1 power and hydrogen generation – description

C:Documents and SettingsNovica PadjenMy DocumentsLicnoPatentsDavis Collison CaveProvisional Aplication Final40139678 speci - FINAL_3248506_1.DOC-12/02/2011

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POWER AND HYDROGEN GENERATION

Background of the Invention

The present invention relates to a method and apparatus for generating power using water, as
well as to a method and apparatus for producing hydrogen using electrolysis of water.

5 Description of the Prior Art

The reference in this specification to any prior publication (or information derived from it), or
to any matter which is known, is not, and should not be taken as an acknowledgment or
admission or any form of suggestion that the prior publication (or information derived from
it) or known matter forms part of the common general knowledge in the field of endeavour to
10 which this specification relates.

Numerous methods of generating power using potential energy stored in a body of water have
been proposed, and several of these have achieved relatively widespread use.

For example, methods of hydroelectric power generation are well known and these supply a
substantial portion of the world's power requirements. These methods typically operate by
15 extracting gravitational potential energy from a body of water. In general, the operation of a
hydroelectric power plant relies upon the existence of a water source that is elevated with
respect to a turbine of the power plant, such that water may be provided to the turbine at a
significant pressure head. The pressure head largely determines the amount of potential
energy that can be extracted, and is proportional to the difference in height between the water
20 source and the turbine.

Hydroelectric power plants are usually constructed together with dams or other means of
artificially controlling the elevation of the water source. As a result, hydroelectric power
plants often require the construction of significant infrastructure, at great capital cost.
Accordingly, conventional hydroelectric power generation is usually only commercially
25 viable in locations where certain desirable geographical conditions are already present.


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Oceans also provide expansive bodies of water holding vast amounts of potential energy that
remains largely untapped for power generation purposes. However, many of the proposed
methods for extracting energy from ocean water rely on the extraction of kinetic energy from
ocean currents or waves, and do not exploit the significant hydrostatic pressures present in
5 deep ocean water.

It is also known to perform electrolysis of water to split water molecules into molecules of
hydrogen and oxygen. Electrolysis of this type can be used to produce hydrogen gas that may
be pressurised to enable storage and/or transportation, so that energy can be extracted from
the hydrogen on demand by combustion, or using fuel cells or the like. However, the
10 electrolysis of water typically requires the supply of significantly more energy to power the
electrolysis process than can be later extracted from the produced hydrogen gas, which tends
to reduce the commercial viability of electrolysis as a method of producing hydrogen. As a
result, other methods of producing hydrogen, such as steam reforming from hydrocarbons,
are dominantly used for economic reasons.

15 Summary of the Present Invention

In a first broad form the present invention seeks to provide a method for generating power,
the method including:
a) supplying water at a first pressure to a turbine, wherein the first pressure is provided
at least in part by hydrostatic pressure;
20 b) passing the water through the turbine to a chamber, wherein the chamber is at a
second pressure that is lower than the first pressure;
c) converting the water in the chamber to a gas and discharging the gas from the
chamber, to thereby remove the water from the chamber at substantially the same rate
at which water is passed through the turbine; and,
25 d) using the turbine to drive a generator to thereby generate power.

Typically the water is converted to a gas using a portion of the generated power.


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Typically at least a portion of the water in the chamber is converted to a gas by electrolysing
the at least a portion of the water in the chamber to thereby produce at least hydrogen gas and
oxygen gas.

Typically the method includes providing an electrical current between an electrode pair
5 positioned in the water in the chamber to thereby electrolyse at least a portion of the water in
the chamber.

Typically at least a portion of the water in the chamber is converted to a gas by heating the
water in the chamber to produce steam.

Typically the heating is performed by providing an electrical current between an electrode
10 pair positioned in the water in the chamber.

Typically the method includes extracting energy from at least a portion of the steam by
passing the at least a portion of the steam through a second turbine.

Typically the energy extracted from steam is used to generate additional power.

Typically the method includes condensing the steam to provide fresh water.

15 Typically the method includes submerging at least the turbine in a body of water, such that a
depth of submergence of at least the turbine at least partially determines the hydrostatic
pressure.

Typically the body of water is one of:
a) a naturally occurring body of water; and,
20 b) a shaft at least partially filled with water.

Typically the method includes substantially desalinating the water.

Typically the desalination is performed using reverse osmosis, and wherein an osmotic
pressure is provided at least in part by hydrostatic pressure.

Typically the method includes using a portion of the generated power for electrolysing water
25 in an electrolysis chamber.


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Typically the electrolysis chamber is at a water pressure that is determined at least in part by
hydrostatic pressure, such that electrolysing the water in the at least one electrolysis chamber
produces hydrogen gas and oxygen gas at a gas pressure that is determined at least in part by
the water pressure.

5 Typically the method includes extracting energy from at least a portion of the oxygen gas by
passing the at least a portion of the oxygen gas through a second turbine.

Typically the energy extracted from the at least a portion of the oxygen gas is used to
generate additional power.

Typically the method includes:
10 a) expanding at least a portion of the oxygen gas to thereby reduce the temperature in the
at least a portion of the oxygen gas; and,
b) using the reduction in temperature in the oxygen gas to cool the hydrogen gas.

Typically the method includes at least one of:
a) storing at least a portion of the hydrogen gas; and,
15 b) extracting energy from at least a portion of the hydrogen gas.

In a second broad form the present invention seeks to provide an apparatus for generating
power, the apparatus including:
a) a turbine, wherein water at a first pressure is supplied to the turbine and the water is
passed through the turbine, and wherein the first pressure is provided at least in part
20 by hydrostatic pressure;
b) a chamber for receiving the water passed through the turbine, wherein chamber is at a
c) a converter for converting the water in the chamber to a gas, such that discharging the
gas from the chamber removes the water from the chamber at substantially the same
25 rate at which water is passed through the turbine; and,
d) a generator for generating power, wherein the generator is driven by the turbine.

Typically the converter is adapted to convert the water to a gas using a portion of the
generated power.


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Typically the converter includes an electrode pair, and wherein supplying a current between
the electrode pair causes at least a portion of the water in the chamber to be converted to a
gas by electrolysing the at least a portion of the water in the chamber to produce at least
hydrogen gas and oxygen gas.

5 Typically the converter includes a plurality of electrode pairs.

Typically the plurality of electrode pairs is arranged in concentric circles and wherein the
apparatus is adapted to periodically apply electrical current to respective pairs of the plurality
of electrode pairs.

Typically the converter includes a heater, and wherein supplying a current to the heater
10 causes at least a portion of the water in the chamber to be converted to a gas by heating the at
least a portion of the water in the chamber to produce steam.

Typically the apparatus includes a desalination device.

Typically the apparatus includes at least one pipe extending from the chamber for discharging
the gas from the chamber.

15 Typically the at least one pipe includes thermal insulation.

Typically the apparatus includes a plurality of pipes, and wherein different pipes are for
discharging different gases.

Typically the chamber is adapted to be submerged in a body of water, such that a depth of
submergence determines the hydrostatic pressure.

20 Typically the apparatus has a mass selected to substantially offset buoyancy forces acting on
the apparatus when the apparatus is submerged in the body of water.

Typically the apparatus includes at least one electrolysis chamber for the electrolysis of
additional water under pressure using a portion of the generated power.

Typically the electrolysis chamber is at a water pressure that is determined at least in part by
25 hydrostatic pressure, and wherein the at least one electrolysis chamber includes an electrode


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pair for electrolysing the water in the at least one electrolysis chamber when a current is
supplied across the electrode pair, to thereby produce hydrogen gas and oxygen gas at a gas
pressure that is determined at least in part by the water pressure.

Typically the apparatus includes a second turbine for extracting energy from at least the
5 oxygen gas.

In a third broad form the present invention seeks to provide a method for producing hydrogen
using electrolysis of water, the method including electrolysing water under pressure to
produce at least pressurised hydrogen gas, wherein the electrical current is supplied from
power generated by:
10 a) supplying water at a first pressure to a turbine, wherein the first pressure is provided
b) passing the water through the turbine to a chamber, wherein the chamber is at a
c) electrolysing the water in the chamber to convert the water in the chamber to a gas
15 and discharging the gas to thereby remove the water from the chamber at substantially
the same rate at which water is passed through the turbine; and,
d) using the turbine to drive a generator to thereby generate power.

In a fourth broad form the present invention seeks to provide an apparatus for producing
hydrogen using electrolysis of water, the apparatus including an electrode pair, wherein
20 supplying an electrical current across the electrode pair positioned in water under pressure
produces at least pressurised hydrogen gas, and wherein the electrical current is supplied by a
power generation apparatus including:
25 by hydrostatic pressure;
b) a chamber for receiving the water passed through the turbine, wherein the chamber is
at a second pressure that is lower than the first pressure;
c) at least one further electrode pair for electrolysing the water in the chamber to convert
the water in the chamber to a gas, such that discharging the gas from the chamber


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removes the water from the chamber at substantially the same rate at which water is
passed through the turbine; and,

Brief Description of the Drawings

5 An example of the present invention will now be described with reference to the
accompanying drawings, in which: -
Figure 1 is a flow chart of an example of a method for generating power;
Figure 2 is a schematic diagram of a first example of an apparatus for generating power;
Figure 3 is a schematic diagram of a second example of an apparatus for generating power;
10 Figure 4 is a schematic diagram of a third example of an apparatus for generating power;
Figure 5 is a schematic diagram of an example of an apparatus for the electrolysis of water;
Figure 6 is a schematic diagram of an example of a combined power generation and
electrolysis apparatus; and,
Figure 7 is a schematic diagram of an example of a power generation and electrolysis plant.

15 Detailed Description of the Preferred Embodiments

An example method for generating power will now be described with reference to Figure 1.

At step 100, water is supplied to a turbine, at a first pressure. The first pressure of the
supplied water is provided at least in part by hydrostatic pressure.

This may be achieved by providing the turbine at a position lower than the surface of a body
20 of water from which the water is supplied, such that a hydrostatic pressure head is developed
by the gravitational force acting upon the water above the turbine's position. In one example,
the turbine may be positioned under water. For instance, the turbine may be submerged in a
lake, ocean or any other large body of water having a substantial depth of water.
Alternatively, a deep body of water may be artificially constructed by filling a shaft with
25 water, and the turbine may be positioned in a lower portion of the shaft to achieve a similar
effect.


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In any event, at step 110 this water is passed through the turbine to a chamber, wherein the
chamber is at a second pressure that is lower than the first pressure of the water entering the
turbine. It will be appreciated that this pressure difference across the turbine may be at least
in part converted into kinetic energy by the turbine, thereby causing the turbine to rotate. At
5 step 120 the rotation of the turbine is used to drive a generator to thereby generate power.

It will be appreciated that this method will only be sustainable if the water passing through
the turbine is removed from the chamber at substantially the same rate as it passes through
the turbine. In order to achieve this, the water in the chamber is converted to a gas in step
130, and this gas is subsequently discharged from the chamber at step 140.

10 There are numerous methods of converting the water in the chamber to the gas and specific
examples will be described in further detail below.

In one example, the water may be converted to a gas by electrolysing the water to thereby
split the water molecules into hydrogen and oxygen, which will take a gaseous form. The
hydrogen gas and the oxygen gas that are produced by the electrolysis of the water will
15 occupy a substantially increased volume compared to the liquid water, and will consequently
have a decreased density, causing these produced gases to naturally rise in the chamber such
that they may be discharged from the chamber via one or more outlets.

In another example, the water may be heated to produce steam, which may be similarly
discharged from the chamber. A combination of electrolysis and heating may also be
20 employed. These examples are not intended to be limiting, and any other means of converting
the water in the chamber to a gas may be employed to perform the above described method.

In any event, it will be appreciated that the gasification of the water in the chamber allows the
water that passes through the turbine to be more easily removed from the chamber than
would otherwise be possible if the water remained in a liquid form.

25 Regardless of whether the method uses electrolysis to produce hydrogen gas and oxygen gas,
heating to produce steam, or any other means of converting the water to a gas, the conversion
will generally require energy to be imparted to the water at a particular rate. However, if the
level of power generated in the turbine is equal to or greater than the level required to convert


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the water to a gas at the required rate, at least a portion of the generated power may be used
to power the process of converting the water in the chamber to a gas.

In the above case it will be appreciated that power that is not used to convert the water to a
gas will be available for external use. However, it may also be possible to recover further
5 energy from the gas produced by the conversion. For example, if hydrogen gas is produced
by electrolysis, the hydrogen gas can be burnt to provide useful energy. Similarly, if steam is
produced by heating the water, this may be supplied to a second turbine to allow additional
energy to be extracted.

Given that the hydrostatic pressure head in the water is proportional to the difference in
10 height between the water surface and the turbine, it will be appreciated that the pressure of
the water supplied to the turbine may be varied by changing the depth position of the turbine
in the body of water. Accordingly, it is possible to position the turbine at a depth selected to
have a predetermined hydrostatic pressure head so that when water is passed through the
turbine at that pressure, at least sufficient power is generated to convert the water to a gas at
15 substantially the same rate at which the water is passed through the turbine. This can be used
to establish a balance of generated power and required power. Useful surplus power may be
generated when the turbine is positioned at a depth beyond that depth at which the power
balance is achieved.

It will be appreciated that the above described method will allow power to be generated using
20 sources of water other than those conventionally used in hydroelectric power generation.
Since the turbine and the chamber may be submerged in the body of water, this allows the
power generation method to be deployed undersea or otherwise underwater. In contrast,
turbines are provided out of the water in conventional hydroelectric schemes, typically at the
base of a dam restraining the body of water.

25 The above method may also allow power generation to occur under higher pressure heads
then can generally be achieved in a conventional hydroelectric plant. The available pressure
head that can be used in this method will only limited by the depth of the body of water and
the capability of the apparatus elements to withstand the pressures involved. In contrast, the


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pressure head available to a conventional hydroelectric plant is limited by geographical and
natural water supply limitations, along civil engineering constraints.

An example of an apparatus for generating power using the above described method will now
be discussed with reference to Figure 2. The power generating apparatus 200 includes a
5 turbine 210, a generator 220 for generating power, a chamber 240 for receiving water passed
through the turbine, and a converter 250 for converting the water in the chamber 240 to a gas,
as described above with reference to Figure 1.

It should be noted that the apparatus 200 is generally shown in a schematic representation to
allow further explanation of the power generation method. Further example embodiments
10 will also be discussed in detail with reference to later figures.

As indicated by arrow 201, water is supplied to the turbine 210 from a body of water and is
passed through the turbine 210 to cause the turbine 210 to rotate. The water that passes
through the turbine 210 is expelled from the turbine 210 into the chamber 240 via a fluid
pathway 212. It will be appreciated that this fluid pathway 212 will not be required if the
15 turbine is provided internally to the chamber 240, however, for the purposes of this example
it has been shown in order to better distinguish between the turbine 210 and the chamber 240.

The turbine 210 is connected to the generator 220 by a shaft 221, such that the rotation of the
turbine 210 will also cause the generator 220 to rotate. The generator 220 generates power as
it is driven by the turbine 210. In this example the power is electrical power which is output
20 from the generator 220 via a power line 231. The chamber 240 receives the water that passes
through the turbine 210 at a second pressure that is lower than the first pressure of the water
supplied to the turbine. In other words, the chamber is maintained at a pressure lower than the
water pressure outside the chamber, and the water pressure drops as the water passes through
the turbine into the chamber.

25 If water was allowed to continue to pass through the turbine into the chamber, without the
water otherwise being removed from the chamber, the chamber would soon fill with water
and potentially increase the chamber pressure, subsequently reducing the pressure drop across
the turbine. In order to mitigate this potential outcome, the converter 250 is provided in the


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chamber 240, and the converter 250 is used to convert the water in the chamber 240 to a gas
at substantially the same rate at which the water is passed through the turbine 210. As
mentioned above, it is possible to power the converter 250 using generated power from the
generator 220, and this is indicated by the optional converter power line 232. It will be
5 appreciated that if the converter 250 is powered from an alternative power source, then a
separate power connection from that alternative power source to the converter 250 will be
required.

The net electrical power 202 remaining after any power is deducted for the conversion
process is output along the power line 231 for use, as indicated by arrow 202.

10 The gas produced by the converter 250 is discharged from the chamber 240 via a pipe 260, or
any other means of discharging the gas from the chamber 240. It may be desirable to also put
this produced gas to further uses, such as the extraction of additional energy from the
produced hydrogen gas or steam, for example. Accordingly, arrow 203 is indicative of the
flow of produced gases from the apparatus 200 for use elsewhere. Further examples of
15 potential uses for the produced gases will be discussed in more detail below.

In one example, the entire apparatus 200 is submerged in the body of water at a depth at
which a sufficient pressure is present for supply to the turbine 210 to allow a level of power
to be produced which exceeds the power required by the converting process.

Example calculations indicative of the magnitudes of power that can be generated will now
20 be discussed, assuming that electrolysis is used to convert the water to a gas, and assuming
water is supplied to the turbine 210 at 1 m3/s. In this case, the power generated will sustain
the process if it is sufficient to power the electrolysis of water at the rate of 1 m 3/s, to thereby
prevent the chamber 240 from filling with water.

From the chemical principles of electrolysis, the electrolysis of a quantity of water requires
25 the application of a current that mobilises the number of valence electrons of the hydrogen
atoms in that quantity of water, at a voltage greater than the standard potential of the water
electrolytic cell for decomposition. For the decomposition of 1 m3/s approximately 1.06 MA


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of current is required, and a voltage of approximately 1.5V is generally appropriate, which
leads to a power requirement of approximately 1.6 MW.

Assuming a total efficiency of 60% for electric power generation, and assuming atmospheric
pressure is maintained inside the chamber, it is possible to generate 1.6 MW of power by
5 submerging the apparatus 200 at a depth of approximately 271 m (the hydrostatic pressure at
that depth will be approximately 27 atm). Accordingly, it will be possible to obtain excess
power generation for a 1 m3/s flow rate at depths greater than 271 m. For example, at a
submerged depth of 1000 m, over 4 MW of excess power can be generated, based on the
above assumptions.

10 It should be noted that these calculations are indicative only. Although actual results may
vary from these idealised calculations, it is nevertheless apparent that substantial quantities of
energy may be produced using the above method and apparatus. By submerging the apparatus
200 at increased depths, increased magnitudes of power can be produced.

Given that the apparatus 200 may be submerged at a substantial depth under water in order to
15 provide large quantities of power, it is desirable to provide an apparatus that is suitable for
withstanding the high pressures that may be present. As such it should be appreciated that the
apparatus 200 configuration shown in Figure 2 is a schematic representation for the purposes
of explanation only, and physical embodiments may have particular configurations of the
above discussed elements that are better suited to the high pressure environments that may be
20 present at the depths required to generate substantial quantities of surplus power using the
above discussed method.

Accordingly, a second example embodiment of an apparatus for generating power will now
be described with reference to Figure 3. It should be appreciated that in this example,
elements that are generally equivalent to elements shown in Figure 2 will be marked with
25 similar reference numerals incremented by 100.

In this example the apparatus 300 includes a turbine 310, a generator 320, a chamber 340,
and a converter 350; although in this case it will be appreciated that the turbine 310 is
provided within the chamber 340, and a lower chamber portion 342 surrounds the generator


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320 such that the turbine 310 and generator 320 are enclosed within a pressure vessel defined
by the chamber 340 and the lower chamber portion 342. The apparatus 300 can be made
capable of submergence to a desired depth by appropriately designing the chamber 340 and
the lower chamber portion 342 to withstand the external pressure of the water surrounding the
5 apparatus 300.

In this example, it can be seen that the lower chamber portion 342 defines a separate
enclosure for the generator 320, such that the shaft 321 connecting the generator 320 and
turbine 310 passes through an internal wall between the chamber 340 and the lower chamber
portion 342. Accordingly the shaft 321 extends between the enclosure for the generator 320
10 and the water filled portion of the chamber 340. By providing appropriate sealing about the
shaft 321, the generator 320 can be enclosed in a separate water tight enclosure, such that the
generator 320 does not need to be surrounded by water in use.

The water is provided to the turbine 310 via inlets 313 provided about a circumference of the
chamber 340 such that the flow of water indicated by arrow 301 from the surrounding water
15 into the chamber 340 is directed through the turbine. In this example, the inlets include
nozzles which cause jets of water to be directed onto suitably adapted rotors 311 of the
turbine 310. The flow of the jets of water onto the rotors 311 causes the turbine 310 to rotate
and thereby drives the generator as the water passes through the turbine. However, it will be
appreciated that the form of the inlets 313 may vary depending on the type of turbine 210 and
20 other factors. In this regard, any configuration of turbine 210 suitable for extracting energy
from the water supplied at pressure may be used, and the example embodiment of Figure 3
should not be considered particularly limiting.

As the water enters the chamber 340 through the turbine 310 this water is removed from the
chamber 340 at substantially the same rate at which it enters the chamber 340. In this
25 example, at least a portion of the water is converted to a gas by electrolysing the water, and
this is performed by providing an electrical current between one or more electrode pairs 350
positioned in the water in the chamber 340. The electrodes may be in the form of conductive
rods, plates or any other suitable shape.


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In this example, the current is provided by an electrolysis power line 332 connected to the
power line 331 which carries the power generated by the turbine 320. In the electrolysis
process, oxygen gas is produced at an anode 351 of the electrode pair 350, whilst hydrogen
gas is produced at a cathode 352 of the electrode pair 350.

5 By appropriately configuring the internal layout of the chamber 340, it is possible to collect
the produced hydrogen and oxygen gases separately. In this example, the chamber includes
appropriately configured internal chamber walls 341 which cause produced oxygen gas
produced at the anode 351 to be discharged through a first pipe 361, and produced hydrogen
gas produced at the cathode 352 to be discharged through a second pipe 362. The discharged
10 oxygen gas is indicated by arrow 303 and the discharged hydrogen gas is indicated by arrow
304 in Figure 3.

It should be noted that the electrolysis of seawater may also produce other gases through
secondary reactions of minerals in solution with the water. For example, sodium hydroxide
and chlorine gas may be produced, and it may be desirable to remove these by-products from
15 the hydrogen and oxygen gas by using known methods. These removed by-products can also
be captured and stored for later use.

In addition, the electrolysis of water requires a large current to be applied between the
electrodes, which can cause substantial heating of the electrodes to occur. Accordingly, steam
may also be produced as a further by-product, and this steam may also be collected and used.
20 It may also be possible to provide heaters for the intentional production of steam, to either
supplement or replace the electrode pair in converting the water in the chamber 340 to a gas.

Produced steam may be discharged to the surface, and provided the pipes carrying the steam
to the surface are appropriately insulated, it may be possible to extract energy from the steam
by passing the steam through another turbine (not shown). This extracted energy may be used
25 to generate additional power, which can be used to supplement the power generated by the
generator 320, or put to any other use. The produced steam may also be condensed at the
surface to form fresh water, such that the conversion of the water in the chamber to steam can
also be used to provide a fresh water source.


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On the other hand, hydrogen and oxygen produced by electrolysis could also be recombined
at the surface to produce heat which again can be used to generate additional power, and this
would also provide a fresh water source

In any event, in this example the apparatus includes a plurality of electrode pairs 350 which
5 are primarily used for electrolysing the water. The provision of multiple electrode pairs 350
helps to reduce heat build up that might occur in a single electrode pair 350 arrangement.

In one example, the plurality of electrode pairs 350 are arranged in concentric circles, such
that a plurality of anodes 351 defines an inner circle and a plurality of cathodes 352 defines
an outer circle. It is possible to simultaneously provide respective currents between each pair
10 of electrodes, thereby splitting the current between each electrode pair 350 and allowing
electrolysis to occur in a distributed fashion between the concentric circle arrangement of
electrode pairs 350. Alternatively, electrical current may be periodically applied to respective
electrode pairs 350 to allow periodic cooling of electrode pairs 350 when current is not
applied.

15 It will be appreciated that the above discussed electrode pair 350 arrangement allows the
internal chamber walls 341 to be provided between the concentric circles of electrode pairs
350 to define a cylindrical volume inside the chamber, so that oxygen gas produced at the
anodes 351 of the inner circle is captured by cylindrical volume, whilst hydrogen gas
produced at the cathodes 352 of the outer circle is not captured by the cylindrical volume.
20 Accordingly, the first pipe 361 is positioned to allow the discharge of the oxygen gas
captured by the cylindrical volume, whilst the second pipe 362 is positioned to allow the
discharge of the hydrogen gas that is not captured by the cylindrical volume.

Given that hydrogen gas and oxygen gas will be produced at a 2:1 ratio by virtue of the
molecular composition of water, the cylindrical volume defined inside the internal chamber
25 walls 341 is ideally half the volume defined between the internal chamber walls 341 and the
outer walls of the chamber 340.

A third example embodiment of an apparatus for generating power will now be described
with reference to Figure 4. It should be noted that this example also has generally similar


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elements as shown in Figure 3, and these will be marked with similar reference numerals
incremented by 100.

In this example, the power generation apparatus 400 shown in Figure 4 includes the generator
420 and turbine 410 positioned above the chamber. The basic concepts of operation remain
5 the same as the above described examples, with water being supplied at inlets 413 at a first
pressure and passing through the turbine 410 in order to drive the generator 420.

Water that has passed through the turbine 410 then flows through a fluid pathway 412
defined by pathway walls 443 through the chamber 440, such that the water enters the
chamber 440. In this case, the fluid pathway 412 extends through the cylindrical volume
10 defined by the internal chamber walls 441, although it will be appreciated that other
embodiments may use different configurations. A flow diverter 470 is optionally provided in
a lower region of the chamber 440 to direct the flow of the water entering the chamber 440.

Ballast 480 is provided below the chamber. The ballast 480 is a quantity of mass which may
be required to counteract or at least substantially offset the buoyancy forces acting on the
15 apparatus when the apparatus is submerged in the body of water. It is generally desirable to
provide the ballast 480 below the chamber for balance reasons, although any configuration of
ballast 480 may be possible. In some scenarios, the ballast 480 may not be required, if the
masses of the apparatus elements, such as the chamber 440 and generator 420, are sufficiently
great.

20 As discussed above, the power generation method described herein is capable of generating
large quantities of power, and the magnitude of power generated is proportional to the depth
of submergence of the apparatus and the rate at which the pressurised water is supplied to the
apparatus. By submerging the apparatus to a depth that is deeper than that required to
establish the equilibrium between power generated and the power required to gasify the water
25 in the chamber, excess power may be produced for other uses.

Rather than transmitting the power to the surface for use, which may result in substantial
transmission losses, it may be desirable to put this excess power to use locally. One possible
use for this excess power is the electrolysis of additional quantities of water to produce


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additional hydrogen and oxygen gas, which can then be stored or transported for later use.
Furthermore, it is possible to produce the additional hydrogen and oxygen gas as a
pressurised gas, due to the significant hydrostatic pressure in the water surrounding the
apparatus.

5 Accordingly, an example of an electrolysis chamber 500 which may be powered by power
generated in the above described method will now be described with reference to Figure 5.

The electrolysis chamber 500 shares some similarities with the power generation apparatus
400 described above with reference to Figure 4, in that the electrolysis chamber 500 includes
a concentric circle arrangement of electrode pairs 550 to produce oxygen gas and hydrogen
10 gas which is separated by an internal chamber wall 541 and discharged from the electrolysis
chamber 500 via first and second pipes 561, 562. However, the electrolysis chamber 500 is at
the same pressure as the surrounding water, such that the water in the electrolysis chamber
500 is substantially maintained at the first pressure described above, rather than a lower
second pressure. Inlets 510 allow water to enter the electrolysis chamber 500 without
15 substantial pressure drop from the surrounding hydrostatic pressure. Accordingly, the
electrolysis chamber walls 540 do not need to withstand a large pressure difference, in
contrast to the walls of the power generation apparatus chamber 440. Ballast 580 is provided
in a similar fashion to the ballast 480 of the power generation apparatus 400.

It is also possible to provide optional desalination membranes (not shown) at the inlets 510
20 such that the pressurised water entering the electrolysis chamber 500 is substantially
desalinated before electrolysis. This can improve the efficiency of the electrolysis by
reducing losses due to competing side reactions which can occur when current is passed
through saline solution. However, there will be a pressure drop associated with passing the
water through desalination membranes, which will ultimately reduce the pressure at which
25 the hydrogen and oxygen gases are produced, and will also require the electrolysis chamber
500 to be constructed to withstand the pressure difference between the surrounding water and
the chamber pressure. The desalination process will also cause the salinity of the water
outside of the electrolysis chamber 500 to increase, and this water with increased salinity may


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be diverted away from the inlets 510 by taking advantage of the increase in the density of the
water with increased salinity.

In any event, by supplying water under pressure to the electrode pairs 550 in the electrolysis
chamber 500, the oxygen gas and hydrogen gas are also produced and discharged from the
5 electrolysis chamber 500 under pressure. It will be appreciated that the production of
pressurised gases will help to reduce the amount of compression required for later storage of
the gases.

Accordingly, the power generated by the power generation method 400 can be put to use
without requiring transmission over long distances, to produce pressurised hydrogen and
10 oxygen gases, which can then be stored and transported. An example of a combined power
generation and electrolysis apparatus 600 is shown in Figure 6, which includes two power
generation apparatus 400 which generate power that is supplied at least in part to an
electrolysis chamber 500, in order to produce pressurised hydrogen and oxygen gases.

It may be desirable to provide more than one power generation apparatus 400 in this way in
15 order to facilitate maintenance of elements of the apparatus such as the turbine 410 of
generator 420. By providing redundant power generation apparatus 400, this allows one of
the power generation apparatus 400 to be out of operation for maintenance without ceasing
the generation of power and production of hydrogen.

In this example, the produced gases are discharged via a plurality of pipes, although it will be
20 appreciated that pipes for discharging like gases at like pressures may be connected to reduce
the number of pipes extending to the surface. The pipes discharging gases from the power
generation apparatus 400 will typically have a larger diameter, in order to withstand the
larger pressure differences between the contents of those pipes and the surrounding water,
compared to the pipes discharging gases from the electrolysis chamber 500.

25 It is to be appreciated that the apparatus shown in Figure 6 is merely one example of a
combined power generation and electrolysis apparatus, and is not intended to be limiting. For
example, other embodiments may include any number of power generation apparatus 400 and
electrolysis chambers 500, in any configuration.


- 19 -

An example of a power generation and electrolysis plant will now be described with
reference to Figure 7.

The power generation and electrolysis plant includes a combined power generation and
electrolysis apparatus 600 submerged in a body of water at a predetermined depth. In this
5 example, the body of water is provided artificially using a shaft 750 which is filled with
water. The water in the shaft is replenished during the power generation and electrolysis
process from a water source indicated by arrow 701.

The combined power generation and electrolysis apparatus 600 can include any combination
of power generation apparatus 400 and electrolysis chambers 500 and is not limited to the
10 example configuration described with reference to Figure 6.

Pressurised hydrogen gas is discharged from the combined power generation and electrolysis
apparatus 600 via a first pipe 661 and pressurised oxygen gas is discharged via a second pipe
662. It will be appreciated that multiple pipes may be provided for the discharge of gases, as
indicated in Figure 6, although only two pipes are shown in Figure 7 for explanatory
15 purposes.

In this example, the plant includes processing equipment for further processing of the
produced gases, and this processing equipment is provided above ground. It will be
appreciated that this is optional only, and the hydrogen and oxygen gas produced by
electrolysis can be simply discharged to the surface for immediate use or storage in
20 alternative embodiments. Given that the gases produced in the electrolysis chamber 500 will
be provided at a substantial pressure, it may be possible to store or use these gases with
minimal additional processing such as compression.

However, in this example, additional processing is performed to gain further utility from the
produced gases. Although oxygen gas produced in electrolysis of water is often viewed as a
25 by-product of the production of hydrogen which does not have economically significant
applications, in this example the pressurised oxygen is used to perform further work.

In this regard, the pressurised oxygen discharged through the second pipe 662 is supplied to a
second turbine 510, such that the oxygen passes through the turbine 710 and is discharged via


- 20 -

an oxygen outlet pipe 764. As the oxygen passes through the turbine, the oxygen expands,
which causes the second turbine 710 to rotate and drive a second generator 720 via a shaft
721. This allows further power to be generated using the pressurised oxygen, where the
oxygen might otherwise have been simply discarded as a by-product. The further power
5 generated using the oxygen can be put to any use, for example, the power can be used to
supplement the power used in the electrolysis chamber 500, used to further compress the
pressurised oxygen, or be transmitted for any other use.

The expansion of the oxygen also causes a substantial reduction in temperature, and a cooling
loop 730, containing a refrigerant such as Freon or the like, is provided to use the temperature
10 drop of the expanding oxygen for cooling purposes. In this example, the cooling loop 730 is
used to cool the hydrogen gas discharged via the first pipe 661. The cooled hydrogen gas is
provided along a hydrogen outlet pipe to a storage tank 740. This technique allows the
already pressurised hydrogen to be cooled and subsequently compressed even further.
Additional power generated in the power generation apparatus underwater can be used to
15 provide even further compression or cooling, such that liquid hydrogen can be provided and
stored in the storage tank 740.

It will be appreciated that the pressurised oxygen may be expanded by other means to cause
the drop in temperature, without passing the oxygen through the turbine 710. In any event,
work of some form is performed by the pressurised oxygen, further enhancing the overall
20 energy efficiency of the plant.

The oxygen that is discharged from the oxygen outlet pipe 764 is indicated by arrow 704.
This discharged oxygen can then be exhausted into the atmosphere or put to any other use.
For example, the oxygen can be supplied to a body of water to increase the oxygenation of
the water, which may be beneficial in algae farming applications or the like. In another
25 example, pure oxygen can be supplied for combustion or other chemical processes.

Although the above described example plant is used in conjunction with a water filled shaft
as the body of water, it will be appreciated that a plant having similar functionality can be
provided for use with combined power generation and electrolysis apparatus submerged in a
natural body of water such as an ocean, by providing the processing equipment on a floating


- 21 -

platform or the like, or locating the processing equipment on-shore. The processing
equipment need not be located above the surface of the water, and can also be provided
underwater, if required.

The above described methods and apparatus enable power to be generated using the relatively
5 unexploited pressures which naturally exist underwater, and further allow the convenient
production of large quantities of hydrogen without requiring an external power source.
Accordingly, the above described methods and apparatus can be used to provide an
alternative sustainable source of energy to help to satisfy increasing global energy demands.

Persons skilled in the art will appreciate that numerous variations and modifications will
10 become apparent. All such variations and modifications which become apparent to persons
skilled in the art, should be considered to fall within the spirit and scope that the invention
broadly appearing before described.


- 22 -

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:
1) A method for generating power, the method including:
c) converting the water in the chamber to a gas and discharging the gas from the
chamber, to thereby remove the water from the chamber at substantially the same rate
at which water is passed through the turbine; and,
2) A method according to claim 1, wherein the water is converted to a gas using a portion of
the generated power.
3) A method according to claim 1 or claim 2, wherein at least a portion of the water in the
chamber is converted to a gas by electrolysing the at least a portion of the water in the
15 chamber to thereby produce at least hydrogen gas and oxygen gas.
4) A method according to claim 3, wherein the method includes providing an electrical
current between an electrode pair positioned in the water in the chamber to thereby
electrolyse at least a portion of the water in the chamber.
5) A method according to claim 1 or claim 2, wherein at least a portion of the water in the
20 chamber is converted to a gas by heating the water in the chamber to produce steam.
6) A method according to claim 5, wherein the heating is performed by providing an
electrical current between an electrode pair positioned in the water in the chamber.
7) A method according to claim 5 or claim 6, wherein the method includes extracting energy
from at least a portion of the steam by passing the at least a portion of the steam through a
25 second turbine.
8) A method according to claim 7, wherein the energy extracted from steam is used to
generate additional power.
9) A method according to claim 7 or claim 8, wherein the method includes condensing the
steam to provide fresh water.


- 23 -

10) A method according to any one of claims 1 to 9, wherein the method includes submerging
at least the turbine in a body of water, such that a depth of submergence of at least the
turbine at least partially determines the hydrostatic pressure.
11) A method according to claim 10, wherein the body of water is one of:
5 a) a naturally occurring body of water; and,
b) a shaft at least partially filled with water.
12) A method according to any one of claims 1 to 11, wherein the method includes
substantially desalinating the water.
13) A method according to claim 12, wherein the desalination is performed using reverse
10 osmosis, and wherein an osmotic pressure is provided at least in part by hydrostatic
pressure.
14) A method according to any one of claims 1 to 13, wherein the method includes using a
portion of the generated power for electrolysing water in an electrolysis chamber.
15) A method according to claim 14, wherein the electrolysis chamber is at a water pressure
15 that is determined at least in part by hydrostatic pressure, such that electrolysing the water
in the at least one electrolysis chamber produces hydrogen gas and oxygen gas at a gas
pressure that is determined at least in part by the water pressure.
16) A method according to claim 14 or claim 15, wherein the method includes extracting
energy from at least a portion of the oxygen gas by passing the at least a portion of the
20 oxygen gas through a second turbine.
17) A method according to claim 16, wherein the energy extracted from the at least a portion
of the oxygen gas is used to generate additional power.
18) A method according to claim 14 or claim 15, wherein the method includes:
a) expanding at least a portion of the oxygen gas to thereby reduce the temperature in the
25 at least a portion of the oxygen gas; and,
b) using the reduction in temperature in the oxygen gas to cool the hydrogen gas.
19) A method according to any one of claims 1 to 18, wherein the method includes at least
one of:
a) storing at least a portion of the hydrogen gas; and,
30 b) extracting energy from at least a portion of the hydrogen gas.
20) An apparatus for generating power, the apparatus including:


- 24 -

by hydrostatic pressure;
b) a chamber for receiving the water passed through the turbine, wherein chamber is at a
5 second pressure that is lower than the first pressure;
c) a converter for converting the water in the chamber to a gas, such that discharging the
gas from the chamber removes the water from the chamber at substantially the same
rate at which water is passed through the turbine; and,
10 21) An apparatus according to claim 20, wherein the converter is adapted to convert the water
to a gas using a portion of the generated power.
22) An apparatus according to claim 20 or claim 21, wherein the converter includes an
electrode pair, and wherein supplying a current between the electrode pair causes at least
a portion of the water in the chamber to be converted to a gas by electrolysing the at least
15 a portion of the water in the chamber to produce at least hydrogen gas and oxygen gas.
23) An apparatus according to claim 22, wherein the converter includes a plurality of
electrode pairs.
24) An apparatus according to claim 23, wherein the plurality of electrode pairs are arranged
in concentric circles and wherein the apparatus is adapted to periodically apply electrical
20 current to respective pairs of the plurality of electrode pairs.
25) An apparatus according to any one of claims 20 to 24, wherein the converter includes a
heater, and wherein supplying a current to the heater causes at least a portion of the water
in the chamber to be converted to a gas by heating the at least a portion of the water in the
chamber to produce steam.
25 26) An apparatus according to any one of claims 20 to 25, wherein the apparatus includes a
desalination device.
27) An apparatus according to any one of claims 20 to 26, wherein the apparatus includes at
least one pipe extending from the chamber for discharging the gas from the chamber.
28) An apparatus according to claim 27, wherein the at least one pipe includes thermal
30 insulation.


- 25 -

29) An apparatus according to claim 27 or 28, wherein the apparatus includes a plurality of
pipes, and wherein different pipes are for discharging different gases.
30) An apparatus according to any one of claims 20 to 29, wherein the chamber is adapted to
be submerged in a body of water, such that a depth of submergence determines the
5 hydrostatic pressure.
31) An apparatus according to any one of claim 30, wherein the apparatus has a mass selected
to substantially offset buoyancy forces acting on the apparatus when the apparatus is
submerged in the body of water.
32) An apparatus according to any one of claims 20 to 31, wherein the apparatus includes at
10 least one electrolysis chamber for the electrolysis of additional water under pressure using
a portion of the generated power.
33) An apparatus according to claim 32, wherein the electrolysis chamber is at a water
pressure that is determined at least in part by hydrostatic pressure, and wherein the at least
one electrolysis chamber includes an electrode pair for electrolysing the water in the at
15 least one electrolysis chamber when a current is supplied across the electrode pair, to
thereby produce hydrogen gas and oxygen gas at a gas pressure that is determined at least
in part by the water pressure.
34) An apparatus according to any one of claims 20 to 33, wherein the apparatus includes a
second turbine for extracting energy from at least the oxygen gas.
20 35) A method for producing hydrogen using electrolysis of water, the method including
electrolysing water under pressure to produce at least pressurised hydrogen gas, wherein
the electrical current is supplied from power generated by:
c) electrolysing the water in the chamber to convert the water in the chamber to a gas
and discharging the gas to thereby remove the water from the chamber at substantially
the same rate at which water is passed through the turbine; and,


- 26 -

36) An apparatus for producing hydrogen using electrolysis of water, the apparatus including
an electrode pair, wherein supplying an electrical current across the electrode pair
positioned in water under pressure produces at least pressurised hydrogen gas, and
wherein the electrical current is supplied by a power generation apparatus including:
5 a) a turbine, wherein water at a first pressure is supplied to the turbine and the water is
by hydrostatic pressure;
b) a chamber for receiving the water passed through the turbine, wherein the chamber is
at a second pressure that is lower than the first pressure;
10 c) at least one further electrode pair for electrolysing the water in the chamber to convert
the water in the chamber to a gas, such that discharging the gas from the chamber
removes the water from the chamber at substantially the same rate at which water is
passed through the turbine; and,
15 37) A method and apparatus for generating power and a method and apparatus for producing
hydrogen, substantially as hereinbefore described.
38) A method and apparatus for generating power and a method and apparatus for producing
hydrogen, substantially as hereinbefore described and illustrated with reference to the
accompanying drawings.

1 power and hydrogen generation – description

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