This is so simple it sounds impossible. Take a compound of some sort that when synthesized is an endothermic reaction. Now this process is done like where there is a heat scource and the proper catalyst like in a heatexchanger in the ocean or something. Now this compound is then transported or pumped or whatever to where you want to get the energy back out. This time the compound is exposed to a different catalyst like say a high voltage field or xrays and it is an exothermic reaction this time. The lack of the endothermic catalyst at the ouput exchanger allows for the seperated molecules to be returned to the input exchanger where they pickup heat again.
i must admit that this may be a little over my head and others,could you elaborate?
This idea could most easily be described by a Thermochemist but I will give it a try. Say we take something like water and pull a vacuum on the whole heat exchanger loop. The water now boils at -10 degrees in the collector heat exchanger. The steam then goes through a turbine and condenses in the second heat exchanger. We get thermal energy out as the vapor condenses in the condensor and electricity through the turbine. The whole system operates at low low pressure. See below
In this system the turbine output is only limited by how fast we remove heat from the heat receiver tank. It may be necessary to build a second stage to pump the heat out of the receiver tank. This could be accomplished by using some of the energy of the turbine. This drives a conventional heatpump system which takes the heat up to real hot to get the flow going even faster. You could go up to many many stages and each addition creates more velocity in the first stage. To power the next stages. The only limiting factor is how fast you can get heat into the first collector tank and how fast you can get it out of the receiver tank.