JP3463062B2 - Photosynthetic reactor with built-in light energy converter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosynthetic reactor for photosynthesis utilizing microorganisms, and more particularly to effective utilization of light energy in photosynthesis.

[0002]

Photosynthetic microorganisms produce useful substances such as hydrogen under light irradiation. The substance production using photosynthetic microorganisms is useful as a method for converting light energy because the device is simple. However, it is necessary to increase the light energy conversion efficiency of the photosynthetic reactor in order to efficiently produce substances.

A typical conventional photosynthetic reactor is a plate-type incubator or structure 1 as shown in FIG. Sunlight 3 hits the light-receiving surface 2, passes through the light-receiving surface 2, and the light energy is utilized by the microorganisms cultured inside to carry out the substance production. This type of photosynthetic reactor has the advantages of simple structure and easy maintenance.

Various improvements have been made for the purpose of improving the light energy conversion efficiency. For example, real public sho 60
In No. -19580, the light receiving area per volume is increased by providing one or more light-transmitting depressions on the light receiving surface of the photosynthetic reactor. See also Applied B
iochem. Biotechnol. , 34/35,
449-458, 1992, Synechococc, which is a type of marine cyanobacterium.
cus sp. Optomu) is cultured to release CO ₂ and form biomass, by arranging a surface-emission type optical fiber (light diffusion optical fiber) inside the photosynthesis reactor, more cells can be irradiated with light. Thus, high density culture is possible.

However, these conventional photosynthetic reactors are
The light is simply transmitted to the inside of the photosynthesis reactor by using a light transmitter to disperse and irradiate the light, and there are problems that the structure is complicated, maintenance is inconvenient, and cost is disadvantageous.

[0006]

Generally, the substance production rate of photosynthetic microorganisms increases in proportion to the light energy intensity of irradiation, but when the light energy intensity exceeds a certain value,
It will not increase any further. This light energy intensity is called saturated light energy intensity. As an example, the photosynthetic bacterium Rhodobacter sphaeroides R
V (Rhodobacter sphaeroides sp.-RV, Deposit No. FERMP-7254) has a saturated light energy intensity of about 0.3 kW / m ² in hydrogen generation.

However, in reality, the light energy intensity of sunlight is 0.3 kW / m ² or more in most of the sunshine hours. Therefore, when the photosynthetic microorganisms are irradiated with sunlight, most of the light energy is wasted. It has been found that such an excessively high light energy intensity of sunlight is a cause of hindering the improvement of light energy conversion efficiency.

[0008] Therefore, an object of the present invention is to provide a photosynthetic reactor and a method for culturing photosynthetic microorganisms, which can recover light energy not used for the production of substances as other energy without reducing the amount of substances produced.

[0009]

As a means for solving the above-mentioned problems, the present inventors have partially covered the surface of the photosynthesis reactor with a photoenergy converter, so that the material production amount has not been lowered, and thus far. It was found that the wasted light energy can be recovered as other energy.

That is, the photosynthetic reactor of the present invention is
A light energy converter for culturing photosynthetic microorganisms
A photosynthetic reactor comprising:
The substitute is 34% of the light receiving area of the photosynthetic microbial reactor
The light energy converter uses a heat collecting pipe
It is a photothermal conversion device .

The method for culturing the photosynthetic microorganism of the present invention
Is a method of culturing photosynthetic microorganisms in a photosynthetic reactor
At 34% of the light receiving area of the photosynthetic reactor
Is shielded by a photothermal conversion device using a heat collecting pipe,
By shining light on the light receiving surface of the synthesis reactor,
The adult microorganism is cultured to produce hydrogen, and
The light energy is converted into heat energy by the converter.
And recover the produced hydrogen and heat energy.
It is characterized by

[0012]

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION If the light receiving surface of a photosynthetic reactor is completely covered with a structure, no light will penetrate into the interior of the reactor, so that material production cannot be expected. However, when it is partially covered, the photosynthetic microorganisms moving inside the reactor by convection or stirring pass through the light and dark portions alternately. Therefore, the light energy intensity received by the bacterial cells per unit time is smaller than that when the surface of the photosynthetic reactor is not covered at all. However, if the light energy intensity received by the bacteria is not lower than the saturated light energy intensity, the same amount of substance production as when the photosynthetic reactor surface is not covered is guaranteed.

Further, by covering the light receiving surface of the photosynthesis reactor with a light energy converter such as a solar cell or a photothermal converter, the light energy which was conventionally wasted can be recovered as other energy, particularly electric energy and hot water. , The overall energy efficiency is significantly improved.

FIG. 1 is a schematic perspective view showing an example of the photosynthetic reactor of the present invention. At least one outer surface of the photosynthesis reactor 10 is a light receiving surface 11, and the light receiving surface 11 is formed of a material through which the light energy of the light 12 from the light source is transmitted. A light shielding portion 13 is provided on a part of the light receiving surface 11. The light-shielding portion 13 may have a stripe shape as shown in (A), a patch shape as shown in (B), a mesh shape as shown in (C), or another pattern. Good. The light-shielding portion 13 does not transmit light inside and is formed of a light energy converter that converts light energy into other energy. As the light source, sunlight, incandescent lamp, arc lamp, fluorescent lamp or the like can be used. Examples of the light energy converter include a photoelectric conversion device such as a solar cell and a light-heat conversion device connected with a heat collecting pipe in which a heat medium such as water is circulated. A photosynthetic microorganism is charged into the photosynthesis reactor 10 from the inlet 14 together with a culture medium, and a cap (not shown) is put on the photosynthesis reactor 10 to cultivate it in sunlight 12. At the same time, the light energy captured by the light shield is used in the form of electric energy or heat energy.

The photosynthetic microorganisms used in the present invention include:
Although any microorganism that produces a useful substance by using light energy may be used, in this example, the photosynthetic bacterium Rhodo is used.
vector sphaeroides RV (Rhodobacter sphaeroides SP-RV, deposit number FERMP
No. 7254). This microorganism releases hydrogen by photosynthesis using fatty acids such as lactic acid, acetic acid, and propionic acid as a medium.

When hydrogen is produced by photosynthesis using the present bacterium, as the amount of light increases, the relationship between the degree of shielding of the light receiving surface and the amount of hydrogen produced is approximately 0.3 kW, as shown in FIG. 2 (A).
Saturate at a light energy intensity of / m ² . Above this saturated light energy intensity, hydrogen production does not increase. Therefore, the increase in light energy intensity will not be used in material production. Therefore, a shield is provided on the light-receiving surface so that the unused light energy is not transmitted to the inside, and this shield receives energy that is not used for photosynthesis, and by using it in the form of other energy, the overall Energy use efficiency can be improved. FIG. 2B shows the relationship between the light shielding rate and the hydrogen production amount when a part of the light receiving surface is shielded. As is clear from the figure, the hydrogen production amount does not decrease until the shading rate reaches 34%, and the hydrogen production amount decreases when the shading rate exceeds 34%. Therefore, it is understood that the light-shielding rate is set to 34%, that is, when the ratio of directing light energy to other energy is 34%, the overall light energy utilization efficiency is optimum.

[0024]

EXAMPLES The present invention will be described in more detail below with reference to examples, but it goes without saying that the present invention is not limited to these examples.

<Embodiment 1> FIG. 3 is a schematic perspective view showing an arrangement relationship of main components of a photosynthetic reactor incorporating a light energy converter according to a first embodiment of the present invention. In FIG. 3, the solar cells 13a, which are light energy converters, are arranged on the light-receiving surface 11 of the photosynthesis reactor at regular intervals. In this case, the surface area occupied by the solar cell 13a as the light shielding portion was set to be 34% of the area of the light receiving surface before the light shielding portion was provided. The photosynthetic bacterium Rhodactor is added to this photosynthetic reactor.
sphaeroides RV (Rhodobacter sphaeroides SP-RV, deposit number FERMP-7254)
And fatty acids such as lactic acid, acetic acid, and propionic acid were added as a medium, and the cells were cultured by exposing them to sunlight.
Power from the solar cell was obtained.

<Embodiment 2> FIG. 4 is a schematic view showing an arrangement relationship of main constituent members of a photosynthetic reactor incorporating a light energy converter according to a second embodiment of the present invention. Figure 4
In, a photothermal conversion device 1 which is a light energy converter
The heat collecting pipes 16 associated with 5 are arranged at regular intervals on the light receiving surface 11 of the photosynthesis reactor. In this case, the area occupied by the heat collecting pipe in the projected view is set to be 34% of the area of the light receiving surface before the heat collecting pipe is provided. When the photosynthetic bacteria were cultured in the same manner as in Example 1 by applying sunlight, hydrogen was generated and heat was recovered.

<Test Example 1> FIG. 5 is a schematic diagram showing the construction of the main part of an experimental apparatus used for testing the effect of the photosynthetic reactor incorporating a light energy converter according to the embodiment of the present invention. In FIG. 5, for example, light emitted from a white light source 20 such as a tungsten lamp or a halogen lamp is a photosynthesis reactor 2 arranged in a constant temperature water tank 21.
Reach 2. The photosynthetic reactor 22 is filled with the photosynthetic bacterial suspension 23, and the hydrogen gas 2 generated here is generated.
4 is guided through a transport pipe 25 to a glass syringe 26 placed in the constant temperature water bath 21. The glass syringe 26 is filled with water in advance so that the hydrogen gas 24 is introduced and water is discharged from the bottom. The constant temperature water tank 21 uses a temperature controller (not shown) to keep the water temperature constant at 30 ° C.

Table 1 shows a schematic diagram showing the light receiving surfaces of the four types of photosynthesis reactors used in the experiment, and the hydrogen generation amount obtained from each photosynthesis reactor. Photosynthesis reactor A
In C, no structure is arranged on the light receiving surface. On the other hand, the photosynthesis reactor B is attached with a black adhesive tape having a thickness of 1 cm, and the photosynthesis reactor D is attached with a metal wire knitted in a mesh shape so as to shield 34% of the light receiving surface. Lactic acid was used as a medium in the photosynthetic reactors A and B, and a 1: 1 mixture of acetic acid and propionic acid was used as a medium in the photosynthetic reactors C and D. In each of the photosynthetic reactors, the light receiving area when the structure (light shielding portion) was not provided was 150 cm ² . Therefore, the area of the light shielding portion was 51 cm ² . In these photosynthetic reactors, the photosynthetic bacteria Rhodobacter sp
haeroides RV (Rhodobacter sphaeroides SP-RV, deposit number FERMP-7254) was cultured. The light conditions during the culture are Photosynthesis Reactor A
And 12 hours at 0.53 kW / cm ² at B, and photosynthetic reactors C and D in 0.60kW / cm ² 12
Irradiated for an hour. As a result, photosynthetic reactors A and B
1.1 liters (L) / 12 hours / reactor and 1.0 liters (L) / 12 hours / reactor, and photosynthesis reactors C and D each produce 0.1 liters (L) / 12 hours / reactor hydrogen did. The results are shown in Table 1.

In Table 1, photosynthetic reactors A and B,
Comparing the photosynthetic reactors C and D, respectively, the photosynthetic reactors B and D generate almost the same amount of hydrogen as when the structures are not arranged, although the structures are arranged and the area where the photosynthetic bacteria receive light is reduced. I know what to do.
The same effect can be expected even if the structure has a patch shape having a small area.

<Test Example 2> The effect of the present invention will be verified using Example 1. For the calculation, the experimental results using the photosynthetic reactors A and B in Table 1 were used.

When hydrogen was produced using the photosynthetic reactors A and B, the light energy conversion efficiencies were 1.8% and 1.7%, respectively. The light energy conversion efficiency is

[0032]

## EQU1 ## Light energy conversion efficiency = [combustion energy of generated hydrogen] / [irradiated light energy] × 100.

Next, in the photosynthetic reactor B, as in Example 1, the conversion efficiency 7 was applied to the portion to which the adhesive tape was attached.
It is assumed that% solar cells are arranged. The light energy conversion efficiency at this time is

[0034]

[Equation 2] Light energy conversion efficiency = [combustion energy of generated hydrogen + electrical energy generated by solar cell] ÷
[Emitted light energy] × 100 gives 4.0%.

That is, as compared with A which is a conventional photosynthetic reactor, the light energy conversion efficiency is improved by about 2 times by implementing the present invention.

[0036]

[Table 1]

[0037]

INDUSTRIAL APPLICABILITY The present invention is an easy technique of covering the light-receiving surface of a photosynthesis reactor, which requires a large area, with a light energy converter, and has the effect of doubling the light energy conversion efficiency. You can Therefore, it greatly contributes to the practical application of the substance production using the photosynthetic microorganism.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing an arrangement relationship of main constituent members of a photosynthetic reactor incorporating a light energy converter according to an embodiment of the present invention, FIG.
(B) shows a patch-like arrangement and (C) shows a mesh-like arrangement.

FIG. 2 is a graph showing the hydrogen production of photosynthetic bacteria,
(A) shows the relationship with the energy intensity, and (B) shows the relationship with the light blocking rate.

FIG. 3 is a schematic perspective view showing an arrangement relationship of main components of a photosynthetic reactor incorporating a light energy converter according to an example of the present invention.

FIG. 4 is a schematic perspective view showing an arrangement relationship of main constituent members of a photosynthetic reactor incorporating a light energy converter according to an embodiment of the present invention.

FIG. 5 is a schematic diagram showing a configuration of a main part of an experimental apparatus used in a test example of the present invention.

FIG. 6 is a schematic perspective view showing a conventional photosynthetic reactor.

[Explanation of symbols]

1 structure (incubator) 2 Light receiving surface 3 sunlight 10 Photosynthesis reactor 11 Light receiving surface 12 Light from the light source 13a solar cell 14 Entrance 15 Photothermal conversion device 16 Heat collection pipe 20 light sources 21 Constant Temperature Water Tank 22 Photosynthesis reactor 23 Photosynthetic bacterial suspension 24 Hydrogen gas 25 Hydrogen gas transport pipe 26 glass syringe

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C12R 1:01) H01L 31/04 Q (73) Patent holder 000154358 Fuji Electric Research Institute, Ltd. 2-2 Nagasaka, Yokosuka City, Kanagawa Prefecture No. 1 (74) Attorney for the above 1 person 100077481 Attorney Yoshikazu Tani (2 outside) (72) Inventor Atsushi Miyake 1-3-1, Higashi, Tsukuba, Ibaraki Prefectural Institute of Biotechnology and Industrial Technology (72) ) Inventor Yasuo Asada, 1-3-1, Higashi, Tsukuba-shi, Ibaraki Institute of Industrial Science and Technology, Institute of Biotechnology (72) Masaaki Kimura 2-8-11 Nishishinbashi, Minato-ku, Tokyo 7th Toyo Kaiji Building 8F Foundation Corporation Global Environment Industrial Technology Research Institute CO2 fixation project indoor (72) Inventor Ju Wakayama 2-8-11 Nishi-Shimbashi, Minato-ku, Tokyo 7th Toyo Kaiji Building 8F Property Institute for Global Environmental Industrial Technology CO2 fixation project indoor (72) Inventor Eiju Nakata 2-8-11 Nishi-Shimbashi, Minato-ku, Tokyo 7th Toyo Kaiji Building 8th floor Foundation for Global Environmental Industrial Technology CO2 fixation Chemical conversion project room (56) References JP-A-6-350119 (JP, A) JP-A-8-275791 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C12M 1 / 00-3/00 C12P 3/00

Claims (2)

(57) [Claims] 1. A for cultivating photosynthetic microorganisms, light energy
A photosynthetic reactor equipped with ghee converter, the light
The energy converter receives light from the photosynthetic microbial reactor .
Shields 34% of the area, and the light energy converter collects heat
A photosynthesis reactor characterized by being a photothermal conversion device using a pipe . 2. A method for culturing a photosynthetic microorganism in a photosynthesis reactor, wherein 34% of the light receiving area of the photosynthesis reactor is a heat collecting pie.
Light is blocked by a photothermal conversion device using a lamp, and light is applied to the light receiving surface of the photosynthetic reactor.
In addition to culturing photosynthetic microorganisms to produce hydrogen , the photothermal conversion device converts light energy into heat energy.
A method for culturing a photosynthetic microorganism , which comprises converting and recovering the produced hydrogen and heat energy .