CN101908633A - A plant-soil microbial fuel cell system - Google Patents

Abstract

The invention discloses a low-cost, practical, effective, green and environment-friendly plant-soil microbial fuel cell system utilizing electricity-producing microorganisms and plant photosynthesis. It includes an anode electrode, a cathode electrode and an external circuit connecting the anode electrode and the cathode electrode, and also includes plants, the anode electrode is placed in the soil around the plant roots, and the cathode electrode is placed on the soil surface. The invention mainly uses the organic matter produced by plant photosynthesis and released to the root as fuel, avoiding the problem of low electricity production efficiency caused by the inhibitory effect of the organic matter on the electricity-producing microorganism when the electricity-producing microorganism uses the organic matter in the sewage as the fuel. At the same time, the present invention uses plants as fuel suppliers to realize the recycling of plant carbon sequestration-secretion of organic matter-power generation energy, and realizes the green supply of fuel. Therefore, the present invention achieves a win-win situation of energy supply and environmental protection by organically combining plants with electricity-producing microorganisms in soil.

Description

A plant-soil microbial fuel cell system

Technical field:

The invention belongs to the field of energy and ecological restoration, and specifically relates to a plant-soil microbial fuel cell system in which photosynthesis of plants is used as a producer and electricity-producing microorganisms in soil are used as consumers.

Background technique:

In order to meet the needs of my country's current social development, energy demand, and environmental protection, various green power resources have emerged as the times require. Green electricity refers to the electricity produced by renewable energy (wind energy, solar energy, ocean energy, geothermal energy, biomass energy, small hydropower and other non-fossil energy sources), because the electricity produced is generated by using specific power generation equipment. The electric power does not produce or rarely produces environmentally harmful excreta (such as CO, _CO2, etc.), and does not need to consume fossil fuels, saving limited resource reserves, which is conducive to environmental protection and the sustainable development of the national economy. Sustainable development (Xiongying, 2008; Hongshuifeng, 2008). However, these green power sources have certain limitations. For example, small hydropower requires abundant local water resources (Lu Shibao, 2009); wind power generation is suitable for areas rich in wind energy resources such as Xinjiang and Inner Mongolia; geothermal energy resources are released in a concentrated manner. In southern Tibet, western Sichuan, and western Yunnan (Gong Yulie, 2008); biomass power generation requires abundant biomass reserves, and there are certain requirements for the scale of power production in terms of its economics (Wu Chuangzhi, 2006).

Based on this, there is an application demand for a new power supply method. As early as 1910, a British botanist put platinum as an electrode in the culture solution of Escherichia coli and successfully produced the world's first bacterial battery. In 1984, American scientists designed a bacterial battery for spaceships. The active substances of its electrodes came from astronauts' urine and live bacteria. But the bacterial batteries at that time had low power generation efficiency. By the end of the 1980s, important progress was made in bacterial power generation. British chemists let bacteria decompose molecules in the battery pack to release electrons and move to the anode to generate electricity. They added certain aromatics such as dyes to the sugar solution The compound acts as a diluent to improve the ability of the biological system to transport electrons, but during the bacteria's power generation, it is necessary to continuously inflate the battery and stir the mixture of bacterial culture and oxide. Theoretically, using this bacterial battery, 1,352,930 coulombs of electricity can be obtained per 100g of sugar, and its efficiency can reach 40%, which is much higher than the efficiency of batteries currently used, and there is still 10 times the potential to be tapped. As long as you keep adding sugar to the battery, you can get 2A current, and it can last for several months: using the principle of bacterial power generation, people are conceiving to build a bacterial power station, for example, based on the bacterial culture solution in a 10m square container, A 1000kW bacterial power station can be established, and the sugar consumption per hour is 200kg. Although the power generation cost is higher, it is a "green" power station that does not pollute the environment (Wu Zulin, 2005). But the reality is that microbial fuel cells currently use a single carbon source, sodium acetate, as fuel to obtain a maximum output power of 1kW/m ³ , while complex compounds such as beer wastewater have even lower output power (Li Lianhua, 2009). In the pilot experiment conducted by Rabaey (2008), the operation of a microbial fuel cell with a volume of ^1m3 was studied using beer wastewater as fuel. In the process, there were problems such as corrosion and low power generation efficiency. The domestic microbial fuel cell conference pointed out that microbial fuel cells have relatively large problems as a method of sewage treatment, but they can be used for hydrogen production.

Plants carry out photosynthesis through chlorophyll, which fixes _CO2 to synthesize carbohydrates. Depending on the species of the plant and the environmental conditions, about 60% of the fixed C is imported to the roots. Studies have shown that 30% to 40% of the total soil organic matter comes from root exudates and dead roots. Mainly include: (1) sugars, organic acids, etc.; (2) high-molecular carbohydrates and enzymes, etc.; (3) dead cell substances; (4) gaseous substances such as ethylene. Gransee (2001) used quartz sand to cultivate corn to study the composition of its water-soluble root exudates, and found that hydrocarbons accounted for 64%, amino acids and amino salts accounted for 22%, and organic acids accounted for 14%. Hydrocarbons are mainly glucose, fructose and sucrose, citric acid and succinic acid account for 80% of organic acids, and amino acids mainly include glutamic acid, aspartic acid and serine. Paynel (2001) found that in alfalfa and ryegrass Among amino acids, serine and aminoacetic acid have the largest proportion. Aulakh (2001) found in rice root exudates that malic acid had the highest concentration in organic acids, followed by tartaric acid, succinic acid, citric acid and lactic acid.

Invention content:

The object of the present invention is to provide a low-cost, practical, effective, green and environment-friendly plant-soil microbial fuel cell system utilizing electricity-producing microorganisms and plant photosynthesis.

Plants use solar energy for photosynthesis and absorb CO ₂ , a part of which is used by the plants themselves, and about 60% is transported by the plants to the roots of the plants to form root compounds. The present invention uses the electrogenic microorganisms in the soil as a catalyst to oxidize and decompose the above source compounds into CO ₂ , and generate electrons and protons in the process. To the cathode, on this basis, protons and oxygen generate water, form a circuit, and generate electric current, thereby realizing the purpose of the present invention.

The plant-soil microbial fuel cell system of the present invention includes an anode electrode, a cathode electrode and an external circuit connecting the anode electrode and the cathode electrode, and is characterized in that it also includes plants, and the anode electrode is placed in the soil around the plant roots, The cathode electrode is placed on the soil surface.

The plants are preferably energy grasses.

Preferably, the cathode electrode is placed flat on the soil surface, and the anode electrode is placed perpendicularly thereto.

The invention utilizes the organic matters absorbed and secreted by plants as raw materials, uses the electricity-producing microorganisms in the soil as catalysts, catalyzes the decomposition of these organic matters into carbon dioxide, and generates electrons and protons in the process, and the electrons are transmitted through the anode electrode through an external circuit. To the cathode electrode, protons pass through the soil to the cathode electrode on the soil surface, without the need for protons to pass through the membrane, and the cathode electrode uses oxygen in the air as the electron acceptor, which reduces the cost. Protons and oxygen generate water and form a circuit to generate current. Compared with conventional microbial fuel cells, the present invention has the following beneficial effects: the present invention mainly uses the organic matter produced by plant photosynthesis and released to the roots as fuel, avoiding the impact of organic matter on electricity production when electricity-producing microorganisms use organic matter in sewage as fuel. The inhibitory effect of microorganisms leads to the problem of low power generation efficiency. At the same time, the present invention uses plants as fuel suppliers to realize the recycling of plant carbon sequestration-secretion of organic matter-power generation energy, and realizes the green supply of fuel. Therefore, the present invention achieves a win-win situation of energy supply and environmental protection through the organic combination of plants and soil electricity-producing microorganisms, especially when energy grass is selected as the supplier of electricity-producing microorganisms to oxidize raw materials, it can be used without affecting the energy utilization of energy grass At the same time, it realizes the recovery of electric energy, and can effectively combine energy utilization and environmental protection.

Description of drawings:

Fig. 1 is the structural representation of plant-soil microbial fuel cell system of the present invention;

Fig. 2 is the placement position diagram of anode electrode and cathode electrode in the present embodiment 1;

Explanation of reference signs: 1. Anode electrode; 2. Cathode electrode; 3. Soil surface.

Detailed ways:

The following is a further description of the present invention, rather than a limitation of the present invention.

Example 1:

As shown in Figures 1 and 2, the plant-soil microbial fuel cell system of the present embodiment is constructed based on cultivated energy grass (such as Pennisetum), and an anode electrode 1 is provided in the surrounding soil of the energy grass root ( ANODE), the cathode electrode 2 (CATHODE) is placed flat on the soil surface 3 near the energy grass, and the cathode electrode 2 is exposed to the air. As shown in Figure 2, the anode electrode 1 (ANODE) is perpendicular to the cathode electrode 2 (CATHODE). The anode electrode 1 (ANODE) and the cathode electrode 2 (CATHODE) are connected through an external circuit, and a load can be connected to the external circuit. After the construction is completed, a multimeter is connected to the external circuit, and the plant-soil microbial fuel cell system is operated, and there is voltage on the external circuit after detection.

The operating principle of the plant-soil microbial fuel cell system in this embodiment is as follows. The cultivated energy grass utilizes solar energy, absorbs carbon dioxide and releases oxygen, and synthesizes organic substances. Some of the organic substances are released to the roots of the plants, and the microorganisms in the soil at the roots of the plants Decompose these organic substances to produce carbon dioxide. In this process, electrons and protons are also produced. The electrons pass through the anode and the external circuit to the cathode, while the protons pass through the soil to the cathode. The cathode uses oxygen as the electron acceptor, and the protons and oxygen generate water. As a result, a circuit is formed and an electric current is generated.

Claims (3)

1. A plant-soil microbial fuel cell system, comprising an anode electrode, a cathode electrode and an external circuit connecting the anode electrode and the cathode electrode, characterized in that it also includes a plant, and the anode electrode is placed in the soil around the plant root , the cathode electrode is placed on the soil surface. 2. The plant-soil microbial fuel cell system according to claim 1, wherein the plant is an energy grass. 3. The plant-soil microbial fuel cell system according to claim 1 or 2, wherein the cathode electrode is placed flat on the soil surface, and the anode electrode is placed vertically thereto.

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