Electricity from ocean thermal energy could provide the territory a stable, inexhaustible, emissions-free power supply with no fuel costs, but we will not know how feasible the process is until the numbers are crunched, Ocean Thermal Energy Corporation officials told the Senate on Wednesday.
Wednesday morning the Legislature signed a memorandum of understanding with Ocean Thermal Energy Corporation to allow a feasibility study of ocean thermal electricity production in the territory. And Wednesday afternoon, OTEC officials gave a presentation to the Legislature on the ocean thermal power generating technology, some of the different options available and extremely preliminary cost estimates.
OTEC generates electricity using heat exchangers and the sharp difference in temperatures between ocean depths, explained Ted Johnson, head of OTEC programs with the company. They use heat exchangers to heat sea water in low-pressure boilers, use the steam for power generation, condense the steam with very cold water, and collect potentially millions of gallons of potable water along the way, Johnson said.
The feasibility study will also look at using cold, deep seawater as the coolant for large scale air conditioning, which Johnson said can cut electricity usage "by 80 to 90 percent" in air-conditioned government buildings.
While still rare, several successful OTEC projects are up and running in Hawaii and will soon be operating in Guam, Johnson said. Costs are coming down with technological advances and reduced costs for heat exchangers and pipes, and the technology is getting more affordable every day, Johnson and other OTEC officials said. But what the actual cost for a particular type of project and what can be offered will not be known until after the feasibility study, Johnson said.
"We are not promising anything until we get all the information we need, but we are very encouraged by these preliminary results," he said.
Sen. Tregenza Roach asked what sort of preliminary information the company could give on what OTEC power would cost for consumers, and when Johnson said he did not know yet, Roach asked what the company’s project in Guam would cost Guam ratepayers.
"That was in the upper 20 cent (per kilowatt hour) range," Johnson said. "But that was with no water production,” he added.
The territory is very well situated for OTEC because it has warm surface waters and easily accessible deep water that is at least 20 degrees Celsius colder than the surface, year-round, he and other OTEC officials said.
OTEC plants can be on land or at sea, in principle. Being on land reduces costs dramatically, if it can be done, and makes seawater air conditioning much easier, officials said. St. Croix has several locations where conditions may be good for a land-based plant and the company has given a preliminary look at Salt River, Butler Bay and Rost Op Twist.
"It is very, very critical where the plant is located (because you) have to get to the deep cold water very, very quickly," Johnson said. "If we can’t do that on land, it will have to be an ocean-based deployment," he said.
St. Thomas would need an offshore plant because of the contours of the seafloor off the island, Johnson said.
Senate President Shawn-Michael Malone said the Legislature may have the study’s findings "before the year’s end." He stressed the study would be "at no cost to the government of the Virgin Islands."
"The only role we have is providing the data," he said.
Established in 2001, OTEC International’s website says it is negotiating a power purchase agreement with Hawaiian Electric Company for a 100-MW plant, power purchase and interconnection agreements with The Caribbean Utilities Company Ltd. for 25-MW, and is meeting with government officials in the Bahamas regarding 3 to 5-MW projects. The company says it has not relied on government funding for its research and development but has been privately funded by The Abell Foundation, a nonprofit based in Baltimore.