An electrochemical direct heat to electricity converter comprising: a working fluid; a first electrochemical cell comprising a first plurality of membrane electrode assemblies being a low temperature stack; each membrane electrode assembly of the first plurality including a first porous electrode and a second porous electrode and at least one ion or proton conductive membrane sandwiched between the first and second porous electrodes; a second electrochemical cell comprising a second plurality of membrane electrode assemblies, being a high temperature stack; each membrane electrode assembly of the second plurality including a first porous electrode and a second porous electrode and at least one ion or proton conductive membrane sandwiched between the first and second porous electrodes; at least one first conduit containing the working fluid at a first pressure and at least one second conduit containing the working fluid at a second pressure which is higher than the first pressure, the at least one first conduit being a low pressure conduit coupled to the first porous electrodes of each of the first and second plurality of membrane electrode assemblies and the at least one second conduit being a high pressure conduit coupled to the second porous electrodes of each of the first and second plurality of membrane electrode assemblies, and an external load connected across the plurality of first porous electrodes and the plurality of second porous electrodes of each of the first and second plurality of membrane electrode assemblies, the converter supplying power to the external load as pressure forces working fluid flow from each first porous electrode to each second porous electrode as electrons are conducted through the external load and ions or protons are conducted through each ion or proton conductive membrane; wherein the number of the first plurality of membrane electrode assemblies is greater by the amount of additional membrane electrode assemblies than the number of the second plurality of membrane electrode assemblies, wherein all membrane electrode assemblies in both stacks (303, 304) are connected in series and additional assemblies are added to the low temperature stack, such that the net voltage of the low temperature stack is still less than the net voltage of the high temperature stack; and the greater number of the first plurality of membrane electrode assemblies (303 + 307) causes an additional amount of the working fluid to be electrochemically pumped from the low pressure conduit to the high pressure conduit by the membrane electrode assemblies of the low temperature stack in order to compensate for a loss of pressure differential resulting from molecular diffusion of the working fluid through the ion or proton conductive membranes. a working fluid; a first electrochemical cell comprising a first plurality of membrane electrode assemblies being a low temperature stack; each membrane electrode assembly of the first plurality including a first porous electrode and a second porous electrode and at least one ion or proton conductive membrane sandwiched between the first and second porous electrodes; a second electrochemical cell comprising a second plurality of membrane electrode assemblies, being a high temperature stack; each membrane electrode assembly of the second plurality including a first porous electrode and a second porous electrode and at least one ion or proton conductive membrane sandwiched between the first and second porous electrodes; at least one first conduit containing the working fluid at a first pressure and at least one second conduit containing the working fluid at a second pressure which is higher than the first pressure, the at least one first conduit being a low pressure conduit coupled to the first porous electrodes of each of the first and second plurality of membrane electrode assemblies and the at least one second conduit being a high pressure conduit coupled to the second porous electrodes of each of the first and second plurality of membrane electrode assemblies, and an external load connected across the plurality of first porous electrodes and the plurality of second porous electrodes of each of the first and second plurality of membrane electrode assemblies, the converter supplying power to the external load as pressure forces working fluid flow from each first porous electrode to each second porous electrode as electrons are conducted through the external load and ions or protons are conducted through each ion or proton conductive membrane; wherein the number of the first plurality of membrane electrode assemblies is greater by the amount of additional membrane electrode assemblies than the number of the second plurality of membrane electrode assemblies, wherein all membrane electrode assemblies in both stacks (303, 304) are connected in series and additional assemblies are added to the low temperature stack, such that the net voltage of the low temperature stack is still less than the net voltage of the high temperature stack; and the greater number of the first plurality of membrane electrode assemblies (303 + 307) causes an additional amount of the working fluid to be electrochemically pumped from the low pressure conduit to the high pressure conduit by the membrane electrode assemblies of the low temperature stack in order to compensate for a loss of pressure differential resulting from molecular diffusion of the working fluid through the ion or proton conductive membranes.