Frequently Asked Questions

How does OTEC work?
Ocean Thermal Energy Conversion (OTEC) is a renewable energy technology that uses the temperature difference between warm surface water and deep ocean cold water to power a Rankine cycle to generate electricity.  OTI uses a closed-cycle where liquid ammonia is vaporized in a heat exchanger heated by the warm surface water.  The ammonia vapor powers turbines that turn generators to produce electricity.  The ammonia is cooled back to liquid state using the deep-ocean cold water and the process begins again.
[ top ]

How does OTEC compare to other renewable technologies?
OTEC is fueled by an infinite supply of solar energy stored in the ocean’s top layer.  Even after the sun goes down, OTEC can tap the stored solar energy and generate power 24 hours a day, 365 days a year.  Solar and wind renewable energy supplies are not consistent and may vary.  Geothermal energy is very site specific and biomass renewable energy consumes precious agricultural resources.  For areas of the globe suitable for OTEC, it is a desirable solution.
[ top ]

How does OTEC compare to other base load power sources?
Due to its high (95 percent) capacity factor, OTEC is best compared to other base load (firm) power generators—oil, coal, nuclear, integrated gasification combined cycle (IGCC), and gas/oil combined cycle. Although OTEC has a higher initial capital cost, its “free” fuel and very low operating expenses make it attractive over the project life cycle.  OTEC projects can charge a predictable fixed rate to its utility customers, eliminating the volatility risk of fossil fuel-based systems.
[ top ]

Why OTI?
OTI’s proprietary OTEC design is the culmination of more than 40 years of research and development focused on system efficiency and reliability as evidenced by a portfolio of eleven patents filed in just the past two years! To our knowledge, OTI’s commercial power plant design is the only one to have been evaluated by an independent engineering firm and deemed ready to move forward to commercial development.  OTI is the first and only company to have received the preliminary “Approval in Principle” by ABS for its floating OTEC power plant.
[ top ]

OTI does not have federal funding, while other OTEC companies do. Does that mean the U.S. government has more confidence in the others’ technologies?
Because OTI is 100 percent funded by private investors , OTI uses a well thought out approach to ensure that its design of an OTEC facility is both technologically sound and economically attractive to target markets.  Because we have been able to obtain private funding for development of our advanced technology, OTI has chosen not to compete with those large companies for federal funding.
[ top ]

Is OTEC proven?
The first OTEC power plants were built and tested in the early 1920s by one of the technology’s pioneers, Georges Claude.  Since then, several test platforms have been built, including in Hawai‘i, with Mini-OTEC in 1979 and OTEC-1 in 1981, to demonstrate the OTEC concept.  In the early 1970s, the inventor of OTI's licensed technology had a major breakthrough in designing a closed-loop cycle, which would make the process more efficient and economically feasible.
[ top ]

Why hasn’t the technology been commercialized?
According to the U.S. Department of Energy, OTEC was ready for development almost 30 years ago.  The oil crisis of the 1970s spurred OTEC R&D, but when the price of oil sharply declined, so did OTEC’s political and financial support.  OTEC energy could not compete with cheap fossil fuels.  Now, as oil prices rise due to growing demand, and the manufacturing technologies to produce affordable OTEC system components have been commercialized, OTEC has again surfaced as a promising source of energy.
[ top ]

Why is a pilot plant necessary?
A pilot OTEC plant would demonstrate the successful generation of energy in an efficient, reliable, and economically feasible way.  A 1MWe (net) pilot plant will demonstrate the scalability of OTI’s modular OTEC technologies.  OTI sees the importance of educating stakeholders and building community and political support for a new, innovative project.
[ top ]

How much of the world’s electric power generation can be produced by OTEC?
According to United Nations (UN) and US CIA statistics, about 40 percent of the world’s population is now within the equatorial band defined by 20⁰N latitude and 20⁰S latitude.  This population is projected by the UN to increase to 60 percent of the world’s total by 2050. The ocean is the largest solar collector on the planet.  Even if all the coastal communities in the earth’s tropical and semi-tropical zone were to harness OTEC energy, the amount of energy being extracted from the ocean would be a small fraction of what the sun is constantly delivering.
[ top ]

Could a developed set of islands such as Hawaii be 100 percent energy independent with OTEC plants?
Hawai‘i has excellent operating conditions for OTEC and a variety of attractive site locations.  OTI believes that in the long term, Hawai‘i could use up to 16 OTEC power plants that could supply all or a substantial portion of the state’s base load energy needs.
[ top ]

What impact would natural disasters like hurricanes and tsunamis have on the OTEC plant?
After thorough analysis, OTI has chosen the highly stable spar design to house its OTEC power plant. U.S. government and industry records have shown that the survivability and performance of spar-designed offshore oil and gas platforms in the Gulf of Mexico held up in the severest storm conditions.  In addition, the OTI design has ample reserve buoyancy systems to cover unusual ocean conditions.  Offshore OTEC plants would be located away from the shelf in deep ocean water.  They will not be affected by tsunami waves which form closer to shore as the pressure wave approaches shallow water in the ocean’s shelf regions.
[ top ]

Would an earthquake affect the plant’s moorings?
The OTI mooring platform was designed by world-renowned mooring systems expert, Intermoor.  It was also evaluated and granted preliminary “Approval in Principle” by ABS (formerly American Bureau of Shipping).  The anchor depth and installation method of the mooring system has been designed to survive earthquakes and geological stresses.
[ top ]

What emissions are associated with OTEC?
There are no emissions.
[ top ]

What impact does OTEC have on ocean water quality?
The OTI OTEC plant is designed to work with, and benefit from, nature; it is compatible with the ocean’s thermal gradients.  Warm surface water is pumped through the evaporators, where energy is extracted for conversion to electricity, and discharged at a lower depth.  Denser cold water is pumped up through the condensers, where it is warmed, and discharged at a depth beneath the warmer surface water discharge. The ocean is so vast that remixing of the amount of different temperature waters actually could be a benefit.  The OTEC cycle discharges nutrient-rich, cold deep-sea water into a warmer layer, potentially increasing the food source for surrounding marine life.
[ top ]

How will the ingestion of marine life into the intake pipes be prevented?
The OTEC plant has been designed with a series of screens and array of cables to prevent ingestion of small or large marine life.
[ top ]

Will there be any irreversible damage to the sea floor from OTEC?
No.  Unlike offshore oil rigs that drill thousands of feet into the subsea floor, an OTEC plant’s links to the ocean floor are only mooring anchors.  In places like Hawai‘i, the sea floor is likely comprised of volcanic rock, so the anchors will be driven into the rock at sufficient depth to ensure adequate strength and survivability.
[ top ]