System for cultivation and processing of microorganisms, processing of products therefrom, and processing in drillhole reactors

Abstract

Methods of cultivating autotrophic microorganisms, particularly microalgae or diatoms, in a bioreactor by entraining a culture of the microorganisms in a tenuous, gelated, thixotrophic carrier medium having nutrients therefor and moving the medium along a passage at a sufficiently slow speed to enable laminar flow which in cross section is closed and which has transparent walls through which the culture is irradiated to enable photosynthesis. The method includes effecting convective turnover of the culture and medium as they flow along the passage by differentially heating the medium laterally relative to the flow direction so as to produce a generally helical flow of the culture and medium. Also described are processing methods, both physical and chemical, performed underground e.g. in drillholes, to utilise decavitation energy under ambient elevated pressures, including processes to implement lysis of the micro-organisms, producing methanol, syngas synthesis, Haber ammonia synthesis, Fischer-Tropsch reactions, supercritical reactions, dimethyl ether synthesis, and nitric acid synthesis.

What is claimed is: 
     
         1 . A method of performing processing operations on a flowable feed material in a drillhole reactor, the flowable feed material being composed of a carrier liquid, reactants to be subjected to and to take part in the processing operations, and gas bubbles of predetermined sizes and/or contents that are entrained in or formed in the carrier liquid and which perform functionally in and promote the performance of the processing operations, the method comprising the steps of: flowing the feed material from an initial level down a confined path or drill hole which descends underground by a substantial vertical distance to a working depth so that the pressure experienced by the feed material at that working depth is substantially greater than the initial level and the gas bubbles are reduced in size by compression, said gas bubbles being of sizes chosen to decavitate at predetermined pressures which are reached or exceeded in the feed material at various working depths; providing working conditions for the flowing feed material at the working dept h to utilise the relatively high pressure in performing the processing operations on the feed material and so produce a flowable output material, the working conditions including promote the processing operations which produce reaction products which are included in the flowable output material, said working conditions comprising conditions in which the gas bubbles collapse violently or implode upon decavitation producing energetic microjets of liquid and intense but short-lived, and highly-localised heating which promote the performance of the processing operations in the immediate vicinity of each gas bubble decavitation even when the bulk temperature of the feed material would otherwise be insufficient to progress the desired reactions; and returning the flowable output material produced by the processing operations at the working depth by a return passage from the working depth at least a substantial vertical distance away from the working depth so as to conduct further processing operations on the reaction products within the flowable output material. 
     
     
         2 . A method as claimed in claim wherein the corn position of the flowable feed material includes at least one promoter agent operative to further promote the performance of the process operations at the working depth, the promoter agent being selected from: gaseous additives in the carrier liquid in addition to said reactants, and catalysts provided in the carrier liquid. 
     
     
         3 . A method as claimed in  claim 2  wherein the promoter agent comprises said gas bubbles that compress at increasing depth, providing adiabatic heating to the processes and cooling when the bubbles decompress. 
     
     
         4 . A method as claimed in  claim 1  wherein the processing operations include chemical reactions induced to occur within the flowable feed material, the chemical reactions being initiated, caused, accelerated, or enhanced as a result of changes in pressure and temperature to which the feed material is subjected in descending from the initial level to the working level or experienced at the working level including adiabatic compression of the gas bubbles, decavitation and the consequent promotion of the chemical reactions, and wherein surfaces of the confined path for the feed material provide locations of catalytic surfaces promoting the chemical reactions. 
     
     
         5 . A method as claimed in  claim 1  wherein the processing operations include chemical reactions induced to occur within the flowable feed material, the chemical reactions being initiated, caused, accelerated, or enhanced as a result of changes in pressure and temperature to which the feed material is subjected in descending from the initial level to the working level or experienced at the working level including adiabatic compression of the gas bubbles, decavitation and the consequent promotion of the chemical reactions, and wherein the path comprises a passage or bore which descends underground by at least 100 metres, and preferably by some thousands of metres, so that the pressure in the fluid at that depth is of the order of 1,000 atmospheres, and wherein the feed material comprises a heated mixture of reactant fluids (typically heated via heat exchangers located on the ground surface level or by the underground introduction of superheated steam or other fluid into the feed material in the passage) which are entrained typically as said bubbles in a fast moving, catalyst bearing high boiling point carrier liquid such as residual fuel oil, and at the working depth in the passage or bore there is generated methanol from stoichiometric volumes of methane, steam, oxygen and carbon dioxide. 
     
     
         6 . A method as claimed in  claim 1  wherein the processing operations include chemical reactions induced to occur within the flowable feed material, the chemical reactions being initiated, caused, accelerated, or enhanced as a result of changes in pressure and temperature to which the feed material is subjected in descending from the initial level to the working level or experienced at the working level including adiabatic compression of the gas bubbles, decavitation and the consequent promotion of the chemical reactions, and wherein the chemical react on comprises synthesis of a syngas comprising a mixture of carbon monoxide (CO) and hydrogen (H.sub.2), the feed material comprising said bubbles composed of a mix of oxygen and car bon dioxide and steam in an aqueous carrier liquid forming a slurry of carbon based, organic substances and wherein the slurry at least upon reaching the working level achieves either sub or supercritical water conditions. 
     
     
         7 . A method as claimed in claim S wherein the syngas synthesised is converted in the drillhole reactor under pressure and in the presence of a multifunction catalyst first to methanol and then to dimethyl ether. 
     
     
         8 . A method as claimed in  claim 6  where the carbon-based substances includes one or more of: microorganisms, algae or algal cell wall material, crop and forestry wastes, lignocellulose products, sewage, plastics and rubber, wastewater, or wastes from agribusiness, pulp mills, or other carbon based products from industrial sources and waste recycling. 
     
     
         9 . A method as claimed in  claim 1  wherein the processing operations include chemical reactions induced to occur within the flowable feed material, the chemical reactions being initiated, caused, accelerated, or enhanced as a result of changes in pressure and temperature to which the feed material is subjected in descending from the initial level to the working level or experienced at the working level including adiabatic compression of the gas bubbles, decavitation and the consequent promotion of the chemical reactions, and wherein the is chemical reaction comprises a Haber ammonia synthesis and wherein the feed material includes said gas bubbles composed of mixed nitrogen and hydrogen gases in stoichiometric proportions, and suitable catalyst substances, promoters and densifiers added to the reactants or carrier liquid to promote the Haber process. 
     
     
         10 . A method as claimed in  claim 1  wherein the processing operations include chemical reactions induced to occur within the flowable feed material, the chemical reactions being initiated, caused, accelerated, or enhanced as a result of changes in pressure and temperature to which the feed material is subjected in descending from the initial level to the working level or experienced at the working level including adiabatic compression of the gas bubbles, decavitation and the consequent promotion of the chemical reactions, and wherein the chemical reaction comprises a Fischer-Tropsch alkane synthesis and wherein the feed material includes said gas bubbles composed of syngas comprising a mixture of carbon monoxide (CO) and hydrogen (H.sub.2) and wherein suitable catalytic substances and promoters are either added to the reactants or to the liquid carrier or are located in a separate assembly to promote the Fischer-Tropsch process. 
     
     
         11 . A method as claimed in  claim 10  wherein the reactants comprise syngas produced by a chemical reaction in which the feed material comprising said bubbles is composed of a mix of oxygen and carbon dioxide and steam in an aqueous carrier liquid forming a slurry of carbon based, organic substances and wherein the slurry at least upon reaching the working level achieves either sub or supercritical water conditions, and wherein the production of syngas is carried out at a first working depth, and wherein the Fischer-Tropsch synthesis is carried out at a second working depth to which the products from the syngas synthesis are flowed. 
     
     
         12 . A method as claimed in  claim 1  wherein the processing operations include chemical reactions induced to occur within the flowable feed material, the chemical reactions being initiated, caused, accelerated, or enhanced as a result of changes in pressure and temperature to which the feed material is subjected in descending from the initial level to the working level or experienced at the working level including adiabatic compression of the gas bubbles, decavitation and the consequent promotion of the chemical reactions, and wherein the carrier liquid is composed of at least one of said reactants and includes lipids, and wherein the chemical reaction comprises a transesterification reaction with excess methanol conducted under controlled temperature and pressure conditions at a predetermined level in a drillhole reactor where elevated pressures and decavitation are experienced sufficient to facilitate the transesterification reaction. 
     
     
         13 . A method as claimed in  claim 12  wherein the further processing operations performed on the reaction products are performed in the upwardly flowing material in the return passage and include applying sub or supercritical conditions which are progressively relaxed as the flowable output material flows upwardly whereby derail precipitations of different fractions occur within the flowing material and successive separations of the precipitating fractions are performed. 
     
     
         14 . A method as claimed in  claim 13  wherein the carrier liquid h a lower supercritical temperature than water whereby molecular fractions liable to damage or denaturing by relatively high temperature exposure can be effectively separated. 
     
     
         15 . A method of cultivating microorganisms, particularly microalgae or diatoms, in a bioreactor comprising the steps of: entraining a culture of the microorganisms in a tenuous, gelated, thixotropic carrier medium having nutrients therefor and moving the medium along a passage which in cross section is closed and which has transparent walls through which the culture is irradiated to enable photosynthesis; providing process parameter control means associated with the passage; and selectively varying the process parameter control means to thereby selectively control parameters or conditions of the cultivation and photosynthetic activity of the microorganisms moving within the passage. 
     
     
         16 . A method as claimed in  claim 15  and further including the steps of: moving the carrier medium at a sufficiently slow speed to enable laminar flow thereof along the passage; and effecting convective turnover of the culture and medium as they flow along the passage by differentially heating the medium laterally relative to the flow direction so as to produce a generally helical flow of the culture and medium, and wherein the carrier medium has a viscosity or tenuous structure sufficient to impede gravitational settling, surface scumming, or deposition onto solid surfaces by the microorganisms, at the same time as prolonging the residence time in the medium of the gaseous phase nutrient and impeding clumping of the microorganisms into less productive clusters. 
     
     
         17 . A method as claimed in  claim 15  wherein the microorganism bearing medium is moved through alternating zones of relatively higher and relatively lower insolation so that microorganisms are exposed to photosynthetically active radiation (PAR) in a pulsed manner, preferably with the duration of each complete cycle of higher and lower PAR exposure being less than one second and preferably with somewhat greater recovery time of relative darkness than the PAR exposure time of each cycle whereby radiation can most efficiently be photosynthesised by microorganisms and reducing the likelihood or effect of photoinhibition in the microorganisms. 
     
     
         18 . A method as claimed in  claim 17  whereby the transparent outer envelope top surface is provided with bands or stripes having PAR attenuating or excluding properties relative to the transparent parts of the envelope between successive bands, the bands extending generally transverse to the direction of flow of the medium, whereby the bands, their adaptive width and their relative placement define the width and separation of the alternating zones of relatively higher and relatively lower insolation within the passage. 
     
     
         19 . A method as claimed in  claim 18  wherein the ribbons, bands, strips or stripes are provided by bodies having shapes or configurations that are thermally responsive so as to provide relatively greater areas to intercept incident radiation upon being heated above a certain threshold, and wherein the bodies comprise transverse-curled or rolled material having the property of progressively uncurling or unrolling upon exposure to a threshold and higher temperatures by incident radiant energy or increasing ambient temperature. 
     
     
         20 . A method of cultivating microorganisms, particularly microalgae or diatoms, in a bioreactor comprising the steps of: entraining a culture of the microorganisms in a carrier medium having nutrients therefor and moving the medium along a closed passage having transparent walls through which the culture is irradiated to enable photosynthesis, the transparent walls having multiple bands or strips or ribbons of material having photosynthetically active radiation (PAR) attenuating properties relative to the transparent walls between successive bands, the bands, strips or ribbons extending generally transverse to the direction of flow of the medium, whereby the bands, strips or ribbons, their effective width and their relative placement define the width and separation of the alternating zones of relatively higher and relatively lower insolation within the passage; providing process parameter control means associated with the passage; and selectively varying the process parameter control means to thereby selectively control parameters or conditions of the cultivation and photosynthetic activity of the microorganisms moving within the passage.