  The recently experienced disruptions in the EU's energy supply pointed out
that supply crises pose a real thread and the member states must be better
prepared do deal with the related challenges. According to the current
practice, member states fill their gas storages independently, while it is not
clear how solidarity could be put into practice in the future, i.e. how the
accumulated reserves of one or more members may be potentially redistributed to
help others in need. In this paper we propose some possible guidelines for a
potential solidarity framework, and formalize a game-theoretic model in order
to capture the basic features of the problem, considering the related
uncertainty of the future conditions related to gas storage levels and possible
transmission bottlenecks as well. The proposed mechanism of supply-security
related cooperation is based on voluntary participation, and may contribute to
the more efficient utilization of storage capacities. Via the computational
model we demonstrate the operation of the proposed framework on a simple
example and show that under the assumption of risk-averse participants, the
concept exhibits potential.
