Pumped-storage hydroelectricity
= Pumped-storage hydroelectricity
{title2=$E=\eta\rho Vgh$}
= Pumped storage
{synonym}
Water is pumped to an upper reservoir and later discharged through a turbine. For approximately constant head, useful discharge <energy> is $\eta\rho Vgh$ while <power> is $\eta\rho Qgh$; reservoir <volume> and flow rating set different properties.