COMBINED ALGAE PRODUCTION SYSTEM AND APPLICATION SYSTEM

Abstract

A combined algae bioreactor and heat-driven CO.sub.2 capture system for algae production is provided. The combined system includes a bioreactor with a parabolic trough collector (PTC) shaped structure, a PTC top surface with a spectrum-splitting coating, a thermal solar receiver, a liquid inlet, a liquid outlet, a CO.sub.2 feed pipeline, and gas release holes. The thermal solar receiver is arranged at the focal point of the bioreactor's PTC shape. The liquid inlet and the liquid outlet are arranged at two ends of a diagonal line of an opening of the bioreactor respectively. The CO.sub.2 feed pipeline is connected to the bottom end of the bioreactor. The gas release holes are arranged at the two ends of the opening of the bioreactor. A spectrum-splitting coating is applied on the bioreactor's PTC top surface, which promotes algae production.

Claims

1. A combined algae production system, comprising: a bioreactor, a parabolic trough collector (PTC) top surface, a thermal solar receiver, a liquid inlet, a liquid outlet, a CO.sub.2 feed pipeline, and gas release holes, wherein the bioreactor has a parabolic trough collector-shaped structure and an interior cavity structure; the thermal solar receiver is arranged at a focal point of the bioreactor; the liquid inlet and the liquid outlet are arranged at two ends of a diagonal line of an opening of the bioreactor respectively; the CO.sub.2 feed pipeline is connected to a bottom end of the bioreactor; the gas release holes are arranged at the two ends of the opening of the bioreactor; and an opening surface of the bioreactor is the PTC top surface.

2. The combined algae production system according to claim 1, wherein the PTC top surface performs transmission and reflection of a spectrum of incident sunlight, transmits a first part of the spectrum to the bioreactor, and reflects a second part of the spectrum to the thermal solar receiver; and the thermal solar receiver receives the second part of the spectrum reflected by the PTC top surface and performs thermal conversion.

3. The combined algae production system according to claim 1, wherein the PTC top surface is a spectrum-splitting coating material.

4. The combined algae production system according to claim 1, wherein the thermal solar receiver has a cylindrical hollow structure; and a position of the thermal solar receiver matches with the focal point of the bioreactor's PTC surface.

5. A combined algae production application system, comprising: the combined algae production system according to claim 1, a heat transfer fluid loop, and an algae fluid loop; wherein the algae fluid loop is configured to circulate algae solution into and out of the combined algae production system; and the heat transfer fluid loop is configured to transfer heat generated by the combined algae production system to a CO.sub.2 capture device to capture CO.sub.2, and convey the CO.sub.2 to the combined algae production system.

6. The combined algae production application system according to claim 5, wherein the heat transfer fluid loop comprises: a liquid storage subsystem and a CO.sub.2 capture subsystem; wherein the liquid storage subsystem supplies the heat generated by the combined algae production system to the CO.sub.2 capture subsystem through a first pipeline.

7. The combined algae production application system according to claim 6, wherein the liquid storage subsystem comprises: a liquid storage tank, a second liquid pump, and the thermal solar receiver, wherein the liquid storage tank, the second liquid pump and the thermal solar receiver are sequentially connected in a series circuit; and the liquid storage tank stores heat generated by the thermal solar receiver, and triggers flow in the heat transfer fluid loop through the second liquid pump.

8. The combined algae production application system according to claim 6, wherein the CO.sub.2 capture subsystem comprises: the CO.sub.2 capture device and a liquid storage tank; the CO.sub.2 capture device is connected to the liquid storage tank through a second pipeline; the CO.sub.2 capture device receives heat and atmospheric air stored in the liquid storage tank, and achieves CO.sub.2 capture by consuming the heat.

9. The combined algae production application system according to claim 5, wherein the algae fluid loop comprises: the bioreactor, an algae separator, and a first liquid pump, wherein the bioreactor, the algae separator and the first liquid pump are sequentially connected in a series circuit; the algae separator separates algae and water produced by the bioreactor, and triggers flow in the algae fluid loop through the second liquid pump to transfer remaining water back to the bioreactor.

10. The combined algae production application system according to claim 5, wherein the PTC top surface performs transmission and reflection of a spectrum of incident sunlight, transmits a first part of the spectrum to the bioreactor, and reflects a second part of the spectrum to the thermal solar receiver; and the thermal solar receiver receives the second part of the spectrum reflected by the PTC top surface and performs thermal conversion.

11. The combined algae production application system according to claim 5, wherein the PTC top surface is a spectrum-splitting coating material.

12. The combined algae production application system according to claim 5, wherein the thermal solar receiver has a cylindrical hollow structure; and a position of the thermal solar receiver matches with the focal point of the bioreactor's PTC surface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] To more clearly illustrate the technical schemes of the present invention, drawings are provided and are briefly introduced below. Indeed, these drawings are merely examples of the present invention and do not necessarily represent the complete scope of the present invention. Basic modifications such as choosing a different heat transfer fluid type, modifying the transmission and reflection spectral ranges of the spectral splitting film, etc. still involve applying the same concept as the present invention and thus are still considered as being within its scope.

[0036] FIG. 1 is a schematic that shows the modified algae bioreactor structure according to the present invention;

[0037] FIG. 2 is a block diagram of the combined algae production system that comprises the new algae bioreactor and according to the present invention; and

[0038] FIG. 3 is a graph that shows the ideal transmission and reflection spectral ranges by the spectrum splitting coating on the PTC top surface.

[0039] In the drawings: 1, bioreactor; 2, spectrum-splitting coating material; 3, thermal solar receiver; 4, incident sunlight; 5, reflected light; 6, transmitted light; 7, liquid inlet; 8, liquid outlet; 9, CO.sub.2 feed pipeline; 10, gas release hole; 11, new bioreactor; 12, liquid storage tank; 13, CO.sub.2 capture device, 14 & 15, liquid pump; 16, algae separator; 17, algae product; 18, atmospheric air; 19, captured CO.sub.2.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] The technical schemes in the embodiments of the present invention will be clearly described below and illustrated via the drawings. Based on these embodiments, all other embodiments that involve minor modifications but do not change the working principle of the present invention shall fall within this invention's protection scope.

[0041] FIG. 1 discloses a modified bioreactor design that comprises a bioreactor 1, a PTC top surface, a thermal solar receiver 3, a liquid inlet 7, a liquid outlet 8, a CO.sub.2 feed pipeline 9, and gas release holes 10.

[0042] Specifically, the bioreactor 1 has a parabolic trough collector (PTC) shaped structure and an interior cavity.

[0043] The thermal solar receiver 3 is positioned at the focal point of the bioreactor 1's PTC top surface.

[0044] The liquid inlet 7 and the liquid outlet 8 are arranged at two ends of a diagonal line at an opening of the bioreactor 1 respectively.

[0045] The CO.sub.2 feed pipeline 9 is connected to the bottom of the bioreactor 1.

[0046] The gas release holes 10 are arranged at the two ends of the opening of the bioreactor 1.

[0047] The walls in bioreactor 1 are made of glass.

[0048] The PTC top surface comprises a glass wall that is coated with spectrum-splitting coating material 2, which is an ideal band-pass dichroic filter.

[0049] The thermal solar receiver 3 has a cylindrical hollow structure.

[0050] The material of the thermal solar receiver 3 can be graphite and ideally should have an absorption coefficient of 1 at all electromagnetic wavelengths to photothermally convert the reflected light 5 into heat.

[0051] During operation, incident sunlight 4 is incident on the PTC top surface of bioreactor 1, which contains light within the broad range of the electromagnetic spectrum (approx. 200 nm to 2500 nm).

[0052] The PTC top surface performs transmission and reflection of incident sunlight, where the spectral range that is favorable for algae photosynthesis (400 nm to 500 nm and 600 nm to 700 nm) is transmitted into the bioreactor space. Specifically, the transmitted light is marked as 6 in FIG. 3 and is progressively absorbed by the algae as it travels through the bioreactor space;

[0053] Meanwhile, the other spectral ranges (marked as reflected light 5 in FIG. 3) are reflected towards the thermal solar receiver, which then performs thermal energy conversion.

[0054] FIG. 2 discloses the combined algae production system that comprises the modified bioreactor design 11 of FIG. 1, a heat transfer fluid loop, an algae fluid loop, and a heat-driven CO2 capture device.

[0055] The algae fluid loop circulates the algae solution into and out of the modified bioreactor design 11.

[0056] The heat transfer fluid loop is configured to transfer heat generated by the modified bioreactor design 11 to a CO.sub.2 capture device 13 to capture CO.sub.2, and the captured CO.sub.2 is passed into the bioreactor 1.

[0057] The heat transfer fluid loop comprises a liquid storage tank 12, and two liquid pumps 15 and 20.

[0058] The first liquid pump 15, the thermal solar receiver 3, and the liquid storage tank are sequentially connected in a series circuit.

[0059] The first liquid pump 15 pumps fluid through the solar thermal receiver 3 to collect and transfer the photothermally generated heat into the liquid storage tank.

[0060] The second liquid pump 20, the heat-driven CO.sub.2 capture device 13, and the liquid storage tank are sequentially connected in a series circuit.

[0061] The liquid storage tank's purpose is to maintain a relatively consistent temperature for the heat-driven CO.sub.2 capture device regardless of fluctuations and intermittent inputs from the thermal solar receiver 3. The liquid storage tank may be any conventional corrosion-resistant tank and should be sized according to the maximum tolerable temperature fluctuation requirement of the heat-driven CO.sub.2 capture device.

[0062] The heat-driven CO.sub.2 capture device 13 may be any method that consumes heat to capture CO.sub.2, which may include chemical absorption or physical adsorption. In the below description, an example is described by considering a typical adsorption technology that operates in a cyclic manner between the adsorption and regeneration modes. During adsorption, atmospheric air is continuously blown through an adsorbent material to adsorb CO.sub.2 from the flowing air. Then, during regeneration, the adsorbent material is isolated from the atmosphere, and high-temperature heat should be applied to regenerate the material (i.e., release the adsorbed CO.sub.2 and make it gaseous). Here, a fluid heat exchanger is installed within the heat-driven CO.sub.2 capture device, and the second liquid pump 20 pumps fluid from the liquid storage tank to this fluid exchanger to provide the required heat for the regeneration process.

[0063] The algae fluid loop comprises the bioreactor 1, an algae separator 16, and the third liquid pump 14 that are sequentially connected in a series circuit.

[0064] The algae separator 16 separates algae from the water solution that originated from the bioreactor 1, and the third liquid pump 14's pumping action allows the remaining solution to return to the bioreactor 1.

[0065] The fluid used in the heat transfer fluid loop can be any common non-toxic liquid provided that it remains as a liquid at the operating temperatures of the thermal solar receiver 3 (≈100° C.). A typical example is a water-glycol solution.

[0066] The algae separator 16 can be comprised of any type of conventional separation technology. In the present description, a separation method based on a 3-way valve is described. Its operation is as follows. The three-way valve is first opened to allow an outflow of the algae-water solution to a collection tank. Then, this collected algae-water solution is further treated in a separation machine such as a membrane separator, a precipitator, flocculation, etc. After a sufficient amount of the algae-water solution is removed, the 3-way valve is then switched to allow the entrance of clean water to replenish that lost from the previously removed algae-water solution.

[0067] Overall, in the present invention, the concept of redirecting the electromagnetic spectrums that are outside the ideal range for photosynthesis has brought many beneficial features that ultimately increased the specific volume of algae growth rate. Firstly, by reflecting the unusable spectrums for photosynthesis, the potential for large heat generation within the bioreactor space is avoided. This is beneficial especially when the algae bioreactor 1 operates in a humid hot climate (e.g. >33° C., RH>75%) where a slight increase in temperature could significantly lower the algae growth rate. Secondly, the unusable spectrums are, for the first time, effectively utilized as an energy source for the capture of CO.sub.2 from the atmosphere. Thus, CO.sub.2 that is void of harmful contaminants (e.g., NOx, SOx, etc.) with concentrations optimal for algae growth (3% to 6%) can be used for algae cultivation without the consumption of significant external energy. In summary, the present invention is simple in design and only requires minor modifications to the geometry of a bioreactor 1. The other components in the present invention, such as an algae water loop and the bioreactor 1 are basic components that would already be required by a conventional bioreactor system, and the HTF fluid loop is easily constructible from commercial parts. Therefore, the present invention is economically feasible and can be easily deployed at industrial scales.