CN103165932A - Green roof system capable of generating electric energy and application - Google Patents

Abstract

The invention discloses a green roof system capable of generating electric energy and its application, belonging to the fields of environmental protection and new energy, including a soil layer, plants planted in the soil layer, and a water layer above the soil layer, and several battery units, Each battery cell includes an anode electrode and a cathode electrode connected by wires, the anode electrode is embedded in the soil layer, the cathode electrode is located in the water layer, the root system of the plant is planted near the anode electrode, and the stems and leaves of the plant pass through The cathode electrode is also located above the water layer; several battery cells are connected with the energy storage device after being connected with wires, and the energy storage device is connected with the load. The invention utilizes soil microorganisms to convert solar energy into electric energy in an electrochemical system, which is environmentally friendly and has high energy utilization efficiency. The invention has a simple structure, relies on natural resources, does not require too much daily maintenance, has low construction and operation costs, and is suitable for popularization in modern cities.

Description

A green roof system capable of generating electric energy and its application

technical field

The invention belongs to the fields of environmental protection and new energy, and in particular relates to a novel green roof system capable of generating electric energy by combining a plant-sedimentation microbial fuel cell with a green roof. The invention also provides the application of such a green roof system capable of generating electric energy.

Background technique

A green roof is a roof on which plants can grow. It is an ecological concept and a form of returning to nature. It turns flat greening into three-dimensional greening, becomes the extension and expansion of the ground landscape in the air, and is also a combination of architectural design and planting. , The combination of natural landscape and man-made green landscape is an indispensable part of sustainable development architecture. The emergence of green roofs has further enhanced the value of ordinary roofs. In addition to playing a basic protective role, it can also produce a series of rich ecological, landscape, and economic values. Green roofs can filter dust in the air, regulate air temperature and humidity, have a buffering effect on rainwater to reduce the peak of rainwater entering the sewage system, isolate noise pollution, and have a good impact on biodiversity. Studies have shown that by planting green roofs, the temperature of urban residential buildings in summer can be reduced to 14°C~44°C, which can reduce electricity consumption by at least 5%~15% in summer, and at the same time reduce urban greenhouse gas emissions by 2.4 million tons per year. Therefore, it has become an urgent need to promote green roofs in modern cities that generally suffer from the "heat island" effect.

Sediment Microbial Fuel Cell (SMFC) is a device based on a sediment environment system that uses the catalysis of microorganisms to directly convert chemical energy in organic matter into electrical energy. It is close to practical application, so it has more development value, but the problem of mass transfer limitation of anode organic matter in SMFC prevents its power generation level and durability from being effectively improved. Based on the characteristics of plant photosynthesis, De Schamphelaire and Kaku added plants to SMFC, and electrogenic bacteria near the anode can oxidize and decompose organic matter released by plant roots, which can effectively improve the mass transfer of organic matter in SMFC. De Schamphelaire's experiments proved that the plant-deposited microbial fuel cell (Plant-SMFC) has 7 times higher power density output than the SMFC without plants, and it does not destroy the biomass (plant) itself, avoiding the destruction of biomass Transport, and the absence of nutrient sources in ecosystems, is a new bioenergy approach that does not compete with current food production.

The basic principle of Plant-SMFC has been proved, the urgent problem to be solved now is how to further improve the system and combine it with practical application. The plants in the green roof provide a good fit for the practical application of this technology. Because Plant-SMFC can be well integrated into the urban landscape, it can be recycled without destroying the original green roof system landscape and environmental protection functions. Solar energy is converted into practical electrical energy. Compared with the chemical pollution caused by rooftop solar panel technology during processing and manufacturing, this bioenergy technology has a simple structure and no secondary pollution during construction and operation; and the indigenous microorganisms in the soil can perform self-renewal and repair, so No special maintenance is required and the operation period is long; soil microorganisms use the root exudates accumulated by plant photosynthesis to generate electricity, so they can continue to generate electricity in the dark and are not restricted by weather conditions; planting suitable economic crops on the roof can also While recycling energy and greening the environment, certain economic benefits are produced, and it does not compete for farmland and arable land, making full use of the environmental space to create value.

Contents of the invention

Aiming at the deficiencies and defects of the prior art, the technical purpose of the present invention is to provide a new green roof system and application technology that can generate electric energy by combining plant-sedimentation microbial fuel cells and green roofs. The original green roof system has landscape and environmental protection functions while recovering electric energy, which is practical, effective and low in cost.

For realizing technical purpose of the present invention, technical scheme of the present invention is as follows:

A green roof system that can generate electricity is mainly composed of plant-sedimentary microbial fuel cells, including the soil layer, plants planted in the soil layer, and the water layer above the soil layer, as well as several battery units, each The battery unit includes an anode electrode and a cathode electrode connected by wires, the anode electrode is embedded in the soil layer, the cathode electrode is located in the water layer, the root system of the plant is planted near the anode electrode, and the stems and leaves of the plant pass through the cathode electrode And it is located above the water layer; several battery units are connected by wires and then connected to the energy storage device, and the energy storage device is connected to the load.

The several battery units are connected in a series-parallel hybrid manner, and 9 battery units can be arranged according to the green roof area of 1m ² , and the 9 battery units are connected in parallel every 3 and then output in series, when The area of the green roof is expanded, and the number of each group of 3 connected in parallel and then connected in series is superimposed accordingly.

The cathode electrode is suspended in the oxygen-enriched water surface of the water layer.

The material of the anode electrode includes carbon felt or activated carbon fiber felt.

The material of the cathode electrode includes carbon felt, activated carbon fiber felt or stainless steel mesh.

The wires are titanium wires, copper wires or stainless steel wires.

Said plants are wetland plants with strong self-sustaining ability, low stature, weak root thorn ability, developed fibrous roots and beautiful appearance, such as sedum and herbaceous plants.

The energy storage device is a device that collects and stores generated electric energy, and then outputs a stable current for use by loads.

The load is a small household electrical appliance or a small weather monitoring sensor.

The water layer contains a plant culture solution, which is 1/2 modified Hoagland's culture solution+10 mM phosphate buffer.

The specific formula of the plant culture solution is: calcium nitrate tetrahydrate 472.5 mg/L, potassium nitrate 253 mg/L, ammonium phosphate 40 mg/L, potassium dihydrogen phosphate 68 mg/L, magnesium sulfate 246.5 mg/L, iron Salt solution 1.25 mL, sodium dihydrogen phosphate monohydrate 490.4 mg/L, disodium hydrogen phosphate 915.2 mg/L, pH=7.0, the iron salt solution is ferrous sulfate heptahydrate 5560 mg/L, ethylenediaminetetraacetic acid di Sodium 7460 mg/L.

1/2 Improved Hoagland's culture medium is a special culture medium for plants, which can meet the needs of inorganic nutrients for general plant growth. The phosphate buffer is added to the plant culture solution on the basis of 1/2 improved Hoagland's culture solution in order to maintain the pH and conductivity of the solution during the operation of the electrochemical system. The plant culture solution is updated once a month, and the soil layer is about 5-7cm each time, and the water phase layer is about 2-3cm (the culture solution can be added to exceed the soil layer by 2-3cm).

The thickness of the soil layer is 5-7cm, and the thickness of the water layer is 2-3cm.

The present invention also provides the green roof system, which includes a roof, and the soil layer is located above the roof.

The working principle is: the plants on the green roof use solar energy to carry out photosynthesis to produce the organic matter needed for their own growth, and release and accumulate root exudates in the soil through the root system, and the indigenous microorganisms in the soil can be domesticated in the electrochemical device. The anode electrode is enriched with high-efficiency electricity-producing bacteria, and the high-efficiency electricity-producing bacteria oxidize and decompose the root exudates accumulated in the soil to continuously generate electrons and protons, which are transferred to the cathode electrode through the wire, and the protons are mass-transferred to the cathode water layer through the solution. The reduction reaction between electrons and protons and oxygen on the water surface makes the entire electrochemical system continue to operate. After connecting all the battery units in a suitable parallel mode, the electric energy is obtained with maximum efficiency and stored by an energy storage device, and then converted into a stable current output for use by small household appliances or small weather monitoring sensors.

The "roof" should be understood in a broad sense, namely: a roof that can be planted with plants and has a certain load-bearing capacity that is specially constructed and designed for the green roof system.

The present invention further provides the application of the green roof system that can generate electric energy, and the application method is:

(1) Select plants with well-developed fibrous roots, easy to grow and reproduce, and resistant to flooding to construct the above-mentioned green roof system that can generate electricity;

(2) After the construction is completed, the green roof system is operated under natural conditions, and the tap water is replenished every other day in summer or dry weather until the cathode electrode is submerged (depending on the evaporation of water vapor, it can be several days in wet weather) to prevent normal water vapor loss by evaporation;

(3) The plant culture solution in the water layer is renewed once a month.

The beneficial effects of the present invention are:

(1) Integrated plant-sedimentary microbial fuel cell and green roof are two new eco-friendly technologies. Under the premise of not destroying the landscape and environmental protection functions of the original green roof system, the root exudates produced by the conversion of solar energy are used for photosynthesis of green plants It is used by soil microorganisms and converted into electrical energy output in the electrochemical system. The whole process is green and environmentally friendly, and the energy utilization efficiency is high;

(2) The battery units are connected in parallel to minimize the energy loss in the connection of each battery. After the electric energy is recovered efficiently, it is stored by the energy storage device and converted into stable electric energy output for small household appliances or small weather monitoring sensors. , based on the maximum power density output of the currently available plant-sedimentary microbial fuel cell, it is estimated that the electricity obtained from a 50m ² roof can drive at least 3 home phones, so this new green roof system can reduce at least 40% of household electricity consumption %, has a great application prospect;

(3) This new type of green roof system that can generate electricity has a simple structure, relies on natural resources, does not require too much daily maintenance, has low construction and operation costs, and has a long stable operation period, making it easier to promote in modern cities.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and comprehensible from the description of the embodiments in conjunction with the following drawings, wherein:

FIG. 1 is a schematic structural diagram of a battery unit of a green roof system capable of generating electric energy according to the present invention.

Among them, 1-anode electrode; 2-cathode electrode; 3-plant stem and leaf; 4-plant root system; 5-energy storage device; 6-load.

Fig. 2 is a graph comparing the output voltage of the deposition-type microbial fuel cell built with four selected plants and the control cell without plants.

Figure 3 is a graph of battery power density and polarization curves under the conditions of two different plant culture solutions.

Fig. 4 is a graph showing the pH change of the battery system solution under two different plant culture solution conditions.

Fig. 5 is a diagram of two connection modes of nine battery cells.

Detailed ways

The technical solutions of the present invention will be further described below through specific examples.

Example 1

As shown in Figure 1, a green roof system that can generate electricity includes a building roof on which a plant-deposited microbial fuel cell is installed. Specifically, the green roof system that can generate electric energy in this embodiment includes a soil layer above the roof, plants planted in the soil layer, and a water layer above the soil layer, and also includes several battery units, each battery unit It includes an anode electrode 1 and a cathode electrode 2 connected by wires, the anode electrode 1 is embedded in the soil layer, the cathode electrode 2 is suspended on the oxygen-enriched water surface of the water layer, and the root system 4 of the plant is planted near the anode electrode 1, The stems and leaves 3 of the plants pass through the cathode electrode 2 and are located above the water layer; several battery cells are connected with the energy storage device 5 after being connected by wires, and the energy storage device 5 is connected with the load 6 .

The several battery units are connected in series-parallel hybrid mode, that is, every 3 battery units are connected in parallel and then output in series. The energy storage device 5 is a device that collects and stores the generated electric energy, and then outputs a stable current for use by the load 6 .

The plants should be selected from plants with well-developed fibrous roots, easy growth and reproduction, and resistance to flooding. In this example, four common flood-resistant plants, cress, fendai evergreen, Phnom Penh lucky bamboo, and small white palm, were selected to construct Plant-SMFC for selecting A plant suitable for constructing a high-efficiency power generation green roof system, wherein the anode electrode 1 is carbon felt, the cathode electrode 2 is carbon felt, the load 6 is a small household appliance or a small weather monitoring sensor with a resistance of 1000Ω, and the wire is titanium wire. The water layer contains plant culture fluid, which is 1/2 improved Hoagland's culture fluid + 10 mM phosphate buffer solution. The specific formula is: calcium nitrate tetrahydrate 472.5 mg/L, potassium nitrate 253 mg/L L, ammonium phosphate 40 mg/L, potassium dihydrogen phosphate 68 mg/L, magnesium sulfate 246.5 mg/L, iron salt solution (ferrous sulfate heptahydrate 5560 mg/L, disodium edetate 7460 mg/L ) 1.25 mL, sodium dihydrogen phosphate monohydrate 490.4 mg/L, disodium hydrogen phosphate 915.2 mg/L, pH=7.0. The plant culture solution is updated once a month, and the soil layer is about 5-7cm each time, and the water phase layer is about 2-3cm (the culture solution can be added to exceed the soil layer by 2-3cm).

At the same time, a SMFC without plants is used as a control, that is, no plants are planted, other conditions are the same as Plant-SMFC, and the power generation performance is compared with Plant-SMFC, so as to optimize the plant with the most obvious improvement in SMFC power production to build a high-efficiency power-producing green roof system.

In this example, the experiment simulates the operation of spring and autumn climate conditions under natural conditions, temperature (20 ℃ ± 5 ℃), light intensity 4000 lux, light-dark cycle 12 h (light): 12 h (dark), and the interval between battery operation is 2 days Supplement tap water to the original water level to prevent the normal water vapor from evaporating and losing. The output voltage data is collected throughout the process (Figure 2). It can be seen that the battery pack built by Xiaobaizhang has the highest output voltage (Umax=509 mV), and the maximum output power density reaches 23.5 mW /m2. The power production levels of watercress, evergreen and Phnom Penh Lucky Bamboo are not much different, and the maximum voltage is about 400 mV. The output voltage levels of all plant battery packs are significantly higher than those of the control battery pack, and the maximum voltage of the control battery pack is only 263 mV. Root exudates produced by plant photosynthesis enhance the electrical energy output of soil electrogenic microbes. These four kinds of plants can be used as the construction of this new type of green roof system, among which the effect of generating electricity is the best.

Example 2

On the basis of Example 1, the plant-sedimentary microbial fuel cell of the green roof system was selected from Xiaobaizhang, and two kinds of plant culture solutions were used to investigate respectively. The plant culture solution 1 was the same as the plant culture solution used in Example 1. Plant culture solution 2 is a plant culture solution without adding 10 mM phosphate buffer, and other experimental conditions are the same as in Example 1. From the power density and polarization curve (Figure 3), it can be seen that the maximum output power density of the plant culture solution 1 battery pack is 24.0 mW/m2, which is 2.5 times that of plant culture medium group 2. The apparent internal resistance of the battery is 190.0 Ω, which is 1106.0 Ω lower than that of plant culture medium group 2. At the same time, the pH change of the solution in the battery system was monitored (Figure 4). It can be seen that the pH of the plant culture solution group 1 dropped slightly to 6.75 on the 10th day of battery operation, and then remained at 6.9-6.9 until the 56th day. Between 7.0, there is no obvious fluctuation in pH during the whole operation process, which better maintains the stable operation of the battery system. However, the pH of the plant culture solution group 2 dropped rapidly to 6.0 around the 12th day of battery operation, and the pH has been fluctuating below 6.3 since then. The experimental results show that the addition of phosphate buffer salt plays an important role in maintaining the pH and conductivity of the solution during the operation of the electrochemical system, improving the stable operation of the battery system, reducing the apparent internal resistance of the battery and increasing its power density output.

Example 3

On the basis of Examples 1 and 2, a new type of green roof system of 1 m2 is constructed by selecting Xiaobaizhang-sedimentary microbial fuel cell. The experiment shows that about 9 battery units can be arranged, and the battery pack connection method of these 9 battery units is investigated. . Method 1: 9 battery cells are output in series; Method 2: Every 3 battery cells are connected in parallel and then output in series, as shown in Figure 5. Under the two modes, the maximum output power density of the battery pack in mode 1 is 184.5 mW/m2, and the maximum output power density of the battery pack in mode 2 is 210 mW/m2. It can be seen that the battery pack in the design of the new green roof system adopts the hybrid power density of mode 2. The connection mode can reduce the energy loss in the series mode and improve the energy recovery efficiency.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications, substitutions and modifications can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the invention is defined by the claims and their equivalents.

Claims (10)

1. one Plants-appositional pattern microbiological fuel cell, comprise soil horizon, plant the water layer of plant in soil horizon and soil horizon top, it is characterized in that, also comprise several battery units, each battery unit comprises anode electrode and the cathode electrode that connects with wire, and described anode electrode embeds in soil horizon, and described cathode electrode is arranged in water layer, the root system of described plant is planted near anode electrode, and the cauline leaf of plant passes cathode electrode and is positioned at the top of water layer; Be connected with energy storage device after connecting with wire between several battery units, energy storage device is connected with load.

2. plant according to claim 1-appositional pattern microbiological fuel cell, is characterized in that, every 1m ²The Green Roof area is arranged 9 battery units, series connection output again after every 3 parallel connections between described 9 battery units, and when the Green Roof enlarged areas, the number of connecting again after every 3 the one group of parallel connections that superpose according to this.

3. plant according to claim 1-appositional pattern microbiological fuel cell, is characterized in that, described cathode electrode is suspended in the oxygen enrichment water surface of water layer.

4. plant according to claim 1-appositional pattern microbiological fuel cell, is characterized in that, the material of described anode electrode comprises carbon felt or active carbon fiber felt.

5. plant according to claim 1-appositional pattern microbiological fuel cell, is characterized in that, the material of described cathode electrode comprises carbon felt, active carbon fiber felt or stainless (steel) wire.

6. plant according to claim 1-appositional pattern microbiological fuel cell, is characterized in that, described water layer contains the plant nutrient solution, and described plant nutrient solution is 1/2 to improve Gram nutrient solution+10 mM phosphate buffers suddenly.

7. plant according to claim 6-appositional pattern microbiological fuel cell, it is characterized in that, the concrete formula of described plant nutrient solution is: four water-calcium nitrate 472.5 mg/L, potassium nitrate 253 mg/L, ammonium phosphate 40 mg/L, potassium dihydrogen phosphate 68 mg/L, magnesium sulfate 246.5 mg/L, iron salt solutions 1.25 mL, sodium dihydrogen phosphate-water 490.4 mg/L, sodium hydrogen phosphate 915.2 mg/L, pH=7.0, wherein iron salt solutions is ferrous sulfate heptahydrate 5560 mg/L, disodium ethylene diamine tetraacetate 7460 mg/L.

8. plant according to claim 1-appositional pattern microbiological fuel cell, is characterized in that, described soil horizon thickness is 5-7cm, and water layer thickness is 2-3cm.

9. a Green roof system that utilizes the produced electric energy of the described plant of claim 1-8 any one-appositional pattern microbiological fuel cell, comprise the roof, it is characterized in that, described Horizon is in the top, roof.

10. the application that produces the Green roof system of electric energy claimed in claim 9, is characterized in that, application process is:

(1) choose the fibrous root prosperity, easily the water-fast plant of flooding of growth and breeding builds the described Green roof system that produces electric energy;

(2) after structure was completed, Green roof system moved under natural conditions, decided according to the water evaporation situation, replenished running water every other day or every a couple of days, guaranteed that water layer is in the state that floods cathode electrode, ran off to prevent normal water evaporation;

(3) the plant nutrient solution in described water layer upgraded once in 1 month.

Images