Development of pyRES: a Python library for time-dependent energy analysis and optimization of Renewable Energy Communities

The subject of study is renewable energy communities (RECs), according to the European definition. The aim is to develop an open-source tool for the design, analysis and optimization of RECs. RECs serve as a tool for member States to achieve energy transition goals. The fundamental principles are the use of renewable sources, decentralized production, self-production and collective consumption, and direct consumer involvement. The REC is a complex energy system whose characteristics are influenced by several key factors, including the time scale, spatial scale, local context, stakeholders, technology, adopted business models, and the organizational models governing its activities. Currently, the activities of an REC involve the production, storage, sale, sharing, and consumption of energy. The adopted technologies can be classified into three categories: distributed generation systems powered by renewable sources, conversion systems, and storage systems. The geographical dimension where energy-related activities are implemented can vary significantly from groups of buildings to entire cities. the REC can be established in a wide range of contexts, ranging from small municipalities with fewer than 5,000 inhabitants to metropolitan cities with millions of residents, from mountainous areas to small islands, and from agricultural areas to industrial districts. The geographical context strongly influences the development of the RES due to factors as the availability of energy sources, climatic conditions, end-uses of energy, energy consumption patterns, type of existing technologies, type and number of available spaces to install renewable technologies. The main actors include, REC members (consumers and prosumers), technology suppliers, energy suppliers, ESCOs, Transmission system operators (TSO), Distribution network operators (DNO), policymakers, regulatory bodies and aggregators. Organizational models are based on the horizontal cooperation and democratic decision-making. The introduction of RECs changes the paradigm of incentives for renewable sources: the incentive tariff is no longer proportional to the installed capacity but rather to the energy consumed on-site. In the introduction, an analysis of changes in the energy system caused by policies against climate change is carried out with the aim to identify the circumstances which led to the spread of renewable sources and the definition of RECs. The interest in RECs as an emerging model for sustainable development, along with their potential applications, is supported through a literature analysis. In addition, a comparison between the traditional 'prosumer' model and the REC as a new model for the production and sharing of energy is conducted. The EU legal framework for RECs is analysed, with a focus on the Internal Electricity Market Directive (IEM) and The Renewable Energy Directive RED II which promote a competitive electricity market and, for the first time, establish an official definition of RECs. The status of the transposition of European directives into national legislation, is described, identifying good and bad practices. Focus is particularly given to the process of transposition of the RED II in Italy, which has launched an experimental phase with the aim of identifying the implications of the directive and facilitating the development of the final regulatory framework. Key responsibilities of entities introduced by the regulatory framework, including the Italian Regulatory Authority for Energy, Networks and Environment (ARERA), the energy services manager (GSE) and The Ministry of Economic Development (MiSE) are outlined. Virtual regulatory model introduced by ARERA, technical constraints and incentive mechanism are accurately described. Then the current spread of RECs in Europe and in Italy is mapped. The complexity of RECs is examined, focusing on several key factors, including the time scale, geographical scope, local context, stakeholders, technology, adopted business models, and the organizational models governing its activities. A comprehensive review is conducted with the aim of identifying the primary indicators for assessing the socioeconomic, environmental, and grid impacts of RECs. Subsequently, the investigation focuses on how the REC model can be applied in specific energy contexts such as smaller islands, and how the expansion of technical constraints may lead to the inclusion of additional energy vectors like heat, as well as the dissemination of RECs within the industrial districts. Elements of success and barriers preventing RECs spread are examined. Finally future pathways and policy recommendations are discussed. The second chapter offers an overview of commercial software and open-source modelling tools for the optimal design of RECs, with the aim of identifying current trends in energy system modelling, challenges in simulating of RECs and requirements for new modelling tools. The modelling approach to develop a digital twin of the REC and the main steps of modelling are identified. Finally, methods to reconstruct production and demand curves along with the most used optimization method are described. The third chapter provides a description of the python tool (pyRES) developed specifically to create digital twins of the RECs, starting with the rationale behind its development. An overview of the software's key features is presented, detailing how it can be effectively utilized to model RECs. Development phases, core components and main models are also presented. The chapter concludes with the description of the potential and future development of pyRES. In the last chapters case studies related to RECs analyzed in pyRES are presented. In the first study the REC model is studied in a minor island disconnected from the national grid, with strongly seasonal energy load and water demand. Two sub-optimal REC configurations were defined using time-dependent simulations on pyRES. Results show the economical unfeasibility of REC when there is a poor mix of users. In contrast, REC can achieve economic profitability including industrial demand of a desalination unit (DES). In the second work the REC model is studied in a small town of Lazio Region. The challenge is to stress the issues of assembling a profitable REC in this scenario, discussing the proper selection of prosumers and consumers, solar panels and battery storage. Major conclusions include the negative impact of BES on the economy of the REC and the benefits of the REC on CO2 emissions and energy costs for the consumers. Finally, a sensibility analysis on these results was carried on discussing the effects of the fluctuations on the energy costs. In the third work the REC model includes a mix of production characterized by the integration of solar panels and biomass plants for cogeneration, several residential and commercial users. Both thermal loads and electric loads are considered. Results show that with a biomass cogenerator prosumers have minor economic interest in being part of a REC as the incentives are proportional to shared energy. Increasing their share of the REC revenue, on the contrary, reduces the appeal to normal users, resulting in a difficult balance.