Igiugig, located 48 miles southwest of Iliamna and 56 miles northeast of King Salmon, is a small village with a year-round population of 56. Igiugig sits at the headwaters of the Kvichak River, which drains out of Lake Iliamna. Because it is located downriver from Lake Iliamna, Igiugig has much less summer/winter variability in flow. This location also results in a reduction in silt loads compared to rivers that are directly glacier fed. The Kvichak is ice free all winter at Igiugig, although ice does pose a concern for two weeks in the spring, as breakup occurs on Lake Iliamna. These factors make Igiugig an excellent candidate for hydrokinetic power generation.
EPRI has considered a hypothetical 40 kW project mounted on a 30-ft pontoon boat anchored to the riverbed. The pontoon was designed to serve as a platform from which four turbine rotors, 4.5 ft in diameter, could be suspended in the water column. A protective ‘trash-rack’ was mounted in front of the rotors and generator to minimize debris impacts. Three of these pontoons, with a total of twelve devices, were considered for this case study.
The 40 kW size of the project was based on village energy consumption (low) and resource availability (high) during summer months. The village currently has three diesel generators ranging in size from 60kW to 100 kW. Historic loads are 40 kW (summer) to 95 kW (December-February). The cost of power in the community is 98¢ per kWh and includes fuel and non-fuel costs.
Grid interconnection would be accomplished using a short (~225 ft) underwater cable from the units to the shore and connecting to the local grid via an existing distribution line. Other project components include a dedicated transformer, revenue metering, a disconnect device, a circuit interrupting device, a multifunction relay, and a real-time SCADA monitoring system.
Costs and Funding
Project costs in 2007 dollars were assessed through a model using historical quotes and existing projects in related technology fields. The capital cost for the 40 kW installation was estimated at $300,000, with annual O&M at $12,000 per year. Total annual energy production was estimated at 200,000 kWh (24 kW average, or 60% capacity factor). This was assuming the installation matched summer loads for Igiugug. The simple payback period was estimated to be three to four years under this scenario. A second scenario was considered in which the project provided baseload power to the village (325,000 kWhrs, 36 kW on average, or 90% capacity factor). This increased the capital and O&M costs for the project accordingly, but resulted in a similar payback period. Both scenarios were based on an avoided fuel cost of 65¢ per kW, which is the fuel portion of the current power cost.
Links, Resources, and Documents
Additional information on this hypothetical installation can be found in the EPRI report .
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