Hawaii ocean energy project makes progress

Makai plans to supply OTEC power to grid by mid-2015

NOVEMBER 3, 2014 — Makai Ocean Engineering, Inc. reports that its Ocean Energy Research Center (OERC) in Kona, Hawaii, has received two new heat exchangers (2-megawatt thermal duty each), and a 100 kilowatt ammonia turbine-generator for its Ocean Thermal Energy Conversion demonstration plant.

Ocean Thermal Energy Conversion (OTEC) produces electricity from the ocean by using the temperature difference between deep cold and warm surface seawater. OTEC plants pump large quantities of deep cold seawater and surface seawater to run a power cycle and produce electricity. OTEC is a constant power source 24 hours per day and 365 days per year. It is clean, environmentally sustainable, and has the potential to provide huge quantities of energy.

To date, Makai has tested four condensers and three evaporators at the OERC, each made of either aluminum or titanium. The facility has been designed to easily swap out OTEC heat exchangers, and test as many as six simultaneously.

The Ocean Energy Research Center is an essential tool for the development and testing of candidate OTEC heat exchangers.

Heat Exchangers will be the single most expensive component in a commercial offshore OTEC plant and optimizing their lifetime, performance, and cost are critical to economic success.

The OERC enables engineers to rapidly design, build, and test candidate OTEC heat exchangers using a sophisticated control and instrumentation system that includes thousands of calibrated, high precision sensors. The test data are fed into plant design software to evaluate heat exchangers for lifetime (corrosion resistance), performance (heat transfer and hydraulic efficiencies), and cost (fabrication and size/weight effects on OTEC platform), as well as to optimize the next generation of heat exchangers.

Makai is in the process of scaling up a design for a low-cost, compact, corrosion-resistant heat exchanger that may significantly reduce the capital cost of OTEC heat exchangers.

In addition to its own research, Makai provides objective engineering services to domestic and international third-party OTEC developers, including testing OTEC heat exchangers, corrosion samples, and providing OTEC plant and marine pipeline design and analysis support. The OERC is primarily dedicated to OTEC research, but includes research programs in other ocean-related areas, such as corrosion prevention and heat exchangers for other marine applications. With its continuous access to large flows of both shallow and deep seawater up to 3,000 feet deep, the OERC serves as a valuable platform for international collaboration on OTEC research and development.

The 100-kilowatt OTEC turbine has been placed on the OTEC tower while heat exchanger testing is being performed. Makai plans to connect the turbine to the OTEC system, and connect power to the local electrical grid in early-2015, followed by a dedication ceremony in mid-2015. This will be the first time that closed-cycle OTEC power has been connected to a U.S. grid, and is an important step toward commercializing this source of renewable energy.