Towards a Secure and Resilient
All-Renewable Energy Grid for Smart Cities

Electric energy systems constitute the backbone of critical infrastructure. National security and economic vitality rely on a safe, secure, and resilient power system. The American electric grid, once considered a marvel of 20th century engineering, has become obsolete in the face of 21st century threats. Our energy grid has numerous shortcomings and can no longer deliver (cyber) secure and (disaster) resilient electric power to businesses and households, leading to an urgent and enormous threat to our society and economy. Vertical power systems with rigid transmission and distribution system control hierarchy have failed repeatedly during extreme threats. Recent studies by the Federal Energy Regulatory Commission (FERC) found that knocking out as 9 of the 55,000 power substations could result in U.S. coast-to-coast blackouts lasting 18 months or more [1]. For example, the Hurricane Michael resulted in 1.7 million power outages along the U.S. Gulf and Atlantic coasts [2]. During June – September 2007, heat waves and forest fires occurred in Greece causing extensive damages to the medium-voltage distribution network and knocking out power in many areas of the country [3]. Recovery from such disasters also costs tens of billions of dollars including time, manpower, and lost economic productivity, and deepen social inequalities. These failures have taught utilities, regulators, and stakeholders that faults cascade across national and continental electric grids, and exacerbating a local phenomenon into a socioeconomic catastrophe. Traditional power systems are prone to such cascading power outages that last long periods of time and are complex and time-consuming to recover – in other words, not secure and resilient. Continuing to operate the electric energy system critical infrastructure using the traditional model is a well-recognized security and resiliency threat and the main barrier for the development of future smart cities.

The integration of photovoltaic (PV) solar systems and wind farms together with other renewable energy sources (RES) into the electric grid, as shown in Fig. 1, helps towards improving security and reliability of the power system during normal operations and enhancing resiliency during and after extreme events. In the first quarter of 2018, solar accounted for 55% of all new generating capacity brought online in the U.S. [4], and Florida alone is expected to add over 8.6 GW of solar generation by 2025. The inclusion of such distributed resources in the form of solar PV, battery-based storage, and demand resources can increase the resiliency to catastrophic events once research efforts would be able to address open system design questions. Examples include how to strategically locate and operate these resources to sustain smart cities infrastructure by guaranteeing continuity or rapid restoration of power to vital loads following large-scale disturbances by formation of ad-hoc self-contained microgrids in outage situations. In addition, as more and more RES are integrated into power systems, it is projected that offshore oil and gas platforms will be re-used at end-of-life stage for the production of renewable energy (e.g., offshore wind, wave and tidal energy, ocean current energy, ocean-based solar energy, deep-water source cooling, etc.). To thwart the existing problems, a transformational development approach needs to be established, able to develop and build a secure and resilient electric grid for future smart cities. Such development will lead to an electric energy system immune to extreme phenomena while supporting the integration of RES and reducing the dependency on oil drilling into power systems, such as those at the North Sea as well as the Gulf of Mexico and its coastal zone.

The objective towards achieving a secure and resilient 100% renewable energy grid requires the development of multi-layer control and system methods, ranging from system stability controls to secure co-design of hardware/software/physical systems, that contribute towards a holistic cyberphysical energy system (CPES) integrated within smart cities [5]. The technological dimensions that will characterize those smart cities are electricity grids and the information and communication networks that can contribute in the development of intelligent transportation systems and support clean energy (e.g., electric vehicles, energy-efficient buildings, etc.). Technological methods will revolve around decision and cyber-resilient mechanisms of critical CPES and smart cities infrastructures dedicated to advance research and developments on renewable energy modeling and simulation. It is necessary to develop a core innovation ecosystem that enables crosscutting and convergent technology, transformative policy, economic and business models, and develop a future workforce to meet the needs of our cities’ future electric grid. Such vision needs to be approached under two main pillars: (1) develop and build a secure and resilient electric grid able to use 100% renewable energy for electricity, heating/cooling, and transportation and be immune to natural disasters and cyber-attacks; and (2) ensure that the new technologies will be used safely and effectively by operators, and that the new system will be accepted and trusted by consumers and citizens. Our daily lives and economy will be secured, transformed, electrified, and propelled to the next generation. The integration and convergence of these two areas will synergistically catalyze a safer, more reliable, and more efficient community and society. The two directions are described below:

While solar and other forms of RES are growing rapidly, they are primarily providing off-take energy and, as yet, are largely not integrated into grid operations, nor do they contribute in any significant way to electric and cities systems resiliency. It is critical to effectively utilize RES as a fully integrated grid operating asset and a resource for enhancing security, reliability, and resilience in a substantial and multi-faceted effort. It is important to expand current utility forecasting capabilities not only in terms of assets, but also develop probabilistic models for asset availability, accessibility, and usability during and succeeding a major disaster. The task is complex and is dependent on multiple, interacting and often counter-intuitive correlations between variables. Thus, there is a need to develop new indices for security and resilience, suited for the extreme event challenges of resulting from adverse events, either malicious or not, such as cyber-attacks and natural hazards including droughts, earthquakes, floods, hurricanes, tornadoes, and fires.

Future research in the area needs to develop interdisciplinary and innovative technologies for secure and resilient electric grid with 100% renewable energy vision; put people in the loop in a cyberphysical human-centered systematic approach, formulate and adopt technical, public, and economic policies to accelerate the use of renewable energy, and develop education programs to train the next generation of power and energy systems engineers. As world urbanization continually grows, smart cities supporting a secure and resilient electric grid will offer an attractive solution that can contribute in economic growth, increased efficiency of energy and transportation systems, and promote sustainable development.

In terms of anticipated impacts, developments in this area will further lead to: (1) greater clarity and improved understanding of the fundamental gaps in the power system infrastructures and how concerted engineering methods can result in revolutionary improvements in the reliability, efficiency, and resiliency of the fully RES-supported critical city infrastructure, (2) convene and co-development of the complementary skills needed to address the current and future challenges as well as foster and grow effective relationships with all stakeholders involved, and (3) preparation of the broader community to adopt the resulting technologies in a timely manner. Societal impact can be achieved by: (1) conducting an inventory of perceived challenges among industry stakeholders to determine prioritized challenges; (2) providing support to industry through advocacy and education; and (3) creating talent pipelines that support industry needs while promoting diversity in the energy sector.

Interdisciplinary environments will facilitate bridging multiple disciplines and viewpoints to enrich the impact of the anticipated research and development as well as learning experiences. Specifically, it would necessary to draw on the strengths of multiple academic disciplines and collaborations including electrical (e.g., impact of RES generation on the stability of electromechanical oscillation), mechanical (e.g., assessing structural resilience of offshore wind turbines), computer engineering (e.g., defense-in-depth strategies to establish attack-resilient and self-healing security frameworks), social sciences (e.g., uneven recovery after hurricanes has only deepened inequalities based on race and class), and government and industrial stakeholders (e.g., ensure that research outcomes truly represents national needs and urgency). This broad coalition is necessary to realize a convergent research approach and lead to significant societal impact. In terms of education, interdisciplinary courses merging concepts together from various disciplines will become a priority in order students to acquire more knowledge and skills in the area [25].

Looking broadly at the goals of security and resiliency in energy systems utilized in industrial applications and smart city ecosystems, there are two areas where significant progress must still be made, as shown in Fig. 5. First, increasing the resilience of critical systems to high-impact low-probability adverse events (e.g., cyber-attacks, weather-induced failures and faults, natural hazards, etc.) is a major priority for CPES and of high significance for safeguarding national economic and security. Such events can lead, for example, to escalating instability in system dynamics and cause large-area failures. It is of paramount importance to develop resilient and operational-secure strategy methods for electric grid applications in smart city environments considering the renewable future of the oil and gas industry. These methods will take into consideration of offshore installations within the oil and gas industry and how to reuse these structures for RES, leading to a “green decommissioning” and to a “green economy”. Towards this energy transition framework, it is necessary to encounter erratic events as well as the presence of modeling weather uncertainty. As a result, future methodologies would require to address disruptive events by exploiting both localized and supervisory RES schemes, and prevent them from escalating into system failures.

Second, a resilient electric grid should eliminate, or at least significantly reduce, impacts induced from extreme weather- and cyber- based events. Thus, it is important to expand current utility forecasting capabilities not only in terms of assets, but also develop probabilistic models for asset availability, accessibility, and usability during and succeeding a major disaster. The task is complex and is dependent on multiple, interacting and often counter-intuitive correlations between variables. Thus, there is a need to develop new indices for security and resilience, suited for the weather challenges and technological advancements of each smart city. Therefore, in the future, it would necessary to develop smarter and cost-effective strategies within comprehensive frameworks and algorithms for enabling resiliency of RES-based power systems – encompassing time-span from planning to post-event restoration and recovery that would minimize the power outages [26]. A framework based on security and resiliency metrics can be engineered to leverage maturation of microgrid technologies, asset management, conformation to cybersecurity standards and support of state-of-the-art attack detection/prevention methods, and increasing customer-ownership of viable, resiliency-enabling energy resources. For example, smart and automated generation fleet continuity of power supply to critical loads, during and after extreme events, can be driven by intelligent optimization algorithms based on multi-dimensional data resources and metrics [27]. Adding layers of probabilistic asset availability forecasting can lead to a better demonstration of metrics-driven monitoring and restoration. Security and resiliency metrics will be foundational components of future technology platforms which would glue together complex and interacting decision variables. This puts security and resiliency of the bulk power system and distribution systems of smart cities at the heart of the modernization challenges.