ENERGY STORAGE SYSTEM

Field of the invention

The present invention relates to energy storage systems, for example for use in a context of renewable offshore energy generation from wind, wave motion and/or tidal flows, although not limited thereto. Moreover, the present invention also concerns methods of storing energy in such systems.

Background of the invention

"Peak-oil" is a concept of there being a maximum for available World oil and gas production; "peak oil" occurs when oil and gas consumption rates exceed discovery rates at which new sources of oil and gas are found to replace old oil and gas sources which have become depleted. In practice, the World is not in imminent danger of running out of oil and gas, but is believed to be presently running out of cheap oil and gas. On account of economic growth within society being closely correlated with energy consumption, peak oil and gas in combination with steadily rising World population, there presently exists an urgent need to exploit alternative energy resources to complement fossil fuel reserves. Environmental considerations such as pollution also require cleaner sources of energy to be found very soon; climate change issues have more recently become a focus for political attention, for example via the International Panel on Climate Change (IPCC). Earlier, nuclear power was presented as a solution to the World's energy supply problems. However, depletion of uranium sources as well as disposal of radioactive by-products from nuclear reactors has rendered nuclear power contemporarily less attractive. Certain countries, for example Norway and India, have rich reserves of thorium which can be blended with uranium to produce nuclear fission fuel; however, radioactive by-products arising from thorium fission represent an especially difficult radioactive waste disposal problem. Nuclear fusion power systems have been under development for many decades, but have tended to become progressively more complex. Moreover, such fusion systems suffer a fundamental problem that slow neutrons resulting from nuclear fusion reactions therein damage walls of partially evacuated chambers in which their fusion reactions occur. There are presently doubts whether or not nuclear fusion is susceptible to being implemented in an economically viable manner.

Certain types of electrical power supply facilities such as coal-fired electrical power stations and nuclear power stations are not able to temporally modify their electrical output production responsively to address dynamically changing electrical power demand on account of long thermal time constants associated with such coal and nuclear power stations. Gas, oil and hydroelectric power stations are able to respond more rapidly to varying electricity demand in order to try to keep a relatively stable line voltage and frequency for electricity supplied to society. However, hydroelectric power is only feasible in certain parts of the World due to issues of geographical terrain and precipitation. As aforementioned, oil and gas are likely to become more seldom and expensive commodities in future as fossil fuel reserves become progressively depleted pursuant to "peak oil".

Such problems will be exacerbated in future if transport systems increasingly use electricity as a source of energy for transport, for example as in widespread use of plug-in hybrid vehicles. Environmental considerations such as pollution are also increasing demands from society for cleaner sources of energy to be urgently found.

Thus, providing electrical supply to society is a complex problem on account of:

(a) temporal variations in electricity usage by society; and

(b) changes in the availability of electricity supply from various sources. Ideally, supply and demand for electricity within society are mutually matched to maintain electricity supply voltages and frequencies within defined threshold limits. When these limits are exceeded, there is a risk that certain types of electrical apparatus in use in society malfunction, potentially with disastrous consequences. Various manners of addressing fluctuations in demand are implemented to render electrical power consuming devices responsive to electrical supply provided thereto to assist stabilize electrical supply networks, for example household appliances which reduce their power consumption when electrical supply line voltages and/or frequencies fall below certain threshold limits. Such regulation has been pioneered by companies such as RLtec Ltd., United Kingdom

Major energy storage facilities for storing large quantities of energy for stabilizing electrical supplies have been in use for many years in the United Kingdom at Dinorwic water pump storage system. The Dinorwic storage system is depicted in Figure 1 and indicated generally by 10. The system 10 comprises lower and upper water reservoirs 20, 30 respectively with a height difference δh therebetween, the reservoirs 20, 30 being coupled together via a water turbine facility 40 and its associated tunnels 50. The turbine facility 40 is operable in conditions of excess electricity production to pump water from the lower reservoir 20 to the upper reservoir 30. Moreover, in conditions of excess electricity demand, water is allowed to

flow via the turbine facility 40 from the upper reservoir 30 to the lower reservoir 20 to generate electricity for supplying to an electrical network. A problem with the Dinorwic system 10 is that it requires a certain type of mountainous terrain for its implementation on account of a need to employ natural geological formations to form the reservoirs 20, 30, for example naturally occurring glacial tarns. Moreover, pumping water from the lower reservoir 20 to the upper reservoir 30 is not without associated viscous energy loss exhibited by increased water temperature of water pumped to the upper reservoir 30.

A contemporary problem with renewable energy systems employing wind power, wave power, ocean tidal power and solar power is that:

(a) certain days are substantially without wind rendering energy yields from wind turbines low;

(b) certain days out at sea are substantially without waves rendering yields from wave energy systems low; (c) solar energy systems are not able to generate electricity during night, and certain days are subject to considerable cloud cover which renders energy yields from solar energy systems low; and

(d) tidal flows only occur at certain times of day and/or certain times of year. Whereas certain desert regions of the World experience a reliable amount of sunlight, for example as in the Sahara Dessert and various deserts within the USA and China, other regions such as Norway experience relatively steady winds and ocean wave amplitude for a majority of time. In extreme weather conditions, for example storm conditions, there is often an excess of wind movement and wave motion such that it is often a contemporary consideration to build renewable energy apparatus to be sufficiently robust to survive such extreme weather conditions but not necessarily to operate through such extreme weather conditions. For example, a contemporary Pelamis wave energy system is designed merely to survive storm conditions but not necessarily generate electrical power in storm conditions. Moreover, for example, it is contemporary practice to apply brakes of a conventional electricity-generating wind turbine in order to prevent damage to its rotor during storm conditions. By such an approach, considerable amounts of electrical energy which are potentially susceptible to being produced during storm conditions remain unobtainable.

Apart from the aforementioned Dinorwic water pump storage system, other forms of energy storage systems tend to be too expensive for use for storing electrical energy. For example, rechargeable polymer lithium batteries are very expensive, even for automotive use in electric vehicles, whereas conventional lead acid and NiMH hydride batteries have insufficient capacity except for low power uses such as emergency lighting, and so forth.

More recently, interest has developed in the use of compressed air as an energy storage medium, for example as described in patent applications as provided in Table 1 attributed to an inventor Mr Guy Negre.

Table 1 : compressed air energy storage technology

Compressed air vehicle technology is extremely promising but requires air to be pressurized to extremely high pressures approaching 300 Bar in specially-designed carbon-fibre- reinforced air tanks in order to store sufficient energy to propel a vehicle for ten's of kilometres, but without causing the vehicle to be too heavy. Safety concerns pertaining to such pressurized air tanks has presently hindered wide-scale adoption of this compressed- air transport technology which potentially promises to solve pollution problems in urban areas without generating dangerous wastes such as worn-out battery packs which pertains to contemporary and future electric vehicles. Another concern with this compressed air technology is that energy is lost pressurizing air which is wasted in comparison to rechargeable-battery electric vehicle systems which can theoretically approach 100% energy efficiency.

A problem arising in practice for electrical energy distribution networks is that adequate energy storage is not contemporarily feasible, with an exception of aforementioned water pumped storage schemes, for example as found at Dinorwic in Wales; United Kingdom. Such lack of energy storage is especially relevant when intermittent renewable energy systems such as wind turbines are taken into consideration.

The present invention seeks to address this problem of energy storage, especially in connection with renewable energy systems.

Summary of the invention

An object of the present invention is to provide an energy storage system for use with a renewable energy generation facility for providing a more uniform and/or continuous supply of energy from the facility.

A further object of the invention is to provide an energy storage system for use with a renewable energy generation facility for enabling the facility to better cope with fluctuations in energy demand applied to the facility in operation.

According to a first aspect of the invention, there is provided an energy storage system as claimed in appended claim 1 : there is provided an energy storage system for storing energy in connection with a renewable energy generating facility, characterized in that the energy storage system is operable to employ one or more of:

(a) compressed air energy storage apparatus for storing energy generated by the energy generating facility, the stored energy being for subsequent release from the facility;

(b) gas energy storage apparatus for storing a gas generated from energy generated by the energy generating facility, the gas being subsequently useable to generate energy, the generated energy being for subsequent release from the facility; and

(c) gyroscopic energy storage apparatus for storing energy generated by the energy generating facility in rotation energy in the gyroscopic energy storage apparatus, the rotation energy being for subsequent release from the facility.

The invention is of advantage in that the energy storage system is capable of buffering in operation energy demand placed upon the facility.

A combination of these options (a) to (c) is especially beneficial because the options (a) to (c) have mutually different temporal responses such that the combination is better able to cope with varying frequencies of dynamically change electrical load. For example, the gyroscope energy storage apparatus is potentially able to react within milliseconds to changing electrical load demand, whereas the compressed air energy storage apparatus is able to respond within tens to hundreds of milliseconds.

Optionally, in respect of the energy storage system, the renewable energy generating facility is an off-shore energy facility including at least one of:

(i) wave power energy apparatus for generating renewable energy from substantially surface ocean waves received at the apparatus; (ii) tidal current energy apparatus for generating renewable energy from underwater tidal flows received at the apparatus; (iii) wind power energy apparatus for generating renewable energy from wind received at the energy generating facility.

Optionally, the energy storage system includes one or more gas and/or air storage tanks for storage of gas and/or air in at least one of: the compressed air energy storage apparatus; the gas energy storage apparatus.

More optionally, in respect of the energy storage system, at least a portion of the one or more storage tanks are disposed in operation in a submerged state. More optionally, in respect of the energy storage system, at least one of the submerged tanks is vented to sea water. More optionally, in respect of the energy storage system, at least one of the submerged tanks are based upon a geological formation providing a volume in which the gas and/or air is storable. Beneficially, the one or more storage tanks are operable to synergistically function as one or more anchors.

Optionally, in respect of the energy storage system, at least one of the one or more gas and/or air storage tanks is provided with a heat recovery apparatus for recovering heat from the one or more tanks for enhancing efficiency of subsequent energy storage within the one or more tanks. Such heat recovery apparatus, for example, enables air compression to be achieved in an isothermal manner. Heat recovery is beneficially used to generate electricity for pumping more air or gas into the one or more storage tanks.

More optionally, in respect of the energy storage system, the one or more gas and/or air tanks are lined with a layer of material for at least partially preventing interstitial gas penetration damage to walls of the one or more tanks.

More optionally, in respect of the energy storage system, the renewable energy generating facility is tethered and/or supported by the one or more storage tanks disposed in a submerged state.

Optionally, in respect of the energy storage system, the tidal current energy apparatus includes at least one rotor, the at least one rotor including at least one blade, the at least one rotor being provided with an associated open-bottom gas- or air-filled chamber, wherein the

at least one blade alternates between being driven by aquatic flow (F) and moving within the chamber as the at least one rotor rotates in operation.

According to a second aspect of the invention, there is provided an energy generating facility as claimed in appended claim 10: there is provided an energy generating facility including an energy storage system pursuant to the first aspect of the invention.

According to a third aspect of the invention, there is provided a method of generating energy in a renewable energy generating facility as claimed in appended claim 12: there is provided a method of generating energy in a renewable energy generating facility including an energy storage system for storing in operation energy generated by the generating facility, characterized in that the method includes a step of storing a portion of the energy generated by the generating facility in at least one of:

(a) a compressed air energy storage apparatus for storing energy generated by the energy generating facility, the stored energy being for subsequent release from the facility;

(b) a gas energy storage apparatus for storing a gas generated from energy generated by the energy generating facility, the gas being subsequently useable to generate energy, the generate energy being for subsequent release from the facility; and (c) a gyroscopic energy storage apparatus for storing energy generated by the energy generating facility in rotation energy in the gyroscopic energy storage apparatus, the rotation energy being for subsequent release from the facility.

Optionally, with respect to the implementing the method, the renewable energy generating facility is an off-shore energy facility including at least one of:

(i) wave power energy apparatus for generating renewable energy from substantially surface ocean waves received at the apparatus; (ii) tidal current energy apparatus for generating renewable energy from underwater tidal flows received at the apparatus; (iii) wind power energy apparatus or generating renewable energy from wind received at the energy generating facility.

Optionally, with respect to implementing the method, the energy storage system includes one or more gas and/or air storage tanks for at least one of: the compressed air energy storage apparatus; the gas energy storage apparatus.

More optionally, the method includes a step of disposing at least a portion of the one or more storage tanks in a submerged state.

More optionally, the method includes a step of venting at least one of the submerged tanks of the energy storage system to sea water. More optionally, when implementing the method, at least one or the submerged tanks are based upon a geological formation providing a volume in which gas and/or air is storable.

More optionally, when implementing the method, the one or more gas and/or air tanks are lined with a layer of material for at least partially preventing interstitial gas penetration damage to walls of the one or more tanks.

More optionally, the method includes a step of tethering and/or supporting the renewable energy generating facility by the one or more storage tanks disposed in a submerged state.

It will be appreciated that features of the invention are susceptible to being combined in any combination without departing from the scope of the invention as defined by the accompanying claims.

Description of the diagrams

Embodiments of the present invention will now be described, by way of example only, with reference to the following diagrams wherein:

Figure 1 (FIG. 1) is a schematic illustration of a known pumped water energy storage system of a type employed at Dinorwic in Wales, United Kingdom;

Figure 2 (FIG. 2) is a schematic illustration of an off-shore energy system pursuant to the present invention;

Figure 3 (FIG. 3) is a schematic illustration of a gyroscopic energy storage device employed in the energy system of Figure 2;

Figure 4 (FIG. 4) is a schematic illustration of a hydrogen energy storage device employed in the energy system of Figure 2;

Figure 5 (FIG. 5) is a schematic illustration of a first configuration of a compressed-air energy storage device employed in the energy system of Figure 2;

Figure 6 (FIG ₁ 6) is a schematic illustration of a second configuration of a compressed-air energy storage device employed in the energy system of Figure 2;

Figure 7 (FIG. 7) is a schematic illustration of a wind turbine for use in the energy system of Figure 2;

Figure 8 (FIG. 8) is a schematic diagram of an alternative implementation of wind turbine pursuant to the present invention;

Figure 9 (FIG. 9) is a schematic illustration of a heat recovery apparatus for use with the devices of Figures 5 and 6 for increasing efficiency of energy storage therein; and

Figure 10 (FIG. 10) is a schematic illustration in side view of an underwater pressure turbine for generating electricity from tidal flows and/or gulf-stream-type flows, with the pressure turbine being shown in front view inset at the bottom of Figure 10.

In the accompanying diagrams, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non- underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.

Description of embodiments of the invention

The present invention relates primarily to off-shoe renewable energy systems and facilities, but is not limited thereto. A future off-shore renewable energy system or facility is indicated generally by 100 in Figure 2. The renewable energy system 100 includes a platform 110; the platform 110 is either floating or supported from a sea bed 120. Moreover the platform 110 includes at least one of:

(a) one or more wind turbines 130 for generating energy from wind received at the platform 110;

(b) one or more wave energy collection devices 140 for generating energy from substantially surface wave motion; (c) one or more submerged aquatic turbines 150 for generating energy from tidal flows; and

(d) one or more solar energy collectors 160.

The one or more wind turbines 130 are susceptible to being implemented with their rotors being centrally supported at a nacelle, or their rotors being edge supported. Edge-supported rotors are more suitable for hostile off-shore environments, for example when hurricane winds are to be withstood.

Optionally, the energy system 100 further includes aquaculture facilities 170, for example salmon enclosures for cultivating salmon. Optionally, the energy system 100 includes industrial activities utilizing energy generated by the renewable energy system 100, for example fish processing to generate food, bauxite processing for producing aluminium, cement manufacture, titanium processing and so forth. Yet optionally, the energy system 100 includes recreational facilities such as one or more pleasure boat harbours, one or more retailing centres, and one or more hotels.

The renewable energy system 100 includes at least one underwater cable 200 electrically linking the energy system 100 to land 210. Electrical energy generated at the energy system 100 is conditioned via first solid state apparatus 220 at the energy system 100 to convert the electrical energy to direct current (d.c.) electricity for conduction via the cable 200 to a second solid state apparatus 230 on the land 210. The second apparatus 230 is operable to convert the direct current electricity to a 50 Hz alternating current format for feeding onto an electricity grid 240 on the land 210. The first and second apparatus 220, 230 are beneficially based upon high-frequency thyristor switching technologies. For example, a company ABB is a World supplier of such underwater cable systems and related equipment.

A technical problem arising with the energy system 100 is that wind and/or ocean and/or tidal flows can at certain times be negligible which results in the energy system 100 being able to generate relatively little electrical energy therefrom, for use within the energy system 100 or transmission via the cable 200 to the land 210. A further problem arising with the energy system 100 is that huge amounts of energy are potentially harvestable in storm conditions when wind speeds can approach 20 metres/second or more and wave trough-peak amplitudes can approach 10 metres of more. In such circumstances, the energy system 100

is often able to harvest much more energy than is possible to convey via the cable 200 to the land 210. Moreover, energy consuming appliances on the land 210 often do not have an instantaneous energy requirement corresponding to an amount of energy the system 100 is able to deliver under such storm conditions.

In order to address this problem, the energy system 100 includes one or more energy storage systems as will now be described.

Referring to Figure 2, the platform 110 beneficially includes first energy storage apparatus 300. The first apparatus 300 can be implemented using one or more energy storage technologies which will be elucidated in more detail later. Moreover, the platform 210 is optionally alternatively or additionally coupled to a second energy storage apparatus 310 mounted upon the sea bed 120, with a connection 320 linking the platform 210 to the second apparatus 310.

Referring to Figure 3, the first apparatus 300 optionally includes energy storage based upon one or more spinning-wheel gyroscopic devices 400. Such one or more gyroscopic devices 400 are of benefit in that they are operable to generate Coriolis forces which assist to maintain the platform 110 in a stable inclination in storm or hurricane conditions. Each gyroscopic device 400 includes a rotor 410 mounted upon one or more bearings 420, the rotor 410 being further provided with an electro-magnetic interface 430. The one or more bearings 420 are susceptible to being implemented as one or more mechanical bearings and/or one or more non-contact magnetic bearings. Moreover, the rotor 410 is beneficially mounted within an at least partially evacuated enclosure for reducing dissipative air drag on the rotor 420, thereby enabling the rotor 420 to be spun at greater speeds than normally possible in ambient air at nominal atmospheric pressure of 760 mm Hg. When excess energy is being generated by the wind turbines 130, the wave energy collection devices 140, the aquatic turbines 150 and/or the solar collectors 160, this excess energy is provided to the electro-magnetic interface 430 to spin up the rotor 410 to a higher rate of rotation, storing an amount of energy Vz l(ω ₂ ² - ω, ² ) whereat O ₁ is an initial angular rotation rate of the rotor 410 and ω ₂ is an angular rotation rate of the rotor 410 after the energy being stored therein When more power is subsequently needed on the land 210, the electro-magnetic interface 430 is operable to extract rotational momentum in the rotor 410 and supply this as electrical energy to the first apparatus 220 for converting to d.c. current for supply via the cable 200 to the second apparatus 230 for subsequently supplying to the electricity grid 240. Beneficially, as aforesaid, the platform 110 employs the gyroscope device 400 synergistically for resisting rocking motion of the platform 110 as well as for energy storage purposes.

One or more of the gyroscopic devices 400 included in the first apparatus 300 can be arranged to rotate at mutually similar rotation rates but in mutually opposite rotation directions so as to generate electricity when being simultaneously decelerated but without an overall turning moment, namely turning torque, being experienced by the platform 110. On account of the platform 110 being anchored and thereby prevented from undergoing unwanted rotation, such gyroscopic devices 400 providing stabilization for the platform 110 are able to store and deliver energy without causing the platform 110 to rotate. The rotor 410 is beneficially furnished with permanent electromagnets 450 around its peripheral edge, and the electro-magnetic interface 430 further includes a series of electronically-switched peripheral coils 460 to interact with the permanent magnets 450 for accelerating or decelerating the rotor 410 and correspondingly storing or retrieving energy respectively.

The first apparatus 300 is beneficially optionally operable to store energy as illustrated in Figure 4 by way of hydrogen gas storage; "gas" here is used to distinguish from air.

Beneficially, the apparatus 300 includes a hydrogen energy storage apparatus 500 which is operable to electrolyse or otherwise decompose water in an electrolysis device 510, for example electrolysing sea water, to generate hydrogen and oxygen, and then to store the hydrogen (H ₂ ) generated by the electrolysis device 510 in a hydrogen reservoir 520, and then subsequently supply the hydrogen from the reservoir 520 to fuel cells 530, for example polymer membrane fuel cells or high-temperature ceramic fuel cells but not limited thereto, for generating electricity for supplying via the connection 200 to the land 210. Alternatively, or additionally, hydrogen supplied from the reservoir 520 is provided to a combustion hydrogen turbine engine or a combustion hydrogen piston engine for generating motive force to drive a generator to generate electricity for supply via the connection 200 to the land 210.

The hydrogen reservoir 520 is implemented using one or more of the following technologies:

(a) hydrogen storage at high pressure within storage tanks;

(b) cryogenic storage of hydrogen in liquid form at low temperature; and/or

(c) hydrogen storage by way of a reversible chemical process, for example by reversibly forming metal hydrides with metals such as nickel.

Beneficially, the second energy storage apparatus 310 includes one or more robust reinforced tanks which are used to store hydrogen generated by the electrolysis device 510, the hydrogen being stored under pressure, for example at pressures up to 100 Bar, and more preferably at pressures up to 50 Bar, via the connection 320. The one or more tanks are beneficially constructed from at least one of: metal, concrete, metal-reinforced concrete, polymer-fibre-reinforced concrete. Suitable polymer fibres include: Kevlar, carbon nano-tube

fibres, high-strength polyethylene fibre such as Dyneema fibre manufactured by DSN Dyneema B.V., Mauritslaan 49, Urmond, P.O. Box 1163, 6160 BD Geleen, the Netherlands.

Such storage in the second apparatus 310 is extremely favourable for safety as well as the one or more tanks synergistically functioning as superb foundations for the platform 110, for example via tethering lines (not shown) or solid connection, thereby enabling the platform 110 to better survive severe storm conditions, for example hurricanes. In an event of a leak or explosion under water, the platform 110 is likely to be substantially unaffected and undamaged.

It is known that hydrogen stored under pressure in a tank causes degradation of walls of the tank due to hydrogen penetrating into interstitial regions between atoms of material forming the walls of the tank. The inventor has appreciated that such degradation can be reduced by lining an inside of the tank with a plurality of projections or similar, for example by employing a severely roughened nobly surface, onto which a gel-like or flexible wax, for example paraffin wax, is added as represented by 1000. The gel-like or flexible wax is operable to flow when subject to mechanical force, for example forced into pores of reinforced concrete. When hydrogen is stored in the tank at high pressure, most pressure drop is arranged to occur across a boundary formed by the gel-like or flexible wax and a relatively small pressure drop across the walls by imparting the walls with relatively high gas porosity, for example an order of magnitude greater porosity than the layer 1000 of gel-like material or flexible was paraffin wax Interstitial damage on account of high hydrogen pressures occurs in the gel- like or wax layer 1000 which is able to reflow to accommodate such damage whilst remaining gas tight, whereas the walls remain undamaged and thereby are able to retain mechanical strength for the tanks. Optionally, the walls include heating elements on their interior surface, and the gel or wax-like wax layer 1000 is subject to one or more flow cycles at elevated temperature provided when the heating elements are energized; the walls are thereby beneficially subject to temporally regular re-melting cycles to repair damage caused by interstitial penetration of hydrogen gas into the layer 1000. By such an approach, the tank can be used reliably for hydrogen storage under high pressure, for example many ten's of Bar pressure, over a period of many decades use. The reservoir 520 is beneficially constructed accordingly. Beneficially, storage tanks of the reservoir 520 are substantially spherical in shape for providing greatest strength, storage volume for a given quantity of construction material employed.

The first apparatus 300 is beneficially operable to store energy as illustrated in Figure 5 by way of compressed air. Compressed air technology for energy storage has been recently

developed by inventor Guy Negre as elucidated in the foregoing in respect of air-propelled road vehicles whose technology is to Tata Motor Corporation, India. In such vehicles, air is compressed to high pressures approaching 300 Bar in carbon-fibre storage tanks, and is selectively discharged via multistage piston engines to provide motive power. Moreover, such air-propelled automobiles are alleged to be able to travel over 100 km distance on one compressed air charge in circa 3 cubic metres storage tank volume. Concerns of safety during accident impact for such air-propelled vehicles is a factor which may have hindered introduction of such vehicles which potentially provide an at least partial solution to urban air pollution problems caused by combustion vehicle exhaust emissions.

When the first apparatus 300 is operable to store energy via compressed air, Figure 5 illustrates that the apparatus 300 includes a device 600 including an electric motor/generator 610 mechanically rotationally coupled to an air compression engine 620, for example implemented as a multi-stage compressor with progressively smaller pistons in a manner akin to technology adopted by Guy Negre which is herewith incorporated by reference, for example with reference to aforementioned Table 1. When the energy system 100 is generating excess energy, for example in storm conditions, the excess energy is employed to drive the electric motor/generator 610 to actuate the compression engine 620 to pump air to a high pressure for storing in one or more robust compressed air tanks 630. These one or more air tanks 630 are beneficially constructed from reinforced concrete and/or steel and/or high-strength polymer fibre and are included at one or more of: on the platform 110, in the second storage apparatus 310 as aforementioned. Optionally, the one or more air tanks 630 are furnished with the aforementioned layer 1000 for hindering or reducing structural damage caused by atomic interstitial penetration of gas molecule under pressure. The connection 320 enables compressed air to be exchanged between the platform 110 and the second storage apparatus 310 in the sea bed 120. At times when the energy system 100 is not able to generate adequate power from wind, wave and/or tidal energy, the system 100 is beneficially operable to control the device 600 so that compressed air is provided from the one or more tanks 630 to drive the compression engine 620 to generate mechanical turning force to turn the motor/generator 610 to generate electricity for the first apparatus 220 to feed via the connection 200 to the land 210, namely to its associated electricity network 240. For providing optimal power control, the one or more tanks 630 are operated in a regime 630 wherein they are partially filled to their maximum allowable pressure to provide for rapid switching between energy storage in and energy delivery from the one or more tanks 630.

In situations where extremely rapid dynamic control to compensate for variations in power output from the energy system 100 is required, for example for providing dynamic short-term

energy stabilization of the electricity grid 240, for example for periods of second or ten's of second, a variant of the device 600 of Figure 5 is employed, the variant of the device being illustrated in Figure 6. Excess electricity is employed to operate an electric motor 610a which drives a first multi-stage air piston compression engine 620a operable as an air pump which pumps air into the one or more tanks 630. As aforementioned, the one or more tanks 630 are accommodated in one or more of: the first apparatus 300, the second apparatus 310. Compressed air from the one or more tanks 630 is supplied to a second multi-stage air piston compression engine 620b operable as an engine which drives a generator 610b for generating electricity for supplying to the first apparatus 220 for converting to d.c. current thereat for feeding via the connection 200 to the electricity network 240 on the land 210. The piston compression engines 610a, 620b operate temporally concurrently to achieve a rapid immediate response for energy supply stabilization purposes.

Tanks included to the second apparatus 310 for storage of compressed air or hydrogen are optionally selectively vented at a bottom region thereof to the sea or ocean. Such venting is optionally achieved via actuated valves; opening and closing operations of the valves are controllable by the system 100, for example from a control unit of the system 100. Such opening and closing operations are beneficially controlled in response to pressure state of the tanks, time and/or power delivered by the system 100. Such a vented arrangement allows sea water to penetrate into the reservoir 520 in the second storage apparatus 310 when the one or more tanks 630 of the second apparatus 310 are emptied of compressed air or hydrogen. Such an arrangement is capable of increasing an effective useable capacity of the tanks for storing air or hydrogen.

Beneficially, the second storage apparatus 310 includes certain tanks for hydrogen storage and certain other tanks for compressed air storage so that both compressed air and hydrogen storage are employed in the system 100 as mechanisms for energy storage and energy supply stabilization; such a combination provides mutually different temporal responses for coping with varying energy consumption demand. Optionally, natural geological formations can be employed for impiementing the second storage apparatus and its associated tanks 630. For example, geological anticlines from which oil and/or gas have been earlier extracted can be used for storage of compressed air and/or hydrogen under pressure.

The energy system 100 is also beneficially equipped with fast-acting energy storage apparatus for enabling the system 100 to cope with rapidly fluctuating demand from the

etectricity network 240, for example within a timeframe of microseconds to milliseconds. Such fast-acting energy apparatus beneficially includes at least one of:

(a) super-capacitors;

(b) lithium ion rechargeable batteries or similar; and (c) sodium-sulphur batteries or similar systems based upon sodium or similar reactive metal in combination with a halide species or sulphur.

Such fast-acting energy storage devices are beneficially provided in the first storage apparatus 300 and/or the second storage apparatus 310 together with electronic power units for charging the fast-acting devices, for example from excess energy generated by the system 100, and for discharging the fast-acting devices to provide energy via the connection 200 to the electricity network 240.

In the foregoing, the wind turbines 130 are briefly described. These wind turbines 130 beneficially are implemented in a conventional manner as illustrated in Figure 7, namely each wind turbine 130 including a substantially vertical tower indicated generally by 1200, the tower 1200 having a lower proximate end 1210 attached to the platform 110 and a higher distal end 1220 onto which is mounted a nacelle machine housing 1230 including a generator 1240 and a gearbox 1250 coupled to a centrally-supported turbine rotor 1260. Such wind turbines 130 have been developed, amongst other companies, by companies such as Vestas AS in Denmark, and Gamesa SA in Spain.

Additionally, or alternatively, the wind turbines 130 are of a type developed by the present inventor as shown in Figure 8. In Figure 8, the wind turbine 130 includes an open frame 2000, for example fabricated from a matrix of aluminium tubes, braced with high strength fibres such as Kevlar, carbon fibre and high-strength polythene fibre, for example as manufactured by DSM Dyneema B.V., the Netherlands. The wind turbine 130 includes a turbine rotor 2010 including a plurality of rotor blades 2020, the rotor 2010 having a peripheral circular edge 2030 which is rotationally edge-supported by wheels and/or rollers 2040 within the frame 2000, wherein energy take-off devices 2050 are provided in a distributed manner around the frame 2000 in close proximity to the peripheral circular edge 2030 of the rotor 2010; the edge 2030 is beneficially furnished with permanent magnets and the take-off devices 2050 are beneficially one or more coils linked to corresponding electronic units operable to rectify and transform electrical energy induced within the take-off devices 2050 when the rotor 2010 rotates relative to the frame 2000. The blades 2020 are beneficially fabricated from:

(a) metal sheet, for example aluminium sheet;

(b) from polymer, for example polypropylene which is susceptible to experiencing numerous bending systems without work hardening;

(c) from woven fabric sheet, for example woven Kevlar and/or woven polyethylene high- tensile strength fibre sheet as aforementioned, or a combination of (a) to (c).

Optionally, one or more actuators are included in association with blades 2020 for adjusting pitch angles of the blades 2020, and also for folding and unfolding the blades 2020. For example, the blades 2020 are fabricated from mutually sliding sheets in a manner akin to a hand-held traditional Chinese or Japanese fan. The one or more actuators are beneficially implemented using electric motors which are operable to rotate around with their respective rotor 2010, 2060. More optionally, the one or more actuators are controlled using wireless signals. The blades 2020 are thereby susceptible to being folded away for protection when the wind turbines 130 are subjected to extremely severe storm conditions, for example hurricane conditions. In offshore environments, such hurricanes would easily destroy conventional turbines of a type illustrated in Figure 7.

Optionally, the wind turbine 130 is furnished with a plurality of concentric rotors, for example also with a central rotor 2060 in addition to the peripheral rotor 2010, and the rotor 2010 is beneficially implemented in a ring-like manner as illustrated. The central rotor 2060 includes one or more blades 2070. More optionally, for example to survive hurricane conditions encountered in seas surrounding Japan, the rotor 2010 is also supported along its inside edge 2100 by one or more wheels and/or rollers 2110 on to a inner annular support frame 2120 rigidly coupled to the frame 2000 via one or more radial beams or struts (not shown). Beneficially, the inner annular support frame 2120 also include energy take-off devices for the rotors 2010, 2060 in a similar manner to the take-off devices 2050. Alternatively, or additionally, energy take-off is also implemented by way of one or more of the rollers and/or wheels 2040, 2110 to corresponding local generator units. Optionally, the wind turbine 130 in Figure 8 is furnished with more then two concentric rotors, for example three concentric rotors.

Optionally, as aforementioned, the blades 2020, 2070 are provide with actuators so that their pitch can be dynamically, varies, their area can be dynamically varied, and they can be retracted, for example by rolling-up or folding up operations, for example to protect the blades in severe storm or hurricane conditions. The rotors 2010, 2060 are capable of rotating at different rates and/or different directions, thereby avoiding a contemporary problem that peripheral blades ends of large conventional wind turbines move through air at

a speed approaching the speed of sound in air which is inefficient and susceptible to causing severe noise nuisance. Moreover, the rotors 2010, 2060 are susceptible to operating with their aerodynamic Betz coefficient approaching a theoretical maximum of 0.59 in comparison to a Betz coefficient of around 0.39 achieved for contemporary wind turbines of a type illustrated in Figure 7. Thus, the wind turbine 130 illustrated in Figure 8 is potentially more robust, more efficient at generating electrical energy and more flexible than hitherto proposed wind turbines.

On account of the energy take-off devices, for example implemented in a direct-induction manner using permanent magnets mounted substantially around an inner and/or outer perimeter of the one or more rotors 2010, 2060 with induction coils mounted upon the frame 2000, 2120 in near proximity thereto, being distributed, failure of a given energy take-off device does not disable their corresponding rotor 2010, 2060 with other of their energy takeoff devices being capable of continuing to operate from generating electric energy from wind impinging upon the one or more rotors 2010, 2060. Moreover, edge supporting the one or more rotors 2010, 2060 renders the wind turbine 130 far more robust than conventional centre-hub mounted configurations as contemporarily employed, for example, by Vestas AS.

Similarly, the one or more wave energy collection devices 140 are beneficially implemented as an array of substantially parallel wall members defining elongate channels along which ocean waves are operable to be formed and propagate, the elongate channels being equipped with floats of progressively diminishing size from a front region of the channels, whereat incoming ocean waves are received, to a rear region of the channels, for example where the aquaculture facility 160 is situated. The elongate channels are beneficially provided with submerged ocean-wave velocity modifying structures near their entrances for tuning the channels to optimally receive incomes waves in a manner of a steered- phased array. The movement of the floats is response to ocean waves acting thereupon is employed to generate electricity via suitable generating apparatus to supply power via the connection 200 to the electricity network 240 on the land 210 for example. Optionally, the elongate channels are provided with submerged paddles which move back and forth in response to a spatially-decaying-with-depth energy field associated with propagation of surface ocean waves; motion of the paddles is also employed to generate electricity for eventual supply to the electricity network 240 for example. More effective energy recovery from waves propagating along the channels is therefore achievable. Optionally, the elongate channels are tapered from their front region, whereat they are widest, to their rear region, whereat they are narrowest.

If the Norwegian coast were equipped with such platforms 110 and their associated devices and apparatus as elucidated in the foregoing, it is envisaged that Norway could more than supply Europe's entire electrical energy needs, including a trend in Europe towards utilizing plug-in hybrid vehicles and also potentially air cars as proposed by aforementioned inventor Guy Negre. Even land agriculture could, in principle, utilize electrical vehicles and/or air- powered vehicles for ploughing, sowing and harvesting. Moreover, transport industries, for example road hauliers, could employ air-powered, plug-in hybrid electric technology or full electric technology for transport purposes. The present invention is thus capable of moving society from a fossil-fuel economy, dominated by the US industrial-military complex and steering economies via the New York petroleum exchange and the International Petroleum Exchange (IPEX) based in the Stock Exchange, London, to a renewable sustainable energy economy without down-sides of radioactive waste as generated by civilian nuclear fission power generating facilities which have been proposed for addressing future energy needs of society.

Referring to Figure 6, the one or more tanks 630 are susceptible to warming up in operation when gas, for example air, is pumped to a high pressure therein. Optionally, heat generated by increasing gas pressure within the one or more tanks 630 is recovered in an arrangement as illustrated in Figure 9. The arrangement includes a first heat exchanger apparatus 3000 installed within an internal volume of the tank 630 and/or within its walls. The first heat exchanger apparatus 3000 is coupled via an outlet pipe 3020 and an inlet pipe 330 to a generating apparatus 3010. The generating apparatus 3010 includes a turbine or compressor 3050 whose rotor is coupled to an electrical generator 3060 for generating electricity, a non-return valve 3070, and a second heat exchanger apparatus 3080 cooled in operation by sea water. The arrangement is configured to provide a closed-circuit for a cooling fluid, for example propane or similar refrigerant material exhibiting a low boiling point temperature. The closed loop circuit comprises the first heat exchanger apparatus 3000 coupled via its outlet pipe 3020 and then via the turbine 3050 and thereafter through the valve 3070 and thereafter through the second heat exchanger 3080 and then via the inlet pipe 3030 back to the first heat exchanger apparatus 3000.

When air is being pumped into the tank 630 to store energy there, a volume of air within tank 630 warms up. Liquid in the first heat exchanger apparatus 3000 is evaporated by heat energy arising within the tank 630 and passes as gas via the outlet pipe 3020 at high velocity to drive the turbine 3050 to drive the electrical generator 3060 to generate electricity for pumping a further portion of air into the tank 630. Air compression in the tank 630 is thereby capable of being achieved in a substantially iso-thermal manner, or partially iso-thermal

manner. Fluid passing through the turbine 3050 passes through the non-return valve 3070 into the second heat exchanger apparatus 3080 whereat it is cooled by seawater 3090 to reform as a liquid for passing back to the first heat exchanging apparatus 3000. Such an arrangement is not any form of perpetual motion machine but utilizes heat energy arising in the tank 630 to store further energy in the air within the tank 630. When stored energy is to be extracted from the tank 630, the tank 630 cools down, although its walls can be heated using sea water to a more moderate temperature in an order to O ⁰ C to 20 ⁰ C for example. Moreover, compressed air subsequently extracted from the tank 630 can be heated using sea water to provide compressed air for the second compression piston engine 620b and its associated generator 610b.

The arrangements illustrated in Figures 5, 6 and 9 and described in the foregoing are capable of providing highly efficient energy storage with very little energy loss and at relatively low cost in a compact, robust and safe manner using well tried technical components. On account of the tank 630 being air-filled, it can synergistically also function as a buoyancy element in operation. In comparison to aforesaid water pump water storage systems, for example as employed at Dinorwic in the United Kingdom and illustrated in Figure 1 , the arrangements illustrated in Figures 6 and 9 represent a technologically far more advanced and efficient system for energy storage. In consequence, a more constant rate of energy transfer through the cable 200 to the land 210 as illustrated in Figure 2 can be achieved. In consequence, it is feasible to adapt the system 100 of Figure 2 to provide energy supply to the land despite natural variations in the availability of wind and/or wave energy.

The energy system 100 is susceptible to being deployed as an energy-producing bridge-like structure, for example for providing a transport link between countries separated by water or for providing transport links between continents whilst synergistically providing renewable energy production as well as defences against coastal erosion and also aquatic food production. For example, the energy system 100 disposed off-shore near the coastline of Mundsley and Happisburgh is susceptible of providing effective protection against coastal erosion as well as contributing to satisfy electrical energy consumption in the United Kingdom. Alternatively, the energy system 100 is susceptible to being deployed as an energy-producing peninsula-type structure. By such an approach, the cable 200 does not need to be submerged which is capable of reducing implementation costs for the system 100.

The aforementioned aquatic turbine 150 for the system 100 is beneficially implemented in a manner as illustrated in side view in Figure 10. The aquatic turbine 150 is conveniently referred to as being a "pressure turbine". The turbine 150 includes a rotor 5000 including at least one radially-projecting blade 5010, and more preferably a plurality of such radially- projecting blades 5010, mounted partially within an open-bottomed chamber 5020 provided with an upper flow-deflection screen 5030, and optionally a lower flow-deflection screen 5040, mounted in respect of the platform 110. A volume 5050 is filled with air. Optionally, a central shaft of the rotor 5000 is within the volume 5050 filled with air as illustrated. An aquatic region 5060 surrounds the chamber 5020. The rotor 5000 is coupled via an aquatic chain or belt 5070, for example fabricated from metal or plastics material, to a generator 5080 mounted upon the platform 110, such that water flow F, for example tidal flow and/or gulf-stream-type flow, causes the rotor 5000 to rotate as illustrated to generate motive force to move the chain or belt 5070 to drive the generator 5080 to generate electricity and/or provide a pumping function. On account of the rotor 5000 and its chamber 5020 being in a submerged state in operation, they are well protected from any wave damage in storm conditions. Optionally, more air can be periodically pumped into the volume 5050 during operation to replace air transported to the aquatic region 5060 on surfaces of the blades 5010. Optionally, the generator 5080 can be housed within the volume 5050. Optionally, the generator is directly coupled to, for example integral with, the rotor 5000.

The aquatic turbine 150 is optionally implemented with a propeller-type rotor whose blades enter the volume 5050 whereat they experience less viscous resistance in comparison to when they are submerged in water. Such viscosity issue pertains also to the rotor as illustrated in Figure 10.

It will be appreciated that the present invention is described in the context of off-shore energy systems. It will be appreciated that features of the invention are susceptible to being used also in on-land installations, for example with regard to energy storage occurring in the apparatus 300, 310. Features of the invention are also susceptible to being used in connection with road vehicles operable to be propelled by non-fossil fuel energy sources, for example in relation to hydrogen-powered road vehicles incorporating fuel cells for generating electricity for energizing wheel traction motors.

Modifications to embodiments of the invention described in the foregoing are possible without departing from the scope of the invention as defined by the accompanying claims.

Expressions such as "including", "comprising", "incorporating", "consisting of, "have", "is" used to describe and claim the present invention are intended to be construed in a nonexclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural.

Numerals included within parentheses in the accompanying claims are intended to assist understanding of the claims and should not be construed in any way to limit subject matter claimed by these claims.