Clean Energy Portfolio Replacement at Tennessee Valley Authority

Sierra Club
Project Completed June 2022.

The Sierra Club retained Synapse to model the Tennessee Valley Authority's (TVA) system and examine the resource options available to TVA to replace retiring coal-fired generators. Synapse used state-of-the-art electric simulation software to determine the cost to ratepayers of replacing coal generators with new gas-fired resources relative to scenarios that forgo new gas builds in favor of resource portfolios with increased volumes of renewables, storage, and energy efficiency.

We modeled three resource portfolios:

  • Business-As-Usual (BAU), in which retiring coal is replaced largely with new gas-fired capacity;
  • Solar/Storage Replacement, in which retiring coal is replaced with new solar and battery storage resources; and
  • Clean Portfolio Replacement, in which retiring coal is replaced with a portfolio of energy efficiency, wind, solar, and storage resources.

Synapse modeling found that replacement portfolios that rely on renewables and storage will achieve the same levels of reliability as more fossil-intensive portfolios while lowering greenhouse gas emissions and the costs to customers.