A proposed ocean thermal-energy conversion (OTEC) system is a heat engine that would operate between warm water (25 degrees C) at the ocean's surface and cooler water (5 degrees C) 1,000 m below the surface. What is the maximum possible efficiency of the system?

Explanation:

Given that

Temperature of warm water ,T₁ = 25 °C

Temperature of cold water ,T₂ = 5 °C

The maximum possible efficiency of any heat is will be same as the efficiency of the Carnot heat engine.Therefore the maximum efficiency of OTEC system is given as follows

T should be Kelvin scale

Now by putting the values

Therefore the maximum efficiency will be 0.067 or 6.7%.