is back to its original position the system 10 is recharged and ready to repeat the process the system described above is a closed loop system in which the working fluid is repeatedly caused to change phase through the use of an evaporator and a condenser it will be understood however that some embodiments of the invention make use of an open system in which the working fluid is continually exhausted and replenished in such embodiments the evaporator may be replaced by any fluid source providing fluid at high pressure and in many cases high temperature and the condenser may be replaced by any exhaust environment at a lower pressure than that of the fluid source typically in such embodiments working fluid is not recaptured one example of such a system is one in which the working fluid is the exhaust from an internal combustion engine and the exhaust environment is the atmosphere with reference to fig3 power generation system in accordance with some embodiments of the present invention will now be discussed in more detail a working spool 100 comprises a cylinder divided into two sides a working evaporator side 130 and a working condenser side 140 these sides are separated by a working spool piston 110 the working spool piston 110 may be magnetized or may have magnets attached thereto a working spool coil 120 surrounds.