1 power and hydrogen generation – description

C:\Documents and Settings\Novica Padjen\My Documents\Licno\Patents\Davis Collison Cave\Provisional Aplication Final\40139678 speci - FINAL_3248506_1.DOC-12/02/2011

- 1 -

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.

Description of the Prior Art 5

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

which this specification relates. 10

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

extracting gravitational potential energy from a body of water. In general, the operation of a 15

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

source and the turbine. 20

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

viable in locations where certain desirable geographical conditions are already present. 25


- 2 -

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

deep ocean water. 5

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

electrolysis of water typically requires the supply of significantly more energy to power the 10

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.

Summary of the Present Invention 15

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;

b) passing the water through the turbine to a chamber, wherein the chamber is at a 20

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,

d) using the turbine to drive a generator to thereby generate power. 25

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


- 3 -

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

positioned in the water in the chamber to thereby electrolyse at least a portion of the water in 5

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

pair positioned in the water in the chamber. 10

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.

Typically the method includes submerging at least the turbine in a body of water, such that a 15

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,

b) a shaft at least partially filled with water. 20

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

in an electrolysis chamber. 25


- 4 -

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.

Typically the method includes extracting energy from at least a portion of the oxygen gas by 5

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:

a) expanding at least a portion of the oxygen gas to thereby reduce the temperature in the 10

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,

b) extracting energy from at least a portion of the hydrogen gas. 15

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

by hydrostatic pressure; 20

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

rate at which water is passed through the turbine; and, 25

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.


- 5 -

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.

Typically the converter includes a plurality of electrode pairs. 5

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

causes at least a portion of the water in the chamber to be converted to a gas by heating the at 10

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.

Typically the at least one pipe includes thermal insulation. 15

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.

Typically the apparatus has a mass selected to substantially offset buoyancy forces acting on 20

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

hydrostatic pressure, and wherein the at least one electrolysis chamber includes an electrode 25


- 6 -

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

oxygen gas. 5

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:

a) supplying water at a first pressure to a turbine, wherein the first pressure is provided 10


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

and discharging the gas to thereby remove the water from the chamber at substantially 15

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

supplying an electrical current across the electrode pair positioned in water under pressure 20

produces at least pressurised hydrogen gas, and wherein the electrical current is supplied by a

power generation apparatus including:



by hydrostatic pressure; 25

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


- 7 -

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

An example of the present invention will now be described with reference to the 5

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;

Figure 4 is a schematic diagram of a third example of an apparatus for generating power; 10

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.

Detailed Description of the Preferred Embodiments 15

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

of water from which the water is supplied, such that a hydrostatic pressure head is developed 20

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

water, and the turbine may be positioned in a lower portion of the shaft to achieve a similar 25

effect.


- 8 -

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

step 120 the rotation of the turbine is used to drive a generator to thereby generate power. 5

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.

There are numerous methods of converting the water in the chamber to the gas and specific 10

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

occupy a substantially increased volume compared to the liquid water, and will consequently 15

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

employed. These examples are not intended to be limiting, and any other means of converting 20

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.

Regardless of whether the method uses electrolysis to produce hydrogen gas and oxygen gas, 25

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


- 9 -

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

energy from the gas produced by the conversion. For example, if hydrogen gas is produced 5

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

height between the water surface and the turbine, it will be appreciated that the pressure of 10

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

substantially the same rate at which the water is passed through the turbine. This can be used 15

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

sources of water other than those conventionally used in hydroelectric power generation. 20

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.

The above method may also allow power generation to occur under higher pressure heads 25

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


- 10 -

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

turbine 210, a generator 220 for generating power, a chamber 240 for receiving water passed 5

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

will also be discussed in detail with reference to later figures. 10

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

turbine is provided internally to the chamber 240, however, for the purposes of this example 15

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

from the generator 220 via a power line 231. The chamber 240 receives the water that passes 20

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.

If water was allowed to continue to pass through the turbine into the chamber, without the 25

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


- 11 -

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

appreciated that if the converter 250 is powered from an alternative power source, then a 5

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.

The gas produced by the converter 250 is discharged from the chamber 240 via a pipe 260, or 10

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

potential uses for the produced gases will be discussed in more detail below. 15

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

be discussed, assuming that electrolysis is used to convert the water to a gas, and assuming 20

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 m3/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

the application of a current that mobilises the number of valence electrons of the hydrogen 25

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


- 12 -

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

submerging the apparatus 200 at a depth of approximately 271 m (the hydrostatic pressure at 5

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.

It should be noted that these calculations are indicative only. Although actual results may 10

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

provide large quantities of power, it is desirable to provide an apparatus that is suitable for 15

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

present at the depths required to generate substantial quantities of surplus power using the 20

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

similar reference numerals incremented by 100. 25

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


- 13 -

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

apparatus 300. 5

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

and the water filled portion of the chamber 340. By providing appropriate sealing about the 10

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

into the chamber 340 is directed through the turbine. In this example, the inlets include 15

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

other factors. In this regard, any configuration of turbine 210 suitable for extracting energy 20

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

example, at least a portion of the water is converted to a gas by electrolysing the water, and 25

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.


- 14 -

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.

By appropriately configuring the internal layout of the chamber 340, it is possible to collect 5

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

oxygen gas is indicated by arrow 303 and the discharged hydrogen gas is indicated by arrow 10

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

the hydrogen and oxygen gas by using known methods. These removed by-products can also 15

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.

It may also be possible to provide heaters for the intentional production of steam, to either 20

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

to generate additional power, which can be used to supplement the power generated by the 25

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.


- 15 -

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

are primarily used for electrolysing the water. The provision of multiple electrode pairs 350 5

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

of electrodes, thereby splitting the current between each electrode pair 350 and allowing 10

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.

It will be appreciated that the above discussed electrode pair 350 arrangement allows the 15

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.

Accordingly, the first pipe 361 is positioned to allow the discharge of the oxygen gas 20

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

walls 341 is ideally half the volume defined between the internal chamber walls 341 and the 25

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


- 16 -

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

the same as the above described examples, with water being supplied at inlets 413 at a first 5

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

defined by the internal chamber walls 441, although it will be appreciated that other 10

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

apparatus when the apparatus is submerged in the body of water. It is generally desirable to 15

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.

As discussed above, the power generation method described herein is capable of generating 20

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

in the chamber, excess power may be produced for other uses. 25

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


- 17 -

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.

Accordingly, an example of an electrolysis chamber 500 which may be powered by power 5

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

gas which is separated by an internal chamber wall 541 and discharged from the electrolysis 10

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

substantial pressure drop from the surrounding hydrostatic pressure. Accordingly, the 15

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

such that the pressurised water entering the electrolysis chamber 500 is substantially 20

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

the hydrogen and oxygen gases are produced, and will also require the electrolysis chamber 25

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


- 18 -

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

electrolysis chamber 500 under pressure. It will be appreciated that the production of 5

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

oxygen gases, which can then be stored and transported. An example of a combined power 10

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

order to facilitate maintenance of elements of the apparatus such as the turbine 410 of 15

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

appreciated that pipes for discharging like gases at like pressures may be connected to reduce 20

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.

It is to be appreciated that the apparatus shown in Figure 6 is merely one example of a 25

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

example, the body of water is provided artificially using a shaft 750 which is filled with 5

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

example configuration described with reference to Figure 6. 10

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

purposes. 15

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

alternative embodiments. Given that the gases produced in the electrolysis chamber 500 will 20

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

by-product of the production of hydrogen which does not have economically significant 25

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

generated using the oxygen can be put to any use, for example, the power can be used to 5

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

drop of the expanding oxygen for cooling purposes. In this example, the cooling loop 730 is 10

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

provide even further compression or cooling, such that liquid hydrogen can be provided and 15

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

energy efficiency of the plant. 20

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

example, pure oxygen can be supplied for combustion or other chemical processes. 25

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

unexploited pressures which naturally exist underwater, and further allow the convenient 5

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

become apparent. All such variations and modifications which become apparent to persons 10

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

chamber to thereby produce at least hydrogen gas and oxygen gas. 15

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

chamber is converted to a gas by heating the water in the chamber to produce steam. 20

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

second turbine. 25

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:

a) a naturally occurring body of water; and, 5

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

osmosis, and wherein an osmotic pressure is provided at least in part by hydrostatic 10

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

that is determined at least in part by hydrostatic pressure, such that electrolysing the water 15

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

oxygen gas through a second turbine. 20

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

at least a portion of the oxygen gas; and, 25

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,

b) extracting energy from at least a portion of the hydrogen gas. 30

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

second pressure that is lower than the first pressure; 5

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,


21) An apparatus according to claim 20, wherein the converter is adapted to convert the water 10

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

a portion of the water in the chamber to produce at least hydrogen gas and oxygen gas. 15

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

current to respective pairs of the plurality of electrode pairs. 20

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.

26) An apparatus according to any one of claims 20 to 25, wherein the apparatus includes a 25

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

insulation. 30


- 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

hydrostatic pressure. 5

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

least one electrolysis chamber for the electrolysis of additional water under pressure using 10

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

least one electrolysis chamber when a current is supplied across the electrode pair, to 15

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.

35) A method for producing hydrogen using electrolysis of water, the method including 20

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:

a) a turbine, wherein water at a first pressure is supplied to the turbine and the water is 5


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 10

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,


37) A method and apparatus for generating power and a method and apparatus for producing 15

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.

Date post:	08-Jul-2015
Category:	Technology
Upload:	novi5036
View:	136 times
Download:	2 times

1 power and hydrogen generation – description

Technology