To promote transparency and allow interested readers to further explore our modeling assumptions, the workbook and data sources used to create our model inputs are available for download here. The full set of input files and associated code is available upon request by emailing the authors.

Integrated resource planning is getting more complex due to rapid technological change, new planning objectives such as emissions reductions, emerging state and federal policy, and increased stakeholder participation. Yet utilities nationwide have been slow to adopt new modeling tools and use their advanced features to help achieve more trustworthy and transparent planning outcomes while reducing costs for customers. A growing set of zero-cost, open-source planning models are creating new opportunities for nonutility stakeholders in the resource planning process — including ratepayer advocates and industry, environmental, and community advocacy organizations — to perform their own modeling.

In this report, we examine how stakeholder-driven modeling that leverages open-source utility planning software with transparent data and assumptions can lead to better planning outcomes. As a case study, we used GenX, a leading open-source tool, to independently explore key concerns raised by stakeholders in the 2021 resource plan filed jointly by the utilities Louisville Gas and Electric (LG&E) and Kentucky Utilities (KU). Our findings, which are summarized in Exhibit 1, reveal opportunities for near-term customer savings through cleaner least-cost planning pathways than those modeled by the utilities.

Regulators across the country have an opportunity to incorporate stakeholder-driven modeling in their decision-making to ensure more robust planning, and we suggest actions they can take that would empower stakeholders to complement utility-led modeling, including:

• Making industry tools and data sets more transparent and accessible, such as by establishing data-access standards so that inputs and assumptions used in utility modeling can be easily reviewed and analyzed;
• Establishing IRP rules that allow for stakeholder review and comment on the inputs and assumptions early in the planning process; and
• Reducing cost barriers to stakeholders by requiring utilities to fund stakeholder licenses for their proprietary models, or by signaling openness to zero-cost open-source models.

This report is a companion to RMI’s forthcoming report Reimagining Resource Planning (January 2023), which identifies a broader set of opportunities for making resource planning more trusted, comprehensive, and aligned with traditional and emerging objectives.