Review of Tennessee Valley Authority’s Draft 2025 Integrated Resource Plan
Synapse supported Sierra Club in its engagement with the Tennessee Valley Authority (TVA)’s 2025 Integrated Resource Plan (IRP) process. Synapse reviewed TVA’s draft IRP with a focus on the reasonableness of TVA’s inputs and assumptions, modeling methodology, strategy and scenario definition, and final results.
We reviewed TVA‘s two-part modeling framework comprised of six world-view scenarios and five resource strategies. We found that while the scenarios featured a variety of future economic, energy, and policy future, only one scenario featured alternative resource cost declines. We were also concerned that TVA didn’t chose a preferred portfolio or design an short-term action plant as part of its draft IRP.
On TVA’s modeling assumptions and key inputs, we found that TVA’s choice of inputs introduced bias into TVA’s consideration of different resource strategies. TVA did not consider the potential for data center growth in its region, did not rely on supported cost and assumptions for advanced resource technologies, relied on high renewable and low gas resource costs, and used static and binding build limits for new renewables. Overall, these choices resulted in a systematic bias against renewables and in favor of conventional gas resources that Synapse finds concerning.
We found that TVA’s own modeling results show that Strategy C, which is commercially viable and relies on more renewable energy and storage resources with fewer gas plants, offers the best balance of cost and risk minimization.
Finally, we evaluated the societal and public health impacts of TVA’s strategies, and found that impacts were minimized under the commercial-ready renewable strategy C. Portfolios that relied on strategy C had lower carbon-related damages and lower health benefits than the portfolios that relied on more fossil-power resources.
We presented a variety of recommendations to address our concerns and findings. Mainly, we recommended that TVA rely on Strategy C in selecting a preferred portfolio to minimize costs and risks to ratepayers.