Renewable Energy Technology Assessments - Kauai Island Utility ...

Kaua’i Island Utility Cooperative
Renewable Energy Technology Assessments
Year Energy,
GWh
3.0 Renewable Energy Technology
Options
Table 3-20. Developable Potential from Hydroelectric Resources.
Capacity,
MW
Notes
3 8 1.5 Development of the Kitano project
5 61 11.5 Development of the Kitano and Kokee projects
10 118 22.3 Development of these and additional sites
20 183 34.3 Development of all INEEL sites, except “Kauai” project
Note: Conceptual only. Hydro development prospects addressed in detail later in this
report.
3.6 Ocean Energy
Ocean energy resources can be captured in numerous ways with a variety of
technologies. The current areas of research and development are ocean thermal energy
conversion (OTEC), wave energy, and tidal energy.
3.6.1 Ocean Thermal Energy Conversion
An OTEC plant uses the temperature difference between warm surface water and
cold deep water to generate electricity via a heat engine system. There are multiple
configurations under development, but all OTEC facilities operate on the same basic
principle. Comparatively warm surface water is used to heat a working fluid to create
vapor and drive a turbine generator. Cold ocean water from depths exceeding 3,000 feet
is then used to condense the working fluid. When compared to other renewable
technologies, one of the largest advantages of OTEC is the capability to provide base
load continuous power output.
Applications
In general, researchers have classified OTEC technology into three main groups:
closed cycle, open cycle, and hybrid cycle. Most commercial developments plan to use
the closed cycle OTEC (CC-OTEC) system, which uses large seawater heat exchangers
to boil and condense a working fluid such as ammonia. Open cycle OTEC (OC-OTEC)
uses the seawater directly, boiling the warm seawater at very low pressures and using the
cold sweater to condense the steam. Hybrid cycle OTEC (HC-OTEC) uses a
combination of the two previous systems. Normally the CC-OTEC is first used to
generate electricity, and then an OC-OTEC is used to produce desalinated water.
OTEC is currently in active R&D by several organizations and corporations
around the world. Most of these facilities are operated by laboratories or research
21 March 2005 3-47 Black & Veatch