PHOTOBIOREACTOR IN A CLOSED ENVIRONMENT FOR CULTIVATING PHOTOSYNTHETIC MICRO-ORGANISMS

Abstract

The invention relates to a photobioreactor for cultivating photosynthetic micro-organisms, comprising: a) at least one cultivation container (1) for containing the culture medium (3) of the micro-organisms, b) photovoltaic cells (2) isolated from the culture medium (3), emitting light towards the culture medium (3), and c) means (4) for powering the photovoltaic cells (2) in order to operate the photovoltaic cells in light emission mode.

Claims

1. Photobioreactor for cultivating photosynthetic micro-organisms, comprising: at least one culture enclosure for containing a culture medium of the micro-organisms; reverse emission photovoltaic cells isolated from the culture medium, made of a direct gap material, and configured to emit light to the culture medium, wherein said reverse emission photovoltaic cells include current injection contacts for receiving electric current which is used by said reverse emission photovoltaic cells to emit light.

2. Photobioreactor according to claim 1, wherein the reverse emission photovoltaic cells are arranged on panels.

3. Photobioreactor according to claim 1, wherein the reverse emission photovoltaic cells are cells with one or two junctions.

4. Photobioreactor according to claim 1, wherein the reverse emission photovoltaic cells are made of a III/V material.

5. Photobioreactor according to claim 1, wherein the reverse emission photovoltaic cells are placed in sealed containers of adapted transparency (TA) immersed in the culture medium.

6. Photobioreactor according to claim 1, wherein the photovoltaic cells are placed outside the culture enclosure(s), at a short distance from the external wall of the culture enclosure(s) and the external wall of the culture enclosure(s) consists of a material of adapted transparency for the passage of the wavelength(s) emitted by said photovoltaic cells.

7. Photobioreactor according to claim 6, comprising a plurality of parallelepipedic culture enclosures, stacked and separated by panels of photovoltaic cells.

8. Photobioreactor according to claim 1, comprising a system for cooling the photovoltaic cells.

9. Photobioreactor according to claim 1, comprising a system for mixing the culture medium.

10. Photobioreactor according to claim 1, wherein further; said culture enclosure for containing the micro-organism culture medium is cylindrical, and said photovoltaic cells isolated from the culture medium cover panels, said panels extending along approximately the entire height of the culture enclosure, placed in sealed tube of adapted transparency immersed in the culture medium and arranged as a tube having a polygonal cross-section.

11. Photobioreactor according to claim 1, further comprising: a plurality of parallelepipedic culture enclosures, stacked and separated by panels containing said photovoltaic cells, said panels having the dimensions of one face of the culture enclosure.

Description

FIGURES

[0084] FIG. 1: LED emission diagram

[0085] FIG. 2: Photovoltaic cell emission diagram

[0086] FIG. 3: Photovoltaic cell emission diagram with injection current boost at edges

[0087] FIG. 4: LED juxtaposition emission diagram

[0088] FIG. 5: Juxtaposed photovoltaic cell panel emission diagram

[0089] FIG. 6a-6b: Perspective and front view diagrams of a parallelepipedic photobioreactor comprising a panel of photovoltaic cells inserted between two culture enclosures

[0090] FIG. 7a-7b: Perspective and radial section diagrams of a cylindrical photobioreactor comprising a panel of photovoltaic cells arranged on a hexagonal cross-section tube placed in a sealed tube immersed in the culture medium.

[0091] FIG. 8: Presentation of the photovoltaic cell cooling system and the photobioreactor temperature regulation system

[0092] FIG. 9: Detailed diagram of the system for mixing the culture medium installed on a wall.

[0093] FIGS. 1 to 5 are energy emission diagrams. A quasi-point LED emits the energy thereof in Lambertian mode (lobe). Most of the energy is emitted perpendicular to the surface of the semiconductor. This energy decreases on moving away from the normal to the semiconductor. It is zero parallel with the surface thereof. Extending the emissive surface beyond the natural lobe width makes it possible, by adding the basic lobes, to create an energy-constant emissive surface in the planes parallel with the surface of the semiconductor (xOy). In the figures, the LED or photovoltaic cell is O-centred and the surface thereof is oriented perpendicular to (Oz). A section of these lobes is shown along the plane (xOz).

[0094] FIG. 1 represents the emission diagram for an LED situated at the centre of the reference. The cathode is assumed to be quasi-point (less than one mm.sup.2 in size). There is invariance by rotating about the axis (Oz).

[0095] FIG. 2 represents the emission diagram for an inverted photovoltaic cell as used by the invention, in this case, with constant spacing of the current injection fingers. The light intensity in the plane parallel with (xOy) is constant in the vicinity of the centre of the cell.

[0096] FIG. 3 represents the energy emission diagram for an inverted photovoltaic cell when the spacing of the current injection fingers is retracted by moving the edges closer together. The injected current density is greater on the edges, hence the increase in light intensity.

[0097] FIG. 4 represents the emission diagram of a strip of LEDs (arranged along (Ox)). The addition of the light outputs gives rise to an inhomogeneous front, the inhomogeneity whereof is dependent on the distance between two successive LEDs on the strip.

[0098] FIG. 5 represents the emission diagram of a strip of LEDs (arranged along (Ox)). If the cells are close enough, the light intensity in a plane parallel with (xOy) is constant), the energy received is thus only dependent on the distance to the cell: indeed, the output inhomogeneity is independent of the distance at which the measurement is made.

[0099] According to a first embodiment, the photobioreactor is cylindrical (FIGS. 7). Photovoltaic cells (2) are arranged on both faces of six panels (7) forming a tube having a hexagonal cross-section together. The length of these panels (7) is the height of the photobioreactor. These panels (7) are placed in a sealed tube (5) made of light-transparent material (glass, plastic, etc.), in turn immersed in the culture medium (3), separating same into an internal par (3a) and an external part (3b), seen in FIG. 7a. The panels are connected to current injection contacts (8).

[0100] According to a second embodiment, the photobioreactor is parallelepipedic (FIGS. 6). Photovoltaic cells (2) are arranged on both faces of one or a plurality of metal panels (7). The dimensions of these panels are those of the photobioreactor. These panels (X) are placed outside the photobioreactor, preferably between two stacked culture enclosures. The panels are connected to current injection contacts (8). The photovoltaic cells are electrically insulated from the metal panel by an insulator having good thermal conductivity such as Mylar.