# Autonomous Cyber-Physical Systems Enabling Smart Positive Energy Districts
## 5 Relationships Between Emerging Technologies in Positive Energy Districts
_Cyber-Physical System-Blockchain:_ Blockchain complements CPSs by supplying transparency, trust, and secure coordination between distributed digital and physical components. Blockchain enhances CPS security by providing an immutable history of CPS actions and events, improving data protection, increasing trust between system participants, and automating processes using smart contracts, as well as enabling forensic analysis in the event of an attack or system failure [95]. Blockchain, together with smart contracts, enables distributed control logic and decentralization of energy markets by utilizing cryptocurrency-based financial transactions. The synergy between CPS and blockchain shows promise for progressing the development and operation of sustainable, secure, and efficient PEDs [96]. 6. _Digital Twins-Artificial Intelligence:_ DTs and AI are two different but complementary technologies. DTs are digital copies of a physical asset that collect information from IoT devices, and apply advanced analytics, ML, and AI real-time processed data about physical assets' lifecycle process [25]. When integrated, they can significantly improve system performance, predictive capabilities, and decision-making. Two AI techniques, ML and NLP, are instrumental in modeling, extracting, and mapping the complex elements of PEDs, facilitating tasks like demand forecasting, system control, and stakeholder mapping [42]. AI instills intelligence in DTs by analyzing large volumes of sensor data in order to detect patterns, anomalies, and trends, while DTs provide the data and real-world context that AI needs to perform. ML models predict future states or failures, making DTs predictive instead of descriptive. Moreover, AI optimizes system parameters or processes in real-time by running simulations through the DT. AI integrated with DT can provide urban traffic management, and energy optimization with grid management and forecasting in renewable energy systems. 7. _Digital Twins-Internet of Things:_ The relationship between DTs and the IoT in the context of PEDs is both complementary and synergistic. The two technologies inter-relate and reinforce each other in the development and management of PEDs. DTs can be divided into three parts: the physical product, the virtual product, and the communication infrastructure/data collection systems. A critical aspect of the DT is the connection between the physical twin and the digital twin, which consists of IoT sensors and actuators [91]. The IoT continuously feeds DTs with accurate data, ensuring a trustworthy digital model, and, in turn, DTs simulate future scenarios using IoT data to visualize IoT data, guide and direct energy management, and facilitate intelligent control of PED operations. For example, at a microgrid network level, a vast number of assets, sensors, meters, controllers, and actuators are connected to the Internet through diverse IoT communication networks [97]. The integration of DTs and IoT creates a feedback loop that continuously improves PED energy performance. 8. _Digital Twins-Edge Computing:_ DTs and edge computing form a synergistic pair in PEDs. Integrating DTs with edge computing in PEDs enables real-time, efficient, and secure resource management, data synchronization, and service optimization for smart grids and urban energy systems [98]. DTs provide the intelligence and simulation capability, while edge computing enables local, fast, and secure execution of the DT insights, and, together, they enable PEDs to be more responsive, efficient, and sustainable. In general, DTs involve sensitive urban data, such as residents' energy usage, but when processing data at the edge, unnecessary personal data transmissions are minimized and compliance with privacy regulations and data sovereignty is enabled. 9. _Digital Twins-Blockchain:_ The integration of DTs and blockchain holds significant promise in the context of PEDs. Blockchain validates and secures the data stream feeding the DTs, ensuring that simulations and decisions are based on tamper-proof, verified inputs.