# The Potential for the Use of Hydrogen Storage in Energy Cooperatives
###### Abstract
Previous research work and papers published by the authors show that integrating individual prosumers into an energy cooperative established under the terms set out in Polish law cannot only be profitable [40], but may meet the new challenges of energy communities, such as support for prosumers also in the light of the COVID-19 effect [42], meeting the requirements of the capacity market [43] or even in the much-needed process of crypto-coin \"greening\" [44]. As the EU will certainly not deviate from the path of developing and supporting the use of hydrogen, and will foster the emergence of local self-sufficient energy communities, we should already consider whether it is viable to combine innovative technological solutions (hydrogen storages) and new institutional solutions for RES (energy cooperatives). In this paper, the authors reflect on the following:  
1. Is it possible for an energy cooperative to achieve full or partial energy independence using its own RES and hydrogen storage? 2. What must be the minimum aggregate capacity of RES held by members of an energy cooperative so that, with the use of a hydrogen storage with certain parameters, it is possible not to exchange electricity with the grid? 3. Is it possible to reduce the capacity of a hydrogen storage operating within a cooperative by oversizing the RES held by members of an energy cooperative? If so, what relationship exists in this case between the scale of such oversized sources and the size of the hydrogen storage? All models of cooperatives proposed and studied in this paper as well as the data on energy production and consumption on farms that are members of a cooperative are based on anonymized actual data obtained from energy consumers and producers living in Polish rural areas. Our research, which is based on real data, allowed us to create several model energy cooperatives taking into account the legal conditions of forming and developing these institutions, while incorporating an innovative element in the form of hydrogen storage. Second, our paper also fills a literature gap and in a methodological gap, as the methodological approach presented here can easily be applied to other distributed-energy institutions that are and will be established in Europe and other continents. Third, it is novel at the European level as it investigates the problem that has only been partially analyzed with respect to EU countries, i.e., there has been no combined analysis on the formation of energy communities with the use of a hydrogen storage. An extensive analysis of the literature on the subject indicates an important publication gap, which the authors of this paper seek to fill. Known research and publications in the subject do not link the unique topic of energy storage in the form of green hydrogen within energy communities. Hydrogen storage in itself is so far not very popular, and in combination with \"prosumersin\" and the development of energy communities it represents a pioneering approach and a non-trivial proposal for building local energy independence. The contribution of the paper to scientific literature lies in proving that: (i) the storage of green hydrogen for later conversion to electricity may also be applicable at the local level; (ii) there is a relationship between the capacity of a hydrogen storage and the capacity of RES that allows for building full energy independence; (iii) the type of RES generating source is important in optimizing the capacity of a hydrogen storage. The paper is structured as follows. The second section presents and describes the requirements for the formation and operation of energy cooperatives. The section also presents the characteristics of dozens of prosumers (meaning simultaneous consumers and producers of energy), living in rural areas in southern and central Poland, who form the energy cooperatives analyzed in the paper. We also discuss the method of selecting 2000 random energy cooperatives that are also analyzed. We present the key assumptions for the simulations carried out.