A hydro-electric station is required to supply a continuous electrical output of 50 MW
PHYSICS · Multi-part · AP · Physics 1: Algebra-based · Work Energy and Power · Work Energy and Power
Problem
A hydro-electric station is required to supply a continuous electrical output of 50 MW. Water of density 1000 kg m⁻³ falls through an effective vertical height of 120 m. The turbine converts 90% of the incoming mechanical energy into rotational energy, and the generator converts 95% of the turbine’s mechanical energy into electrical energy.
(i) Write an expression for the overall efficiency of the station in terms of the individual efficiencies of the turbine and the generator.
(ii) Calculate the overall efficiency for the given values.
(iii) Determine the mass flow rate of water that must pass through the turbine per second to achieve the required electrical output.
(iv) Express this mass flow rate as a volume flow rate in m3/s.