On the role of districts as renewable energy hubs

Although inevitable, the process of transforming urban areas into sustainable living environments presents many challenges. The decentralization of the energy system, the interconnection of multiple energy carriers, and the need to account for conflicting interests renders it a complex task. As key stakeholders, authorities often lack appropriate decision tools to frame and encourage the transition and to monitor the impact of implemented policies. This work aims to provide useful insights into the role of districts as renewable energy hubs by showing requirements and highlighting constraints, leading to an increase in renewable energy penetration. The benefits and trade-offs between centralized and decentralized renewable energy hubs are emphasized to contribute to the ongoing discussion regarding sustainable urban planning. Mathematical programming is used to build a multi-objective optimization platformthat integrates several renewable technologies with a special focus on solar integration. Specifically, this approach includes the role of the orientation of photovoltaic (PV) panels and the use of facades, including mounting partly shadowed PV panels and receiving solar heat gain. A decomposition algorithm (Dantzig–Wolfe) is used to bypass the computation effort associated with centralized energy hubs at the district scale. The results highlight that a low-emission electrical gridmix has a high impact on sustainable design of renewable energy hubs at the building scale and led to less independent system configurations. Optimally integrating of solar systems had a significant impact on their interaction with the electrical grid: rotating the panels 20° westwards reduced the grid exchange peak by 50% while increasing cost by only 8.3%. Moreover, the studied district could achieve carbon neutrality based on PV energy alone, whereas self-sufficiency is more ambitious that confirmed the importance of storage systems: even with 100% round-trip efficiency of storage systems, the required ratio of area covered in PV modules to the energy reference area (ERA) was Apv/Aera = 0.44 and 16% of available facades were needed to be covered with PV modules. However, energy demand reduction through thermal renovation would allow self-sufficiency with half of the PV and storage capacity. Overall, this work demonstrates thatmoving froma decentralized to coordinated and centralized design strategy allows a higher electrification rate and an increased integration of renewable energy in the district for the same total expenses. The centralized investment strategy differed most from the decentralized strategy for PV panels; using the centralized strategy, a wide range of PV installation on less–optimal surfaces became economically interesting. The most economically convenient solution to overcome transformer limitations were district storage for peak shaving and photovoltaic curtailment. The cost increase were around 600 CHF per kWyr annual capacity shortage, regardle