provide a unitary cylindrical housing 18 which is fixed on base 20 base 20 is positioned on the sea floor and the oil well christmas tree passes through its center a top 22 fig5 may be secured to the upper end of cylindrical housing 18 base 20 cylindrical housing 18 and top 22 combine to provide a pressure housing 25 which contains the oil well christmas tree together with the alternator working fluid pump and all other equipment except for the condenser to provide a one atmosphere dry environment for the system if top 22 is not used and cylinder 18 is left open as shown in fig6 those components of the present invention requiring a dry or pressure balanced environment may be contained in the retrievable housing 19 after the working fluid leaves the turbine it is passed through a condenser 23 wherein it is cooled and reduced once again to a liquid the condenser is composed of a plurality of vertically arranged tubes 24 having their upper and lower ends connected to headers 26 and 28 the upper one of which receives the working fluid through tube 30 from the turbine and the lower one of which passes the condensed working fluid to the pump through tube 32 condenser 23 is mounted on the side of cylindrical housing 18 and is spaced therefrom a sufficient distance so that any heat which may escape through the magnesia insulating material and concrete will not affect the cooling function of the condenser the normal convection of the sea water around tubes 24 is sufficient to cool and liquefy.