OTEC exploits the steady temperature difference between sun-warmed surface water and near-freezing deep water to run a continuous heat engine.
eta_Carnot = 1 - T_cold/T_warm
P ~ flow * eta
- Column resolution — how finely the vertical temperature profile from surface to deep water is sampled.
- Pipe intake depth — how deep the cold-water intake pipe reaches — deeper means colder, wider ΔT.
- Surface-deep ΔT — the temperature difference driving the Rankine-type working-fluid cycle.
- Working-fluid flow rate — throughput of the ammonia/working fluid cycling between the two heat exchangers.
OTEC plants need only about a 20°C gradient to run continuously, making tropical island nations with deep offshore water natural candidates for baseload ocean power.