When we look at the future of mobile networks, the picture is clearly full of innovation, from high speed to ultra-reliable low-latency communications (URLLC). However, one significant aspect of the hardware that will drive these future networks is often left aside when beyond 5G (B5G) and 6G is discussed: efficiency and power. As electricity is a basic universal need in modern society, its use affects both adopters and non-adopters of the technology, including those who do not even own a mobile device. For instance, to achieve the desired levels of performance, B5G/6G will operate at higher frequencies with estimates to reach the Tera-Hertz (THz) band in the future, requiring more and denser cells, which comes at the price of higher energy consumption and therefore, if we do not work to optimize the efficiency of the network, the higher demands for electricity - maintaining the same supply capacity - will increase cost. Thus, to cope with the higher demand, electricity suppliers will need to find means to increase generation, which may come to the unfortunate use of fossil fuels, contributing to climate change, air pollution, and driving us further from achieving net-zero targets in the future.

In this chapter, we review the current efforts being explored to optimize future mobile networks' energy efficiency, targeting net-zero, and the United Nations (UN) Sustainable Development Goals (SDGs). A brief analysis of electronic waste (e-waste) will also be discussed in Section 2.6.

In the last two decades, energy harvesting technologies have generated significant interest, attributed to the decline in the power consumption of digital electronics. Electromagnetic (EM) power harvesting and delivery mechanisms, across the frequency spectrum, have been researched. In this chapter, we start by introducing the state-of-the-art in RF-enabled energy harvesting and wireless power transfer (WPT) technologies. Moving from device-level to system-level perspectives, the key enabling platforms are discussed with their environmental impact evaluated to assess their potential use enablers of net-zero intelligent systems.

Over the last few years, more and more countries are looking to increase their use of renewable energy, reduce emissions, and create a more sustainable future. Towards that end, they have been implementing net-zero targets and low carbon objectives. And to reach these goals, particularly in power industry, disruptive technologies such as smart grids, electric vehicles (EVs), and demand response (DR) systems are needed. In the communications industry, recently deployed 5G networks have inherently pushed the industry to move forward towards 6G networks which will be an important part of the future of mobile communications worldwide. The first step towards implementing these networks is to have a better understanding of what they mean for the industry and how it will affect infrastructure. This chapter aims to provide the role of 6G towards sustainable net-zero targets and how it could enable various smart energy-related applications such as DR and ancillary services for power networks. To that end, this chapter, first, presents an overview of 6G technology, underlying technology and envisioned performance. Second, an analysis of climate change and envisioned associated transformations in our society is presented. Third, potential smart-grid applications that can be unlocked or improved with 6G applications are given and discussed. In the last two parts, two cases studies, DR and vehicle-to-grid applications, are provided. Considering the fact that both the introduction of 6G networks and serious net-zero targets are set for 2030 and beyond, the interaction between these two transformational changes is very important and impactful for our society.

This chapter provides a comprehensive analysis of net-zero ITSs and highlights the crucial role of 6G networks in ITS technology, mitigating carbon emissions. The findings underscore the significance of integrating advanced technological solutions to address the pressing global challenge of climate change. First, net-zero ITSs have emerged as a promising approach to curbing carbon emissions in the transportation sector. By leveraging intelligent systems, data analytics, and connectivity, these systems enable efficient traffic management, optimized routing, and enhanced V2V communication. The research demonstrates that the implementation of such systems can lead to substantial reductions in fuel consumption, congestion, and overall environmental impact. Furthermore, the advent of 6G technology is poised to revolutionize the transportation industry and further enhance the effectiveness of net-zero ITSs. The ultra-high-speed, low-latency, and massive connectivity capabilities of 6G enable seamless integration of various components, such as autonomous vehicles, smart infrastructure, and real-time data analytics. This integration unlocks new possibilities for optimizing transportation networks, reducing energy consumption, and improving overall sustainability. Importantly, the research reveals that the successful implementation of net-zero ITSs and 6G technology requires collaborative efforts from stakeholders across multiple domains. Policymakers, industry leaders, researchers, and the public must collaborate to establish supportive regulations, invest in infrastructure development, foster innovation, and promote public awareness. Looking ahead, this chapter provides valuable insights into the future prospects of net-zero ITSs and 6G technology. In conclusion, the convergence of net-zero ITSs and 6G technology presents an unparalleled opportunity to address carbon emissions in the transportation sector. By leveraging advanced connectivity, data analytics, and collaborative efforts, we can pave the way towards a more sustainable and environmentally conscious future.

Conventional free-space optical receivers carry out the beam tracking and symbol detection functions in two separate units inside the receiver. This leads to a more complex receiver architecture that is also more inefficient in terms of energy. In this chapter, a detector array receiver is proposed that integrates the beam tracking and symbol detection functions in one single unit. This not only simplifies the receiver architecture but also leads to a more energy efficient system as compared to a conventional receiver. Among other applications, such energy efficiency will help meet the low transmission energy constraints of an optically connected CubeSat network in low earth orbit.

"The Role of 6G and Beyond on the Road to Net-Zero Carbon" has explored the transformative potential of 6G technology in addressing the urgent global challenge of climate change and achieving a net-zero carbon society. Throughout this book, we have examined various facets of 6G's contribution to sustainability, from energy-efficient hardware and architectures to innovative applications and integration with renewable energy sources.

The journey towards a net-zero carbon future requires collaborative efforts from researchers, engineers, policymakers, and industry leaders. By harnessing the power of 6G, we can create a greener and more sustainable communication infrastructure that significantly reduces carbon emissions while providing seamless connectivity and technological advancements.