Smart and renewable energy systems: A critical overview on drivers, challenges and opportunities

Smart and renewable energy systems have recently drawn increasing interest as cornerstones for the development of a more sustainable society. Emerging smart and renewable energy systems are primarily focused on synergistically integrating smart electricity, thermal (district heating and cooling networks) and gas grids with the transportation sector to attain the most cost-effective overall solution. New stricter environmental policies and regulations for the reduction of carbon footprint in line with the Paris agreement, as well as the increasing global energy demand, are undisputable reasons for the development of smarter renewable energy systems. Nevertheless, the optimal design of integrated renewable energy systems is a demanding task that must take into account economic, environmental and social concerns, in addition to balancing energy supply and demand sides. In this work, we provide a critical overview on main drivers, challenges and opportunities for the design and implementation of smart and renewable energy systems as a promising pathway to achieve a low carbon future. The major challenges of more efficient design and optimization of integrated systems are discussed, particularly when considering the flexibility required for the different sub-systems under uncertainty linked to scenarios of renewable energy generation and transition to zero fossil-fuel-based systems. Several case studies in the EU scenario are critically reviewed to assess underlying difficulties, with special attention paid to the development and implementation of 100% renewable energy systems. Finally, perspectives are outlined to present potential alternatives for surmounting barriers to the broader application of smart and renewable energy systems.