## 2 State of the Art  
This section underlines the relevance of the aforementioned ambiguity issues in decision making and the originality of the proposed methodology in terms of a brief state-of-the-art overview of the following related topics: SETs and issues related to their acceptability for integration into the built environment, highlighting the need for research on community involvement in grid planning decisions; different types of citizen participation and engagement formats that demonstrate the possibilities and opportunities for public participation in decision making in smart cities; and MCDA in the context of renewable energy systems, emphasizing the added value of multicriteria evaluations of different decision alternatives, especially taking into account public opinion. Sustainable energy technologies are diverse, and differ fundamentally in their basic functionality, which can be conversion, storage, or transport (e.g., [16]). Potential SET for electricity generation and storage, which can be implemented in a decentralized manner and will potentially play a role in urban environments, includes photovoltaic and wind power plants, renewable gas power plants, but also chemical, electrical, thermal, rotational kinetic, or potential energy storage. In many countries, hydrogen is seen as a key enabler of the energy transition [11; 17], as electrolyzers, for example, can be used to produce hydrogen from excess electricity, which can be converted back into electricity or used for heat generation, e.g., by means of fuel cells or combustion. Application scenarios are envisaged in the energy, industrial, and transport sectors; thus, in addition to the implementation of generation plants and storage facilities, one must also assume a massive expansion of the transport and distribution network infrastructure [18; 19]. In addition to essential basic functional properties, SETs differ at the visual-haptic level, since these technologies have a spatial extent, a characteristic appearance, and also differ in terms of special requirements for their location, as well as implying expenses with regard to grid connection. The environmental impact of SET integration is often viewed with suspicion by local residents, who often expect a lasting deterioration in their quality of life. Aesthetic aspects or negative economic effects in the form of a decrease in tourism or a decline in the value of real estate and land usually play a special role here [14; 15; 19; 20], also leading to the introduction of new terms such as \"scenic beauty value\" and methods for their assessment [21]. However, SETs can also differ in terms of fundamental issues of sustainability--especially when it comes to life-cycle assessment--and can give rise to corresponding reservations [22]. In general, hesitant or dismissive attitudes in this context can be attributed to the \"not in my back yard\" (NIMBY) phenomenon [14; 15; 19]. This phenomenon can be observed for different regional implementation plans, whatever type of technology and infrastructure measure is at stake--from the integration of wind turbines to the development of hydrogen generation, distribution, and transport infrastructures [19]. In general, it can be observed in many countries--including Germany--that although there is a strong awareness of the problem of manmade climate change and a positive attitude towards the need to take measures, and the energy transition is welcomed in principle, the implementation of measures is rather slow [13]. Different studies on decision making have shown that people tend to prioritize short-term risks, such as an economic slowdown, over long-term risks, such as climate change [13]. In the context of regional expansion plans, communication, awareness raising, attitudes regarding renewable energy, and engagement and participation, in conjunction with social factors, play an essential role in accelerating SET integration [13].