The energy sector in the United States stands at a critical juncture as utilities balance the soaring electricity demands of artificial intelligence data centers, manufacturing reshoring, and the ongoing transition toward a decarbonized grid. In its sixth annual Dirty Truth Report, the Sierra Club has provided a comprehensive assessment of 76 of the nation’s largest utility companies, evaluating their commitments to retiring coal-fired assets, expanding renewable energy portfolios, and curbing new investments in natural gas infrastructure. The findings, released in September 2026, paint a concerning picture for the Southeast, where Mississippi Power earned a grade of 44 out of 100, reflecting a persistent reliance on legacy fossil fuel infrastructure.
A Declining National Trend
The aggregate performance of the 76 utilities evaluated in the 2026 report reached a historic low, with a collective score of just 7 out of 100. This marks an eight-point decline from the 2025 assessment, signaling that despite the plummeting costs of solar, wind, and battery storage technologies, the pace of the energy transition is not merely stalling—it is, in some regions, retreating.
The report methodology is rooted in three primary pillars: the timeline for the retirement of existing coal-fired power plants, the volume of new fossil fuel gas capacity currently in the pipeline, and the rate of integration for renewable energy resources. By weighting these factors, the Sierra Club aims to measure how effectively utility providers are aligning their long-term capital expenditure plans with global climate goals and economic efficiency. The current industry trend suggests that many utilities are prioritizing the perceived security of traditional thermal generation over the economic and environmental benefits of a decentralized, renewable-heavy grid.
Mississippi Power’s Position in the Southern Company Strategy
Mississippi Power, a subsidiary of the Atlanta-based Southern Company, operates within a regulatory environment that has historically favored traditional rate-based fossil fuel generation. While other subsidiaries within the Southern Company umbrella have faced increasing pressure to diversify their portfolios, the Sierra Club highlights Mississippi Power as a outlier in its approach to coal retirements.
Amy Kelly, the Sierra Club Beyond Coal Campaign Manager, emphasized the systemic nature of these challenges. "The fact that Mississippi Power is the only one of Southern Company’s subsidiaries to maintain its retirements is a condemnation of Southern Company’s reckless strategy to keep coal plants online across the Southeast," Kelly noted. This critique points toward a broader tension between centralized corporate strategy and the localized energy needs of communities in Mississippi. For ratepayers, this strategy has direct financial implications. The report argues that by maintaining older, less efficient coal plants, utilities are often forced to pass the rising maintenance and fuel costs onto consumers, rather than capitalizing on the lower levelized cost of energy (LCOE) associated with modern renewable installations.
The Economic Case for Renewables
The economic argument for shifting away from fossil fuels has become increasingly robust. According to data from financial analysts at Lazard, renewable energy has maintained its status as the most cost-effective source of new electricity generation for several consecutive years. In contrast, coal-fired power plants are subject to volatile commodity markets and the significant cost of environmental compliance measures, such as carbon capture and storage (CCS) or rigorous air and water pollution controls.
When utilities like Mississippi Power move to authorize new gas-fired power plants, they risk "locking in" carbon-intensive infrastructure for decades. This phenomenon, known as the "carbon lock-in," creates a situation where ratepayers may be burdened with "stranded assets"—investments in power plants that become economically unviable before they have reached the end of their useful life due to carbon pricing, stricter environmental regulations, or the rapid advancement of cheaper clean-energy alternatives.
The AI Energy Demand Paradox
One of the most significant factors influencing the current energy landscape is the explosive growth of artificial intelligence and high-performance computing. Data centers require massive, constant, and reliable power loads, often referred to as "baseload" power. While industry proponents of fossil fuels argue that natural gas is the only reliable way to meet this demand, the Sierra Club and other clean energy advocates contend that the rush to build gas plants is a short-sighted response to an urgent need.
Holly Bender, Sierra Club Chief Program Officer, framed the issue as a failure of foresight. "Every year that utilities drag their feet on the clean energy transition is another year where families pay record bills for expensive fossil fuels, another year of extreme weather events, and another year of air and water pollution threatening our health," Bender stated. The report suggests that by investing heavily in modular renewable energy paired with long-duration battery storage, utilities could meet the demands of the digital economy while insulating the grid from the price volatility inherent in natural gas markets.
Implications for Regulatory Oversight
The grades assigned in the Dirty Truth Report serve as a bellwether for state utility commissions. In states like Mississippi, the Public Service Commission holds the authority to approve or deny utility plans for new power generation. The report acts as a tool for public advocacy, providing a framework for stakeholders to challenge traditional energy planning in regulatory proceedings.
The report also highlights the environmental justice implications of the utility status quo. Fossil fuel plants are disproportionately located near low-income communities and communities of color, where the externalities—air pollution, water contamination, and thermal discharge—have historically had the most significant impact on public health. By failing to transition to cleaner energy sources, these utilities are not only ignoring the economic reality of the 21st-century energy market but are also perpetuating long-standing health inequities in the regions they serve.
Moving Toward a Sustainable Future
As the energy landscape continues to shift, the metrics used by the Sierra Club provide a clear benchmark for what a forward-thinking utility looks like. Successful utilities are those that have set firm "net-zero" targets, established clear dates for the retirement of coal fleets, and demonstrated a willingness to integrate grid-scale solar and wind projects.
The 2026 report serves as a formal call to action for utility executives and regulators alike. With the global energy transition accelerating, the cost of inaction is mounting. For Mississippi Power, the path forward involves a fundamental reassessment of its current reliance on fossil fuel assets. As the Sierra Club concludes, the transition to clean energy is not merely an environmental imperative but a necessary step to modernize the electrical grid, stabilize energy costs for families, and ensure the long-term reliability of the power supply in an era defined by rapid technological and climatic change.
The full details of the 2026 Dirty Truth Report, including individual utility scorecards and the methodology used to calculate the rankings, are available via the Sierra Club’s online portal. The findings represent an ongoing effort by civil society to hold large-scale energy providers accountable as they navigate the most significant transformation of the power sector in over a century. Whether this report will catalyze a shift in strategy for Southern Company and its subsidiaries remains to be seen, but the data clearly indicates that the status quo is increasingly untenable in both the boardroom and the public eye.
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