending on construction. This air could possibly be used to operate a Wells type turbine 117 & 120 to generate additional energy.

[0023] In the Pump mode the system operates as follows: when the lower storage reservoir 109 is full and/or excess power is available in the system the unit is switched to pump mode which enables the water in the reservoir to be forced back into the main body of water. The power flow is reversed and the generator/motor 101 spins in reverse which causes the turbine/impeller to suck water back through the draft tube and force the water back out the distributor gates past the valve and back into the main water body. As the water exits the lower reservoir and the water level 115 changes air is vented back into the reservoir through the access shaft and air vent 106 or air equalization tubes 118 or both depending on construction. This air could be used to operate a Wells type turbine 117 & 120 to generate additional energy.

[0024] If the preferred method is to use a normal hydroelectric unit to generate the energy the same steps would occur during generation, but the clearing of the lower storage reservoir would occur by sealing the air vent 111 or air equalization tubes 118 or both and using high pressure air to purge the lower storage reservoir through multiple check valves 125 whose inlet is located below the top of the ballast water 110 area then discharge straight out or travel up the side of the reservoir discharging near the top of the lower reservoir.

[0025] Once the air injected into the top of the lower reservoir through the air vent 111 from the air storage tank is at a higher pressure than that of the external water pressure, the water will be ejected out the check valves 125. When the lower reservoir water level reaches the ballast water (dead storage) area 110, the inlet of high pressure air is stopped and the high pressure air is vented out the air vent 106 or air equalization tubes 118 turning the Wells Turbine 117 & 120 to recover residual energy. The high pressure air would be supplied and stored by compressor as outlined in paragraph [0027]

[0026] An optional feature of the invention is to provide the intake/discharge sections with a coating and making such surfaces smoother so as to promote higher efficiency flow. Similar coatings may be applied to the exposed surfaces of the pump/turbine for the same or other reasons (possibly to prevent marine growth). [0027] The station could also be designed using a conventional hydroelectric turbine and storage for compressed air 123. The compressed air could be used to purge the water from the lower reservoir when it is full by sealing the vents. The compressed air could be supplied from wind turbines 124 which operate as compressors and/or electrically driven compressors.

[0028] It also is to be appreciated that the electrical motor/generating units may be Alternating Current or Direct Current motor/generators and that they may be located within the airtight module, outside the module or both. Another possible modification is to have more than one rotor on a shaft, with the number of stator stages increased correspondingly .

[0029] It is to be understood that the invention disclosed herein is to illustrate the preferred setup. Still other modifications will be obvious to persons skilled in the art.

Submerged Pump/turbine Prior Art

U.S. Patent Documents

6347910 Bl Feb., 2002 Morishige 405/210

US2003/0059292 Mar., 2003 Baker 415/3.1

US7188471 B2 Mar., 2007 Walters 60/398

US3970859 July, 1976 Riem 290/54

US4092828 June, 1978 Garza 60/506

Description of Components in Figures 1 to figure 6

Component Number Description

100 Pump/Gen Module

101 Pump/Turbine Unit

102 Transformer and switchgear

103 Turbine inlet / pump outlet

104 Power cable to shore

105 Elevator shaft

106 Access shaft & air vent

107 Upper Erection Bay

108 Upper Water level

109 Lower Reservoir

110 Ballast water (dead storage)

111 Air vent area

112 Upper bridge crane

113 Multi-megawatt Wind Turbine (tension leg platform)

114 Lower reservoir structure (manmade)

115 Lower Reservoir water level (varies ~ +/- 30 m)

116 Lower Bridge Crane

117 Air Vent (possible Wells Turbine)

118 Air Equalization (vent) Tube

119 Remote Storage Reservoir Module Component Number Description

120 Wells (air) Turbine

121 Connecting Tube

122 Tension Leg Platform (TLP) tether cables

123 Compressed Air Storage Tank

124 Compressed Air Wind Turbine

125 Check Valves

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows;

[Claim 01] The generation of power and energy with water using submerged lower storage reservoirs mounted on the floor of a body of water with said lower storage reservoirs being at the same pressure as and vented to the air directly above the upper water level of the body of water in which said storage reservoirs are submerged and after a period of power generation purging the water from said lower reservoirs with compressed air.

[Claim 02] The generation of power and energy with water using submerged lower storage reservoirs mounted on the floor of a body of water with said lower storage reservoirs being at the same pressure as and vented to the air directly above the upper water level of the body of water in which said storage reservoirs are submerged and after a period of power generation pumping the water from said lower reservoirs with the pump turbine.

[Claim 03] For use in generating electrical power and energy an apparatus comprised of water intake/discharge, turbine generator, pump/turbine, electric motor/generator contained in a structure to hold said intake/discharge, pump/turbine and motor/generator along with electrical equipment connected to the conductors of the motor/generator to receive the energy transmitted therein and retransmit elsewhere via an underwater power cable. The structure to be anchored to the bottom of a body of water. Lower storage reservoir of the apparatus consists of watertight man made structure or structures sized to store sufficient water volume to enable generation operation for multiple hours before pumping. This lower storage reservoir also anchored to the bottom of a body of water and vented to and kept at the same atmospheric pressure as that at the water surface such that while generating and filling the lower reservoir with water the air can easily exit the reservoir and while pumping and clearing of water air can easily enter the reservoir.

[Claim 04] Apparatus as claimed in claim 3 in which the underwater structures are used to anchor or support wind turbines to supply electricity and/or compressed air.

[Claim 05] Apparatus as claimed in claim 3 that uses the variation in surface water level due to tides to increase the cycle efficiency of the power station.

[Claim 06] Apparatus as claimed in claim 3 that uses the airflow into and out of the lower reservoir to create energy using an air turbine.

[Claim 07] Apparatus as claimed in claim 3 where when the lower reservoir is full a means is used to create a higher pressure within the lower reservoir to expel the water through multiple check valves back into the main body of water. This means could be high gas pressure created by controlled explosion or gas pressure created by operation of a compressor.

[Claim 08] Apparatus as claimed in claim 3 where the lower reservoir is located under the floor of the body of water.

[Claim 09] Apparatus as claimed in claim 3 in which the turbine or pump/turbine rotor is driving the generator or motor/generator directly. [Claim 10] Apparatus as claimed in claim 3 in which the turbine or pump/turbine rotor is driving a gearbox and the gearbox driving the generator or motor/generator at variable speed.

[Claim 11] Apparatus as claimed in claim 3 in which the turbine or pump/turbine rotor is driving a torque converter with a gearbox and said torque converter adjusts to drive the generator or motor/generator at constant speed even though the turbine or pump/turbine speed may change.

[Claim 12] Apparatus as claimed in claim 3 in which the turbine or pump/turbine rotor is driving a torque converter without a gearbox and said torque converter adjusts to drive the generator or motor/generator at constant speed even though the turbine or pump/turbine speed may change.

[Claim 13] Apparatus as claimed in claim 3 in which the generated energy is transferred to the shore via multiple underwater cables.

[Claim 14] Apparatus as claimed in claim 3 in which energy generated is constant cycle Alternating Current (AC).

[Claim 15] Apparatus as claimed in claim 3 in which energy generated is variable cycle Alternating Current (AC).

[Claim 16] Apparatus as claimed in claim 3 in which energy generated is Direct Current (DC).

[Claim 17] Apparatus as claimed in claim 3 in which Direct Current energy generated is converted to Alternating Current. [Claim 18] Apparatus as claimed in claim 3 in which energy transmission to the shore is by microwave, laser or other wireless means.

[Claim 19] Apparatus as claimed in claim 3 in which the generator or motor/generator is supplied with permanent magnets for the field poles.

[Claim 20] Apparatus as claimed in claim 3 in which the generator or motor/generator is a superconducting motor/generator with HTS.

[Claim 21] Apparatus as claimed in claim 3 in which the poles of the generator or motor/generator are mounted on an outer support ring of the turbine or pump/turbine blades and rotate with these blades within the generator or motor/generator stator that surrounds the ring & blades.