The £1m hydroelectric power plant will be incorporated into an existing weir on the Thames.
The Queen has won planning permission for her own hydro-electric power plant on the Thames.
The £1m plant at Romney Weir in Berkshire will supply a third of Windsor Castle’s power.
Four turbines will be incorporated into two of the weir’s bays and will be virtually silent and invisible according to supplier Npower Renewables.
Electricity will be fed straight into Windsor Castle and not the local grid. Construction is expected to begin next year, and Windsor Castle is set to start using the electricity by the end of the 2006.