Ocean Thermal Energy Conversion (OTEC) generates electricity using the difference between the temperatures at the surface of the ocean, where the water is warm, and far below the surface, where the water is cool. A test system off Hawaii operated between temperatures of 28.0 °C (the water temperature at the surface) and 4.00 °C. Calculate the theoretical maximum efficiency (in percent) that you would expect for a system operating between those two temperatures.