AU2009200346A1

AU2009200346A1 - Planar bioreactor

Info

Publication number: AU2009200346A1
Application number: AU2009200346A
Authority: AU
Inventors: Angela K. Coaldrake; Eric H. Dunlop
Original assignee: Pan Pacific Technologies Pty Ltd
Current assignee: Pan Pacific Technologies Pty Ltd
Priority date: 2008-02-01
Filing date: 2009-01-30
Publication date: 2009-08-20
Anticipated expiration: 2029-01-30
Also published as: AU2009200346B2

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Standard Patent Applicant (s): Pan Pacific Technologies Pty Ltd Invention Title: PLANAR BIOREACTOR The following statement is a full description of this invention, including the best method for performing it known to me/us: P76290 AU I PatSetFiNng Applicion 2009-1-30 do (M) -2 PLANAR BIOREACTOR FIELD OF THE INVENTION 5 The present invention relates generally to apparatus and methods for promoting efficient photosynthetic reactions within bio-fluids. In one form, the present invention relates to planar 10 bioreactors having a shallow depth of bio-fluid enabling light to penetrate through the depth of the bioreactor to more efficiently utilise the light in photosynthetic algal reactions using carbon dioxide to produce oil materials as the bio-fluid flows through the bioreactor. 15 The present invention finds particular application as an improved planar reactor for photosynthetic algal suspensions producing carbon dioxide in which the depth of the reactor is such that light is able to penetrate 20 substantially through the depth of the fluid in the bioreactor as the fluid flows more or less uniformly through the bioreactor to enable increased photosynthetic reactions to occur within the bio-fluid to provide more efficient utilisation of the light, and hence, increase 25 the amount of carbon dioxide being consumed in the bioreactions taking place within the planar reactor. The present invention finds particular application as a new form of planar bioreactor for algal photosynthetic 30 reactions utilising sunlight and carbon dioxide to produce oil in which the planar reactor is provided with one or more devices for producing uniform flow and/or turbulent flow of fluid through the reactor. N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Specis\Speciication-Final.doc 30/01/09 - 3 Although the present invention will be described with particular reference to one form of the planar bioreactor, to forms of the uniform flow distributor, and to forms of 5 the turbulent flow inducing device, it is to be noted that the scope of the present invention is not restricted to the described embodiment or embodiments but rather each of the bioreactor and/or uniform flow distributor and/or turbulence trigger can take many different forms and 10 arrangements. BACKGROUND OF THE INVENTION Energy costs continue to rise because of decreasing 15 reserves of existing energy sources and because of geopolitical instability of the sources of energy. One of the major sources of energy includes petroleum reserves which can be refined to produce oil, gas, liquid fuel and the like. Another source of energy is coal which can be 20 combusted to produce power. Alternatives to existing liquid petroleum products and fuels and coal products are required, particularly for use in transport industries, and in the power generation industries. Such alternatives include solar power, wind power, hydro power, biodiesel 25 and other fuels and the like. However, existing technology in respect of many of the alternative energy supplies is barely sufficient to enable large scale use of such alternative resources. Thus, there is a need for improving the development of technology relating to 30 utilising alternative energy sources and to methods of utilising the alternative energy sources, such as for example, developing more efficient methods of capturing solar energy, especially as the source of or in the N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.l\Specia\Specification-Pinal.doc 30/01/09 - 4 production of substitutes for existing liquid fuels used in the transportation industries. Thus, there is a need to produce substitute liquid fuels from solar energy in commercially viable amounts. 5 Another significant consideration regarding the production and use of existing liquid fuels is the amount and nature of the by-products produced during manufacture and use of such fuels such as for example, greenhouse gas emissions 10 and similar. There are now increasing concerns about pollution abatement and climate change. One of the main culprits of greenhouse gasses and global warming is the production of carbon dioxide both during the manufacture of the liquid fuels and, more particularly, during their 15 use since carbon dioxide is produced as a byproduct of combustion of such fuels. Thus, there is an imperative to reduce the amount of carbon dioxide produced during the production of energy and to capture the carbon dioxide produced when liquid fuels combust by for re-using or 20 containing the carbon dioxide either directly or indirectly, such as for example, by obtaining carbon dioxide directly from the air rather than merely discharging the carbon dioxide into the atmosphere to further contribute to global warming 25 Thus, it would be beneficial if both of these considerations of using alternative energy supplies and capturing carbon dioxide could be combined within the one technology to produce viable liquid fuels as substitutes 30 for petroleum derived liquid fuels. Although some thought has been given to, and development work has been carried out on, using solar energy to produce liquid fuel whilst capturing carbon dioxide by-products, such efforts to date N:\Melbourne\Casea\Patent\76000-76999\P76296.AU.l\Specis\Specification-Final.doc 30/01/09 - 5 have met with limited success, owing in part, to the inefficiencies of many of the various steps in the overall scheme of producing the alternative liquid fuels, such as for example, producing bio-diesel from alternative energy 5 sources, particularly using algae or other biomass materials to consume carbon dioxide to produce intra cellular oil that can be refined subsequently to produce a fuel that can be used directly in a motor vehicle or similar. 10 The present invention sets out to address some of the deficiencies of existing technologies and to overcome, at least partially, some of these problems by providing an improvement in one or more of the steps of converting 15 carbon dioxide to oil, particularly in providing the access to sunlight used in the conversion, resulting in more efficient overall methods and processes of using carbon dioxide to produce oil products from algae. 20 In the past, different forms of photo-bioreactors have been used to house biomass containing algae for converting carbon dioxide into oil in the presence of sunlight which can be refined into fuel for use as substitutes for liquid fuels derived from petroleum. However, such previous 25 attempts have not been entirely successful for a variety of reasons, mainly to do with the high cost of producing bio-diesel from the algae. In times when world oil prices are at record highs , there is a greater emphasis on producing commercially viable alternatives to petroleum 30 fuel. One of the contributing reasons for the high cost of bio-diesel fuel was due to the inefficient conversion of carbon dioxide to oil in the initial stages of oil production owing to the inability of light to penetrate N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.l\Specia\Specification-Final.doc 30/01/09 - 6 through the biomass contained in the reactor to complete conversion of the biomass/fluids undergoing fermentation. Hitherto before used bioreactors have suffered from one or 5 other problems relating to inefficiencies of operation when used for conducting photosynthetic algal bioreactions of the type utilising carbon dioxide and sunlight to produce intra cellular oil. 10 A major limitation of almost all bioreactors for housing algal containing fluids that require light for the reaction to take place is that most of the light is absorbed close to the surface of the fluid, frequently restricted to about the top one centimetre or so thereby 15 resulting in the overall inefficient operation of the bioreactor. In such cases, most of the remaining depth of the bioreactor has low or very low productivity particularly as the depth of the bioreactor increases. 20 One of the types of previously used bioreactor is the so called closed photo-bioreactor. However, such closed photo-bioreactors are expensive to manufacture and to operate, and are inefficient in their operation. Closed tubular photo-bioreactors attempt to overcome the problems 25 of low light penetration by being comprised of a multitude of very small diameter tubes arranged in substantially side by side parallel relationship to one another defining a multitude of flowpaths, allowing light, such as sunlight, to penetrate through the diameter of each small 30 tube in an attempt to improve the efficiency of such reactors. Such arrangements are prohibitively expensive to manufacture and to operate, as well as being expensive to maintain, such as for example, by requiring extensive N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.I\Specis\Specification-Final.doc 30/01/09 - 7 periodic cleaning to maintain efficiency. Such arrangements cannot be used in commercially viable installations for producing intracellular oil in algal suspensions utilising photosynthetic reactions at a 5 commercially acceptable price because of their excessively high cost. Another type of previously used bioreactor is the raceway paddle wheel type bioreactor using one or more paddle 10 wheels located at one or more strategic locations in the bioreactor, such as for example, within an open channel to produce flow of fluid through the bioreactor whilst being exposed to sunlight. However, such reactors have a very low efficiency and hence require an extremely large 15 surface area to produce even minimal amounts of intracellular oil. Also, such open reactors including the typical paddle wheel raceway reactor require a reasonable raceway depth to be functional. However, light is unable to penetrate through the entire depth of the raceway 20 further contributing to poor efficiency and thus resulting in low conversion of sunlight and carbon dioxide to oil within the algae. Again, such installations are not commercially viable since the price of the biodiesel provided using such reactors is excessively high. 25 One of the problems contributing to the poor or low efficiency of currently available reactors, even reactors having a more shallow depth, relates to non uniform or uneven flow of fluids through the bioreactor. The non 30 uniform flow leads to different residence times for different parts of the fluid flow in the bioreactor so that different parts or flows are exposed to differing amounts of sunlight and hence to differing rates of N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.I\Specis\Specification-Final.doc 30/01/09 - 8 reaction, which in turn leads to different production rates and amounts of oil accumulating within the cells This differing rate of reaction results from some flows not being exposed to sunlight for sufficiently long 5 periods to allow more or less complete reaction and other flows being exposed for periods greater than required for complete reaction, all of which results in non effective utilisation of sunlight and to less than optimal efficiency of the bioreactor. Thus, there is a need for a 10 bioreactor having increased efficiency by having a more uniform flow of fluid through the bioreactor. Another of the problems contributing to currently available bioreactors having poor or low efficiency is 15 either lack of turbulence or insufficient turbulence as the fluids flow through the bioreactor. It is believed that increased turbulence of the fluid flowing through the reactor would increase the efficiency of the reactor by exposing more of the fluid to sunlight by promoting more 20 rapid surface renewal of the fluid so that more of the algal in the fluid is circulated to the top surface of the fluid and hence exposure to sunlight, which could contribute to an increase in efficiency of the bioreactor. Thus, there is a need for a system of inducing turbulence 25 within the fluids in the bioreactor, particularly the flow of fluids in the bioreactor so as to increase the efficiency of the bioreactor. Therefore, there is a need to provide an alternative type 30 of bioreactor that addresses one or more of the above mentioned short comings by enabling photosynthetic algal suspensions to produce intra-cellular oil more efficiently through more efficient design and operation of the N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Specis\Specification-Final.doc 30/01/09 -9 bioreactor. Accordingly, it is one aim of the present invention to provide a bioreactor having an increased efficiency 5 resulting in improved algal growth and lipid production in a photosynthetic algal suspension. It is another aim of the present invention to provide a bioreactor having more uniform flow of fluid through the 10 bioreactor enabling increased utilisation of sunlight when the fluid in the bioreactor is exposed to sunlight. It is another aim of the present invention to provide a bioreactor having increased turbulence of flow through the 15 bioreactor to promote more rapid surface renewal of the active component of the fluid in the bioreactor. It is to be noted that not all embodiments of the present invention will satisfy all aims of the present invention. 20 Some embodiments will satisfy one aim while other embodiments will satisfy another aim. Some embodiments may satisfy two or more aims. SUMMARY OF THE INVENTION 25 According to one aspect of the present invention there is provided a bioreactor in which light induced bioreactions of fluids can be conducted, the bioreactor comprising an inlet device for introducing a flow of fluid into the 30 bioreactor, a main reactor bed for receiving the flow of fluid from the inlet device, said main reactor bed being arranged so as to allow light to penetrate substantially through the depth of fluid in the main reactor bed as the N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Specis\Specification-Final.doc 30/01/09 - 10 fluid flows through the main reactor bed, and an outlet for discharging the flow of fluid from the main reactor bed wherein the main reactor bed is provided with a flow distribution device to promote uniform flow of fluid 5 through the main reactor bed thereby promoting more efficient reaction of the fluid in the bioreactor as the fluid flows through the main reactor bed. According to one aspect of the present invention, there is 10 provided a method of conducting a light induced bioreaction of a fluid in a bioreactor having an inlet device, a main reactor bed and an outlet device comprising introducing flow of fluid into the bioreactor using the inlet device, passing the flow of fluid from the inlet 15 device into and through the main reactor bed, the main reactor bed being provided with a flow distribution device, , producing a uniform flow or plug flow of fluid in the reactor bed by passing the flow in the reactor bed through the flow distribution device, allowing light to 20 penetrate substantially through the depth of the fluid flow in the reactor bed in the uniform or plug flow to initiate the light induced bioreaction within the fluid, and discharging the fluid from the main reactor bed through the outlet device wherein producing the uniform 25 or plug flow of the fluid in the reactor bed promotes more efficient reaction within the fluid as the fluid flows through the reactor bed thereby increasing the efficiency of the reaction taking place in the reactor bed. 30 According to one aspect of the present invention, there is provided a bioreactor for carrying out light induced bioreactions of a fluid comprising an inlet for introducing a flow of fluid into the bioreactor, a main N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Specis\Specification-Final.doc 30/01/09 - 11 reactor bed for receiving the flow of fluid from the inlet device, said main reactor bed being arranged so as to enable light to penetrate substantially through the depth of fluid in the main reactor bed as the fluid flows 5 through the main reactor bed, and an outlet for discharging the flow of fluid from the main reactor bed wherein the main reactor bed is provided with a turbulence inducing device for producing turbulence in the flow of fluid through the main reactor bed to promote surface 10 renewal of the fluid thereby increasing the efficiency of the bioreactor. According to one aspect of the present invention, there is provided a method of carrying out a light induced 15 bioreaction of a fluid having a light reactive active component in a bioreactor comprising introducing a flow of fluid into the bioreactor using an inlet device, passing the flow of fluid from the inlet device into and through the main reactor bed arranged so as to enable light to 20 substantially penetrate the depth of fluid in the main reactor bed as fluid flows through the main reactor bed, producing a turbulent flow of fluid in the reactor bed using a turbulence inducing flow device to provide surface renewal of the active component of the fluid to expose 25 more of the active component to sunlight to increase the rate of reaction of the active component, allowing light to penetrate substantially through the depth of the fluid flowing through the main bed, and discharging the fluid from the main reactor bed through an outlet device thereby 30 resulting in more efficient operation of the bioreactor. BRIEF DESCRIPTION OF THE INVENTION N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.3\Specis\Specification-Final.doc 30/01/09 - 12 Carbon dioxide represents the lowest energy form in which carbon exists in the environment. It is the end point of combustion of organic materials with atmospheric oxygen. Photosynthesis reverses the process using the energy from 5 the sun. The carbon dioxide is converted to higher energy carbon materials such as oil lipids, sugars and so on. Oxygen is liberated as a gas as a by-product of the process. One example of intracellular oil is lipids. 10 Typically, the fluid undergoing reaction in the bioreactor is a liquid suspension of biomass. Preferably, the fluid is an algal biomass or algal suspension. More preferably, the algae of the algal biomass is an oil producing algae. Most preferably, the algae converts carbon dioxide to oil, 15 preferably in the form of lipids, usually in the form of triglycerides. Typical examples of the algae include Chlorella, Scenedesmus, Spirulena, Botrycoccus Nanochloris,Nanochloropsis or the like. Typically, the bioreactor of the present invention is used 20 in combination with or is provided with a flow distribution device and/or with a turbulence inducing device. More typically, the flow distribution device is also the turbulence inducing device. Even more typically, the flow distribution device/turbulence inducing device 25 provides a balanced working system in terms of the product of liquid depth, residence time, algal dry cell weight, particularly when related to photosynthetic efficiency and mean solar energy input. 30 Typically, the inlet device introduces the fluid into the bioreactor and/or bed reactor as well as originating flow of the fluid through the bed reactor. More typically, the inlet device introduces turbulence into the flow, in N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Specis\Specification-Final.doc 30/01/09 - 13 addition to introducing the flow into the device, preferably turbulence into the flow of fluid as the fluidflows through the bed reactor. More typically, the turbulence promotes surface renewal of the active 5 component of the fluid, preferably surface renewal of the algae so as to expose more of the algae to sunlight. Even more typically, there is rapid surface renewal of the fluid or algae in the fluid. Typically, momentum is imparted to the fluid to flow 10 through the bed reactor and outlet by the inlet device of the bed reactor. In one form, the inlet includes one or more ducts as well as the inlet device. Preferably, the inlet device is a 15 gas lift device, acting as a gas lift pump. In one form, the gas lift pump is placed either above or below ground and typically comprises two chambers, namely, a rising section and a down coming section joined in some way both at the top and at the bottom. A typical 20 configuration includes two concentric cylinders in which the central cylinder is shorter so as to leave a space at the top and at the bottom. Typically, for example in a system filled with water to a level above the central cylinder, any gas injected near the bottom of the cylinder 25 will rise causing circulation to occur. More typically, the gas lift pump is a gas lift reactor wherein there are no moving parts and the energy for circulation of fluid within the pump is provided by the work of compression on the gas in order to pump it against the hydrostatic head 30 of the water. In one form, the present invention requires the pumping of a gas, typically carbon dioxide, either alone or in combination with another gas, such as for example, with air, into a liquid, typically, the algal N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.l\Speci\Specification-Pinal.dc 30/01/09 - 14 suspension so as to bypass the need for mechanically crude paddlewheels and similar devices. Typically, the gas lift system generates a typical 5 velocity of from about 10 to 50 centimetres per second. More preferably, the velocity imparted to the flowing fluid promotes maximum turnover at the surface of sunlight absorption. 10 Typically, the bioreactor is a planar reactor sometimes referred to as a flat bed reactor. More typically, the reactor has a surface area very much greater than the depth of fluid in the reactor bed. Even more typically, the main reactor bed is an essentially shallow trough, 15 pond, receptacle, container or other construction. Preferably, the reactor bed is a planar reactor, a sheet reactor, a pan reactor or the like having a surface area very much greater than the depth of the reactor. Another form of the reactor bed is a shallow open pond. 20 In one form, the planar reactor is a single reactor. In one form, the planar reactor has two, three, four or more individual flat bed reactors. Preferably, the individual planar reactors of the multiple bed reactor are 25 interconnected, typically interconnected with one or more other planar reactors to form the bioreactor. In one form, the reactors are connected in parallel or in series or in combinations of groups or sets of individual planar reactors in combinations of parallel and/or series 30 arrangements. Typically, the, any or each planar reactor has a depth of up to about 20 centimetres or more, preferably from about N:\Melbourne\Case\Patent\76000-76999\P76296.AU.1\Specis\Specification-Final.doc 30/01/09 - 15 1 cm to 20 cm, more preferably from about 3 cm to about 20 cm and more preferably from about 3 cm to about 10 cm. It is preferred that the depth be less than about 10 cm. Operating conditions within the planar reactor of the 5 present invention, especially including depth, is defined by the proposed equation in which the product of the reactor depth times the algal cell dry weight times the algal cell growth rate is a constant whose value is determined by the solar energy input divided by the 10 calorific value of the fuel multiplied by the photosynthetic efficiency. Typically, the, any or each planar reactor has a length 15 of up to about 1000 metres or more, preferably from about several metres up to about 1000 metres in length, more preferably from about several hundred metres to about 1000 metres in length. 20 Typically, the pond forming the planar reactor is up to about 1000 metres wide, preferably from several metres to several hundred metreB wide. Typically, the flow distribution device of the present 25 invention assists in maintaining velocity of flow of fluid in the bed reactor in addition to producing uniform flow of the fluid in the reactor. More typically, the velocity of flow from the inlet device and/or through the flat reactor bed is from about 10 to about 50 cm per sec. to 30 promote optimisation and/or maximum turnover at the surface for sunlight adsorption. Typically, the flow distribution device generates maximum N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Speci,\Specification-Final.doc 30/01/09 - 16 turnover at the surface of the fluid in the bed reactor in order to mix the fluid, typically in the form of a suspension to homogenise the suspension to promote efficient reaction. More typically, the flow distribution 5 device improves, preferably optimises, conditions for algal growth and/or oil production. Typically, the flow distributor device is located at, or close to, the entrance to the bed reactor or in a first 10 part of the bed reactor near to where the inlet device is located, preferably at the beginning or along the upper edge of the bed reactor, when in the form of a flat sheet or the like, or in the form of a fluid sheet. 15 In one form, the flow distributor is a weir, preferably an overflow weir, an underflow weir, or combination of underflow and overflow weir. Typically, the weir allows control of the depth of the liquid in the planar reactor by essentially acting in two ways. First the weir acts as 20 a dam to allow build up of fluid to the required depth. Second, the weir acts as a method to even up flow distribution of liquid. The purpose of having non-uniform spaces or gaps in the weir through or over which fluid can flow to assist in producing uniform distribution of 25 velocities. Thus there are greater restrictions at the centre of the weir and lesser restrictions at or towards the outer edges including having the greatest restriction in the centre and the least restrictions at or towards the outer edges. Gradation of restrictions applies 30 symmetrically about the centre of the weir extending on either side. In one form, the flow distributor is a weir or N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Specis\Specification-Final.doc 30/01/09 - 17 obstruction, typically made from brick, concrete, masonry or other suitable or convenient durable material or the like. 5 Typically, the height of the weir is fixed. Alternatively, the height of the weir is adjustable. More typically, the height of the weir is of sufficient height to determine the desired depth of the bioreactor, typically of the fluid in the planar reactor. 10 Preferably, the height of the weir is set to produce a depth of fluid in the reactor bed of 10 cm. However, it is to be noted that any depth is possible. Further, it is to be noted that as the height of the weir controls the depth of fluid in the reactor, the height is variable 15 according to the expected photosynthetic efficiency actually achieved in the bioreactor for any process. The depth of fluid is calculated in accordance with variables or parameters, such as for example, residence time in the reactor, algal dry cell weight or the like. 20 In one form, the flow distributor is solid, rigid, elongate or the like. In another form, the flow distributor is provided with gaps, spaces, cut-outs, apertures, bores, channels, culverts, ducts or the like. 25 Typically, the gaps etc occur above the depth of the liquid in which the weir is located. Typically, the sizes of the weir are from about 5 cm to about 40 cm to permit flow of this depth in the planar reactor. 30 In one form, the gaps etc provided in the wall of the weir are uniformly distributed along the length of the weir. In one form, the gaps etc. are distributed randomly along the length. Preferably, the gaps are distributed in N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.l\Specis\Specification-Final.doc 30/01/09 - 18 graduated relationship along the length of the weir. In one form, the gaps are uniform in size. In one form, the gaps have different sizes and/or are of graduated sizes. Preferably, the smaller or smallest sized gaps, are 5 located at, towards or adjacent to the centre or central section of the weir. More preferably, the larger or largest sized gaps are positioned at, towards or adjacent the end portions of the weir closer to the wall of the planar reactor when the flow distributor is located in the 10 flat bed reactor. Specifically, in the planar reactor, the greatest impediment to flow is located at or towards the centre and/or close to the inlet device whilst the smallest impediment to flow are positioned away from the centre or inlet device, such as at either end of the weir 15 and/or closer to the wall of the pond and/or planar reactor. Typically, the gaps are rectangular in shape. More typically, the edges of the gaps are rounded so as to be streamlined to reduce energy losses. 20 It is to be noted that the gaps act to counter the natural parabolic flow whereby the fluid flows fastest in the centre and/or near to the inlet device and slowest near to the reactor wall and/or away from the inlet device by evening out the flow of fluid to produce a more uniform 25 flow or plug flow to enhance the efficiency of the reaction(s) taking place within the fluid flowing into and through the reactor. It is to be used that the terms "uniform flow" and "plug flow" can be used interchangeably. 30 The algal suspension cannot spontaneously travel to complete a circuit of the bioreactor because the flow it is opposed by friction and momentum losses. The necessary N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.l\Specis\Specification-Final.doc 30/01/09 - 19 energy to enable the suspension to complete the circuit ideally should be added to the flow. There are a number of ways of imparting this momentum which include the following: 5 1.) A pump, which is generally less preferred because of the possible damage to the algal cells 2. 2.) By using a paddle wheel device or similar 3. 10 3.) By using an airlift device, or, preferably. 4.) By using gravity to create a hydrostatic head by having the beginning of the bioreactor at a sufficiently 15 higher elevation than the other of the bioreactor whereby the difference in height is made sufficent to overcome the frictional and momentum losses. Typically, the height difference is between about one to 20 metres over the length of the bioreactor permitting the algal suspension 20 to move at a velocity of 0.1 to 0.5 metres per second. In order to achieve the initial hydrostatic head, a retention device such as a dam or similar device may be 25 required. A distribution device may be incorporated into the design of the dam. This distribution device may take the form of gaps in the base of the wall of the dam in a manner similar to that described previously for the weir. Typically, the gaps are rectangular in shape. More 30 typically, the edges of the gaps are rounded so as to be streamlined to reduce energy losses. In one form the difference in height occurs along a smooth N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Specis\Specification-FinaldoC 30/01/09 - 20 descending gradient such as for example, a constantly sloping floor. Alternatively, and preferably, the change in elevation occurs in a series of steps over the length of the bioreactor. Having a series of consecutive steps 5 has advantages including ease of construction of the gradient. Further, the steps create a small scale waterfall effect which encourages disengagement of inhibitory super-saturated dissolved oxygen produced by the photosynthesis reaction. Additionally, at the base of 10 each step of the waterfall, there is a region where additional nutrients, including carbon dioxide, could be introduced into the algal suspension. In one form, the bioreactor typically has a difference in 15 height from one end to the other end, requiring the fluid to be raised to the top level of the bioreactor on the return flow. Typically, any suitable form of fluid raising device can be used, including pumps, such as for example, centrifugal pumps, water pumps or the like. One 20 preferred form of fluid raising device is an Archimedes screw or similar device to raise the algal suspension to the highest level in order to minimize or reduce potential damage to the algae cells owing to the shear forces encounter by the algal cells when being raised to the top 25 level. Typically, the outlet or outlet device of the planar reactor and/or fluid sheet reactor includes one or more outlet ducts. More typically, the outlet duct is a return 30 duct for returning fluid back to one or more reactors. Even more typically, the return duct enables management of the return of the reacted fluids and permits multiple passes of the algal suspension through the bioreactor. N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Specis\Specification-Final.doc 30/01/09 - 21 Typically, the multiple passes occur in series or in parallel. Typically, the algal suspension or biomass will have dissolved CO 2 present in a concentration of from 5 about 0% to 5% by weight. Typically, the dissolved oxygen in the fluid will also have built up to levels that are potentially inhibitory, typically in the range of 10 to 50 milligrams per litre. In one form, the return duct is a flat sheet whereas in 10 another form, the return duct can be a deep channel, conduit, trough or the like. Typically, the bioreactor of the present invention is provided with a turbulence inducing device. More 15 typically, the turbulence inducing device produces additional turbulence to that produced by the uniform flow distributor and/or the inlet device. Even more typically, the turbulence device maintains turbulence during flow of fluid through the reactor. Even more typically, the 20 turbulence device is located in or on the planar reactor downstream of the uniform flow distribution device. The first purpose of the turbulence inducing devices is to induce rapid mixing of the surface layers of the body of the liquid. As light penetrates poorly into the algal 25 suspension, only the algae nearest the surface receive light thereby reducing the effectiveness of the rest of the reactor or the algae may receive excessive light resulting in cellular damage. If the flow was totally laminar, the lack of penetration or cellular damage could 30 be a serious problem for the effectiveness of reactor process. One form of the turbulence inducing device is a cylinder or series of cylinders introduced at right angles to the flow. Such cylinders are either both horizontally N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Specis\Specification-Final.doc 30/01/09 - 22 or vertically aligned. Most preferably, the cylinders are incorporated in both horizontally aligned directions in the shape of a mesh that extends across the width of the pond. 5 In one form, the turbulence inducing device is a turbulence trigger or similar. One form of the turbulence trigger is a multitude of turbulence devices or elements arranged in side by side relationship. In one form, the 10 turbulence devices are arranged in substantially parallel side by side relationship. In one form, the devices induce or produce edy currents or eddies in the flow of fluid. In one form, the devices are cylinders or similar. The most preferable type of eddies in the fluid are 15 homogeneous isotropic turbulence. The limitation on the turbulence is determined by the turbulence Reynolds stresses with a value less than the stress levels that would result in shear sensitivity of the cells occurring 20 In one form the turbulence inducing device is a barrier element extending under, over or at the surface of the fluid so as to induce turbulence in the fluid flow. The barrier element can take any suitable form. In one form 25 the barrier element is flexible whereas in another form it is rigid or semi-rigid. In one form the barrier element is filamentary or is a filament, such as for example, in the form of a wire, rope or similar. In one form the barrier element is a rod skimmer, chain or the like. 30 In one form, the device is a wire laced from alternate sides of the reactor extending lengthwise along the long side of the reactor by progressing down the opposite sides N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Specis\Specification-Final.doc 30/01/09 - 23 of the reactor and extending to the other side. Typically the wire is from about 1 to about 10 millimetres in diameter, preferably from about 2cm to about 5cm in diameter. The wire is preferably of a non-corrosive 5 material, typically nylon or plastic rope or the like or hollow plastic tubing or the like. The barrier element can be of a solid core construction, a hollow construction, or a coaxial construction, and preferably be provided with an outer protective layer or coating. 10 Typically, the turbulence devices extend substantially perpendicularly across the direction of flow of the fluid from one side of the reactor to the opposite side of the reactor. 15 Typically, heating and/or cooling can be applied to the bioreactor preferably in the return duct to control temperatures for the next pass of fluids through the reactor, particularly to maintain optimal growth 20 efficiency. In one form, heating is applied to counteract cold night temperatures and cooling is applied to counteract intense solar activity during the day in order to establish and maintain optimal conditions within the reactor for substantially maximum efficiency of the 25 reactions. Typically, the bioreactor of the present invention is provided with a degassing unit. More typically, the degassing unit is located in the outlet of the bioreactor, 30 even more typically, in the return line of the bioreactor returning biomass discharged from the bioreactor back to the bioreactor for further processing. N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.l\Specis\Specification-Final.doc 30/01/09 - 24 Typically, the carbon dioxide can be sourced from a variety of situations, including concentrated forms resulting from operation of commercial or industrial plants, such as, power generating stations, manufacturing 5 processes, or the like, or can be obtained directly from existing sources of carbon dioxide, including the atmosphere, such as, obtaining the carbon dioxide directly from the air or similar environments or locations, including natural and artificial deposits of carbon 10 dioxide. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described by way of 15 example only with reference to the accompanying drawings in which: Figure 1 is a schematic plan view of one form of a combination of individual planar reactors interconnected 20 to form a bioreactor. Figure 2 is a schematic top side perspective view of one form of the uniform flow distributor device of the present invention. 25 Figure 3 is a schematic plan view of one form of a planar reactor provided with one form of the turbulence inducing device of the present invention. 30 Figure 4 is a schematic top plan view of one form of the planar reactor of the present invention showing the steps at the bottom of the reactor bed for producing the small scale waterfall effect. N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Specis\Specification-Final.doc 30/01/09 - 25 Figure 5 is a schematic side elevation view of the bioreactor of Figure 4. 5 DETAILED DESCRIPTION OF THE INVENTION With particular reference to Figure 1, one form of the planar bioreactor of the present invention, generally denoted as 2, will now be described. Bioreactor 2, in one 10 form, comprises four individual flat bed reactors 4, denoted respectively as reactor 4A, reactor 4B, reactor 4C and reactor 4D interconnected together to form a generally square arrangement. However, it is to be noted that any suitable or convenient arrangement is possible. Each 15 reactor 4A, 4B, 4C, 4D is a planar reactor, such as for example, an open, generally square or rectangular pond having a surface area very much greater than its depth. Each pond is lined with a suitable impervious membrane (not shown) such as for example, with commercial grade 20 pond liner, particularly pond liners made from rubber, polyvinyl chloride (PVC) or other suitable material. Each pond typically has a depth of from about 10 to 20 cms, a length of several hundred to about 1000 metres and a width of several hundred meters. However, any suitable size is 25 possible as is any suitable ratio of the length of the sides of the reactor to one another. An inlet device is located in the centre of bioreactor 2, particularly in the area or region intermediate all of the 30 four reactors, to admit photosynthetic algal suspension into bioreactor 2. The inlet device is located centrally to assist in even flow and distribution to each of the ponds. In one form, the inlet device is a CO 2 absorber 10, N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.l\Specie\Specification-Final.doc 30/01/09 - 26 preferably in the form of a lift pump. Operation of CO 2 absorber 10 introduces fresh algal suspension into bioreactor 2. It is to be noted that CO 2 absorber introduces the fluid in the form of a flow having 5 sufficient velocity to flow through the bioreactor into bioreactor 2 as well as imparting momentum to the fluid flow.. Fluid introduced through CO 2 absorber 10 flows into and along each of four inlet ducts 14a, 14b, 14c, 14d in the form of shallow open channels extending from CO 2 10 absorber 10 to each of the flat bed reactors 4A, 4B, 4C and 4D to admit fluid thereto. Although a cruciform of ducts 14A, 14B, 14C and 14D are shown, such a form is one of many different forms that can be utilised to introduce an even flow to all four reactors 4. It is to be noted 15 that inlet ducts 14 can have any suitable form and be arranged to distribute flow in any manner to the reactors 4A, 4B, 4C, 4D. One preferred form of CO 2 absorber 10 will now be 20 described. Absorber 10 is a closed cylindrical vessel of about several metres in height containing liquid at a high pH so that CO 2 is readily absorbed by the liquid. As a result, only the first (lower) metre of the CO 2 unit that provides CO 2 may be necessary for CO 2 absorption. 25 Typically, the CO 2 absorber unit will be integrated into the gas lift device. If pure CO 2 is used, the absorption efficiency of the CO 2 can be increased by including conventional industry packing such as Raschig rings which will permit most of the CO 2 to be absorbed up to the bottom 30 metre or so depth of the absorption device. As the gases typically encountered will be 5% to 30% CO 2 with the remainder being an oxygen-nitrogen mix from air, the imbalance will be used for gas lift purposes to drive the N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.l\Specis\Specification-Final.doc 30/01/09 - 27 circulation of algal suspension through the flat planar reactor. Any suitable source of CO 2 can be used.including sources 5 from commercial or industrial plants, such as a concentrated source, including, power generating stations, manufacturing plants, such as cement works, or other installation producing carbon dioxide. Additionally, the source of carbon dioxide can be the atmosphere, such as by 10 obtaining or putting the carbon dioxide directly from the air or the like. If the source of CO 2 is an industrial process, such as for example, cement manufacture, only about 20% to about 30% of the source of the gas may need to be CO 2 with the remainder of the gas consisting of 15 nitrogen and about 1% to 2% oxygen. The gas can be either supplied at high pressure from its source or is compressed to high pressure by a pump at or close to the bioreactor. The nitrogen and oxygen is sparingly soluble and the algal suspension fluid will rise in CO 2 absorber 10 20 creating circulation. In the process of the present invention, the work of the compression of the algae is converted to hydrostatic pressure load which in turn is converted to fluid momentum necessary to drive the subsequent flow of algal suspension along reactors 2, and 25 optionally to introduce turbulence to the flow. A flow distributor is located at, or close to, the entrance 16 or beginning of each planar reactor 4 for forming a substantially uniform and even flow over almost 30 the entire width of each reactor 4. In one form, the flow distributor is in the form of an overflow weir 20. A particularly preferred form of the overflow weir 20 is shown in Figure 2. Although weir 20 may be made of any N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Specis\Specification-Pinal.doc 30/01/09 - 28 suitable materials and /or be any suitable construction, owing to its size, a particularly preferred construction material for the weir is brick, concrete, masonry, rock or the like or other suitable durable material and/or 5 construction having the strength and durability to withstand the open environment in which it is used. If necessary, weir 20 can be coated with a suitable exterior coating, such as for example, to resist fouling by unwanted growth of microorganisms or the like. 10 Further, it is to be noted that in some embodiments the height of the wall of the overflow dam of weir 20 is sufficient to determine the desired depth of the bioreactor, such as for example, to maintain a depth of 10 15 cm in reactor 4 in the event the optimal depth of the reactor is 10 centimetres. The depth of fluid in reactor 4 is variable according to the expected photosynthetic efficiency and is selected to achieve optimal effective photosynthetic reactions. 20 With particular reference to Figure 2, one form of weir 20 will now be described. This form of weir 20 is provided with a continuous solid base portion 22 upon which are located piers 24, or similar in spaced apart relationship 25 to each other defining gaps 26 or similar therebetween. Piers 24 may be formed integrally with base 22 or be separate components or constructions placed upon base 22. It is to be noted that the height of dam wall 22 located between piers 24 determines the depth of fluid in reactor 30 4 so that gaps 26 are formed at and above the level of fluid in reactor 4. Although gaps 26 can take any suitable arrangement, a preferred arrangement, as shown in Figure 2, comprises larger gaps 26 located at or towards N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.l\Specis\Specification-Final.doc 30/01/09 - 29 the ends 28 of weir 20 and smaller gaps 26 located at or towards the centre 29 of weir 20. The graduation in size of the gaps counteracts the natural parabolic flow of fluid flowing through weir 20 whereby the liquid moves 5 fastest in the centre and slowest near the walls of reactor 4 to even out the flow through weir 20 to produce a more or less uniform flow of fluid through each individual reactor 4. 10 The floor, base or lower surface of reactor 4 can have a number of different forms. In one embodiment the floor of the reactor is flat so that the reactor bed is of a substantially uniform depth. In another embodiment the floor of the reactor is partially inclined having part of 15 the floor as a sloping surface and is partially flat having another part of the floor flat. In another embodiment the floor can be inclined from one end to the other end, either in a continuous smoothly descending gradient or inclination or alternatively in a gradient 20 which changes over the length of the reactor so that there are more steeply inclined parts and less steeply inclined parts to the floor surface. In another embodiment, which is preferable, the floor has a stepped configuration having a number of consecutive steps in side by side 25 relationship. One particularly preferred form of the stepped relationship is shown in Figures 4 and 5. In this form, the end 82 at which fluid flow is introduced to reactor 4 is at a relatively higher level as denoted by 84. The height of water 86 above level 84 provides a 30 suitable head of water to provide hydrostatic pressure to assist in fluid flow through reactor 4. Base 88 of the 1 t step 90 is substantially flat and ends in substantially vertical riser 92 which falls to base 94 of the second N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Specis\Specification-Final.doc 30/01/09 - 30 step 96. Base 94, being substantially flat terminates in riser 98 which falls to base 100 of third step 102, and so on until the discharge end 104 of reactor 4. thus, in this embodiment the floor is stepped. 5 During operation of the bioreactor of the present invention, there is significant frictional loss of energy which can be expressed as an equivalent pressure drop or hydraulic head of water as the algal suspension flows down 10 the length of the reactor. Typically, this is equivalent to a hydraulic head in the range of one to twenty metres.However, the exact height is determined by many operational parameters such as length of the reactor, width of the reactor, number of directional changes, the 15 depth of the reactor, the velocity of the flow, and the like. In the present invention this can be applied in two ways. In one form, at the beginning of the flow, the water is backed up behind an obstruction to create a dam to a height at least equivalent to the expected loss of 20 hydraulic head of the bioreactor. In this embodiment, the obstruction is a wall, divider, partition or the like, with openings at the bottom i.e. one example is a weir, particularly the weir as previously described. The construction of these openings is typically rectangular, 25 but other shapes may be used. The number and distribution of the openings would normally follow the pattern of the flow distribution weir described in Figure 2. The effective height of an opening can be adjusted to be smaller or larger to enable the algal suspension to reach 30 the desirable depth based on the equation or formula described elsewhere in this specification. The algal suspension will then emerge from the dam with sufficient energy to overcome frictional and momentum losses and N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.l\Specis\Specification-Final.doc 30/01/09 - 31 carry it along the length of the bioreactor, and sometimes sufficient to do a circuit of the reactor. Alternatively, in a second embodiment, the required 5 hydraulic head can be supplied by the algal suspension moving from a higher to a lower elevation such that the difference between the beginning and end of the bioreactor flow is sufficient to overcome fictional and momentum losses. Typically, the height difference would be between 10 one and twenty metres over the length of the bioreactor. This height difference may take two forms. In one form, (not shown) the change in elevation occurs along a smooth descending gradient. Alternatively and preferably, the change in elevation occurs by means of a series of steps 15 over the length of the bioreactor as shown in Figures 4 and 5. The purpose of the steps is typically twofold. Firstly, the construction provides ease of construction of the gradient as it is anticipated that typically the base between the steps is flat and does not require careful 20 measurement or control of angles during construction i.e the floor between two substantially vertical or perpendicular adjacent risers is substantially flat as shown in FIGURE 5. Secondly, and most significantly, the steps create a small-scale waterfall effect to encourage 25 the disengagement of inhibitory super-saturated dissolved oxygen produced by the photosynthesis. Additionally, at the base ofeach step of the waterfall, there is a region where additional nutrients including carbon dioxide could be introduced into the algal suspension. 30 In these embodiments, the fluid will have to be raised to the top level of the bioreactor on the return flow. Simple centrifugal or similar water pumps may be used, but N:\Melbourne\Caees\Patent\76000-76999\P76296.AU.1\SpeCis\SpeCification-Final.doc 30/01/09 - 32 the shear forces encountered in such pumps are likely to cause substantial damage to the algae and accordingly are less preferred. It is proposed to prevent this damage by using an Archimedes screw or similar device to raise the 5 algal suspension to highest level of the bioreactor without subjecting the algal suspension to unnecessary shear or other forces which have the potential to damage the algal cells. 10 At the other end of reactor 4, the discharge end 32, is provided a suitable outlet discharging fluid from reactor 4. One form of the outlet is a return duct in the form of an open channel 30 for receiving the flow of fluid from reactor 4, such as for example, by fluid spilling over the 15 discharge edge of reactor 4 into open channel 30 serving as the return duct. Return duct 30 may have any suitable depth, such as for example, from about 10 cm to about several metres, as it is optional as to whether further photosynthetic reactions are to take place in return duct 20 30. Return duct 30 extends from discharge end 32 of reactor 4 around one outboard side of reactor 4 to be in fluid communication with a central conduit 34 for returning reacted fluid to CO 2 absorber 10. One form of the central conduit 34 is a pipe whereas another form is 25 an open channel, duct, trough or the like. Central conduit 34 can have any suitable or convenient form. A degassing apparatus, (not shown), such as for removing excess amounts of oxygen from the reacted fluid, is 30 optionally located within return duct 30 or central conduit 34 as required. In a preferred form, the oxygen degassing unit is located in return duct 30 to one side of bioreactor 2. Return duct 30 and/or central conduit 34 is N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Specis\Specification-Final.doc 30/01/09 - 33 optionally provided with a heating and/or cooling installation 40 for heat exchange with fluid therein to regulate the temperature of the fluid, such as to optimise and/or maximise the efficiency of the photosynthesis 5 reactions, by counteracting cold night time temperatures and/or counteracting intense solar activity during the day. In a preferred form, heating/cooling heat exchanger 40 is located in duct 30 to one side of bioreactor 2. 10 Makeup water inlet 50, typically in the form of a conduit, duct, pipe, hose, or similar, is provided, typically at the side of bioreactor 2, to admit makeup water to return duct 30 or central conduit 34 of bioreactor 2. Inlet 50 can have any suitable form or be of any suitable type. 15 Makeup water introduced through makeup water inlet 50 can be fresh water, recycled water, reprocessed water, recycled process water or the like. A preferred form of makeup water is recycled process water. 20 Bioreactor 2 is provided with an outlet 60 for continuously discharging fluid from bioreactor 2 for subsequent processing, such as for example to recover oil from the algal suspension. In one form, the outlet 60 is 25 located within return duct 30, typically at or towards the discharge end of reactors 4 and preferably is in the form of a closed conduit, such as a pipe, hose or similar. Fluids discharged through outlet 60 are processed further, such as to recover and/or refine the oil content of the 30 cells of the algal suspension. Turbulence triggers 70 are optionally provided in one or more reactors 4 for creating and/or maintaining additional N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Speis\Specification-Final.do 30/01/09 - 34 turbulence either in place of the turbulence created by CO 2 absorber 10, overflow weir 20 or in addition to the turbulence produced by these devices. As the optical density of the algal suspension results in light 5 dissipating in the top one centimetre of the fluid in reactor 4, additional turbulence is desirable to mix the components in the fluid in the bioreactor to promote effective use of the light for photosynthesis by circulating the algal cells into the light. 10 The turbulence triggers 70 can take any suitable form or arrangement including hollow core, solid core, layered, laminated, coaxial, coated filaments, tubes, or the like. One form of turbulence trigger 70 comprises cylinders (not 15 shown) laid at right angles to the flow of fluid in reactor 4. This arrangement produces eddy currents and flows around the cylinders which result in vertical mixing of the components in the fluid. 20 Another form of turbulence trigger 70, which is a particularly preferred form is shown in Figure 3. This form of the turbulence trigger is thin wire of about 2 to 5 mm in diameter strung between suitable anchors, such as for example in the form of hooks, located at spaced apart 25 locations along either opposite longitudinal side of reactor 4 to form an alternating lacing pattern of wires. The wire extends from one side of reactor 4 to the other side of reactor 4 transversely to the direction of flow of fluid in reactor 4, as shown more particularly in 30 Figure 3 to provide optimal turbulence conditions. In operation of bioreactor 2 of the present invention, carbon dioxide from a suitable source, such as for N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Specis\Specification-Final.doc 30/01/09 - 35 example, an industrial installation, for example, a cement works, power station or the like, is introduced into carbon dioxide absorber 10 where it is absorbed into the biofluid containing the photosynthetic algal suspension, 5 together with other additives promoting the required reactions if desired. In the process of absorbing C0 2 , the work of absorber 10 in compressing the gas is converted to hydrostatic pressure head which in turn is converted to fluid momentum for introducing the flow of fluid to 10 bioreactor 2 in a turbulent flow, more particularly to one or more of the four reactors 4. The momentum imparted to the fluid causes the fluid to flow through reactors 4 to discharge end 32. 15 The present invention will be described with reference to reactor 4A only for the sake of clarity and ease of understanding. The same comments apply equally to the other reactors 4B, 4C, 4D, or to any other reactors that may be present in the bioreactor installations 20 The carbon dioxide containing fluid is conveyed from absorber unit 10 to reactor 4A through inlet duct 14a where it flows into reactor 4A upstream of weir 20. The fluid then flows over the dam wall 22 of weir 20 through 25 gaps 26. Owing to the graduation of sizes of gaps 26, there is a more or less uniform flow of fluid through reactor 4A from weir 20 discharge end 32 of reactor 4A. Alternatively, if the floor of the reactor has a stepped arrangement, the fluid flows over the small scale 30 waterfalls in a cascading movement from the inlet to the outlet end as shown in figures 4 and 5. Fluid spills over the discharge edge of reactor 4A into N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Specia\Specification-Final.doc 30/01/09 - 36 return duct 30. Whilst the fluid is in the shallow planar reactor 4A, sunlight penetrates through the depth of fluid to interact with the CO 2 to produce intracellular oil or the like. Turbulence triggers 70 maintain 5 turbulent flow to renew the surface of the fluid in the reactor. Excess oxygen build up as a by-product of the photosynthetic reaction occurring in the reactor is removed through the optional degasser located in return duct 30 to prevent inhibition of further conversion to oil 10 when the fluid is passed through one of reactors 4. Fluid flows from return duct 30 after having its temperature regulated by exchanger 40 if required to central conduit 34 for return to a suitable reservoir for reintroduction to absorber unit 10 to receive further dissolved carbon 15 dioxide for transport to one of reactors 4A, 4B, 4C, 4D to commence the cycle once again and thus be recirculated through the reactor installation 2. The fluid is passed through reactors 4 as many times as is 20 required for conversion to oil. The outflow from absorber 10 can be delivered to any of reactors 4A, 4B, 4C, 4D as desired. The reactors can be operated in series or in parallel or in any combination depending upon the specific needs of the process taking place in the reactor and the 25 desired end product or result. If or when required, makeup water, either fresh water, water containing nutrients or recycled process water, is introduced through inlet 50 to replenish, supplement or 30 similar to the existing fluid. When required, the converted algal suspension is drawn off continuously through outlet 60 in order to collect the N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.l\Specis\Specification-Final.doc 30/01/09 - 37 fluid for subsequent processing and to replenish water lost through evaporation. In one embodiment, in the subsequent downstream process, water is discarded as a bleed stream or flow down stream to prevent the build up 5 of inhibiting materials in the bioreactor, such as for example, excess salts, additives or the like. ADVANTAGES OF THE INVENTION 10 Advantages of the present invention include the following: Turbulence inducing devices promote micromixing for increased photosynthetic efficiency in algal production 15 The balancing and interaction of the factors relating to operative conditions of the reactor of the present invention as hereinbefore described, permits mass energy balancing to maximise the scales of efficiency in multiple bed reactor systems, thus leading to more 20 efficient production of oil within the algal cells. The incorporation of the CO 2 absorber unit and air gas lift device into the reactor of the present invention permits multiple returns to derive maximum output from algal 25 suspension and solar energy. The planar reactors of the present invention are cost effective especially in comparison with paddlewheel raceways that are the current standard in the industry. 30 The use of non damaging lift devices to raise the algal suspension to the top level of the reactor, such as for example, by using an Archimedes screw or the like causes less damage to the algae than some other mechanical N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.l\Specis\Specification-Final.doc 30/01/09 - 38 methods.The described arrangement has been advanced by explanation and many modifications may be made without departing from the spirit and scope of the invention which includes every novel feature and novel combination of 5 features herein disclosed. Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. 10 It is understood that the invention includes all such variations and modifications which fall within the spirit and scope. N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Specis\Specification-Final.dOc 30/01/09

Claims

1. A bioreactor in which light induced bioreactions of fluids can be conducted comprising an inlet device 5 for introducing a flow of fluid into the bioreactor, a main reactor bed for receiving the flow of fluid from the inlet device, said main reactor bed having a surface area very must greater than the depth of fluid in the bioreactor so as to allow light to 10 penetrate substantially through the depth of fluid in the main reactor bed as the fluid flows through the main reactor bed, and an outlet for discharging the flow of fluid from the main reactor bed wherein the main reactor bed is provided with a flow distribution 15 device to promote uniform or plug flow of fluid through the main reactor bed thereby promoting more efficient reaction of the fluid as it flows through the main reactor bed. 20

2. A method of conducting a light induced bioreaction of a fluid in a bioreactor comprising introducing flow of fluid into the bioreactor using an inlet device, passing the flow of fluid from the inlet device into and through the main reactor bed having a surface 25 area very much greater than the depth of fluid in the main reactor bed, producing a uniform or plug flow of fluid in the reactor bed by passing the flow in the reactor bed through the flow distributor device, allowing light to penetrate substantially through the 30 depth of the fluid flow through the reactor bed in the uniform or plug flow to initiate the light induced bioreaction within the fluid and discharging the fluid from the main reactor bed through an outlet N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Specis\Specification-Final.doc 30/01/09 - 40 device wherein producing the uniform flow of the fluid in the reactor bed promotes more efficient reaction within the fluid as the fluid flows through the reactor bed thereby increasing the efficiency of 5 the reaction taking place in the reactor bed.

3. A bioreactor for carrying out light induced bioreactions of a fluid comprising an inlet for introducing a flow of fluid into the bioreactor, a 10 main reactor bed for receiving the flow of fluid from the inlet device, said main reactor bed having a surface area very much greater than the depth of fluid in the bioreactor enabling light to penetrate substantially through the depth of fluid in the main 15 reactor bed as the fluid flows through the main reactor bed, and an outlet for discharging the flow of fluid from the main reactor bed wherein the main reactor bed is provided with a turbulence inducing device for producing turbulence in the flow of fluid 20 through the main reactor bed to promote surface renewal of the fluid thereby increasing the efficiency of the bioreactor.

4. A method of carrying out a light induced bioreaction 25 of a fluid having a light reactive active component in a bioreactor comprising introducing a flow of fluid into the bioreactor using an inlet device, passing the flow of fluid from the inlet device into and through the main reactor bed having a surface 30 area very much greater than the depth of fluid in the main reactor bed, producing a turbulent flow of fluid in the reactor bed using a turbulence inducing flow device to provide surface renewal of the active N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Specio\Specification-Final.doc 30/01/09 - 41 component of the fluid to expose more of the active component to sunlight to increase the rate of reaction of the active component, allowing light to penetrate substantially through the depth of the 5 fluid flowing through the main bed, and discharging the fluid from the main reactor bed through an outlet device thereby resulting in more efficient operation of the bioreactor. 10

5. A bioreactor or method according to any preceding claim in which the carbon dioxide is derived from an industrial process a commercial process or similaror from combustion of a fuel or carbon containing material or in 15 which the carbon dioxide is pulled directly from the environment, atmosphere, air or the like.

6. A bioreactor or method according to any preceding claim in which the fluid is a liquid suspension of bio 20 mass containing an algal biomass or algal suspension.

7. A bioreactor or method according to any preceding claim in which the algae of the algal biomass is an oil producing algae of the type able to convert carbon dioxide 25 to oil.

8. A bioreactor or method according to any preceding claim in which the oil produced by the algae is intracellular oil and is in the form of lipids including 30 triglycerides.

9. A bio-reactor or method according to any preceding claim in which the algae includes chlorella, scenedesmus, spirulena, botrycoccus, nanochloris, 35 nanchloropsis. N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Speci\Specification-Final.doc 30/01/09 - 42

10. A bioreactor or method according to any preceding claim in which the bioreactor is provided with a flow distribution device or a turbulence inducing device, or a 5 flow distribution device and turbulence inducing device.

11. A bioreactor or method according to any preceding claim in which the inlet device introduces fluid into the bioreactor and or bed reactor as well as originating flow 10 of the fluid through the bed reactor.

12. A bioreactor or method according to any preceding claim in which formation of turbulence within the fluid promotes surface renewal of the active component of the 15 fluid, including surface renewal of the algae so as to expose more of the algae to sunlight thereby increasing the efficiency of the bioreactor.

13. A bioreactor or method according to any preceding 20 claim in which there is rapid surface renewal of the fluid or algae in the fluid.

14. A bioreactor or method according to any preceding claim in which the inlet device introduces momentum to the 25 fluid, to enable the fluid flow within the reactor to the outlet.

15. A bioreactor or method according to any preceding claim in which the inlet includes one or more conduits, 30 ducts, channels, pipes or the like.

16. A bioreactor or method according to any preceding claim in which the inlet device is or includes a gas lift device, preferably in the form of a gas lift pump. 35

17. A bioreactor or method according to any preceding claim in which the gas lift pump is located either above N:\Melbourne\Casee\Patent\76000-76999\P76296.AU.1\Speci.\Specification-Final.doc 30/01/09 - 43 or below ground and comprises two chambers being a rising section and a downcoming section interconnected to one another. 5

18. A bioreactor or method according to any preceding claim in which the gas lift pump includes two concentric cylinders being an inner cylinder and an outer cylinder in which the central cylinder is shorter than the outer cylinder so as to provide a space at the top and/or base 10 of the gas lift pump.

19. A bioreactor or method according to any preceding claim in which the gas lift pump is a gas lift reactor having no moving parts and wherein the energy of 15 circulation of fluid within the pump is provided by the work of compression of the gas in order to pump the gas against the hydrostatic head of water.

20. A bioreactor or method according to any preceding 20 claim in which the gas includes carbon dioxide either alone or in combination with air.

21. A bioreactor or method according to any preceding claim in which the gas lift pump generates a velocity of 25 from about 10 to 50 cms per second.

22. A bioreactor or method according to any preceding claim in which the reactor is a planar reactor having a surface area very much greater than the depth of fluid in 30 the reactor bed.

23. A bioreactor or method according to any preceding claim in which the reactor is a single reactor or has 2 or more individual reactors forming the reactor. 35

24. A bioreactor or method according to any preceding claim in which the reactor is a multiple bed reactor N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.l\Specis\Specification-Final.doc 30/01/09 - 44 having a multitude of individual reactors interconnected together to form the reactor.

25. A bioreactor or method according to any preceding 5 claim in which the reactor or each individual reactor has a depth of up to of about 20 cms or more preferably, from about 1cm to about 20cms, more preferably from about 3 cms to about 20 cms and most preferably from about 3 cms to about 10 cms. 10

26. A bioreactor or method according to any preceding claim in which the operating parameters of the reactor including the depth of fluid within the reactor is established or calculated using the equation in which the 15 product of the reactor depth times the algal cell weight times the algal cell growth rate is a constant having a value which is determined by the solar energy input to the reactor divided by the calorific value of the fuel multiplied by the photosynthetic efficiency. 20

27. A bioreactor or method according to any preceding claim in which any, each or all of the planar reactors, have a length of up to about 1000m or more, preferably from about several metres to about 1000m and has a width 25 of about 1000m or more, preferably from several metres to several metres wide.

28. A bioreactor or method according to any preceding claim in which the flow distribution device assists in 30 maintaining velocity of fluid in the reactor in addition to producing uniform flow of fluid in the reactor.

29. A bioreactor or method according to any preceding claim in which the flow distribution device is located at 35 or close to the entrance to the bed reactor or in a first part of the bed reactor near to where the inlet device is located for introducing fluid into the reactor, preferably N:\Melbourne\Caaes\Patent\76000-76999\P76296.AU.I\SpeciB\Specification-Final.doc 30/01/09 - 45 the distribution device is located at the beginning or along the upper hedge of the bed reactor.

30. A bioreactor or method according to any preceding 5 claim in which the flow distribution device is a weir, an overflow weir, an underflow weir, or a combination of overflow and underflow weir in which the height of the weir or part of the weir wall determines the depth of the fluid in the reactor. 10

31. A bioreactor or method according to any preceding claim in which the distribution device acts as a damn to allow build up of fluid to the required depth and/or to the required pressure and acts to even flow distribution 15 of fluid to the reactor.

32. A bioreactor or method according to any preceding claim in which the weir is provided with gaps, spaces, or voids, apertures, parts, cavities, chutes, channels or 20 similar allowing the flow of the fluid through the wall of the weir.

33. A bioreactor or method according to any preceding claim in which the spacing of the gaps, spaces, voids, 25 apertures or the like is to promote even or uniform distribution of velocities of the fluid so that there is a generally uniform flow of fluid through the reactor across the reactor. 30

34. A bioreactor or method according to any preceding claim in which the gaps and the like are uniformly distributed along the lenghth of the weir or are distributed in graduation from one end to the other of the weir from the centre to either end along the length of the 35 weir.

35. A bioreactor or method according to any preceding N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Specis\Specification-Final.doc 30/01/09 - 46 claim in which the size of the gaps, spaces, voids or the like are uniform in sized or are graduated in size in which the smaller or smallest size gaps are located at towards or adjacent to the centre of the central section 5 of the weir and the larger or largest size gaps are positioned at or towards or adjacent to the inlet portions of the weir or located closer to the side walls of the reactor. 10

36. A bioreactor or method according to any preceding claim in which the gaps provided in the weir are to counter the natural parabolic flow of fluid whereby the fluid flows fastest in the centre and/or near to the inlet device and slowest near to the reactor walls and or away 15 from the inlet device so as to even out the flow of the fluid to produce a more uniform flow to enhance the efficiency of the reactions taking place within the reactor. 20

37. A bioreactor or method according to any preceding claim in which the base or floor or lower surface of the reactor is flat, inclined, stepped or any other arrangement including combinations of two or more arrangements. 25

38. A bioreactor or method according to any preceding claim in which the floor or base of the reactor is arranged so as to have a high end and a low end with a multitude of steps over the length of the reactor 30 extending from the high end to the low end in which the steps create a small scale waterfall effect to assist in promoting efficiency of the reactions taking plave in the bioreactor. 35

39. A bioreactor or method according to any preceding claim in which the outlet device is an outlet duct in the form of a return duct for returning fluid back to one or N:\Melbourne\Cases\Patent\76000-76999\P26296.AU.l\Specis\Specification-Pinal.doc 30/01/09 - 47 more of the reactors forming the reactor.

40. A bioreactor or method according to any preceding claim in which the algal suspension has a dissolved carbon 5 dioxide concentration of form about zero percent to about 5 percent by weight.

41. A bioreactor or method according to any preceding claim in which the dissolved oxygen in the fluid builds up 10 during reactions within the reactor to be in the range from about 10 to about 50 mgs per litre.

42. A bioreactor or method according to any preceding claim in which the bioreactor is provided with a 15 turbulence inducing device for producing additional turbulence to that produced by the flow distribution device and/or inlet device by maintaining turbulence during flow of fluid through the reactor. 20

43. A bioreactor or method according to any preceding claim in which the turbulence device is located in or on the planar reactor downstream of the uniform flow distribution device. 25

44. A bioreactor or method according to any preceding claim in which the turbulence inducing device is a cylinder or series of cylinders located at substantially right angles to the direction of flow in the reactor. 30

45. A bioreactor or method according to any preceding claim in which the turbulence inducing device is a turbulence elements or trigger in the form of a multitude of turbulence devices arranged in side by side relationship to one another including extending barrier 35 element in the form of a tubular element, filamentary element, solid core element, hollow core element including from one side of the reactor to the opposite side of the N:\Melbourne\Cases\Patent\76000-76999\P?6296.AU.1\Specis\Specification-Final.dC 30/01/09 - 48 reactor.

46. A bioreactor or method according to any preceding claim in which the turbulence device is a wire laced from 5 alternative sides of the reactor extending lengthwise along all sides of the reactor by progressing down the opposite sides of the reactor and extending transversely to the other side of the reactor of the side. 10

47. A bioreactor or method according to any preceding claim in which the turbulence inducing device is one or more wires form about 1 to 10 mm in diameter, preferably up to about 5mm, or is a wire like material including nylon or plastic rope, string or other flexible tubing or 15 solid core material.

48. A bioreactor or method according to any preceding claim further comprising a degassing unit located in the outlet of the reactor. 20

49. A bioreactor substantially as herein described with reference to the accompanying drawings.

50. A method substantially as herein described with 25 reference to the accompanying drawings. N:\Melbourne\Cases\Patent\76000-76999\P76296.AU.1\Specis\Specification-Final.doc 30/01/09