Device and Method for the Sequestration of Atmospheric Carbon Dioxide

Abstract

The invention relates to a device and to a method for sequestering atmospheric carbon dioxide using at least one air capture module in conjunction with a biorcactor equipped with an autotrophic microorganisms.

Claims

1. A device for sequestering atmospheric carbon dioxide, the device comprising at least one module comprising a capture unit configured for binding the atmospheric carbon dioxide by way of an adsorber material and, after treatment by way of heat or a vacuum, the atmospheric carbon dioxide being kept available, and the at least one module being connected to at least one bioreactor, wherein the atmospheric carbon dioxide is continuously supplied to autotrophic microorganisms in the at least one bioreactor.

2. The device for sequestering atmospheric carbon dioxide according to claim 1, wherein the atmospheric carbon dioxide is kept available in a container.

3. A device for sequestering atmospheric carbon dioxide, the device comprising a module comprising a capture unit, wherein the atmospheric carbon dioxide is bound by way of an adsorber material and, after treatment by way of heat or a vacuum, the atmospheric carbon dioxide is kept available in a pressurized container, and at least one bioreactor containing autotrophic microorganisms.

4. The device for sequestering atmospheric carbon dioxide according to claim 1, further comprising at least one gas-liquid separator.

5. The device for sequestering atmospheric carbon dioxide according to claim 1, wherein the at least one bioreactor is a photobioreactor or an open pond bioreactor.

6. The device for sequestering atmospheric carbon dioxide according to claim 1, wherein the at least one module is an air capture module.

7. The device for sequestering atmospheric carbon dioxide according to claim 1 wherein the autotrophic microorganisms are photoautotrophic microorganisms, or chemoautotrophic microorganisms.

8. The device for sequestering atmospheric carbon dioxide according to claim 1, wherein the atmospheric carbon dioxide is supplied to the autotrophic microorganisms in the at least one bioreactor together with air.

9. The device for sequestering atmospheric carbon dioxide according to claim 1, wherein 5 to 50% of a culture medium in the at least one bioreactor is replaced.

10. A method for sequestering atmospheric carbon dioxide, at least one module comprising a capture unit configured for binding the atmospheric carbon dioxide by way of an adsorber material and, after treatment by way of heat or a vacuum, the atmospheric carbon dioxide being kept available, and the at least one module being connected to at least one bioreactor, wherein the atmospheric carbon dioxide is continuously supplied to autotrophic microorganisms in the at least one bioreactor.

11. The method for sequestering atmospheric carbon dioxide according to claim 10, wherein the at least one bioreactor is operated continuously.

12. A method for sequestering atmospheric carbon dioxide from ambient air, the method comprising utilizing the device according to claim 1.

13. The device according to claim 2, wherein the container is a pressurized container.

14. The device for sequestering atmospheric carbon dioxide according to claim 7, wherein the autotrophic microorganisms are of the genus Chlorella.

15. The device for sequestering atmospheric carbon dioxide according to claim 8, wherein a ratio of carbon dioxide to air is from 1:99 vol. % CO.sub.2/air to 10:90 vol. % CO.sub.2/air.

16. The device for sequestering atmospheric carbon dioxide according to claim 7, wherein the autotrophic microorganisms are selected from the group consisting of Archaea bacteria, algae, micro algae, Chlorella, Scenedesmus, Spirulina, Nannochloropsis, Nostoc, and Chlorococcus.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0018] FIG. 1A shows an exemplary embodiment of a device for sequestering atmospheric carbon dioxide according to the invention.

[0019] FIG. 1B shows another exemplary embodiment of a device for sequestering atmospheric carbon dioxide according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0020] It is an object of the invention to provide a suitable device or a method for sequestering atmospheric carbon dioxide by producing biomass.

[0021] To achieve this object, the invention thus relates to a device for sequestering atmospheric carbon dioxide, wherein at least one module comprising a capture unit binds atmospheric carbon dioxide by way of an adsorber material and, after treatment by way of heat or a vacuum, the atmospheric carbon dioxide is kept available, and the module is connected to at least one bioreactor, wherein atmospheric carbon dioxide is continuously supplied to autotrophic microorganisms in at least one bioreactor.

[0022] In another preferred embodiment, the invention relates to a device for sequestering atmospheric carbon dioxide, wherein at least one module comprising a capture unit binds atmospheric carbon dioxide by way of an adsorber material and, after treatment by way of heat or a vacuum, the atmospheric carbon dioxide is kept available in a container, in particular a pressurized container, wherein atmospheric carbon dioxide is continuously supplied to autotrophic microorganisms in at least one bioreactor.

[0023] In another embodiment, the invention relates to a device for sequestering atmospheric carbon dioxide, comprising a module comprising a capture unit, wherein atmospheric carbon dioxide is bound by way of an adsorber material and, after treatment by way of heat or a vacuum, the atmospheric carbon dioxide is kept available in a pressurized container, and at least one bioreactor containing autotrophic microorganisms.

[0024] A pressure reducer can be assigned to such a pressurized container, so that a continuous CO.sub.2 stream can be provided, if necessary using measuring and control technology.

[0025] In another preferred embodiment, atmospheric carbon dioxide can be supplied to autotrophic microorganisms in at least one bioreactor together with air. Ratios of 5:95 vol. % CO.sub.2/air, and in particular from 1:99 vol. % CO.sub.2/air to 10:90 vol. % CO.sub.2/air, are preferred.

[0026] To achieve this object, the invention thus likewise relates to a method for sequestering atmospheric carbon dioxide, wherein at least one module comprising a capture unit binds atmospheric carbon dioxide by way of an adsorber material and, after treatment by way of heat or a vacuum, the atmospheric carbon dioxide is kept available, and the module is connected to at least one bioreactor, wherein atmospheric carbon dioxide is continuously supplied to autotrophic microorganisms in at least one bioreactor.

[0027] The prior art describes the sequestration of CO.sub.2 from industrial waste gases by way of a bioreactor, which, however, is entirely different, since such waste gases are of a different quality and, air contains other harmful substances and has an insufficient CO.sub.2 concentration.

[0028] In a preferred embodiment, the device according to the invention includes such features according to FIG. 1a or FIG. 1b, whereby the above-described problems can be solved completely for the first time.

[0029] Preferably, bioreactor modules that run parallel and are connected to one another are used (1a-1n, FIGS. 1a, 1b). These are fed a nutrient solution including the autotrophic microorganism to be cultivated, preferably microalgae of the genus chlorella, Scenedesmus, Spirulina, Nannochloropsis, Nostoc or Chlorococcus (3, FIGS. 1a, 1b). Chemically pure CO.sub.2 is introduced into the nutrient solution, preferably together with air, wherein the CO.sub.2 preferably stems from a connected air capture module (carbon dioxide recovery installation) (2, FIGS. 1a, 1b). In particular, the aforementioned algae exhibit favorable growth rates in the device according to the invention, including the method according to the invention that is carried out.

[0030] The company Climeworks in Switzerland (climeworks.com) produces functional air capture modules, for example, which can be connected to the bioreactor in accordance with the invention. Atmospheric CO.sub.2 is bound by way of these air capture modules (10, FIGS. 1a, 1b) and can subsequently be released again by way of heating at approximately 100 C. In contrast, atmospheric oxygen or nitrogen is not bound, but is returned into the atmosphere (11, FIGS. 1a, 1b). By combining the air capture module with a bioreactor, it is achieved for the first time that atmospheric CO.sub.2 is pre-concentrated in a form that is optimal for microorganisms, without additional interfering components, such as harmful substances or algae predators, being present. The latter are efficiently destroyed by the heating process for CO.sub.2 release.

[0031] A measuring and control unit (5, FIGS. 1a, 1b) measures critical parameters such as the CO.sub.2 concentration, pH value, algae biomass per unit of volume. Thereafter, the solution is transferred into the bioreactor via a system pump (6, FIGS. 1a, 1b). In the case of photobiorcactors, illumination takes place (9, FIGS. 1a, 1b). As a result of the translucency of the material, the preferred algae according to the invention, serving as the microorganism, are able to carry out photosynthesis. The optimal CO.sub.2 concentration, which can be flexibly set by way of the air capture module, causes considerable reproduction in the reactor modules. Algae biomass can, on the one hand, be given off continuously via a central measuring and control unit (7, FIGS. 1a, 1b) and processed by way of common methods.

[0032] On the other hand, this is preferably a continuous bioreactor, which can operate in a circuit. The algae are conducted across a vapor-liquid separator (also: gas-liquid separator) (8, FIG. 1a). The principle of gas separation from a photobioreactor operated with microalgae is known. For example, the algae can be conducted through a chamber containing a semipermeable membrane, by which the gases (O.sub.2/CO.sub.2) present in the liquid are removed by way of diffusion. Another technical solution is the use of a mechanical, vortex-driven gas separator (Fasoulas et al., University of Stuttgart, status report on the 2nd preliminary result within the scope of the project 50 JR 1104 Regenerative Lebenserhaltungssysteme fr die Raumfahrt mit synergetisch integrierten Photobioreaktoren und Brennstoffzellen (Regenerative life-sustaining systems for the aerospace industry with synergetically integrated photobioreactors and fuel cells) funded by the DLR space agency in the time period, 2014). The gas (oxygen and unconsumed CO.sub.2) is returned into the air capture module via the separator (2, FIGS. 1a, 1b). In the process the O.sub.2 escapes, wherein the CO.sub.2 is bound again and conducted into the circuit. This advantageously solves the problem of the continuous removal of O.sub.2. The algae are conducted from the vapor-liquid separator into the central cultivation tank again (3, FIGS. 1a, 1b). Here, the CO.sub.2 concentration can now be set to the optimal value again, and nutrient solution can be supplied from outside (4, FIGS. 1a, 1b).

[0033] The invention thus relates to such a device according to the invention which additionally comprises a gas-liquid separator, so that a continuous circulatory process can advantageously be achieved, and arising oxygen can be removed.

[0034] In another preferred embodiment, 5 to 50% of the culture medium or nutrient solution is replaced within a day. The device comprises a measuring unit (7, FIG. 1a), for example, which opens a faucet at a defined biomass concentration (for example, 1 g/liter, measured by way of the optical density (OD650.sub.nm) of the medium) so as to conduct a defined proportion of the culture medium into a collection vessel. At the same time, the missing and fresh culture volume (4, FIG. 1a) is supplied again.

[0035] The installation can likewise be operated with chemo (litho) autotrophic bacteria, such as Archaea bacteria, which likewise receive CO.sub.2 via the air capture module. A light reaction is not required, but an energy source in the form of H.sub.2 (molecular hydrogen) is.

[0036] NaHCO.sub.3 (4.0510.sup.2 M), Na.sub.2CO.sub.3 (9.5010.sup.3 M), K.sub.2HPO.sub.4 (7.1710.sup.4 M), NaNO.sub.3 (7.3510.sup.3 M), K.sub.2SO.sub.4 (1.4310.sup.3 M), NaCl (4.2710.sup.3 M), MgSO.sub.47H.sub.2O (4.1510.sup.4 M), CaCl.sub.2)2H.sub.2O (9.0110.sup.5 M), FeSO.sub.47H.sub.2O (1.6410.sup.5 M), EDTA=Titriplex III (0.04 g/L)+2.5 ml/L micro nutrient medium (2.2 mg/L ZnSO.sub.47H.sub.2O, 25 mg/L MnSO.sub.44H.sub.2O, 28 mg/L H.sub.3BO.sub.3, 2 mg/L Co[NO.sub.3]26H.sub.2O, 0.21 mg/L Na.sub.2 MoO.sub.42H.sub.2O, 0.79 mg/L CuSO.sub.45H.sub.2O)+1 ml/L Vitamin B12 (1.5 g/L). The pH value is 9.3.

[0037] Initially, a sterile starter culture (1 L) is inoculated with Spirulina platensis (Culture Collection of Algae Gttingen, SAG) in the above-described nutrient solution in a shake flask (shake frequency of 100 to 120 rpm) and cultivated in the batch for 3 to 4 days. The photon flux density (PFD) is set to 100 to 150 mol/m.sup.2s. The gasification is carried out by way of a cotton stopper and diffusion.

[0038] The flat plate photobioreactor is inoculated with this starter culture, and the entire system (see FIG. 1) is put into operation. It is gasified with a mixture of 5% CO.sub.2/air. The medium is preferably moved by way of a system pump, or the medium can also be circulated by way of a membrane-assisted so-called air-lift technique. The temperature of the nutrient medium in the reactor is preferably 30 C.

[0039] The installation is designed so as to be operable in a batch process, that is, the biomass is only harvested once at the end of the experiment. In this case, the bioreactor is operated for 5 to 8 days. The highest productivity, however, is preferably achieved during continuous or semi-continuous operation. A defined proportion of the reactor volume is replaced with fresh culture medium or nutrient medium in the process (see devices 4 and 7 in FIG. 1a). The highest productivity is achieved when 30% of the nutrient medium is replaced every day. In the batch process, the productivity is, on average, 500 to 800 mg algae biomass/liter/day. By continuously replacing the nutrient medium (30% per day), a productivity of 1.5 g algae biomass/liter/day is achieved.

[0040] Algae biomass using open pond bioreactor (Appl Microbiol Biotechnol (2007) 74:1163-1174)): Instead of the flat plate photobioreactor, an open system is used, which has a volume of 500 L. The nutrient medium (see above) is continuously circulated using a flow rate of 0.2 to 0.5 m s.sup.1 by way of electrically operated bucket wheel-like paddles. The open pond system is operated in a batch process or in a semi-continuous process. After inoculation with 10 liters of spirulina starter culture (see above), the cultivation is carried out in a batch process up to 7 days. In the semi-continuous process, a certain proportion (for example 10%) of the medium in which the microalgae have multiplied is harvested every day, and replaced with new medium. The open pond system is illuminated in a closed space from above using LEDs of the BX180 series (Valoya, Finland). The open pond system is gasified with a 2.5% CO.sub.2/air mixture. The CO.sub.2 is provided by way of an air capture module. The room temperature is 24 C. After seven days, the biomass is harvested or the bioreactor is run on a semi-continuous basis. The concentration of the biomass is approximately 5 g/L.

Example 5

Example of Carbon Sequestration by Way of Humus Formation

[0041] One of the following microalgae capable of nitrogen fixation is inoculated in the closed photobioreactor or in the open pond system with CO.sub.2 supply (mixture of 2.5% CO.sub.2 and air): Nostoc, Anabaena, Aulosira, Tolypothrix, Nodularia, Cylindrospermum, Scytonema, Aphanothece, Calothrix, Anabaenopsis, Mastigocladus, Fischerella, Stigonema, Haplosiphon, Chlorogloeopsis, Camptylonema, Gloeotrichia, Nostochopsis, Rivularia, Schytonematopsis, Westiella, Westiellopsis, Wollea, Plectonema, Chlorogloea.

[0042] Nostoc muscorum is well-suited for the open pond system and grows in liquid medium in a manner similar to spirulina. Nostoc muscorum is cultivated for 14 days and then harvested as a batch. As an alternative, a semi-continuous cultivation is carried out, wherein every day approximately 10% of the resultant biomass is harvested, and the withdrawn medium is replaced with fresh culture medium. During the cultivation phase, atmospheric nitrogen is fixed by the algae. The algae biomass is dried. The batch process results in a yield of 700 mg biomass/L. The dry biomass is pressed to form granules, which are distributed in the soil as biofertilizer. This algae biomass is largely composed of carbon (>50%), which stems from the CO.sub.2 fixation in the case of autotrophic growth. The inoculation of a suitable soil substrate with Nostoc also results in an improvement in the supply of nitrogen. The biomass has a ratio of carbon to nitrogen of 10 to 15:1.

[0043] The biofertilizer made of algae biomass improves the growth of plants, such as trees, whereby further CO.sub.2 sequestration is enabled.