Renewable Energy Technology Assessments - Kauai Island Utility ...

Kaua’i Island Utility Cooperative
Renewable Energy Technology Assessments
3.0 Renewable Energy Technology
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build-up from local trade winds and swell generated by extratropical storms in the north
Pacific Ocean. There are additional wave producing forces that originate in the southern
hemisphere, but these are a minor contribution to the wave energy resource. The
analyses for this report found that the wave power density along the 80-m depth contour
typically averages 10 to 15 kW/m. This is surprisingly low considering Hawaii’s location
in the Pacific. The recently released EPRI Innovation Institute Survey and
Characterization of Potential Offshore Wave Energy Sites in Hawaii notes that the wave
energy resource on the northern shores of the Hawaiian Islands far exceeds the electricity
demand for all islands, except Oahu. 37
Hawaii’s reasonable wave resource, centers of population close to the coast, and
high electricity prices mean that wave energy may have potential for utilities in the near
future (5-10 years). However, development will be limited by environmental constraints
(particularly visual appearance and any potential or perceived effect on tourism), and
utility constraints due to the variability of wave power output. Further, as the industry is
still in its formative stages with a limited number of commercial products, potential is
limited by the ability of the technology developers to supply the necessary equipment.
Based on these considerations, the following table summarizes the potential for OTEC in
Kauai over the next 20 years.
Year Energy,
GWh
Table 3-24. Developable Potential from Wave Energy.
Capacity,
MW
3 3.5 1
5 17.5 5
Notes
Constrained by technology supplier ability to provide
product
10 175 50
20 > 500 > 140 Sufficient potential to supply all of Kauai’s electricity
3.6.3 Ocean Tidal
The generation of electrical power from ocean tides is very similar to traditional
hydroelectric generation. A tidal power plant consists of a tidal pond created by a dam, a
powerhouse in the dam containing a turbo generator, and a sluice gate in the dam to allow
the tidal flow to enter and leave. By opening the sluice gate in the dam, the rising tidal
waters are allowed to fill the tidal basin. At high tide these gates are closed and the tidal
37 Electricity Innovation Institute and EPRI “Survey and Characterization of Potential Offshore Wave
Energy Sites in Hawaii”, available at: http://www.e2i.org/e2i/docs/003_Hawaii_Site_Report.pdf, June
2004.
21 March 2005 3-55 Black & Veatch