Enhancing Transparency

Heatmap Add Visibility into Transmission System Capability

In years past, and even in months past, when interconnection customers wanted to connect a new or significantly modified generating facility to TVA’s transmission system, they submitted an interconnection application without knowing if the request was viable from a baseline perspective.

They would wait their turn for a full interconnection study to be completed, then would receive results on whether the transmission system had – or didn’t have – the interconnection capability to meet their specific request, as well as the extent of upgrades that might be required.

Today, thanks to a new tool called a heatmap, interconnection customers have visibility – before submitting an interconnection study request – into the areas that may or may not have the transmission capability needed for a particular generator interconnection.

“The heatmap will enable users to visualize available interconnection capability and make better-informed decisions about generator interconnections,” said Heather Smith, manager of TVA Stakeholder Services and Contracts.

“It will not necessarily reduce the timeline of required steps to interconnect, but it should help reduce the number of speculative, non-viable interconnection requests submitted, which will make the interconnection process more efficient,” Smith said.

TVA developed the heatmap to meet the requirements in Federal Energy Regulatory Commission (FERC) Order No. 2023, which was issued in July 2023 to improve Generator Interconnection Procedures and Agreements.

FERC Order No. 2023 is intended to address interconnection queue backlogs, uncertainty regarding the cost and timing of interconnecting to a transmission system, and undue discrimination of new technologies.

One of the requirements in Order No. 2023 is that all public utility transmission providers create and make publicly available an interactive visual representation of their interconnection capability.

“The heatmap is for informational purposes only and is not a silver bullet, but it will be a great tool that we are excited to provide developers,” Smith said. “It is meant to be a compass for developers, not a specific roadmap for siting generation. It is not a substitute for the comprehensive interconnection study process.”

The heatmap represents estimated interconnection capability on the TVA transmission system in certain scenarios and limited conditions.

TVA collaborated with a leading heatmap developer to create the heatmap, which uses outputs from the same power flow analysis software used in the interconnection study process.

A user guide and tutorial helps walk interconnection customers through the tool. The user provides information that helps define the analysis, then the heatmap shows available transmission grid interconnection capability for the selected year and scenario.

On the heatmap, blue and green indicate more capability and orange and red indicate less or no capability without transmission upgrades.

“Areas on the heatmap showing up orange or red do not necessarily mean the TVA transmission system does not have the capability for a generator interconnection,” said Jason Adams, senior program manager of TVA Transmission Services and Regulatory Services. “However, it does indicate transmission capability is limited or not available without additional network upgrades which, in turn, could make the point of interconnection cost-prohibitive.”

Before the heatmap, interconnection customers would be required to submit an application. TVA would conduct the necessary interconnection studies and, at that point, the interconnection customer could discover there was no transmission capability where they proposed to interconnect their generator.

“With the addition of the heatmap, interconnection customers are no longer just throwing random darts hoping to find transmission capability,” Adams said. “The heatmap will give them an idea of where the transmission constraints might be. The heatmap aims to increase transparency for interconnection customers so they know where the transmission system is expected to have capability. It will be a helpful tool.”

Interconnection customers can access the heatmap on TVA's Open Access Same-Time Information System (OASIS).