Floating power plant would reduce reliance on fossil fuels

Study will look at ammonia storage, disaster plans

A floating power station using the solar energy stored in Grand Cayman’s warm tropical waters could provide the first firm renewable energy supply capable of replacing diesel generators on the island, according to documents setting out the scope of an environmental study. 

If successful, the Ocean Thermal Energy Conversion plant would be able to provide firm, reliable power to the national grid 24 hours a day, reducing reliance on fossil fuels.  

The technology, unlike solar or wind, would not require diesel generators to be constantly spinning as a backup, according to the terms of reference for an Environmental Impact Assessment on the proposed project. 

“Each megawatt of distributed OTEC power would displace and subsidize a portion of the power generated by fossil fuels, thereby lowering the need to import gasoline and diesel that are both economically and environmentally costly,” the document says. 

“By contrast, non-firm intermittent power renewable technologies such as wind and solar photovoltaic do not eliminate the need to maintain fossil fueled spinning reserve capacity for those times when wind and solar energy sources are absent or reduced.” 

The project, commissioned by OTEC International LLC, would be the world’s first commercial power plant using ocean thermal energy conversion.  

The technology converts solar energy stored in tropical oceans to utility-scale power through a process that exploits the large temperature gradient between water on the surface and that found at depth.  

The company initially aims to supply 6.25 megawatts of wholesale electric power, increasing production to 25 megawatts following a trial period. 

Charles Farrington, managing director of the Cayman Islands Electricity Regulatory Authority and a member of the Environmental Assessment Board that is overseeing the study, said the project has the potential to be a significant one in Cayman’s energy future. 

“It will obviously be an important development if they can bring it to commercial reality,” he said. “If it works and it goes through a period where it proves itself to be reliable, the expectation is that it would be classified as firm renewable power.” 

The OTEC process involves using large amounts of warm surface water to boil ammonia, creating an “ideal gas” to power conventional turbines. Cold water, piped up from a target depth of 3,770 feet below the surface, is used to convert the ammonia vapor back to a liquid for recycling in a “closed loop system,” the document states. 

The up-front cost of building the plant and associated infrastructure are likely to be extensive, though OTEC International has not revealed exactly how much it expects to spend on the project. 

Mr. Farrington expects the initial impact on the cost of electricity to be limited. He said the prices would have to be competitive with current rates for a power purchase agreement with the Caribbean Utilities Company to be approved. 

He said the long-term advantage of OTEC, despite the high up-front costs, would be that, unlike oil, the price would be stable and not subject to fluctuations in the international market. 

The entire cost of the project, including the environmental impact assessment, is borne by the OTEC International, which is backed by Baltimore-based charitable organization the Abell Foundation. 

Mr. Farrington said, “They are confident enough to invest that money and we are hoping they are not mistaken – it is essentially their risk.” 

A meeting was held in North Side last week to allow residents’ input into the environmental study. 

The power plant would be moored off the north coast of Grand Cayman and connected to the power grid through a buried cable running to a substation on shore, close to the Over the Edge restaurant. 

Wendy Williams, an environmental assessment officer with the Department of Environment, said residents’ concerns would be considered in the environmental impact assessment if they were filed in writing with the department before Oct. 3. 

Ms. Williams, who is also a member of the Environmental Assessment Board overseeing the study, said the ability of the platform to withstand hurricanes, as well as the safety procedures to ensure the ammonia used in the process is contained, would be part of the assessment. 

“The Department of Environment is very keen to explore alternative sources of energy generation that don’t rely on fossil fuels. We are very interested [in OTEC] but we need to know the coasts and benefits to the country and that’s what the environmental impact assessment will discover.” 

She said an environmental statement would be produced by weighing the positive and negative effects and allowing decision makers to take a balanced view.  

Eileen O’Rourke, president of OTEC International and treasurer of the Abell Foundation, said the company has been working for more than a decade to bring the technology to Cayman and is happy to address any environmental concerns raised through the study. 

“In particular, OTEC International recognizes its responsibility in any future decommissioning of its facilities and in implementing rigorous safety standards, including, but not limited to, addressing ammonia storage, in coordination with and under guidance to be provided by the Department of Environment. 

“OTEC International looks forward to getting the required authorizations to build the project and providing another source of renewable energy to Cayman.” 


  1. I’m sorry, but it seems like pie in the sky to me. The risk of an ammonia gas/liquid leak and of catastrophic damage from a hurricane make it too risky for my liking.

  2. Sorry, but a lot of this story reads like a press release from OTEC International LLC because it carefully avoids all the negative points. Pie in the sky sums it up nicely.

    In 2007 when I was at Cayman Net News CUC proposed OTEC as a source of renewable energy and an alternative to proven alternatives like solar panels and wind turbines.

    Unfortunately, all the Net News records from those days have been lost but the bottom line when we researched this option was that OTEC didn’t work. In fact CUC seemed to be proposing OTEC because unlike wind or solar power it posed no realistic threat to their diesel-powered generating operations and represented a convenient excuse to block more realistic sustainable energy options.

    One of the problems we immediately discovered was that the promises of OTEC delivering viable results were full of words like maybe, might, should, could and projected. In short nobody involved was able to tell us what the system would actually do. Rather than extolling the virtues of OTEC the proponents of the system chose to use arguments against established alternatives like the sun doesn’t shine at night and the wind doesn’t blow every day. What they conveniently ignored was the effect on an OTEC plant of little things like hurricanes.

    Seven years on and there is not one viable OTEC plant operating in the world. A project in the Bahamas has been cancelled and the US Government withdrew funding for an established experimental unit in Hawaii four years ago. The US Navy has also dropped plans to develop OTEC as an alternative energy source.

    As the story above says – The project, commissioned by OTEC International LLC, would be the world’s first commercial power plant using ocean thermal energy conversion. Note the word ‘first’.

    Considering how much money the US Government poured into efforts to create a viable OTEC plant before giving up on it doesn’t that tell you something? If the US Government with all its resources couldn’t make the process work what chance has the Cayman Islands?

    My advice – do not put one cent of public money into this project. If OTEC International think this is viable (and there is still absolutely no evidence to suggest it is) make sure the whole thing is privately funded. No tax breaks, no financial easements, no concessions.

    Bluntly, you would do better to put money and effort into solar, wind and other less capital-intensive options. That is not just my opinion – it came from Jean-Michel Cousteau when I interviewed him at the Ritz-Carlton in 2007.

  3. Of course OTEC International is willing to absorb the costs because it is financially beneficial to them. There are no water-based plants anywhere in the world, so Grand Cayman will be the Beta test site for OTEC. Having an actual site will allow them to approach investors for additional revenue because they no longer are peddling a theory.

    It is not a proven technology and has never been tested in the open ocean on any large scale. In fact, NOAA performed an Information Needs Assessment and generated a report in 2012; on page 8 of that report; a conclusion was drawn: In conversations with federal regulators it became clear that an accurate determination of the spatial and temporal extent of the discharge plume and intake zones forms the foundation for determination of potential impacts. Without this information, it is difficult to determine the magnitude of the impact, and impossible to determine the overall effect on the environment. (http://coastalmanagement.noaa.gov/otec/docs/otecassessment.pdf)

    In an article by Mr. Whittaker on May 16, 2014 ,he stated that at its peak Cayman requires 100 megawatts of power. A single platform will provide approximately 6 megawatts of power. It is just not worth the threat to the environment with so little benefit.


  4. Whittaker, when discussing an untested technological project, never use the expression – IF SUCCESSFUL.
    If you had a million yacht, would you consider leaving it on a permanent mooring outside the reef on North Side.

  5. I have to agree with Cheryl on this where she says it will only produce about 6 percent of the needed power so I don’t see a huge benefit to Cayman. It’s not likely to create many jobs if any and will only scratch the surface of what’s needed to put a dent in CUC’s monopoly. So I can’t see any reason to support it either. I have to agree that Cayman would be better off investing into solar or Wind Power. Find a way to make the batteries required to store electric cheaper so there’s alternatives to connecting your panels to CUC. I saw a wind mill on someone’s house on Seaview Road last week which I found interesting. I’d like to find out what that’s all about..

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