Our Methodology

1. Data Acquisition: Conducted an initial sweep of unit- and process-level data from the U.S. EPA’s 2020 National Emissions Inventory (NEI) as well as Justice40 Disadvantaged Communities from the Climate and Economic Justice Screening Tool (CEJST) 2.0.
2. Processing & Refinement: Cleaned raw data to focus on each boiler’s industry, unit capacity, fuel type, and emissions of key pollutants selected based on U.S EPA National Emissions Standards for Hazardous Air Pollutants (NESHAP).
3. Spatial Intersection: Applied spatial analyses to determine whether boilers are sited in communities disproportionately burdened by air pollution, including ozone non-attainment areas and federally recognized Disadvantaged Communities (DACs).
4. Evaluation: Analyzed emissions profiles, industry and unit data, and environmental justice indicators to identify key takeaways on environmental and community health impacts.

The analysis reviewed nearly 14,000 industrial boiler units and found that boilers are significant sources of emissions that disproportionately impact communities already facing elevated air pollution risks.

1. Boilers as Sources of NOx: Approximately 6% of all industrial NOx pollution is attributed to boilers, more than coal-fired power plants, cement production facilities, and petroleum refineries.
2. Geographic Concentration: Nearly 40% of U.S. industrial boilers are installed in five states: California, Illinois, Minnesota, Massachusetts, and Texas.
3. Non-Attainment: 25% of all industrial boilers are located in ozone non-attainment areas where pollution exceeds National Ambient Air Quality Standards (NAAQS) limits.
4. Disadvantaged Communities: Over 40% of industrial boilers nationwide are sited within federally recognized DACs. Average annual boiler NOx emissions in DACs are nearly double those elsewhere, 20.8 versus 10.8 tons, respectively.

In its analysis, AJW also conducted a technology review to evaluate low- or zero-emissions technology solutions to replace conventional industrial boilers. The review identified numerous models and manufacturers of electric and electrode boilers and heat pumps that are readily available and demonstrated in commercial, institutional, and industrial applications.

AJW also analyzed state-level emissions and geographic trends in states active on permitting and clean air advocacy. Highlights include:

• California: 92% of California’s industrial boilers are located in non-attainment areas where ozone pollution already exceeds NAAQS limits, nearly four times the national average of 25%.
• Illinois: The top 1% of highest-emitting units each emit approximately 220 tons of NOx annually, cumulatively generating 2,202 tons per year.
• Michigan: Reported boiler units in DACs emit more particulate matter and VOCs than non-DAC counterparts, with more than twice the lead and seven times the formaldehyde emissions.
• Wisconsin: The highest-emitting reported unit in Wisconsin produces 999 tons of NOx annually—exceeding 99.9% of U.S. boiler units by NOx emissions.

AJW has also overlaid industrial boiler data with geospatial data on data centers to identify waste heat reuse opportunities. View this analysis here.

If you To discuss these findings or explore what this data means for your state or sector, please contact us.