The challenges arising from the inclusion of decentralised energy providers have a spatial and temporal dimension. The spatial dimension affects the local distribution grids as well as the national transmission grid. The temporal dimension ranges from seconds to seasonal fluctuations. The basic principle here is that quick and smaller-scale fluctuations are managed at a local level to the greatest extent possible, while slow and larger fluctuations are handled at a national level in the transmission grid. Swiss hydropower plants will play an important role here as they can operate flexibly.Synthesis on “hydropower and market” However, an important question is whether the balancing capacity of hydropower will still be sufficient in the case of a massive expansion of photovoltaics. In future, seasonal fluctuations will also be balanced out via exchanges with other countries – at least in part.

In principle, the challenges can be tackled with two different approaches. Some problems can be resolved with new control systems, while others require the development or improvement of new physical grid components such as transformers and storage solutions.

The fluctuations to be expected in the electricity grid with respect to the provision of power can be absorbed in part with local energy storage devicesNew storage technologies for the balancing of daily fluctuations – primarily batteries. In most cases, these do not have a large capacity and are therefore best suited to smaller-scale intermediate storage over shorter periods of time. The batteries of electric cars also offer storage capacity that can be utilised for the adjustment of tariff and taxation systems. However, other systems are required for multi-day and seasonal storage: compressed air reservoirs, pumped-storage plants and power-to-gas (P2G). Heat can be stored in underground storage tanks, as is planned, for example, in the energy concept of the ETH Hönggerberg campus.ETH Real Estate 2017; The energy of tomorrow, ETH Zurich