Ocean Thermal Energy Conversion Plant OTEC-20 Commissioned in Hawaii: Generating 24/7 Zero-Emission Power from Seawater Temperature Differences
Makai Ocean Engineering commissions the world's first commercial-scale OTEC plant OTEC-20 in Hawaii at 20MW capacity, using temperature differences between warm surface and cold deep seawater for round-the-clock power generation.
Ocean Thermal Energy Conversion Plant OTEC-20 Commissioned in Hawaii: Generating 24/7 Zero-Emission Power from Seawater Temperature Differences
Makai Ocean Engineering announced on December 24 that its OTEC-20 plant in Hawaii's Big Island has officially connected to the grid. This is the world's first commercial-scale Ocean Thermal Energy Conversion plant at 20MW capacity.
OTEC exploits the temperature difference between warm tropical surface water at about 25 degrees Celsius and cold deep water at about 4 degrees Celsius 1,000 meters below. Warm water evaporates a low-boiling-point working fluid, and the vapor drives a turbine, while cold deep water condenses it back to liquid. Because ocean temperature differentials are permanent, OTEC plants generate power 24/7 regardless of weather or daylight.
OTEC-20 uses a 2.4-meter diameter cold water pipe extending 1,000 meters below the surface, made of high-density polyethylene. The plant also produces large volumes of cold seawater usable for air conditioning and aquaculture. CEO Greg Poe said Hawaii currently imports 90% of its electricity from petroleum at 3x US mainland prices. OTEC provides a fully local, zero-emission baseload power source for tropical islands.
Construction cost was approximately $320 million with levelized cost around $0.18/kWh. While currently above solar and wind, OTEC's advantage is stability. At 100MW scale, costs could drop below $0.10/kWh. OTEC is geographically limited to tropical waters within 20 degrees of the equator.
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