The Idaho Public Utilities Commission has accepted Rocky Mountain Power’s long-term Integrated Resource Plan (IRP), which serves as a roadmap for how the utility plans to meet future electricity needs. Rocky Mountain Power, a subsidiary of the utility giant PacifiCorp, serves parts of eastern Idaho and much of Utah and Wyoming.

While Rocky Mountain plans to use many of its coal plants well into the future, this IRP says it plans to meet much of its future electricity demand, or “load growth,” with added energy efficiency and also from power purchases off the wholesale market. In is filing with the PUC, Rocky Mountain said its load growth will be lower than estimated in earlier IRPs due to reduced residential customer electricity use due to a number of factors, including the adoption of more efficient lighting and reduced electricity use related to changes to the economy. The utility also said its energy efficiency will rise 59 percent from estimates included in its 2013 IRP, and that it believes efficiency measures will meet 86 percent of its anticipated growth in demand from 2015-2024.

Among public comments in response to the IRP, the Snake River Alliance noted that the retirement of coal plants or their conversion to natural gas could reduce Rocky Mountain’s coal capacity by about 2,800 megawatts. But the Alliance expressed concern that the reduced coal plant emissions are on a too-long timeline and that in 20 years the utility will still rely on coal for 30 percent of its generation, exposing its customers to undue risk in light of coming coal plant emission regulations. Included in its comments, the Idaho Conservation League said Rocky Mountain’s modeling of future coal costs is “fundamentally flawed”.

Idaho regulated utilities are required to file their IRPs every two years. The PUC does not approve these non-binding IRPs, but in accepting them it shows the Commission is satisfied utilities complied with planning requirements.

Go here to read the IRP, the PUC’s acceptance order, public comments, and other documents in the case.