Abstract

The need for energy is inevitable for mankind. Climate change, depletion of natural resources, pollution and other factors have created the necessity to look for energy from renewable sources. Furthermore, there are challenges aplenty in the field of renewable energy as renewable energy sources are unpredictable, non-dependable and limited such as wind, solar photo voltaic and tidal power. Apart from these there are few unconventional renewable energy sources that have not been explored thoroughly or exploited. The photosynthetic power cell is one among them.
The photosynthetic power cell (PSC) harvests the energy produced at the lowest level of the food cycle which is “photosynthesis” in plants. The photosynthetic power cell extracts the energy produced during photosynthesis and respiration in form of electrical energy. The developed device differs from other published works in terms of improved performance, fabrication technique and material of structure. The two main types of sources used in the photosynthetic power cell are aerobic unicellular organisms (e.g. algae and cyanobacteria) and sub-cellular thylakoid photosystems / chloroplasts isolated from plant cells (e.g. spinach plant’s sub-cellular thylakoid photosystems isolated from the plant cells). The photosynthetic power cell produces energy under both dark and light conditions. The developed PSC is a polymer based structure instead of silicon, integrating the conventional MEMS processes with polymers. The principle of the operation of the device is based on ‘photosynthesis’. Photosynthesis and respiration both involve electron transfer chains. The electrons are extracted with the help of electrodes and a redox agent, and a power electronic converter is designed to harvest the energy. The developed device is capable of producing an open circuit voltage of 0.9 volts and about 200 μW of peak power. The μPSC has an active area of 4.84 cm2 which approximately translates to a power density of 400 mW/m2. This makes it as one of the best performing μPSC. The other top performing μPSC devices report power densities between 100 to 250 mW/m2.
In order to harvest energy from μPSC, power electronic converters are a necessity. Three different power electronic topologies are investigated to find the feasibility of energy harvesting using μPSC. Also, the cell should be operated at the maximum power point in order to get the best results. Common maximum power point tracking (MPPT) techniques as well as a novel MPPT technique is devised and tested for the energy harvesting application using μPSC.
In this thesis work, the device’s working principle, fabrication of the device and testing of the developed prototype along with the design and development of the power electronic converters with MPPT algorithm for energy harvesting application with μPSC are presented. A short introduction, basic photosynthesis process, background and history of μPSC are discussed in first chapter. The cell design, construction, working and fabrication of the cell are discussed in the second chapter. The third chapter deals with the experimental set up, characterization and testing of the cell. In the fourth chapter, modeling, analysis, simulation of PSC is executed. Analysis, identification and simulation of suitable power electronic converters with MPPT are investigated in the fifth chapter. Conclusions, future work form the epilogue.