As the population is increasing so is the demand to fulfill their resource requirement leading to global warming. Decreasing carbon footprints is crucial for every individual; proper measures must be taken to achieve this goal. One such way of limiting nonrenewable energy usage is to opt for more non-conventional sources of energy such as Ocean Thermal Energy Conversion (OTEC).
This system utilizes the difference in temperature at the surface and the bottom of the sea to operate heat engines and produce electricity. This difference in water temperature is caused due to the amount the sunlight reached at that specific level of water. The water at the surface is in close contact with the sunrays thus having a higher temperature gradient whereas sunlight does not reach the bottom of the sea leading to lower temperature.
There exists a direct relation between the temperature difference and the OTEC system I.e., the higher the temperature gradient the higher the efficiency of the system. Tropical regions receive a great amount of sunlight and therefore the temperature difference is greatest in this region which ranges from 20-25 degrees Celcius. The renewable nature of the OTEC system is estimated to meet the requirements of more than twice the world’s demand for electricity.
Types of Ocean Thermal Energy Conversion (OTEC)
There exist three types of OTEC power plants cycle based on the nature of its function which are mentioned as follows:
1. Closed Cycle
It is also popularly known as the Anderson cycle. In this system, the turbine is operated by using a fluid having a low boiling point, such as Ammonia to generate electricity. At first, the water is collected from both the surface and the deep ocean; thereafter the fluid vaporizes due to the action of the surface water leading to the rotating of the turbine of the generator and producing electricity. As the evaporated fluid comes in contact with the cold water it condenses back to liquid and is reused to further produce electricity. This system is known as a closed system due to its reusable fluid.
2. Open Cycle
It is termed the Clude cycle. This system is different from the closed cycle system as there is no requirement for fluids to generate electricity. In this system the warm sea water is pumped into a chamber where it boils at low pressure and steam is formed which moves the turbine of the generator which produces electricity.
3. Hybrid Cycle
It is the most efficient type of system in which both open and closed system mechanism is combined. There exist two methodologies for such a system:
In the first concept, the water converts into vapors when it passes through the chamber and then moves on to the second chamber to condense back into the liquid form as it utilizes the closed type of cycle. The vapors released from the chamber help in turning the turbine which eventually generates electricity. It is important to keep in mind to remove the non-condensable gases from the ammonia evaporator and release them back into the atmosphere to ensure the proper functioning of the system.
In the second concept, two open cycles OTEC are used to generate electricity. In the heat exchanger chamber vacuum is created and the amount of desalinated water produced is twice the other concept methodology.
Recommended: What is Black Liquor?