======Green IoT Design====== Green IoT design is a paradigm based on a holistic IoT design framework that focuses on maintaining a balanced trade-off between the functional requirements, Quality of Service (QoS), interoperability, cost, security, and sustainability within the IoT ecosystem. It emphasises the need to prioritise energy efficiency and the reduction of waste in the IoT ecosystem by manufacturing IoT devices, deploying IoT systems, and operating IoT systems. The emergence of modern technologies such as Fifth Generation (5G) mobile networks, blockchain, Artificial Intelligence (AI), and fog/cloud computing are unlocking new IoT use cases in various industries and sectors of the modern technology-driven economy or society. As a result, the number of IoT devices connected to the internet and the volume of traffic generated from IoT infrastructures will increase significantly, increasing the energy demand in the IoT ecosystem. The result is an increase in the carbon footprint and e-waste (especially from battery-powered IoT devices) from IoT-related services or the IoT ecosystem. An effective green IoT strategy should span the entire IoT product lifecycle from the design to production (manufacturing) to the deployment, operations and maintenance, and recycling. The primary goal in each stage is to reduce energy consumption, adopt sustainable resources (e.g., harvesting energy from sustainable energy sources, using sustainable materials) usage, minimise e-waste and other pollutants, and adopt recycling of resources or waste. Therefore, a shift toward green IoT (G-IoT) emphasises the need to adopt energy-efficient practices and processes prioritising resource conservation, waste reduction, and environmental sustainability((Corey Glickman, "Green IoT: The shift to practical sustainability." ETCIO.com (cio.economictimes.indiatimes.com, July 2023, Accessed on Aug. 24, 2023 )). Green IoT design is a design framework consisting of design, production, implementation, deployment, and operation choices to reduce energy consumption and waste from the IoT ecosystem. They are energy-efficient strategies devised to reduce the carbon footprint from manufacturing, deploying, and operating IoT systems (IoT sensor devices, networking nodes, data centres or computing devices). They are also strategies devised to reduce the waste from IoT infrastructures. They may involve hardware, software, management or policy decisions. The green IoT design framework should consist of the following design considerations: developing and deploying energy-efficient mechanisms, choosing energy sources, and mechanisms to ensure environmental and resource sustainability. **Energy-efficient design** It involves designing and deploying energy-saving mechanisms to reduce the energy consumption of IoT devices. These mechanisms include the following: - Green computing: Energy-efficient strategies designed to minimise energy consumption or to maximise energy efficiency to decrease the carbon footprint of computing devices and processes in IoT infrastructures (from the devices at the IoT layer to the computing servers at the fog computing servers). - Green communication and networking: Selecting energy-efficient technologies, products, and practices designed to minimise energy consumption or to maximise energy efficiency decreases the carbon footprint from networking and communication nodes in nodes and processes in IoT infrastructures (from the IoT access nodes through the Internet core network to the cloud data centres). - Green security: Design and implement energy-efficient security algorithms to minimise energy consumption or maximise energy efficiency in IoT infrastructures. - Green architectures: Designing and organising IoT and other ICT architectures within the IoT infrastructure to minimise energy consumption or maximise energy efficiency. - Green hardware design: Design energy-efficient hardware chips and devices (computing and networking nodes) to minimise energy consumption or maximise energy efficiency and decrease the carbon footprint from computing and networking hardware nodes in IoT infrastructures. Energy-efficient chips and hardware devices can save a lot of energy. With the increased use of AI and blockchain in IoT applications, energy efficiency at the hardware level becomes essential. - Green software design: Optimising software algorithms and programs to minimise energy consumption, maximise energy efficiency, and decrease the carbon footprint from software programs running on IoT infrastructure. The above energy-efficient or sustainable computing, security, networking, hardware, and software design strategies can significantly reduce the energy demand from large-scale IoT infrastructures deployed throughout the world. Although significant amounts of energy can be saved by applying these strategies, the rapid growth in the size of the IoT industry may offset these gains, but they offer a significant gain for the environment. **Design choices for energy sources** The type of energy sources required to power IoT infrastructures varies from the IoT cyber-physical infrastructure to the core infrastructures. Electrical and electronic devices in the IoT infrastructure can be powered with energy from: - Main: Powering electrical and electronic systems within the IoT infrastructure using electricity from the main power supply. This method is suitable for energy-hungry devices like networking nodes and servers but not for a massive number of IoT devices, especially when the devices are supposed to be mobile. - Energy harvesting: Renewable energy sources power electrical and electronic systems within the IoT infrastructure to reduce dependence on fossil fuel and other environmentally unsustainable energy sources. The kind of renewable energy source depends on the energy demand of the networking and computing nodes. For IoT devices, energy harvesters that can be scaled down to produce a small amount of energy to power small IoT devices, while larger energy harvesters that can produce more significant amounts of energy are used to supply power-hungry computing and networking nodes. - Energy storage: The energy storage systems used to store energy in IoT infrastructure are battery energy storage systems (BESS) and super-capacitors. Small-sized batteries with limited energy often power most IoT devices. Due to the intermittent nature of renewable energy sources, large energy storage systems are frequently used to store harvested extra energy. That is, if the energy harvested is more than the load demand of the computing and networking system to be powered within the IoT infrastructure, the extra energy is stored in an energy storage system. The energy stored in the energy storage system is then later used to supply the load (IoT infrastructure) when the renewable energy source can no longer produce sufficient energy to meet the load demand. **Environmental sustainability mechanisms** IoT systems should be designed, implemented, and operated in such a way as to ensure the conservation of natural resources and reduce the waste or pollutants that are generated by the IoT industry. Energy-efficient design and use of renewable energy sources are sustainability mechanisms. Deploying energy-efficient mechanisms and using renewable energy reduces the carbon footprint of IoT infrastructures. Other environmental sustainability strategies are: - Biodegradable materials are used to fabricate some components of the IoT devices. - Reuse of IoT components. - Recycling some of the waste generated, especially e-waste (electronic parts and batteries) from the IoT industry.