In the gas-turbine cycle, both turbines are isentropic therefore it does not matter whether the two turbines are combined or have separate shafts. In the case of the AVE cycle, expansion in the turbine and expansion in the upward conduit are both isentropic processes; therefore the turbine could be at the bottom or the top of the conduit or anywhere in the conduit. The turbine could be divided into 100 smaller turbines spread over the upward flow conduit. The turbine could even be in the downward conduit.