## 3 Methodology
### Decision Criteria for SET Integration  
For determining decision criteria for SET integration, future safety and resilience requirements on the power grid need to be considered; for example:1. The possibility of autarky at the city level: In the case of a long-lasting outage of the supraregional power grid, the operation of downstream critical infrastructure in particular needs to be ensured by a city's own supply via its local grid. The distance between energy sources and storage facilities and critical infrastructure should be kept as short as possible in order to minimize transmission losses and reduce the probability of failure due to external influences, such as extreme weather conditions; 2. The capability to manage unpredictable impacts of climate change: Global warming increases the number of people around the world who are affected by extreme weather events [3], and has increased the probability of unprecedented extreme hot and wet events [4]. Strong winds, hailistorms, heavy rainfall, and subsequent flooding, for example, endangering overhead power lines, pylons, substations, and transformer stations, may lead to potential damages and, consequently, have impacts on the power supply; 3. The need to meet unforeseeable future demands for electricity: Changing climate conditions and, for example, a general increase in warm temperature extremes in the future [47], may increase the demand for air conditioning in public and private buildings. Furthermore, despite the use of renewable heat sources as an alternative, an increase in electricity consumption for heating can be expected [48]. The growing importance of electromobility will also increase the load on the power grid, as well as the further decentralization of power generation from individual large power plants to many small-scale generators based on renewable energies. Based on these requirements, the following criteria, among others, may be considered in the framework of integrating SETs: * Profitability: Reasonable price/performance ratio (including research costs); * Reaction time: Coupling fast-responding storage types with slow ones to fill all power gaps in the power supply and, thus, increasing the overall absorptive capacity of the distribution network; * Safety of the urban area: Considering the potential harm of the various technologies for people and the environment in the event of an accident; * Location dependency: Suitability for the built environment according to size, distance to critical infrastructures, and dependency on geological conditions, for example; * Scalability: Ability of a technology to be deployed at different scales due to various requirements for the power supply of critical infrastructure, for example; * Volatility: Ensuring that the emergency solution supplies power with the same stability as the distribution grid; * Relative land use: Reasonable ratio of output and available land due to limited space in the urban environment; one may consider combinations with other uses; * Citizen acceptance: The public's attitude towards local SET implementation. This list is of course not final, and may be adapted by new insights in the future and according to the changing outlines of the task at hand. Some of the criteria mentioned are techno-economic in nature or relate to safety and security of supply and, thus, can only be evaluated by corresponding experts and stakeholders, e.g., electric utilities, urban and regional planners, or operators of other critical infrastructure.