The thermal energy of the oceans can also be exploited by exploiting the temperature difference between the warmer surface water and the colder bottom water. Ocean thermal conversion technology first uses hot water to heat a special chamber with a low boiling point such as ammonia or a mixture of ammonia and water. When this mixture boils, the gas released creates enough pressure to drive a gas turbine that produces the energy. This gas then freezes as it passes through the cold water of the ocean floor.