IRP Questions and Responses

Relevant questions or comments submitted using the form below or via email will be made public, along with Idaho Power’s responses, on this page.

We will respond to questions within two weeks.

IRP Questions, Comments and Responses

Following are IRP-related questions from members of Idaho Power’s IRP Advisory Council or other members of the public, either at IRPAC meetings or via email or using the form above. More information is available at

Regarding the “low” carbon adder, one might more accurately label that scenario “zero” carbon adder given it is an analytical boundary case and not a forecast.

We agree; thank you for the recommendation. We will change the label from “low carbon adder” to “zero carbon adder.”

Does the transmission benefits study show both transmission and distribution losses at summer peak?

The transmission benefits study focused only on transmission losses at summer peak. Adding B2H or other transmission projects would not impact distribution system losses.

Will the climate scenario reflect fire risk?

The climate scenario includes evaluation of impacts we are likely to see as a result of climate change: greater water variability and more temperature extremes.

Separately, Idaho Power conducted a complete wildfire risk assessment of its service area and transmission corridors. That assessment identified higher risk zones, and also identified proactive wildfire mitigation strategies. The Company’s Wildfire Mitigation Plan can be found as an Attachment to its application in Idaho PUC case IPC-E-21-02.

Historical flows assume a stable climate and are not necessarily predictive of flows over the next 5 years. Is that taken into account?

Historical transmission path flows were utilized for the loss benefit analysis to determine the average loss savings. Changes in peak loads or resource dispatch patterns driven by extreme weather will impact the peak hour loss savings. Given uncertainty around peak load hour dispatch, the loss benefit analysis focused on average loss benefits.

Can Idaho Power quantify/measure the CO2 emissions of EIM and purchased energy? With respect to transmission, there are benefits and risks. How would Idaho Power reduce the risk of line loss? What would the costs be of hardening transmission and distribution to climate change and other risks?

When energy is purchased from the market, the sourcing of the energy many times is not known. However, we do anticipate that the Pacific Northwest region, similar to Idaho Power, will move towards the implementation of more clean resources.

The B2H line will be built utilizing best industry practices to reduce line loss risk. In general, higher voltage transmission lines that are built higher from the ground and are more resistant to unexpected outages.

Idaho Power has developed a Wildfire Mitigation Plan to prepare and respond to wildfire risks. It can be found here: Wildfire Mitigation Plan 2021 (

How do we know the markets are “economic resources” over the IRP planning horizon?

When Aurora estimates market prices within each zone, supply-side resources are modeled individually using numerous cost and operating constraints with hydro generation units having additional constraints. Transmission resources connect the zones and are modeled to include transfer capability, losses, and wheeling costs. Finally, demand-side resources and price-induced curtailment allow the model to balance use of generation against alternatives to reduce customer demand. The Aurora model uses the information above to build a cost optimized economic dispatch for the markets. Market-clearing price is determined by observing the cost of meeting an incremental increase in demand in each area.

Given the challenge to irrigators for the later hours, is there any opportunity for a narrow time window specific to that class?

We recognize the program changes will be challenging for our participants. The new parameters of the program were developed based on the needs of Idaho Power’s system. Unfortunately, allowing some participants to sign up for earlier hours erodes the effectiveness of the program.
— Posted Sept. 7, 2021

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