Hi My problem is 1. The problem statement, all variables and given/known data To raise 1°C the temperature of 1 liter of water, we spend 1 kcal. Therefore, cooling of 1°C 1 liter of water, it should be possible to extract 1 kcal of energy. Based on this principle, a ship could be propelled by the energy and simultaneously cool their cargo: the ocean would be a virtually inexhaustible reservoir of energy. Explain why this is not working. 2. Relevant equations N/A 3. The attempt at a solution I think is not possible because the neighborhood is very big ( ocean ) and the temperature of water is constant is impossible to extract energy from ocean and cool the water -1° C .