Hidroelectricas

Technical Brochure No.37

IEA OECD
re n e w a b l e e n e rg y

Hydro-power for a Remote Alaskan Community

Summary
Residents of a remote fishing community, the city of King Cove, Alaska, live far from the nearest utility grid. For a long time they have paid a premium for dieselgenerated electrical power. This changed in December 1994 when, after years of studies and planning, arun-of-river hydro-electric facility dedicated solely to King
The King Cove hydro-power station.

Cove’s power needs went on line. The 800 kW plant exploits abundant precipitation and glacier melt in the area. Funded by a loan, as well as state and federal grants, the plant will provide electricity to residents for the next 30 to 40 years. King Cove is a demonstration of clean energy production forother remote Alaskan communities and for those with suitable water resources.

Highlights
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Clean, and environmentally acceptable electricity Reduced consumption of fossil fuels Cheaper electricity for consumers

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HYDRO

Project Background
King Cove is a community of about 700 residents, most of them native Aleuts. The village has about 200 households and a cluster of commercialand government facilities, including a large fish processing company. Numerous hydrological surveys, geotechnical studies, load inventories and feasibility assessments finally led in 1993 to a series of grants, including a Title 26 award through the US Department of Energy to the Agdaagux Tribal Council. Title 26 grant funding is authorised under the 1992 Energy Policy Act to assist Indian
Duringconstruction of the hydro facility.

reservations in developing local energy resources. The tribal council was the prime grant applicant and the city of King Cove acted as contributing partner. HDR Engineering Inc of Anchorage performed feasibility studies, helped secure financing and designed and managed construction of the hydroelectric facility.

500 ha (2 square miles) Delta Creek basinnear the town generates a maximum stream flow of 25 m3 per second. Unlike most hydro facilities, King Cove’s plant draws water from two sources rather than one. Both are tributaries to Delta Creek. The primary water source is Glacier Creek, a glacier-fed stream. The secondary source is Clear Creek, a rain-fed stream that is tapped when additional flow is needed. Intakes erected on the twotributaries generate 90 m gross head and 74 m net head at full load. Diversion structures measure 3 m high by 30 m long; the pipe diameter is 0.8 m. A check valve prevents water from Glacier Creek

The Project
King Cove receives 130 cm of snow and 85 cm of rain annually. The quantities and flows of water in the region are evident: during floods, small boulders have been seen tumbling down the creekbeds.The

Economic comparison of the hydro-electric plant with diesel generation
Summary for 30 Year Project Life Diesel base case net present value = $15,372,212 Hydro project net present value = $15,137,175 Cost/cost ratio = 1.02 Economic parameters Nominal interest rate Annual inflation rate Real discount rate 8.0% 4.5% 3.0% Load Forecast Assumptions City load factor Hydro project on line 50.0%1995 Community load growth 2.5% Diesel System Assumptions Diesel efficiency Economic life O&M cost 12 kWh/gal 10 years $0.11/kWh Hydro Project Assumptions Efficiency Total cost O&M cost 80% $7,602,000 0.09/kWh Amortised funding life 24 years

Replacement cost $700/kW*

Installed capacity 805 kW

*Note: Allowing for expansion of the city’s power requirements, about 700 kW of diesel capacityis replaced every 10 years at a cost of $700/kW.

from backing up into the lower intake of Clear Creek during high flow conditions. A special intake design employing a sluiceway with side-intake trash-racks overcomes problems associated with streambed flushing during floods, while eliminating icing of the intake screen in severe weather. The remainder of the system consists of a powerhouse,...