The US power sector is in the midst of a major transformation, driven by coal plant retirements, the expansion of renewables, evolving regulatory pressures, and shifting investor expectations.

This analysis examines the top 10 ultimate parent companies by financial control of power generation ("the Big 10"), assessing their absolute emissions, emissions intensity, and capacity changes from 2024 to 2029. While some companies are making steady progress, others are seeing sharp reduction in emissions likely tied to major transition milestones, such as plant closures or technology shifts. Natural gas continues to serve as a bridge fuel, while nuclear power plays a growing role in ensuring grid reliability amid the shift to low-carbon energy sources.

We also look at the 10 most emissions-efficient companies ("the Clean 10") to showcase those leading in clean energy production. Finally, a forward-looking scenario analysis of NextEra Energy, Duke Energy, and Constellation Energy explores how their emissions trajectories align with different transition scenarios.

This analysis provides key insights into how the sector is evolving, the pace of decarbonization, and the challenges that remain in meeting climate commitments.

‍The “Big 10”

The 10 largest ultimate parent companies in the US power sector. Consolidated by financial control of power generation (MWh) (see footnotes for details).

Absolute emissions 2024–2029 (MtCO₂e)

• All the largest 10 ultimate owners are shrinking their absolute CO₂ emissions between 2024 to 2030. However, the level of decline, its speed and timing varies between companies depending on their strategy.  ​
• For example, although Calpine Corp and Dominion Energy only reduce their emissions slightly, the declines are smooth and linear, which avoids sudden shocks.
• On the other hand, the emissions of American Electric Power and Xcel Energy remain steady until 2028 where they drop sharply, suggesting potential milestones in their decarbonization strategies, such as plant retirements.​
• American Electric Power is forecast to reduce their emissions the most by 2029.

Power generation 2024– 2029 (TWh)

• All but two of the largest 10 ultimate owners are forecast to see their capacity decline over the next few years.​
• Companies with the steepest declines in generation (American Electric Power Co., Inc. and Xcel Energy, Inc.) align with earlier observed trends of rapid emission reductions. ​
• Companies with stable or growing generation (for example, NextEra Energy) typically cut their coal energy and shift to renewables.​

Emissions intensity 2024– 2029 (gCO₂e/Mwh)

• Most companies demonstrate a downward trend in emissions intensity, reflecting progress in cleaner energy production and efficiency.​
• American Electric Power Co., Inc. has the highest emissions intensity in 2024 (560g CO₂e/MWh) but shows significant improvement by 2029, reducing by ~40% to 330g CO₂e/MWh, however even after that it still ranks 9th highest in.
• Dominion Energy, Inc. also achieves a substantial reduction over the period.​
• Constellation Energy Corp. maintains the lowest emissions intensity (~50g CO₂e/MWh) across all years due to its heavy reliance on nuclear. ​

Technology mix of capacity, 2024 vs 2029 (%)​

• Coal’s contribution to the energy mix of the largest 10 companies is rapidly diminishing.  American Electric Power, a major player in the sector, is reducing itsreliance on coal from ~50% in 2024 to ~21% in 2029, leading to the company's steep drop in emissions intensity as shown on the previous graph.​
• While non-hydro renewables, such as wind and solar, are seeing notable growth the rate is far too slow given that the US power sector is supposed to be net zero by 2035. NextEra Energy, a leader in renewable energy, is increasing its share of renewables from ~30% in 2024 to ~32% in 2029, while Xcel Energy, Inc. expands its renewable portfolio from ~14% to ~20%.​
• While gas continues to act as a bridge fuel, companies like The Southern Co. and Xcel Energy rely largely on nuclear to ensure reliability as coal phases out and renewables ramp up. Dominion Energy, Inc. and Entergy Corp. are also expanding their nuclear capacity. ​

‍The “Clean 10”

The top 10 ultimate parent companies with the lowest emissions intensity out of largest generators (see footnotes for more details).

Emissions intensity 2024– 2029 (gCO₂e/MWh)

• Even among the "Clean 10" emissions intensity vary given the diverse approaches to reduce emissions and transition towards cleaner energy sources. ​
• Constellation Energy Corp. consistently has one of the lowest emissions intensities (~50 gCO₂e/MWh) across all years. This stability is due to its long-term reliance on nuclear power.​
• The biggest improvements come from Invenergy and the US Government, by 28% and 30%, respectively.
• While the Canadian Government and Public Service Enterprise Group both maintain zero emissions intensity (0 gCO₂e/MWh) throughout the period thanks to their their carbon-neutral energy generation strategies. ​

Technology mix of capacity, 2024 vs 2029​ (%)

• Even with the lowest emissions intensity, the "Clean 10" are still actively transitioning. By 2029, low-carbon energy is forecast to grow (renewables by 19 percentage points, nuclear by 8 percentage points, and hydro by 2 percentage points); while fossil fuels are forecast to decline (gas by 21 percentage points and coal by 7 percentage points).​
• Invenergy LLC has the most significant change in its energy mix between 2024 and 2029 with a total change of 22 percentage points across its energy sources, replacing gas with non-hydro renewables. ​

Company forecast scenario analysis 2022-2029

We conducted a forward-looking scenario analysis of three major players in the power sector: NextEra Energy, Duke Energy, and Constellation Energy. Leveraging our detailed, real-time asset-based data, we evaluated how their emissions trajectories compare across various climate scenarios, highlighting their pathways toward alignment with global climate goals and their projected temperature scores by 2029. The analysis reveals significant differences in their transition strategies and underscores the value of independent, forward-looking insights in understanding future climate performance within the energy sector.

NextEra Energy Inc.

Duke Energy Corp.

Constellation Energy Corp.

Footnotes

In this analysis we define power sector assets as electricity generation facilities, spanning coal-, gas-, and oil-fired power stations, hydroelectric dams, nuclear power plants, and renewables (including solar photovoltaic, concentrated solar power, onshore and offshore wind, biogas, and biomass). All references to emissions are to Scope 1 (direct) emissions from combustion of fuels and do not include emissions embedded in construction materials or indirect emissions associated with facilities’ operations. The data used for this analysis is the 2024Q1 Asset Impact company-level database.  

The scope of our analysis includes power plants located within the United States of America (US). Most, but not all, of the power plants in these countries are owned by US-domiciled companies; we still include non-US companies with shares in US assets, such as the Government of Canada.

To link both electricity generation and associated emissions not just to the companies that own plants directly but also to their ultimate owners, we have consolidated by financial control. This means all the emissions from an underlying asset are allocated to the company that has majority ownership of it.  In practice, minority-owned assets are excluded and majority-owned assets are allocated 100% to the parent company if it only owns over 51%.  

The 'Big 10' are the top 10 ultimate parent companies in the US power sector consolidated by financial control of power generation (MWh).

The 'Clean 10' are the top 10 ultimate parent companies with the lowest emissions intensity out of the "large" energy generators (defined as those generating >10TWh in 2024) of which there were 54 ultimate owners).