Hydroelectric power stations are already used as environment-friendly energy storage: if there is a surplus of energy, water is pumped into the reservoir. Durin

Hydroelectric power stations are already used as environment-friendly energy storage: if there is a surplus of energy, water is pumped into the reservoir. During peak demand, the power station provides additional electric energy. There are long-term considerations to increase this capacity significantly by including hydroelectric power stations in Scandinavia, as part of a European grid.