On this trip, Chao and his team planned to push their invention deeper than it had ever gone before. From the outside, Seatrec’s ocean thermal generator doesn’t look like much. The bottom of the cylinder is packed with a specially designed wax that changes its phase depending on the temperature. Yet they still managed to generate enough energy to power many types of research tools deployed by oceanographers. Two SL1 generators from Seatrec flank a profiling float during a test in Hawaii last year.