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Hydro
Introduction
Hydroelectric power is generated by capturing the kinetic energy
of water as it moves from one elevation through a turbine to a
lower elevation. The amount of energy captured by the
turbine is dependent on the head (distance the water is falling)
and flow rate of the water. Often, the water is raised to
a higher potential energy level by blocking its natural flow
with a dam. Another method of capturing the kinetic energy
is to divert the water of a natural waterway, through a penstock
and back to the water. KIUC is most interested in
developing such "run-of-river" applications. Other forms
of hydro generation include wave, tidal, and pumped storage
technologies.
Potential for Kauai and KIUC
Hydro generation is a mature renewable energy technology which
can provide competitively priced electricity. Hydro
resources on Kauai are very good with consistently heavy
rainfall and sharp elevation drops. On the other hand,
Kauai stream flows vary considerable throughout the year, making
hydro an intermittent, "as available" resource unless dams are
utilized.
Kauai currently has seven hydro units (8.9 MW) that were
originally installed by the sugar industry. A recent
"Renewable Energy Technology Assessment" report for KIUC
identified an additional 60 MW or 320 GWh of hydro potential.
However, social opposition, environmental concerns, and access
issues make some of this potential un-developable.
Cost
The capital costs for a typical hydro plant is between
$1,700-$5,700 kW. The capital costs vary widely due to
site-specific requirements for penstocks and civil works.
The levelized costs of electricity is between 3.6-10.9 cents/kW.
Advantages and Disadvantages
Advantages
Disadvantages
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environmental impact due
to dams and diversions
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"run-of-river" facilities
are intermittent and require storage or backup generation
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significant public
opposition due to environmental, cultural, and tourism
concerns.
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