Climate and Energy Resources for State, Local and Tribal Governments

Assessing Air Quality, Greenhouse Gas, and Public Health Benefits

What are the Air Quality, Greenhouse Gas, and Public Health Benefits of Clean Energy?

Electricity generation from fossil fuels is a major source of various types of air pollution. Many states and localities are exploring or implementing clean energy policies to achieve reductions in greenhouse gases (GHGs) and criteria air pollutants, such as particulate matter, ground level ozone, carbon monoxide, sulfur oxides, and nitrogen oxides. While GHGs have a global effect, contribute to climate change, and can last more than 100 years, criteria air pollutants have a local to regional effect on air quality and human health and can dissipate in hours or days. Clean energy measures that reduce criteria air pollutants, therefore, can result in almost immediate local improvements in air quality and human health.

Tools and methods are available to help states estimate the impact of clean energy policies on criteria air pollutant emissions, ambient air quality, and the related environmental and health impacts.

Steps in Estimating Benefits

Steps in Estimating Benefits

Develop and project a baseline emissions inventory

Select method, compile emissions from available sources into inventory, and develop a forecast

Quantify emission reductions

Develop emissions from clean energy using energy savings estimates, load profile, emissions factors, and control technology or fuel data. Compare against baseline.

Estimate changes in air quality resulting from emission reductions

Use criteria air pollutant data to estimate changes in air quality with an air quality model.

Estimate human health and related economic effects of air quality changes

Use data on air quality changes and epidemiological and population information to estimate health effects. Apply economic values of avoided health efforts to monetize benefits.

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Developing an Emissions Inventory Forecast Baseline

States can use many sources of data as they compile top-down or bottom-up inventories. Some of these data sources focus specifically on criteria air pollutants, some focus on GHGs, and some include both. More information is available about Developing a GHG Inventory.

Sources of Air Pollutant and GHG Emission Data

Date Source

Type of Air Pollutant or GHG Emissions





Other GHGs




National Emissions Inventory (NEI)



Emissions Collection and Monitoring Plan System (ECMPS)


World Resources Institute Climate Analysis Indicators Tool  Exit




Local GHG Inventories




State Examples

A 2011 evaluation (PDF)(218 pp, 6.48 MP, About PDF) Exit of the Wisconsin Focus on Energy Program's energy efficiency and renewable energy projects funded by the Utility Public Benefits fund shows the state displaced annual emissions from power plants and utility customers in 2010 of about:

  • 1.8 million pounds of NOX
  • 1.3 billion pounds of CO2
  • 2.3 million pounds of SO2
  • 8.6 pounds of mercury (Hg)

The cumulative lifecycle verified gross emissions from program inception on July 1, 2001 through December 31, 2010 were approximately:

  • 8.7 million pounds of NOX
  • 6.6 billion pounds of CO2
  • 10.7 million pounds of SO2
  • 41.6 pounds of mercury (Hg)

In 2012, the Texas Commission on Environmental Quality evaluated (PDF) (21 pp, 671 KB) Exit the Texas Emissions Reduction Plan and calculated that it achieved an annual reduction in NOx emissions of more than 4,600 tons through energy efficiency and renewable energy. The Plan is expected to reduce NOx emissions by nearly 7,400 tons per year in 2020.

Quantifying Emission Reductions

A starting point for quantifying emission reductions from clean energy policies is the estimate of expected energy savings and generation likely to occur. States can explore available projections of energy impacts from existing policies and programs that affect power sector or develop their own estimates of the potential energy impacts of new policies and programs.

States can use a range of tools and approaches to quantify the emissions changes from clean energy policies, which can then be compared to the baseline emissions inventory to determine emission benefits.

Basic approaches provide policymakers with approximate estimates of emission reductions from energy supply and demand changes they can use for preliminary short-term studies and program evaluation or design. They are often less expensive than more complicated models, but because of their simplicity they are unable to provide the levels of detail that some policymakers require.

Sophisticated approaches are more complex and can offer a wider range of modeling options. These tools provide policy makers with richer insight into the range of emission results that are likely to occur from energy efficiency or renewable energy policies and are appropriate to use for regulatory decisions and long-term analyses. They are more costly to run, however, and can require significant technical expertise.

EPA offers the AVoided Emissions and geneRation Tool (AVERT), a tool that falls in between basic and sophisticated approaches and enables users to estimate country, state and regional NOx, SO2 and CO2 emissions displaced at electric power plants by energy efficiency, solar and wind policies and programs. EPA also offers descriptions of other tools and methods states may use.

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Modeling Air Quality Changes

Clean energy policies that reduce both primary (e.g., NOx) and secondary (e.g., ozone) air pollutants may improve ambient air quality. States can use models to estimate changes in ambient air quality, such as those currently used for State Implementation Plans, as required by the Clean Air Act.

Modeling ambient air quality impacts can be a complex task requiring sophisticated air quality models and extensive data inputs (e.g., meteorology). States can use one of three types of models to conduct this type of analysis: dispersion models, photochemical models, and receptor models. All of the models require location-specific information on emissions and source characteristics, although they may represent photochemistry, geographic resolution, and other factors to very different degrees. States can learn more information about these models through EPA's Support Center for Regulatory Atmospheric Modeling (SCRAM).

Estimating Health Effects and Related Economic Value

Where clean energy measures improve air quality or avoid damage to air quality, they may prevent negative health incidences, such as illnesses and deaths. States can use basic and sophisticated modeling approaches to estimate the human health effects of air quality changes and the monetary value of avoided health effects-a key component of a comprehensive economic benefit-cost analysis. This information can help states compare across alternative program options and communicate some of the most important advantages of clean energy. One example of a screening tool states can use to estimate the health effects from clean energy policies, and their health-related economic value, is EPA's Co-Benefits Risk Assessment (COBRA) Screening Model.

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Tools & Resources

Assessing the Multiple Benefits of Clean Energy

Assessing the Multiple Benefits of Clean Energy: A Resource for States provides an overview of the multiple benefits of clean energy and their importance. It includes information on:

  • The importance of and approaches to calculating or estimating energy savings as the foundation for deriving multiple benefits
  • A range of tools and approaches to estimating energy systems, environmental, and economic benefits across varying levels of rigor
  • How states have supported the use of clean energy through the estimation of multiple benefits

AVoided Emissions and geneRation Tool (AVERT)

AVERT is a free tool with a simple user interface designed to meet the needs of state air quality planners and other interested stakeholders. Non-experts can easily use AVERT to evaluate county, state and regional levels of NOx, SO2 and CO2 emissions displaced by energy efficiency, wind and solar policies and programs. AVERT uses public data, which is accessible and auditable.

Co-Benefits Risk Assessment (COBRA) Screening Model

COBRA is a screening tool that enables users to:

  • Roughly estimate the impact of emission changes on ambient air pollution
  • Further translate this into health effect impacts
  • Monetize the value of those impacts
  • View the estimated county-level results in tables and maps


E-Calc Exitis a Web-based calculator that allows government and building industry users to design and evaluate a wide range of projects for energy savings and emissions reduction potential. This tracking tool was developed by Texas A&M University's Energy Systems Laboratory in response to legislative incentives to quantify emissions reductions from building energy savings and distributed renewable technology. E-Calc evaluates residential, commercial, retail, and municipal buildings energy and emissions savings, as well as savings from renewables like solar heating, solar PV, and wind power.

Environmental Benefits Mapping and Analysis Program – Community Edition (BenMAP-CE)

BenMAP-CE is an open-source computer program that calculates the number and economic value of air pollution-related deaths and illnesses. The software incorporates a database that includes many of the concentration-response relationships, population files, and health and economic data needed to quantify these impacts.

Power Profiler

Power Profiler is a Web-based tool that allows users to evaluate the air pollution and greenhouse gas impact of their electricity choices. Using only a ZIP code, the tool generates a report describing the characteristics of one's electricity use.

Projected Impacts of State Energy Efficiency and Renewable Energy Policies

EPA has projected the energy impacts of energy efficiency and renewable energy state policies not included in the Energy Information Administration's Annual Energy Outlook 2013. These projections are intended for use by states developing State Implementation Plans (SIPs) for ozone and other criteria air pollutants under the National Ambient Air Quality Standards (NAAQS). States may also use EPA's draft methodology to develop their own estimates of EE/RE policy impacts and associated emissions reductions. Jurisdictions not currently preparing a SIP but interested in better understanding the energy and emissions impacts of EE/RE policies may likewise use EPA's methodology and estimates to identify strategies for staying in attainment with NAAQS.

Support Center for Regulatory Atmospheric Modeling (SCRAM)

EPA's SCRAM website provides descriptions and documentation for three types of air quality models: dispersion, photochemical, and receptor models; modeling guidance & support for applying air quality models for regulatory applications; and information on Meteorological data used in air quality models as derived from both ambient measurements and meteorological models.