NOVELTY - An electrochemical conversion system comprises a housing divided by a hydrogen electrochemical cell to define two chambers containing two masses of hydrogen absorbent material.    USE - To be worn upon the skin of a person or other animal.    ADVANTAGE - The invention does not require a continuous source of reactant and does not require an electrolyte. It can be plugged over time, operate without notice, and operated at low temperatures. It can be worn by a person without the need for a large battery to store enough power to provide multiple bursts of power in transmitting data.    DETAILED DESCRIPTION - An electrochemical conversion system comprises two masses of hydrogen material (17, 18) spaced from each other, two electrodes (20, 21) , a proton conductive membrane (22) positioned between the electrodes, a housing (11) containing the above components, a hydrogen supply, and an adhesive layer for mounting the housing to a skin of an animal. The housing has a first chamber (13) containing the first mass of hydrogen material to thermally transfer heat between the material and the animal skin wearing the conversion system, and a second chamber (14) containing the second mass of hydrogen material to thermally transfer heat to ambience. The masses of hydrogen material are in fluid communication with each other through the electrodes and conductive membrane, where the hydrogen can be desorbed by one mass of hydrogen absorbent material and absorbed by the other mass of hydrogen material while passing past and reacting with the electrodes and proton conductive membrane to cause an electric potential difference between the electrodes.    An INDEPENDENT CLAIM is also included for a method of producing electricity comprising mounting a housing first portion into the skin of an animal to transfer body heat from the animal to a first mass of hydrogen absorbent material while simultaneously exposing a housing second portion to ambience to transfer ambience heat to a second mass of hydrogen absorbent material; and flowing hydrogen from one mass of hydrogen absorbent material to the other mass of hydrogen absorbent material and through an electric conversion cell (12) having spaced apart electrodes and a proton conductive membrane.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of an electrochemical conversion system.    Housing (11)    First chamber (13)    Second chamber (14)    Two masses of hydrogen material (17, 18)    Electrodes (20, 21)    Proton conductive membrane (22)