In recent years, mankind has been undergoing a massive transition due to increasing energy demands and environmental concerns. Issues like biodiversity loss and climate change have made the world a more challenging place to live in. Currently, most of the world's energy needs are met through fossil fuels. However, many nations are shifting towards green renewable energy sources for long-term sustainability. These efforts align with the UN's Sustainable Development Goals (SDGs) that aim to provide clean, secure, reliable, and affordable energy. This has led to the exploration of innovative technologies harnessing renewable resources.

Solar energy, wind energy, geothermal and hydrothermal energy are undoubtedly fast-increasing renewable energy sources and have provided promising results in shifting our dependence on the conventional non-renewable source. However, high energy-intensive processes, sizeable initial capital requirements, geographical constraints and landscape transformation creates ecological disturbances, which are some of the limitations associated with the kind of energies mentioned above.

Advancing towards newer forms of renewable energies, Plant Microbial Fuel Cells (PMFCs) represent a potential to be a renewable, self-sustainable, green, eco-friendly and an economical system requiring less energy-intensive process and needs no landscape transformation. It is a promising technology, which combines the principles of plant physiology and microbial electrochemistry to generate electricity. PMFCs offer a unique approach to harness the power of plants and microorganisms, to lower carbon footprints and to provide a green energy solution with simultaneous power generation and biomass production.

Working Principle of PMFCs

A plant microbial fuel cell consists of two compartments separated by a semi-permeable membrane. The anode chamber houses electrochemically active microorganisms, often derived from the rhizosphere, which utilize organic compounds released by the plant roots. These microorganisms, typically bacteria or fungi, break down the organic matter through anaerobic respiration, releasing electrons as a by-product. The released electrons then flow through an external circuit towards the cathode chamber, creating an electric current.

The cathode chamber, on the other hand, facilitates the reduction of electron acceptors, such as oxygen, by forming water or other benign compounds. This reaction completes the electron flow, closing the electrical circuit. Through this process, PMFCs efficiently convert the chemical energy stored in plant-derived organic matter into electrical energy, making them an attractive option for sustainable power generation.

Combating Indoor Air Pollution and Generating Bioelectricity

Indoor air pollution is a significant yet often overlooked environmental health risk. Unlike outdoor air pollution, which is visible and widely recognized, indoor air pollution is insidious, affecting the air quality within homes, offices, schools, and other enclosed spaces. Examples of some air pollutants include asbestos, formaldehyde, and volatile organic compounds (VOCs). Many indoor plants have the ability to mitigate various indoor air pollutants, and NASA recommends the use of indoor plants to improve air quality by removing toxic substances and absorbing CO₂. As these indoor plants are easy to grow, research is now exploring their capacity for bioelectricity generation alongside their environmental benefits. Therefore, as a part of our ongoing research work at The Energy and Resources Institute, Northeast Regional Centre, Guwahati, we are working on the design and development of indoor plant-based microbial fuel cell. We are using some of the widely known indoor plants such as Philodendron erubescens (Blusing plant), Epipremnum aureum (Money Plant) and Dracaena braunii (Lucky Bamboo) for large scale bioelectricity generation. It represents a cost-effective approach for the long-term sustainable bioelectricity generation, which is entirely green and operates 24×7, 365 days a year.

In today's world of advanced lifestyle, electronic gadgets are becoming increasingly widespread in daily life. Unlike our mobile phones, a smartwatch can make everyday life more accessible because of its multi-functionality including daily health monitoring. Similarly, at present a missing headphone jack in our mobile phones has pushed people to use True Wireless Stereo (TWS) to talk and stream music or audiobooks via Bluetooth. Therefore, our study is an effort to power LED lights and two crucial day-to-day use gadgets, i.e., smartwatch and wireless earbuds using plant microbial fuel cell. This innovative approach not only addresses indoor air pollution but also provides a sustainable solution for powering essential electronic devices.

Advantages of Plant Microbial Fuel Cell

The advantages of PMFCs are numerous and highlight the potential of this technology as a sustainable energy solution. Some key advantages are as follows. Renewable and Sustainable Energy: PMFCs utilize plants, which are renewable resources, as their primary fuel source. Unlike fossil fuels, which are finite and contribute to climate change, plants can be grown and harvested repeatedly, making PMFCs a sustainable energy option.

Waste Utilization: PMFCs can utilize various forms of organic waste, such as agricultural residues, food scraps, or wastewater, as fuel sources. This ability to harness waste materials not only provides an eco-friendly energy solution but also helps in waste management and reduces pollution.

Carbon Neutrality: PMFCs operate on a closed-loop system, where the carbon dioxide released during the plant's growth is offset by carbon dioxide consumed during microbial respiration. This carbon-neutral nature makes PMFCs environment friendly and helps reduce greenhouse gas emissions, contributing to mitigating climate change.

Low Environmental Impact: Compared to conventional energy generation methods, PMFCs have a significantly lower environmental impact. They do not require mining or drilling for fuels, and their operation does not produce air pollution or toxic by-products. PMFCs can be implemented in sensitive ecosystems without causing harm to the environment.

Scalability and Versatility: PMFCs can be scaled up to meet different energy demands, making them suitable for various applications. They can be deployed on a small scale to power individual devices or scaled up to power larger systems or communities. This scalability and versatility make PMFCs adaptable to different energy needs and locations.

Energy Access in Remote Areas: PMFCs have the potential to provide clean and sustainable electricity to remote or off-grid areas. In regions with limited access to traditional energy sources, PMFCs can utilize locally available plants and organic waste to generate power, improving the quality of life for communities in these areas.

Educational and Research Opportunities: PMFCs provide an excellent platform for educational purposes and scientific research. They allow students and researchers to explore the principles of plant physiology, microbial electrochemistry, and renewable energy generation. PMFCs can foster innovation, interdisciplinary collaboration, and the development of new technologies.

Integration with Green Infrastructure: PMFC technology can be integrated into green infrastructure projects, such as green roofs or vertical gardens. This integration enhances the sustainability of these structures by not only providing environmental benefits from declining urban landscape but also generating electricity, maximizing their potential as multifunctional systems.

Conclusion

Plant microbial fuel cells represent a groundbreaking technology with the potential to address multiple environmental challenges simultaneously. It provides a remarkable approach to renewable energy generation by harnessing the natural synergistic relationship between plants and microorganisms. Therefore, PMFCs offer a sustainable and eco-friendly solution to energy production, and climate change mitigation. As research progresses, PMFCs could play a crucial role in the global transition to a greener and more sustainable future. #