Alaskan Towns

The city of Nome, Alaska, is a microgrid powered primarily by diesel generators augmented by wind power and a very small amount of solar power. It is proposed to add geothermal source (figure on right) to this mix of sources. The geothermal plant could provide 40% or more of the base load, reducing dependence on diesel fuel.

Under all conditions, the city has sufficient diesel units on standby and one in service. In the event of contingencies, the diesel units can serve the entire city and restore service in under 20 minutes. However, what is desired is to reduce the dependence on diesel and operate a single, under-sized diesel generator in parallel with the renewable resources.

Intended geothermal interconnection at Nome. Left: Nome's diesel power plant. Top: 60-mile tie line to geothermal plant. Center: City of Nome electric load (5 MW). Right: Proposed 2 MW geothermal plant and existing wind farm.

The research in collaboration with the University of Alaska at Fairbanks developed frequency-stability margins to maintain proper operation and used a computer model of Nome's power system to validate the predictions. The simulations validated several probable loss-of-line events, and made clear the need for energy storage to increase system reliability under loss-of-line contingencies.

The computer model considered different seasons with different load and diesel-unit commitments. It was shown that to prevent frequency instabilities, an energy storage unit must respond by the proposed critical response times to prevent blackouts. The combination of analytical stability margins and a computer model of Nome allowed simulating alternate and cost-efficient storage solutions as well.

See information video:

More information below: