Ocean Thermal Energy Conversion: Techno-Economic Reassessment for Tropical Island Microgrids in the Era of Advanced Heat Exchangers

Abstract

Ocean thermal energy conversion (OTEC) has long been considered technically feasible but economically marginal. We present a comprehensive techno-economic reassessment incorporating recent advances in compact titanium plate-fin heat exchangers (CPFHX), ammonia/CO₂ cascade working fluids, and deep-water polyethylene cold-water pipes. For a 10 MW closed-cycle OTEC plant serving a tropical island microgrid (ΔT = 22°C), our analysis projects a levelized cost of electricity (LCOE) of $0.138/kWh — a 45% reduction from previous estimates — with a capacity factor of 92% providing baseload power. When accounting for desalinated water co-production (4,800 m³/day) and cold-water air conditioning credits, the effective LCOE drops to $0.096/kWh, making OTEC competitive with diesel generation ($0.25-0.40/kWh) that currently powers most tropical island communities.