Over the past few decades, depleting energy resources has become a primary concern pertaining to the sustainability of our planet. In addition, climate change and its cascading effects are showing up in the form of extreme, unusual, and unpredictable weather patterns. Engineering and technological innovations must explicitly address these issues to make our planet more sustainable. Along these lines, smart infrastructures have been conceptualized and designed that take into consideration various environmental metrics – starting from energy and power consumption minimization to climate-friendly designs and operations. These smart infrastructures are characterized by the following elements: (i) Internet-of-Things, where a network of sensors and actuators are placed in an intelligent manner to enable a broader view and control of overall operation; (ii) connectivity among various stakeholders via advanced communication technologies; (iii) autonomy to reduce direct human intervention and reduce human-error related safety issues; and finally; and (iv) feedback-based decision-making to operate the overall system in a more environmental-friendly and efficient manner.

Examples of such smart infrastructures are as follows: (i) smart power grids which are empowered by various renewable forms of energy sources, such as solar, wind, and hydro; (ii) smart energy storage systems, such as batteries, which provide high energy- and power operations; (iii) intelligent transportation systems which utilizes autonomy and connectivity to enable fuel-efficient and safe vehicular operation; and (iv) smart buildings that utilize intelligent decision-making techniques to enable sustainable and comfortable operation. In all this smart infrastructure operation, energy plays a crucial role. Specifically, how energy is generated, transferred, stored, and utilized – all become critical to maintaining the sustainable operation of smart infrastructures. In this context, this special issue focuses on the energy storage and utilization aspects of smart infrastructure.

Besides discovering amenable materials and physically constructing various components of the smart infrastructure, systems and control play a crucial role in understanding, designing, and controlling the energy networks for smart infrastructures. Some of the critical undertakings of the systems and control domain include (i) development of mathematical models for energy systems based on physics knowledge and/or data which should also be computationally efficient for the real-time utilization purposes; (ii) development of real-time estimators when sensors are not available to enable a clear view of internal system states; (iii) development of diagnostic algorithms for diagnosing anomalies to stay away from unsafe and catastrophic situations; and (iv) development of optimal energy management algorithms to ensure efficient routing of energy among various subsystems of the smart infrastructures.

This special issue touches upon various systems and control related topics that contribute to the area of smart infrastructures. A breadth of topics has been included. Doosthosseini et al. tackles the problem of parameter identifiability in a newer battery chemistry – namely, lithium–sulfur batteries – which is challenging as there are numerous parameters but only one output measurement. They address this challenging problem and present an optimal input shaping framework to enhance the accuracy of the lithium–sulfur battery parameter estimation – ultimately leading to more accurate battery models for estimation, control, and diagnostics. Weng et al. focuses on parallelly connected battery systems and analyzes how initial cell variability influences imbalance within the battery system as the cells age. They develop a closed-form solution for imbalance dynamics in conjunction with a degradation update based on solid electrolyte interphase growth – which will be important in analyzing large scale battery system degradation in the face of heterogeneous cell characteristics. Aksland et al. explores control codesign aspects of hybrid electric unmanned aerial vehicle where the system and control action are designed simultaneously. Specifically, they develop and study the scalability of closed-loop codesign leading to physically realizable plant and closed-loop control law – which will ultimately enable enhanced functionality in electrified aircrafts. Rodriguez et al. explores the problem of state-of-charge prediction in lithium-ion batteries which involves complex electrochemical behavior – ultimately leading to nonlinear and high-dimensional dynamics. Relaxing the need for detailed knowledge of the battery's composition, they present a data-driven solution to discover governing equations pertaining to state of charge dynamics – which will be useful in real-time battery management. Paulson et al. focus on online self-optimization of vapor compression cycles in the context of building energy systems. They present a safe local search region Bayesian optimization, a global optimization methodology that enforces safety constraints – which will be beneficial in minimizing power consumption at the same time maintaining safe operating conditions. Ahuja et al. explores hybrid electric locomotives by adding battery storage with traditional diesel engines. Specifically, they study a route-specific optimization of battery and diesel energy/power split, to minimize fuel consumption – which will be beneficial in understanding locomotive electrification. Finally, Lin et al. contributes a new large-scale submetering HVAC dataset for building flexibility and demand response research. They show that closed-loop control of commercial building heating, ventilating, and air conditioning (HVAC) components for demand response would not be effective using Building Automation System (BAS) data alone – ultimately demonstrating the value of submetering HVAC components.