Forecasting annual power demand growth of 1.6% during the next 20 years, Spokane, WA-based Avista Utilities told state regulators it plans to add 1,000 MW of mostly natural gas-fired generation along with wind and energy efficiency savings to meet the steady growth anticipated for customers in northern Idaho.

Avista outlined plans for future generation that include at least three new gas-fired facilities as part of its biennial Integrated Resource Plan (IRP) being considered by the Idaho Public Utilities Commission (PUC). Regulators said they are taking comments on the IRP from the general public through Dec. 5.

About 760 MW of new power would come from the gas-fired plants, and the rest (about 240 MW) would come from wind resources, a PUC spokesperson said. That mix represents a change from Avista’s 2009 plan, which called for more power from wind sources.

“The plan includes less wind because of lower expected retail loads resulting from the present economic downturn and increased conservation acquisition,” Avista told the PUC in its filing. The combination utility said it elected gas-fired peaking resources because of a lower gas price forecast, lower retail loads and the need to acquire more flexible generation as a backup when supplies from wind are low.

Avista’s IRP forecasts annual energy deficits by 2020 without the addition of new resources, a PUC spokesperson said.

Proposed gas-fired facilities include an 83 average megawatts (aMW) simple-cycle peaking plant and two separate 270 MW combined-cycle baseload plants. The peaker would be built by 2020 and the two baseload plants would be sited in 2023 and 2026. There would also be 43 MW of added wind by 2020, and 310 MW of energy efficiency during the next 20 years, reducing peak demand by 207 MW in 2022 and 419 MW in 2031.

Most immediately, Avista’s IRP calls for an additional 100 MW of wind from its Palouse project near Spokane that is expected to be online by the end of next year. Its capacity is 100 MW, but output is expected to be 40 aMW because of intermittency, the PUC spokesperson said. The gas-fired peaking plant and smaller wind project would follow the Palouse development.

Avista also plans to make distribution system improvements and upgrades that will result in another 27 MW of peak load reduction during the next 20 years.

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