GC: nm

CT: Ocean thermal energy conversion, or OTEC, uses seawater to turn solar energy into electricity. It relies on the ocean’s thermal gradient – the temperature decline from the sun-warmed waters on the surface to the cold waters found at great depths. OTEC plants pipe in hot and cold seawater and run them through heat exchangers and water condensers, in the process spinning turbines that generate electricity. It can only be done efficiently where the thermal gradient within the upper 1,000 meters of the ocean is more than 20° Celsius. These conditions occur in most of Earth’s tropical seas.
The concept of OTEC power is enormously appealing. Sunlight is free and renewable every morning. And scientists estimate that OTEC has the potential to generate billions of watts of electricity. Yet only a few, mainly experimental, plants have been built. One of the problems that restrict OTEC is that the necessary thermal gradient is found at sea, but the power it can generate is needed on land. In this activity, you will examine some of the issues involved in this dilemma by comparing onshore and offshore OTEC facilities.

S: http://oceanexplorer.noaa.gov/edu/learning/player/lesson11/l11la1.html (last access: 21 December 2014)

N: 1. ocean thermal gradient: Differences in the temperature of layers of the ocean potentially useful for running a heat engine.
2. ocean thermal gradients: The temperature differences between deep ocean water and surface water. These may range from 14 to 25°C.

S: 1. TERMIUM PLUS (last access: 21 December 2014). 2. GDT (last access: 21 December 2014).

SYN:
S:

CR: geothermal gradient, gradient, hydraulic gradient, ocean thermal energy conversion, OTEC power plant.