Disadvantages – Sometimes there will not be a lot of waves (which means no energy), It could interfere with ocean ecosystems in the area of the currents, and the temperature is raised wherever ocean currents are happening (which could also ruin an ecosystem).

Disadvantages of OTEC system

• Capital investment is very high.
• Conversion efficiency is very low about 3-4% due to small temperature difference in between the surface water and deep water.
• Low efficiency of these plants coupled with high capital cost and maintenance cost makes them uneconomical for small plants.

Capital cost is very high. Efficiency of energy conversion is very low. Needs very large sized turbines due to use of low pressure of steam having high specific volume in case of open cycle. It uses expensive power working fluids in case of closed cycle.

The biggest disadvantage to getting your energy from the waves is location. Because of its source, wave energy is not a viable power source for everyone. Landlocked nations and cities far from the sea have to find alternate sources of power, so wave energy is not the clean energy solution for everyone.

Ocean thermal energy is used for many applications, including electricity generation. Closed-cycle systems use the ocean’s warm surface water to vaporize a working fluid, which has a low-boiling point, such as ammonia. The vapor expands and turns a turbine. The turbine then activates a generator to produce electricity.

Most of the sulfur comes from the Earth’s interior; a small portion (less than 15 percent) is produced by chemical reaction of the sulfate (SO4) present in the sea water. Thus, the energy source that sustains this deep-ocean ecosystem is not sunlight but rather the energy from chemical reaction (chemosynthesis).

Ocean energy refers to all forms of renewable energy derived from the sea. There are three main types of ocean technology: wave, tidal and ocean thermal.