It is well known that for undisturbed functioning of an electrical network which is relying to a large extend (beyond 10% to 30% of total yearly energy consumption) on the stochastically varying renewable energy sources (like solar and wind) a certain amount of storage capacity is indispensable. Such a storage system fulfills two missions: First, it stores power at times where electric power production (in case of solar power for example around noon) by far exceeds the consumption, and delivers power when consumption exceeds production (evening or night). Second, this storage/delivery concept stabilizes the fragile equilibrium between consumption and production power of the network itself which is required to provide constant voltage and frequency for the reliable and undisturbed functioning of most electrical consumers.
While for short term storage (from hours to a few days) battery systems provide already a viable local (or decentralized) technical solution (even though still at high but decreasing costs), for the seasonal storage required in moderate latitude regions (i.e. central Europe) only centralized large scale pump-turbine hydroelectric storage is available. An interesting alternative commonly known as power-to-gas is presently developed to cope with the strong wind generated electric overcapacities in Northern Germany with the financial support of public organizations and industrial partners.
Since the canton Valais covers a region of high solar radiation and hydroelectric power (strongly seasonal variation due to snow melting) it is the ideal location for demonstrating now the potential solutions for the future. Since cost and performance will always be the central arguments for decision makers we need to demonstrate on the basis of a real functioning system how these parameters are linked. Simulations are insufficient since installation, maintenance and troubleshooting costs are not accessible, neither are realistic performance measurements on the real day to day performance.