🔬Research StageRenewable Energy • Hydro/Tidal

Ocean Thermal Energy Conversion (OTEC)

Ocean Thermal Energy Conversion (OTEC) systems generate electricity from temperature differences between warm surface water and cold deep water in tropical oceans, providing continuous baseload power with 3-5% thermal efficiency. These systems can produce 10-100 MW^[1] of power while providing additional benefits including air conditioning, desalination, and aquaculture. Companies like Makai Ocean Engineering and Ocean Thermal Energy Corporation are developing commercial systems with electricity costs targeting $0.15-0.25 per kWh.

How It Works

OTEC systems use thermodynamic cycles to extract energy from temperature differences of 20°C or more between surface and deep ocean water. Closed-cycle systems use working fluids like ammonia that vaporize from warm surface water and condense using cold deep water. Open-cycle systems flash-evaporate seawater in low-pressure environments and condense vapor using cold water. Hybrid systems combine both approaches for optimized efficiency and freshwater production.

Advantages

Provides continuous baseload renewable power 24/7 throughout the year, produces no emissions and has minimal environmental impact, and enables co-production of freshwater, air conditioning, and mariculture. OTEC systems have 20-30 year operational lifespans with minimal maintenance. The technology provides energy security for island nations and coastal communities.

Challenges

Very low thermal efficiency of 3-5% requiring large, expensive infrastructure, limited to tropical regions with sufficient temperature gradients, and faces high capital costs of $8,000-15,000 per kW. Complex deep water pumping systems require substantial energy input. Unproven commercial viability with limited demonstration projects.