Plant e1

Plant e is a technology by which plants can produce electricity with help of electrochemically active bacteria

1. P L A N T - E Living plants can generate electricity

2. Wha t is plant-e? Plant-e is a technology of producing electricity from living plants. This technology is also called Plant-Microbial Fuel Cell (Plant MFC) . Fuel cell is one of the source of electrical energy. Since, the plant-e technology produces electricity with the help of microorganisms present in the soil, this tech. sometimes referred to Plant MFC. The plants transform solar energy into organic matter which is transformed into electricity by electrochemically active bacteria in the fuel cell.

3. Evolution The proof‐of‐principle was realized in 2007 by Wageningen University with financial support of Nuon. Wageningen university established “Plant-e” company with the aim of implementing this technology world wide. The first estimates of theoretical long term output was 0.066 W/m 2 . Now a days long term performance at 0.22 W/m 2 is reached.

4. Electricity production The main process which helps plants to function as a source of electricity is Photosynthesis . The electrochemically active bacteria assists the release of electrons i.e., oxidation. We know that “photosynthesis” is a process carried out by plants in which light energy in fact solar energy is converted into chemical energy.

5. Two carbon electrodes (anode & cathode) are inserted into the soil. The electrons liberated will flow from anode to cathode via energy harvester. The electrons after coming out of cathode helps in forming water. Thus electricity is produced. The electrochemically active bacteria present in the soil oxidize the organic compound thus liberating the electrons. The energy thus converted is stored in the form of sugars (organic compounds) such as glucose.

6. Energy flow diagram UV light Solar energy O 2 H 2 O CO 2 Organic Compound (Glucose) Electrons Oxidation by active bacteria Anode e - Energy Harvester e - Cathode Water

7. Process of electricity production During photosynthesis process, plants absorb CO 2 and release O 2 into the atmosphere. When the plant is fed with water, the CO 2 absorbed from the atmosphere reacts with H 2 O and forms Glucose (C 6 H 12 O 6 ). The glucose thus produced is stored in roots of plants. The roots of plants are present in rhizosphere. The rhizosphere is the narrow region of soil that is directly influenced by root secretions and associated soil microorganisms. The rhizosphere contains many bacteria that feed on sloughed-off plant cells, termed rhizodeposition, and the proteins and sugars released by roots.

8. The electrochemically active bacteria such as protozoa and nematodes breaks down glucose into CO 2 and H + and e - Glucose Electrochemaically active bacteria x CO 2 + y H + + n e - The anodic oxidation of glucose takes place and the chemical equation is C6H12O6+12H2O = 6HCO3+30H++ 24e

9. The electrons thus liberated are attracted towards anode since the electrons are negatively charged and anode is positive. The electrons flow from anode to cathode via energy harvester such as LED bulb . They are then come out of cathode. Few of the electrons react with O 2 and remaining flow back to the anode thus forming a closed path. 6O2 + 24H + + 24e = 12H2O

10. Types of electrodes The best pair of electrodes that produces highest power output has to be determined prior to any further optimization effects. In the present work, four different material of electrodes have been selected because they are locally available and easily abundant. They are Cu, Fe, Zn, Al. The electrode with higher and lower electrode potential E i s selected as anode and cathode, respectively. Simultaneous oxidation and reduction process occur at anode and cathode allow the flow of negative ions to the anode and positive ions move towards cathode

11. Voltage developed for different electrodes 1) Pulai tree

12. 2 ) Banana tree

13. 2 ) Aloe vera

14. Test on Some Practical Applications Figure shows the digital clock is functional when connected to two pairs of Cu- Zn electrodes with aloe vera as organic energy source. The digital clock requires a single AA 1.5V battery to operate. Longer periods of testing time were carried out and it was found to be in an operation mode for more than half day.

15. Similar result was observed when scientific calculator was used. Figure 8 shows that the calculator can be switched on and show numerical input on its screen. Not only that, the calculator is also capable of performing scientific calculation with this new organic energy source

16. Green roofs One of the most promising PMFC application is green roof because it can dominate the advantages of these roofs with electricity generation OTHER ADVANTAGES: STORM-WATER RUNOFF RETENTION HIGH AESTHETIC VALUE INCREASED BIODIVERSITY IMPROVEMENTS IN AIR QUALITY BUILDING INSULATION AND DECREASE IN TEMPERATUREWITHIN CITIES

17. Electricity ge neration potential Electricity generation potential depends upon 1) Types of plant/crop 2) Types of microorganism 3) Sediments / soil 4) Weather condition

18. Benefits

19. European research consortium is working on optimal electricity production of 3.2W/M2. On a flat roof of 50 M2 , 150W could be continuously produced. Assuming an average electricity need of 500W, a green roof could provide approximately 1/3 rd of household’s electricity need. Energy use by the household will decrease further due to the insulation capacity of the green roof. At an electricity price of RS. 4.00/KWH, A 50-M2 electricity producing green roof could potentially save a household RS 5250 per year approx .

20. Non-Effectiveness Output power is less Require more land to generate more power