Urban-Rural Cooperation for an Economy with 100% Renewable Energy and Climate Protection towards 2030 - the Region Berlin-Brandenburg

The German states of Berlin and Brandenburg are committed to the Paris Agreement with the goal of keeping global warming safely below 2 degrees to protect the Earth system from uncontrollable warming. This claim implies targeting 1.5 degrees to keep a reasonable chance of realisation. Renewable energies are the only sources that can be considered to accomplish this task. We use a linear cost minimization model for the Berlin-Brandenburg region to show how a 100% renewable energy target is possible without relying on contributions from other regions. We find that a 100% renewable energy system based predominantly on photovoltaics on buildings and on green hydrogen production, and a transition essentially to electricity for all purposes, is feasible in time and at a reasonable cost below that of fossil-nuclear energy. Hydrogen storage technology appears as one of the key cost determinants, while a sensible integration of German and European transition systems potentially limits costs to the lowest levels ever realized in real terms.