The process flow diagram illustrates how electricity is produced using Ocean Thermal Energy Conversion (OTEC), which relies on the temperature difference between warm surface seawater and cold deep ocean water.
Overall, the system operates in a continuous cycle using ammonia as a working fluid, with warm water causing evaporation to drive a turbine, while cold water allows the gas to condense and be reused.
Initially, warm surface water at around 15°C is pumped into a vaporiser, where it heats liquid ammonia. As a result, the ammonia evaporates into gas. This expanding gas flows through a turbine, causing it to rotate and generate electricity, which is then delivered as power output.
After passing through the turbine, the ammonia gas enters a condenser. At this stage, cold deep ocean water, with a temperature of approximately 5°C, is pumped from a depth of about 1,000 metres. The cold water cools the gas, turning it back into liquid form. Finally, the liquid ammonia is pumped back to the vaporiser, allowing the cycle to repeat continuously.