Ocean Thermal Energy Conversion (OTEC) is a technology that dates back to the late 1800’s and makes use of temperature differences between surface and deep ocean waters to drive a heat engine, and extract energy via the Rankine cycle. While pilot scale plants (< 1 MWe) have successfully generated energy, a combination of technical and economic feasibility limitations tempered investment and interest in OTEC. However, the decreasing supply, and increasing costs, of fossil fuels, advancements in OTEC technology, renewable energy mandates, and energy security concerns have resulted in a resurgence in interest in OTEC for tropical locations.
As the lead licensing agency for OTEC, NOAA’s Office of Ocean and Coastal Resource Management (OCRM), in cooperation with the Coastal Response Research Center (CRRC), held the first in a series of workshops to determine the technical readiness of seven major components of OTEC: 1) cold water pipe; (2) heat exchangers; (3) platform/pipe interface; (4) platform; (5) power cable; (6) platform mooring system; and (7) pumps and turbines. The first workshop, discussed in this report, sought to gather information on the technical readiness of OTEC and evaluate advancements to the technology since the last major attempt, OTEC-1 in 1980.
The qualitative analysis of the technical readiness of OTEC by experts at this workshop suggest that a < 10 MWe floating, closed-cycle OTEC facility is technically feasible using current design, manufacturing, deployment techniques and materials. The technical readiness and scalability to a > 100 MWe facility is less clear. Workshop participants concluded that existing platform, platform mooring, pumps and turbines, and heat exchanger technologies are generally scalable using modular designs (several smaller units to achieve the total capacity needed), however, the power cable, cold water pipe and the platform/pipe interface present fabrication and deployment challenges for ≥ 100 MWe facilities, and further research, modeling and testing is required. The experience gained during the construction, deployment and operation of a ≤ 10 MWe facility will greatly aid the understanding of the challenges associated with a ≥ 100 MWe facility, and is a necessary step in the commercialization and development of OTEC.