ME4212 NANOTECHNOLOGY NANOTECHNOLOGY IN ENERGY HARVESTING ASSIGNMENT 02 NAME : WANASINGHE H.I.M. REG NO : EG/2020/4336 GROUP NO : 02 DATE : 16/08/2023 1. ENERGY HARVESTING The definition of energy harvesting is the process in which energy is captured from a system's environment and converted into usable electric power. An energy harvesting system generally includes circuitry an energy storage cell, and manage power. Providing regulation and protection. The types of energy harvesting include light , vibration, temperature differentials, radio energy and biochemically produced energy. [1] 2. NANOMATERIALS USED IN ENERGY HARVESTING Nanomaterials have been widely employed in energy harvesting applications due to their unique features and improved performance. Energy harvesting is a key scientific area with enormous human applications, and nanomaterials have played a critical role in developing energy harvesting and storage systems, enabling more efficient and sustainable energy consumption. Due to the increased strength of physical effects, nanomaterials and nanostructures have improved the performance of many energy-harvesting devices. Nanomaterials have been used in a variety of energy harvesting applications, including solar cells, piezoelectric nanogenerators, thermoelectric generators, and nanogenerators. Carbon nanomaterials, such as carbon nanotubes and graphene, have been widely explored and used in energy harvesting applications. These materials possess excellent electrical conductivity, high surface area, and mechanical strength, making them suitable for various energy conversion processes. [2] Carbon nanomaterials – carbon nanotubes and graphene are mainly used in energy harvesting applications due to excellent electrical conductivity and its mechanical strength. Photovoltaic Nanomaterials – these nanomaterials are specially used to increase the efficiency of photovoltaic cells. These nanomaterials increased the power generation by enhancing the light absorption. Piezoelectric Nanomaterials – these types of nanomaterials can convert mechanical energy into electrical energy. Special nanomaterials like zinc oxide nano wires used to develop nanogenerators that harvest energy from vibrations and movements. Thermoelectric Nanomaterials - thermoelectric nanomaterials can convert waste heat into electricity. Nanoscale structures and engineered interfaces in thermoelectric materials can enhance their efficiency in energy conversion. Triboelectric Nanogenerators – these are used in triboelectric energy harvesting as a device for transforming mechanical energy into electrical energy. 3. NANOTECHNOLOGY USED IN ENERGY HARVESTING 3.1. SOLAR ENERGY HARVESTING In solar energy harvesting, photovoltaic cells are used to store and generate the electricity from sunlight. In first generation of PV technologies crystalline silicon cells was used as the device to convert energy. Then in second generation PV technologies thin film solar cells were used because they are less expensive than the traditional silicon solar cells. In these cells, cadmium telluride, gallium arsenide, copper indium as the materials for these cells. When the energy consumption began to increase and demand for the electricity was also increased. Therefore, the efficiency of the solar cells should have to be enhanced. To solve this problem nanotechnology is used in solar cells. The main purpose of these new third generation PV technology is to increase the efficiency of the solar cell. To fulfill this purpose nano materials like quantum-confined nanomaterials, smart coatings, nano fluids, carbon nanostructures, nano fluids etc. used. In general, these nanomaterials have higher optical absorption, lower reflectance, and tunable band gaps, which are important for solar cell efficiency. Nanomaterials can also interact with light in different ways, such as scattering, trapping, and plasmonic effects, which can increase the effective path length of light in the solar cell and reduce the losses. these properties help to enhance the efficiency of the solar cells and increase the durability and life style of the device, reduce the consumption of materials. [3] 3.2. TRIBOELECTRIC ENERGY HARVESTING Triboelectric charging occurs when two materials are brought into contact then separated, or slide against each other. This phenomenon used to harvest energy by converting mechanical energy into electrical energy based on coupling effect of triboelectrification and electrostatic induction and is utilized as the basis for triboelectric generators. Triboelectric Nanogenerators(TENGs) is used for this conversion and it is a type of mechanical energy harvesting technique where mechanical energy is transformed into electrical energy. Triboelectricity is caused by adhesion and during this process charges exchanged from one material to another to balance electrochemical potential. During separation, the materials become positively or negatively charged. Then a contact with an oppositely charged object may cause electric discharge. Nanomaterials used in TENGs include metallic materials like gold and silver, metallic oxides like TiO2 and ZnO, graphene and graphene oxides, perovskites, ferroelectric nanomaterials, amorphous or crystalline carbon nanomaterials etc. These nanomaterials help to transfer charges generated in the material to the external circuit with minimum loss, improve the mechanical properties of TENGs, making them more durable and resistant to wear and tear. These properties help to increase the efficiency of the TENGs. [4] 3.3. THERMOELECTRIC ENERGY HARVESTING At the atomic scale, an applied temperature gradient causes charge carrier in the material to diffuse from the hot side to the cold side. This effect can be used to generate electricity, measure temperature or change the temperature of objects. This is the basic theory that used in thermoelectric energy harvesting. For advancing thermoelectric energy harvesting, nanotechnology is widely utilized. For example, nanoscale thermoelectric thin films, pyroelectric nanogenerators have been developed to improve the energy efficiency, to enhanced thermoelectric properties. new type of energy harvesting devices can be developed by utilizing nanotechnology, for example pyroelectric nanogenerators a type of nanotechnology-based device, can harvest thermoelectric energy by utilizing the pyroelectric effect. These devices generate an electric charge in response to temperature fluctuations, which can be harnessed at the nanoscale to convert thermal energy into electrical energy. Also, Nanoparticles have been used to enhance the performance of thermoelectric materials. For example, nanoparticles can be used to enhance solar radiation absorption and thermoelectric power output. By using nanotechnology in thermoelectric energy harvesting, its performance can be enhanced, energy efficiency can be improved, also the wasted heat can be utilized again as an energy generation. 3.4. ELECTROMAGNETIC ENERGY HARVESTING Electromagnetic energy harvesting is the process of converting ambient electromagnetic energy into electrical energy. This energy can then be used to power small electronic devices, such as sensors, actuators, and medical implants. there are two types of electromagnetic harvesting, 1.far-field harvesting – use antennas to collect electromagnetic energy from radio waves, micro waves etc. 2.near-field harvesting – uses resonant structures to collect electromagnetic energy from magnetic or electric field. And nanomaterials are being used to enhanced the efficiency of the harvesting devices by increased surface area, enhanced electrical properties. Another way of increasing is that nanomaterials used to design new and innovative device configurations that are not possible with bulk materials such as metasurfaces. Metasurfaces is an artificial structure that can be used to manipulate electromagnetic waves, it is designed to catch wider range of frequencies. [5] 3.5. PIEZOELECTRIC ENERGY HARVESTING Piezoelectricity is the ability of certain materials (piezoelectric materials) to produce a voltage when subjected to mechanical stress. Piezoelectric energy harvesters can be used to power a variety of devices, including sensors, actuators, and medical implants. Same as other energy harvesting methods used nanotechnology, this also used nanotechnology mainly to increase the efficiency and enhanced the piezoelectric properties. Nanomaterials, such as graphene and boron nitride nanotubes, have enhanced piezoelectric properties, which means that they can generate more electrical energy from the same amount of mechanical energy. Nanostructures, such as nanorods and nanowires, can be designed with optimized geometry to maximize the amount of mechanical energy that is converted into electrical energy. That means eventually the efficiency of the device is increased that used piezoelectric energy. Graphene based piezoelectric energy harvesters are more efficient than the traditional energy harvesters because graphene has high piezoelectric coefficient and large surface area. This allows to generate more energy. [6] [7] 4. ADVANTAGES AND DISADVANTAGES USING NANOTECHNOLOGY FOR ENERGY HARVESTING ADVANTAGES DISADVANTAGES Increased efficiency Toxicity Reduced size and weight Efficiency limitations Lower cost Regulations and standardization Enhanced performance Durability and flexibility 5. CONCLUSION The topic of nanotechnology is one that is expanding quickly and has the potential to completely change how we power our electronics. Energy harvesting methods including thermal, piezoelectric, and electromagnetic energy harvesting are being employed in conjunction with nanomaterials and nanoscale devices to increase their effectiveness and power production. We may anticipate seeing even more cutting-edge and effective energy collecting technologies as this field of study develops. This will make self-powered gadgets more accessible and useful while also assisting in the reduction of our dependency on fossil fuels. 6. REFERENCES [1] "Analog Devices," [Online]. Available: https://www.analog.com/en/design-center/glossary/energyharvesting.html. [Accessed 15 08 2023]. [2] D. Dragoman, "MDPI," 24 03 2023. [Online]. Available: https://www.mdpi.com/2079-4991/13/7/1154. [Accessed 15 08 2023]. [3] P. R. Himanshu Kumar Rai, "Solar Energy Harvesting Using Nanotechnology," Research India Publications., 2018. [4] C. P. D. A. D.A. barkas, "Sustainable Energy Harvesting through Triboelectric Nano – Generators : a review of current status and applications," Elsevier Ltd., 2018. [5] m. a. a. d. d. v. s. i. d. d. mircea dragoman, "Nanomaterials and Devices for Harvesting Ambient Electromagnetic Waves," 2023. [6] x. p. h. y. h. zho wang, "hindawi," 25 06 2015. [Online]. Available: https://www.hindawi.com/journals/amse/2015/165631/. [Accessed 15 08 2023]. [7] s. T. M. w. a. Z. a. muhammad faisal wasim, "MDPI," 15 07 2020. [Online]. Available: https://www.mdpi.com/1424-8220/20/14/3931. [Accessed 15 08 2023].
