OTEC harnesses the temperature difference between the warm surface waters and the cold deep waters of the ocean to generate electricity.

Closed-Cycle OTEC systems use a working fluid, such as ammonia or a hydrocarbon, to transfer heat from the warm surface waters to the cold deep waters, generating electricity in the process.

Closed-Cycle OTEC systems have higher efficiency compared to Open-Cycle OTEC systems due to the use of a working fluid with a lower boiling point.

Open-Cycle OTEC systems directly use the warm surface waters to generate electricity by evaporating a working fluid, such as seawater, and driving a turbine with the resulting steam.

Open-Cycle OTEC systems have lower efficiency compared to Closed-Cycle OTEC systems due to the use of seawater as the working fluid, which has a higher boiling point.

Hybrid OTEC systems combine the features of both Closed-Cycle and Open-Cycle OTEC systems, utilizing a working fluid in a closed-loop cycle while also using seawater in an open-loop cycle.

Hybrid OTEC systems have higher efficiency compared to both Closed-Cycle and Open-Cycle OTEC systems due to the combination of the advantages of both systems.

A large temperature difference between the warm surface waters and the cold deep waters is essential for the efficient operation of OTEC plants.

A temperature difference of at least 20°C - 25°C is generally required for OTEC plants to generate electricity efficiently.

Equatorial regions are particularly suitable for OTEC plants due to the consistent high temperature difference between the warm surface waters and the cold deep waters.

The high cost of constructing OTEC plants, particularly the large-scale facilities required for commercial electricity generation, is a major challenge.

OTEC plants can potentially cause thermal pollution by releasing cold water back into the ocean, which may have ecological implications.

Developing efficient heat exchangers that can withstand the harsh conditions of the ocean environment is a major technological challenge for OTEC plants.

Ammonia is a commonly used working fluid in Closed-Cycle OTEC systems due to its low boiling point and high efficiency.

Seawater is a readily available and inexpensive working fluid, making it advantageous for use in Open-Cycle OTEC systems.