Thermal water currents can be used to power a ship’s engine
We have always known that indefinite motion is a physical impossibility but the US Navy and NASA’s Jet Propulsion lab have set out to prove that belief wrong. They have designed an ingenious propulsion motor that could power itself and propel a ship indefinitely. This engine, called SOLO-TREC, is fitted with tubes containing phase change materials. On encountering warmer currents near the surface these materials expand and they contract as the tubes go deeper in the water due to the cooler temperature. This expansion and contraction pressurizes oil, which drives a hydraulic motor. This motor generates electricity to recharge batteries that power a pump. This pump can then be used to control the buoyancy of the float facilitating its vertical motion in the water column.
In essence, this mechanism enables the engine to derive power from water currents. This also implies that it will run out of power when there is no energy left in the ocean, which will never happen. This technology when developed could a long way in further empowering the Navy while protecting the environment.