After requesting temporary power outages across its seven-state footprint to preserve the electrical grid during the historic cold weather in December, the Tennessee Valley Authority has determined it needs to modernize its system and find ways to keep additional power in reserve.

That’s among the findings in an after-action report the federal utility released Friday.

Related: With growth, blackouts, does north Alabama have enough electricity?

TVA again acknowledged its shortcomings in resorting to asking local power companies to cut power to their customers as part of rolling blackouts on Dec. 23-24.

With its objective to be a “reliable energy partner,” TVA said in the executive summary, “we fell short of that objective.”

As temperatures dipped below zero in some parts of the TVA region — which includes parts of north Alabama — the utility experienced the highest demand for electricity in its 90-year history just after midnight on Dec. 24. To keep from losing control of its electrical grid, TVA sought to reduce demand through the rolling blackouts.

In Huntsville, blackouts were in effect for about 60 percent of customers on Dec. 24, according to Huntsville Utilities, with most customers experiencing two blackouts that lasted about 30 minutes.

“We are already investing in our system and building new infrastructure to address the challenges before us,” the executive summary said, “and we will continue to pursue innovative technologies to achieve our goals.”

TVA outlined a dozen steps as part of its commitment to provide “energy security by building the energy system of the future” with an emphasis on clean energy.

Among the steps:

• Investing and modernizing the system with $18 billion since 2014 and $3 billion through 2027.
• A goal of 10,000 megawatts of solar energy by 2035.
• Building 3,800 megawatts of new generation.
• Pursuing a small modular nuclear reactor at the Clinch River site in Oak Ridge, Tenn.
• Exploring energy storage, including batteries and pumped hydropower and hydrogen.

“While the Winter Storm Elliott after-action report is solely a product of the TVA team, we appreciate the opportunity to challenge TVA’s assumptions, ask penetrating questions and appreciate the transparency and openness of the process,” a statement from TVA’s “blue ribbon commission” said. Commission members are former Tennessee Sen. Bob Corker, former president for American Public Power Association Joy Ditto and Mike Howard, retired CEO of Electric Power Research Institute.

“TVA’s affordable, reliable and resilient electricity is critically important to the economic growth of the (Tennessee) Valley,” the statement went on to say, “and we encourage TVA to continually improve its ability to carry out its mission.”

Days after the blackouts, TVA issued a statement and took “full responsibility” for the need to resort to the power-saving measures for the first time in its history.

“This is not the way we want to serve our communities and customers,” the Dec. 28 statement said.