Ocean thermal energy plant proposed at Keahole

A Maryland-based ocean thermal energy developer is poised to build a test plant at the Natural Energy Laboratory of Hawaii, according to a draft environment assessment recently filed with the state.

A Maryland-based ocean thermal energy developer is poised to build a test plant at the Natural Energy Laboratory of Hawaii, according to a draft environment assessment recently filed with the state.


OTI officials said the 1 megawatt test plant would take two years to build and employ at least five people full-time once construction was completed. The demonstration plant would operate 25 years. If successful, OTI would like to build a commercial plant on Oahu, which would employ nearly 500 workers. The cost to build the test plant was not included in the draft document, but the document did note roughly $10 million in materials would be used during construction of the Kona facility.

OTI would build the research, development and demonstration plant on 1.9 acres of NELHA’s Hawaii Ocean Science and Technology Park. The company considered several locations in other parts of the world before selecting Hawaii.

“OTEC is the appropriate technology for the HOST Park, and the proponent has expertise in development of OTEC,” officials said in the draft assessment. “The HOST Park is currently the preeminent location for OTEC development, and the proposed action will maintain that position to the benefit of the consumers in Hawaii.”

Officials said they anticipate a finding of no significant impact for the project.

NELHA’s existing land-use permits allow OTEC testing, the document said. The type of use does not require conforming with any additional National Oceanic Atmospheric Administration rules relating to OTEC, official said in the draft assessment. NOAA’s regulations apply to commercial OTEC projects, the document said, which the research facility is not. The OTI project is also not on the makai side of the high water mark, another requirement that would make the project subject to NOAA’s rules.

“The proposed action is a privately owned research, development, and demonstration facility, which utilizes an existing, permitted state-owned pipeline to derive water,” the document said. “The pipeline is not for the exclusive use of the proponent, but part of a much larger system that includes other thermal energy research, aquaculture operations, pharmaceutical companies, water bottlers and educational institutions. NELHA retains full ownership of the infrastructure, its maintenance, operation and even ownership of the water.”

The Abell Foundation Inc. of Baltimore is OTI’s principal member and sponsor. OTI’s precursor was Sea Solar Power International LLC. Abell and OTI bring more than 40 years of research and engineering on “optimizing the OTEC cycle and its key components,” the document said.

“(OTEC) offers a sustainable alternative to fossil fuel-based technologies presently driving Hawaii’s energy economy,” the document said. “Unlike most of the renewable energy systems constructed and contemplated for deployment in Hawaii, OTEC is a base load, or firm power technology, producing electricity 24 hours a day, every day.”

Any OTEC power used will displace the same amount of power generated by fossil fuels, the document said.

By contrast, non-firm power technologies such as wind and photovoltaic do not eliminate the need to maintain fossil-fueled reserve capacity when wind and solar energy sources are absent or reduced, the document said.

The process to create energy begins with the plant drawing in warm surface water to boil ammonia, creating a gas to generate electricity with conventional turbine-generators. The plant then uses cold ocean water to convert the ammonia vapor back to a liquid for recycling in a closed-loop system.

“The key technical challenge for OTEC is to produce enough gross energy to run its power-intensive production facility and to efficiently generate net energy at competitive prices for the electric grid,” the draft assessment said.

The Kona plant will be land based, which OTI officials said is appropriate for research, but not for commercial production.

“OTI believes that land-based plants are appropriate for OTEC research facilities, but they do not generate the economic returns, at this time, to be commercially viable,” the assessment said. “Offshore OTEC power plants include water intake and power generation systems on site that are positioned in deep ocean water, generally several miles from shore. The first generation of OTI-designed commercial plants will be offshore facilities.”

Using warmer surface water cools it several degrees and warms the cooler deep sea water. Injection wells will return the water to a depth where the ambient temperature matches the temperature of the used water.