Seatrec's TREC (Thermal Recharging) Battery harvests thermal energy from temperature differences in the environment and converts it to electrical energy.
The Seatrec TREC Battery
A class of substances called phase change materials (PCM) expand and contract substantially as they change between liquid and solid. The TREC Battery contains a quantity of PCM which undergoes a volume change as the host platform transits the ocean thermocline. This volume change generates high pressure which is used to drive a small electric generator. While the amount of energy derived from a single cooling-heating cycle is small, the process can be repeated indefinitely. For oceanic applications it is convenient to use a PCM that changes phase (melts) at a temperature near 10C -- typically within the main thermocline in tropical and subtropical oceans. PCMs that change phase at other temperatures are available.
The Seatrec energy harvesting technology has immediate application in the ocean and has been thoroughly demonstrated at sea on both profiling floats and underwater gliders. The same technology can also be integrated with other platforms including profiling moorings. TREC technology may also be useful in polar environments and in terrestrial locations where wind and solar are operationally or tactically inconvenient.