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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An especially attractive hydro resource is the upgrading and modernization of
existing facilities, many of which were built more than 30 years ago. Such “incremental”
hydro includes unit additions, capacity upgrades, and efficiency improvements.
Resource Availability
Hydroelectric resource can generally be defined as any flow of water that can be
used to capture the kinetic energy of its water. Projects that store large amounts of water
behind a dam regulate the release of the water through turbines over time and generate
electricity regardless of the season. These facilities are generally baseloaded. Pumped
storage hydro plants pump water from a lower reservoir to a reservoir at a higher
elevation where it is stored for release during peak electrical demand periods. Run-ofriver
projects do not impound the water, but instead divert a part or all of the current
through a turbine to generate electricity. This technique is used at Niagara Falls to take
advantage of the natural potential energy of the waterfall. Power generation at these
projects varies with seasonal flows.
Figure 3-9. 3 MW Small Hydro Plant.
All hydro projects are susceptible to drought. In fact the variability in
hydropower output is rather large, even when compared to other renewable resources.
The aggregate capacity factor for all hydro plants in the US has ranged from a high of 47
percent to a low of 31 percent in just the last 5 years. 33
33 Based on analysis of data from Energy Information Administration, Renewable Energy Annual 2002.
21 March 2005 3-43 Black & Veatch