Limitations of intermittent electricity production

Germany has nearly doubled its electricity supply system because about 80 GW of wind and photovoltaic (PV) power have been added to the traditional supply forms. The peak demand in Germany is about 83 GW. Under these circumstances the major characteristics of this new technology based on intermittent supply can be identified.
There are not many options for a sustainable electricity supply system. Electricity production by intermittent sources – one of them - has many negative aspects – low power density, overproduction in active periods, and a need for large-scale storage. Such a system causes many technical and economic problems. Here we concentrate more on system-technology aspects.
The following topics will be addressed:
 
-      How much wind and PV power is needed to come to a nominally 100% supply?
-      How much surplus energy is produced and how much back-up capacity is needed?
-      How can the surplus power be used?
-      Storage technologies and the economy of their operation.
-      On the potential of demand-side-management.
-      The reduction of CO2-emission by electricity generation Germany can achieve in comparison to other European countries.
-      On the consequences of a full decarbonisation with electricity adopting the role of primary energy.
-      The benefits of an EU-wide use of renewable energy.
 
In my view, it is not possible that Germany comes to full decarbonisation based primarily on wind and photovoltaic power. Something else will be needed. The options are scarce.