1.30 Future Energy Directions Canan Acar, Bahcesehir University, Istanbul, Turkey Ibrahim Dincer, University of Ontario Institute of Technology, Oshawa, ON, Canada r 2018 Elsevier Inc. All rights reserved. 1.30.1 Introduction 1198 1.30.2 Issues With Energy 1200 1.30.3 Smart Targets of Future Energy Systems 1202 1.30.4 Future Energy Systems 1204 1.30.4.1 Cleaner Technologies 1205 1.30.4.2 Energy Conservation 1206 1.30.4.3 Renewable Energies 1207 1.30.4.4 Nuclear Energy 1207 1.30.4.5 Energy Storage and Carrier Options 1209 1.30.4.6 Overall Comparison of Future Energy Systems 1209 1.30.4.7 Future Energy Solutions 1210 1.30.5 Concluding Remarks 1212 References 1212 Further Reading 1213 Relevant Websites 1213 1.30.1 Introduction Energy is the key to tackling the most important issues of today and tomorrow such as climate change, sustainable development, health and environment, global energy and food security, and environmental protection. Nevertheless, traditional energy systems fail to accomplish meeting the multidimensional and multidisciplinary requirements of the 21st century. During the transition from traditional to future energy systems, it is primarily expected to design, analyze, develop, and utilize transitional solutions to enhance their energetic, exergetic, and environmental performance for better sustainability. In this regard, there is a strong need to greenize them in the best possible way by considering various criteria, such as environmental impact, resource utilization, efficiency, and cost effectiveness which will help achieve better sustainability ultimately. For that reason, a substantial change in energy systems is needed to meet the increasing global energy demand in a sustainable fashion without hurting the environment, society, economy, and the well-being of the forthcoming populations. This chapter demonstrates that transition to future energy systems is the most suitable approach to meet this need. Future energy systems can possibly be beneficial when resolving many of the aforementioned requirements all together and provide multiple advantages at the same time. The successful functioning of future energy systems necessitates strong-minded, continuous, and direct action. There are substantial benefits of future energy systems. However, in order to be considered as smart, an energy system should meet many expectations simultaneously. These expectations ultimately address the global energy challenges from various dimensions, including efficiency, effectiveness, cost, environment, resource use, sustainability, integrability, commercial viability, etc. The key expectations from future energy systems are illustrated in Fig. 1 and described below: • Exergetically sound: Exergy is an indicator of the quality of energy. For a system to be considered as smart, it should be exergetically sound. This means the system should have minimum exergy destructions and maximum exergy efficiency possible. In that case, a system could not only conserve the quantity, but also the quality of its energy content. • Energetically secure: This is basically about energy security. A future energy system should be designed and implemented in a way by taking advantage of affordable, reliable, locally available, abundant, and replenished sources. Such future energy systems then become self-sufficient, safe, efficient and hence secure. With future energy systems, end users have access to dependable, practical, safe, and efficient energy supply which eventually provides energy security. • Environmentally benign: Future energy systems are clean at every stage from source to their end use with less emissions and efficient resource utilization. Future energy systems also include waste and loss recovery for both energy and materials. Less waste and loss means more efficient systems, lower emissions, and better environment for future. • Economically feasible: Future energy systems are expected to use affordable, reliable, available, and abundant resources. In addition, future energy systems minimize losses and waste and maximize system efficiencies and desired outputs. Together with dependable, affordable, and practical end use options, future energy systems have significant economic benefits. • Commercially viable: From their sources to end use, future energy systems essentially take local and market conditions into account. A future energy system uses what already available or easily accessible resources and provides the goods and services that are desired and considered as commercially viable. This way they will have ability to compete effectively and economically Comprehensive Energy Systems, Volume 1 doi:10.1016/B978-0-12-809597-3.00139-5 1198