Executives from the company designing Cayman’s first floating platform for generating electricity from the ocean hope to complete a power purchase agreement with the Caribbean Utilities Company by late next month.
Ocean Thermal Energy Conversion International, or OTI, said it would move the project forward in a series of conference calls with CUC “in the next two weeks.”
CUC said only, “There is nothing new to report at this time.” However, the company acknowledged that “discussions are continuing and progressing,” and promised an update as developments occur.
Eileen O’Rourke, president of OTI, in a statement on Tuesday, pointed to “significant progress with CUC on contract negotiations and [we] await their confirmation that the agreements are ready to proceed to the ERA” – the Electricity Regulatory Authority, which oversees Cayman’s power industry.
Ms. O’Rourke said an environmental assessment is nearly complete and would be given to the ERA within 30 days of the proposed CUC power purchase agreement.
The project, unveiled in September 2014 and proposed to generate between 6 megawatts and 6.5 MW of electricity in its first phase, is based on the temperature difference between surface and deep water. Shallow pipes draw 80-degree water into a chamber onboard the floating platform. The heat causes evaporation of an ammonia solution in an adjacent chamber. The ammonia vapor drives a turbine, generating electricity, which is transferred to an onshore substation. From the turbine, the vapor moves to a condenser, where it is re-liquefied by 40-degree deep-sea water pumped onto the platform through a second set of pipes.
The water is returned to the ocean depths, and the liquid ammonia is recycled to its original chamber.
The original OTEC power plants were tested in the early 1920s and ‘30s in Brazil and Cuba, generating 22 kilowatts. The technology was ultimately demonstrated in test platforms in Hawaii in 1979 and 1981.
The Cayman platform will be the first commercial application of the technology. It has raised environmental worries about the proximity of the platforms to the shore and the consequences of an ammonia leak. An environmental assessment which was commissioned in September 2014 will be completed by late March, Ms. O’Rourke said, and forwarded to the Department of the Environment early this year.
While the environmental study does not necessarily form part of the power purchase agreement, the ERA is unlikely to approve the agreement without a nod from the Department of Environment.
“The environmental approval is a necessary precursor to the ERA approving any proposed PPA,” said the authority’s managing director, Charles Farrington.
“It is unlikely that the full EIA report would form part of the PPA, but depending on the EIA findings, the report could result in one or more conditions being added to the PPA.
“This is very speculative at this time,” he added.
Among the concerns are high up-front capital costs, particularly in the face of sharply declining oil prices, explaining the lack of widespread commercial OTEC projects.
OTI is privately funded by Baltimore’s nonprofit Abell Foundation, founded in 1953 to invest in – among other things – “innovative technologies … including energy efficiency and alternative energy.”
Apart from concerns about sight lines from shore to the platform – 140 feet wide, 200 feet long, 16 feet high and moored less than a mile offshore – and potential leaks of ammonia, which is flammable and toxic, other environmental worries include hurricanes and deep-sea pipes clogged by saltwater erosion and marine life.
OTI’s website says visual disruptions will be minimal because of the platform’s low profile, further limited by “a paint scheme that will help it blend in with the surrounding environment.”
The company says it has carefully tracked Cayman’s hurricane history, enabling the company to identify secure locations, while “flexible moorings can help the platform ride out a severe storm.
“In the event of such a forecast, operations would be shut down and personnel would be moved off the [platform]. Operations would resume when the weather improves.”
The simple addition of mesh screens over pipe openings, the company said, would eliminate ingestion of most marine material.
Mr. Farrington said he was unaware of any EIA conclusions, or of any pending submissions to the authority.
“The ERA does not at the moment have an expectation with a time frame attached,” he said.
“The ERA’s most recent information on this proposal as of [the] last week of January 2016 was that OTI and CUC were continuing to discuss a potential PPA.
“The ERA is broadly familiar with the proposed technology, but there may be specific aspects of what OTI is proposing that we are unaware of. The ERA would expect the EIA assessment and the PPA to illuminate any such areas,” he said.