The first known seawater district cooling, or SDC, system is set to debut at the new, $3.5-billion Baha Mar Resort in Nassau, Bahamas. The $100-million, 12,000-ton system, developed by Ocean Thermal Energy Corp., Lancaster, Pa., will service the 3.5-million-sq-ft resort’s chilled-water needs with 40º F seawater drawn from a depth of more than 3,600 ft in the open Atlantic Ocean, off the New Providence Island Oceanic Shelf.
DCO Energy LLC, Mays Landing, N.J., the project’s engineering, procurement, and construction contractor, is designing the system, which will include four 500-hp turbine deep-well pumps to draw 25,000 gallons of seawater each minute through a 15,000-linear-ft HDPE pipeline, the outside diameter of which is 55 in. The water will be pressured to 100 lb and circulated through the 1,000-acre gaming and entertainment resort complex via a closed-loop system.
In accordance with the Bahamas' environmental regulations, the seawater then will be discharged to the island’s aquifer via 600-ft-deep injection wells.
With no chillers and cooling towers, the SDC system will cool the property using as little as 10% of the energy required by traditional cooling technology, a major consideration in a location in which the inherently high price of electricity has been exacerbated by rising oil prices, according to DCO President and CEO Frank DiCola.
"Equally important to the resort’s developers are the major environmental benefits of the SDC system," DiCola adds. For example, the SDC system requires no refrigerants and is expected to eliminate approximately 25,000 tons of carbon dioxide emissions a year.
While the SDC system itself is innovative, the deepwater pipeline likely will prove to be DCO’s key engineering challenge. Along with traversing undersea topography, including 150-foot cliffs, the pipeline must withstand the stresses of normal ocean currents and the forces of Class V hurricanes.
To develop the pipeline specifications, DCO conducted a multifaceted undersea survey that included the use of remotely operated vehicles (ROVs). Plans call for the pipe to be fabricated in Norway in 1,500-ft segments, then barged to the Bahamas. There, the pipe will be assembled into a single unit and fitted with weights and buoyancy components. Installation will be performed using ROVs.