Customer Support

Protecting Air Quality

Our Approach

We are committed to improving air quality and strive for our generating plants to meet or surpass all clean air requirements. We continually evaluate our operations to look for proactive, cost-effective opportunities to reduce emissions. As part of our clean energy strategy, we have undertaken comprehensive emission-reduction projects, such as Clean Air Clean Jobs in Colorado and the Minnesota Metro Emissions Reduction Program, which have transitioned our conventional generating fleet for the future and significantly reduced emissions. Both projects were proposed and designed with the participation of local policy makers, regulators and other stakeholders to help our company and the states where we operate meet current and future environmental requirements.

We also are increasing the use of emissions-free wind and solar energy and are implementing plans to own new wind farms that offer our customers low-cost clean energy.

We have installed state-of-the-art emission controls on some coal plants, retired other coal plants and replaced some with cleaner, more flexible natural gas. With half the emissions of coal, natural gas-fueled plants can efficiently ramp up or down to respond to variable wind and solar energy, which is a definite advantage as we increase the renewable resources on our system. This provides our customers with cleaner and more efficient energy while maintaining reliability and affordability.

Clean Air Clean Jobs Comes to a Close

With construction complete, Xcel Energy’s Clean Air Clean Jobs project has essentially wrapped up and is producing benefits for customers. All that remains in the seven-year effort is the official retirement of two coal units. Valmont Unit 5 in Boulder ceased coal operations in March of 2017 and Cherokee Unit 4 in Denver will switch from coal to natural gas by the end of 2017.

Xcel Energy worked with a coalition of policy makers and legislators to support the passage of Colorado’s Clean Air-Clean Jobs Act in 2010. Under the legislation, we were directed to propose and implement a comprehensive plan for reducing emissions of nitrogen oxides by at least 80 percent from 900 megawatts of coal-fueled generation.

After extensive public review, the Colorado Public Utilities Commission approved the project and it became part of Colorado’s State Implementation Plan to address Regional Haze. It is also anticipated to help both the state and Xcel Energy meet future environmental requirements. The $1 billion project is estimated to have an average-annual rate impact for customers of approximately 2 percent over a 10-year period.

Under the project, we built a highly efficient natural gas combined-cycle unit at Cherokee Generating Station that began operating in 2015. The new 570-megawatt plant replaces power from six retired coal units, totaling 700 megawatts, with the final 352-megawatt unit at Cherokee plant switching to natural gas. Additionally, modern emission controls were installed at two coal plants, Pawnee and Hayden generating stations.

The entire project was completed on time and under budget, with emission savings that are greater than expected. Both sulfur dioxide and emissions of nitrogen oxides are down 90 percent from the affected units, compared to original projections of 83 percent and 86 percent, respectively. Mercury emissions are down 90 percent, compared to original projections of 82 percent.

Air Emission Reporting and Reductions

Since 2005, Xcel Energy has reduced emissions of nitrogen oxides by 73 percent company-wide from the generating plants it owns.

Sulfur dioxide emissions are down 70 percent company-wide since 2005 from Xcel Energy’s owned generating plants.

Particulate matter emissions are down 68 percent company-wide since 2005 from Xcel Energy’s owned generating plants.

For full emissions reporting for Xcel Energy and each of its operating systems, please see the Environment Performance Summary.

Air-related Regulatory Developments

Regional Haze and Visibility

The Clean Air Act requires EPA and states to routinely evaluate impacts to visibility at national parks and wilderness areas through regional haze. These evaluations may require our facilities to install additional emission controls to reduce visibility impacts of sulfur dioxide, nitrogen oxides and particulate matter emissions.

In Minnesota and Colorado, regional haze state implementation plans are approved and include emission controls and other measures put in place at our Sherco Generating Plant and through Clean Air Clean Jobs. However, issues with regional haze requirements in Texas remain unresolved as EPA has proposed federal implementation plans.  These plans are under review by EPA and Xcel Energy is working to secure an outcome that is consistent with the regional haze regulation and cost effective for our customers and other stakeholders.

In January 2016, EPA issued its final regional haze rule requiring reduced emissions at Texas power plants, with the goal of improving visibility in Guadalupe Mountains National Park in southwest Texas and Big Bend National Park in southern Texas. Xcel Energy’s Tolk Generating Station near Muleshoe, Texas, is among the plants for which EPA has prescribed new emissions controls through the rule. Under the final rule, Tolk is required to meet a new emissions limit for sulfur dioxide by February of 2021, based on the expected performance of dry scrubbers. Installing scrubbers on the plant is estimated to cost approximately $400 to $600 million.

Because this rule exposes our customers to significantly higher energy costs while producing very little, if any, improvement to visibility in national parks, we filed an appeal, along with the state of Texas and others. The rule was stayed, pending the outcome of litigation, and in December 2016, EPA requested that the Fifth Circuit Court of Appeals remand the rule for further consideration. We, along with others, requested that the rule be vacated in response to EPA’s request. In April 2017, the court decided to hold the litigation in abeyance and remand the rule to EPA for further consideration and review.

In addition, EPA has proposed a rule to satisfy Best Available Retrofit Technology requirements to address visibility at Class I protected areas in Texas and neighboring states. The proposal seeks to require the installation of dry scrubbers to reduce sulfur dioxide emissions from Harrington Units 1 and 2 in Amarillo, Texas at a cost of approximately $300 to $400 million. Again, we have concerns with the requirement because it imposes significant costs to our customers while producing little, if any, improvement to visibility. We plan to file comments opposing the rule, which EPA must finalize by September of 2017.


Ozone, commonly referred to as smog, is formed from the reaction of nitrogen oxides and volatile organic compounds in the presence of sunlight. EPA finalized a new ozone standard of 70 parts per billion (ppb) in 2015. In early 2017, EPA signaled that it may reconsider the standard. Any changes to the standard will require a notice-and-comment rulemaking, which could take up to two years.

All parts of our service territory in the Upper Midwest and Southwest are in attainment and will likely stay in attainment with the 70 ppb standard. The areas we serve along Colorado’s Front Range are already in non-attainment for ozone under earlier, less-stringent standards, and will likely go further into non-attainment if the more stringent standard remains in place.

All of our coal units and many of our combined-cycle natural gas units are controlled for nitrogen oxides through pre-combustion controls, post-combustion controls or both. Any new requirements on our Colorado plants would likely occur in the early 2020s.

We will continue to monitor the situation and work with our states on meeting any revised or current standards.

Additional Resources

Learn more about Xcel Energy’s greenhouse gas emissions and reporting on Mercury and Other Hazardous Releases.

Find more detailed emissions reporting in the Performance Summary

Read about our Environmental Policy and Management.

Protecting Air Quality (PDF)

Energy Saving Tip

Create your own shade by planting a tree in a strategic location in your yard to block sunlight from pouring into your windows. It doesn't get much more green than a tree!


Gas Meter Safety

Keep your natural gas meter dry and clear of snow and ice at all times to avoid the potential for dangerous indoor natural gas buildup.

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