Guidance Resources for Power Plants

This page last reviewed August 6, 2008



Under existing law, the State Energy Resources Conservation and Development Commission (Energy Commission) has the exclusive authority to approve the construction and operation of thermal energy-driven power plants that have electric generating capacities of 50 megawatts (MW) or larger. The State's local air pollution control and air quality management districts (districts) have the authority to issue construction permits for the operation of power plants of less than 50 MW generating capacity.

New or modified power plants that will emit air pollutants typically must meet certain emission control requirements and obtain preconstruction and operating permits from the local district. The district prepares an engineering analysis, and places conditions in the permits to ensure that the source will comply with the requirements of federal, State, and local air pollution regulations. For major power plants under the Energy Commission's jurisdiction, the district's engineering analysis and proposed conditions, known as a Determination of Compliance, are used in the Energy Commission's licensing process. After licensing by the Energy Commission, and upon completion of construction, the district issues and enforces a district-issued operating permit.

The Air Resources Board (ARB) is the State agency charged with coordinating efforts to attain and maintain federal and State ambient air quality standards, and the federal Clean Air Act (42 U.S.C., Section. 7401, et seq.). State regulations permit, and in some cases require, that the ARB participate in the Energy Commission's siting process to help ensure that power plants are constructed and operated in compliance with all applicable laws, ordinances, regulations, and standards.

The ARB is typically an informal participant in the power plant siting process; however, the ARB also has the option of applying to be a formal participant (as an intervenor). Consistent with the ARB's overall responsibilities, staff follows each power plant siting proceeding. Staff attends many of the workshops and hearings, and functions as a technical resource to district and Energy Commission staff. Staff also reviews, and if necessary, comments on district preliminary and final Determination of Compliance documents.

The Green Team

Assembly Bill 970 (AB 970, chaptered September 7, 2000) authorizes the districts to issue temporary, expedited, consolidated permits for thermal power plants if specified conditions are met. AB 970 also requires the Energy Commission to establish a process for the expedited review of applications to construct and operate power plants and related facilities.

The adoption of AB 970 added Section 12078 to the Government Code. Section 12078 established the Governor's Clean Energy Green Team (Green Team), which consists of a chairperson and not more than 15 members.

Among its duties, the Green Team is required to compile and make available guidance documents and information on the environmental effects associated with power plants proposed to be certified for operation in California. The compilation of information must include information on best available control technologies (BACT), air emissions offsets, and state-of-the-art technologies that could be used to mitigate those environmental effects.

The ARB is a participant in the certification of power plants in California and has developed much of the guidance and information required by the Green Team for distribution to interested parties. This document contains links to power plant-related resources available on the ARB's web pages.


  1. Air Resources Board "Guidance for Power Plant Siting and Best Available Control Technology" (Issued September 1999)

  2. Air Resources Board "Guidance for the Permitting of Electrical Generation Technologies" (Issued July 2002)

  3. Air Resources Board "Emission Reduction Offsets Transaction Cost Summary Report for 1999" (Issued May 2000)       

  4. Best Available Control Technology Clearinghouse

  5. Air District Contacts for the Registry of Emission Reduction Credits (ERCs)

  6. Summary of Offset Packages for Recently-Evaluated Power Plants

  7. Summary of Control Technologies for Recently-Evaluated Power Plants

  8. Prevention of Significant Deterioration

  9. Air Resources Board "Mobile Source Emission Reduction Credits" (Issued February 1996)  

  10. California Air Pollution Control Officers Association Risk Assessment Guidelines

  11. New Source Review Guidance

Air Resources Board "Guidance for Power Plant Siting and Best Available Control Technology" (Issued September 1999)

The ARB adopted the "Guidance for Power Plant Siting and Best Available Control Technology" (guidance) on July 22, 1999, to assist the districts in making permitting decisions as the districts participate in the Energy Commission's power plant siting process. The guidance outlines ARB staff's position on air quality-related issues for power plant projects. The guidance is intended to provide district staff with information to promote the siting of new power plants that utilize the best available control technology, and that are constructed and operated in a way that eliminates or minimizes adverse air quality impacts. Power plant proponents may also find the guidance useful when developing and planning a proposed power plant project. An electronic copy of the guidance may be obtained from the ARB's web page.

Air Resources Board "Guidance for the Permitting of Electrical Generation Technologies" (Issued July 2002)

SB 1298 required the ARB to develop guidance for electrical generation technologies that are subject to district permits. These technologies include larger turbines and reciprocating engines. The purpose of the guidance is to assist the districts in making permitting decisions for these types of technologies. The guidance includes recommended Best Available Control Technology (BACT) levels and suggested permit conditions. An electronic copy of the guidance may be obtained from the ARB's web page.

Air Resources Board "Emission Reduction Offsets Transaction Cost Summary Report for 1999" (Issued May 2000)

The California Health and Safety Code and the Government Code require local districts to collect information about the cost of offset transactions from stationary source owners who purchase offsets required by district New Source Review programs. Districts must also collect information about offset transactions, which includes the price paid, the pollutant traded, the amount traded, and the year of the transaction. This information must be published annually. The ARB compiles offset transaction information collected from the State's 35 districts. The information is assembled into the attached report, which covers calendar year 1999. An electronic copy of the report may be obtained from the ARB's web page.

Best Available Control Technology Clearinghouse


Air District Contacts for the Registry of Emission Reduction Credits (ERCs)

The attached document is a listing of the 35 air districts in California, along with contact persons and phone numbers for general questions, including emission reduction credits. The phone list may also be accessed on the ARB's web page.

The ARB web page also contains a searchable database of district rules and regulations.  Type in "emission reduction credits" to see which districts have web-published emission reduction credit rules and regulations.

Summary of Offset Packages for Recently-Evaluated Power Plants

The attached document contains a summary of proposed offset packages for new power plant projects in California. The projects are grouped in two categories: 1) projects licensed by the Energy Commission and 2) projects currently undergoing review by the Energy Commission. or (PDF - 25K)

Summary of Control Technologies for Recently-Evaluated Power Plants

The attached table is a listing of control equipment and corresponding emission limits proposed to meet best available control technology requirements for new power plant projects in California. (PDF - 59K)

Prevention of Significant Deterioration

A major source in an attainment or unclassified area for one or more of the criteria pollutants must receive a preconstruction Prevention of Significant Deterioration (PSD) permit. In some air districts, the United States Environmental Protection Agency (U.S. EPA) is the PSD permit agency, and runs its program pursuant to regulations in Title 40 of the Code of Federal Regulations section 52.21 (40 CFR 52.21). If certain criteria are met, the U.S. EPA can delegate its authority for the administrative and enforcement aspects of the program to a district (see 40 CFR 52.21(u), Delegation of Authority). There are currently six districts that have received delegation from the U.S. EPA to issue PSD permits: Bay Area Air Quality Management District (AQMD), Kern County Air Pollution Control District (APCD), San Diego APCD, Santa Barbara County APCD, Shasta County AQMD, and South Coast AQMD.

PSD permits issued by the U.S. EPA or by a delegated district are subject to review by the Environmental Appeals Board (EAB), an independent panel whose scope of responsibility is set by U.S. EPA regulations in 40 CFR section 1.25(e). The EAB hears permit appeals from U.S. EPA-issued permits and state-issued permits where the state is operating pursuant to U.S. EPA delegation, but not where permits are issued by a district under an authorized state program, i.e., the State Implementation Plan (SIP). This is why the EAB does not hear New Source Review permit appeals. There are at least five districts that issue PSD permits pursuant to the SIP, rather than by delegation: Mendocino County AQMD, Monterey Bay Unified APCD, North Coast Unified AQMD, Northern Sonoma County APCD, and Sacramento Metropolitan AQMD. Mendocino, Monterey Bay Unified, North Coast Unified, and Northern Sonoma PSD rules reference the U.S. EPA regulation. The Sacramento Metropolitan AQMD used a model rule jointly developed by the Air Resources Board and the California Air Pollution Control Officers Association in the early 1980's.

A table summarizing the PSD Program status for California air districts is provided as an attachment. (PDF - 7K)

Air Resources Board "Mobile Source Emission Reduction Credits" (Issued February 1996)   

The ARB provides California districts with the ARB's guidelines for the development and implementation of mobile source emission reduction credit (MERC) programs. The guidelines cover overall program development and implementation, uses for MERCs, and specific guidelines for the generation of credits using various reduction methods. The guidelines may be obtained from the ARB's web page.

An alternative MERC program was developed in San Diego for the Otay Mesa power plant project. Details are included in the attached file. (PDF - 67K)

California Air Pollution Control Officers Association Risk Assessment Guidelines

A health risk assessment is an evaluation of the potential for adverse health effects that can result from public exposure to emissions of toxic substances. The information provided in the health risk assessment can be used to decide if, or how, a project should proceed.

Some districts may have regulations or established policies on health risk assessments for making risk management decisions. Other districts have relied on the authority provided by California Health and Safety Code Section 41700 to manage health risk impacts. When applicable policies or regulations are not in place, ARB staff recommends that health risk be assessed according to guidance established by the Office of Environmental Health Hazard Assessment (OEHHA) pursuant to Section 44360.b.2 of the California Health and Safety Code. ARB staff also recommends that districts make decisions consistent with the California Air Pollution Control Officers Association (CAPCOA) Air Toxics "Hot Spots" Program Risk Assessment Guidelines, dated October 1993.  An electronic copy of the guidelines may also be obtained on-line.

It should be noted that there are new cancer potency values and noncancer acute and chronic Reference Exposure Levels that are not reflected in the CAPCOA guidelines. The OEHHA is currently in the process of developing new risk assessment guidelines that will update and replace the CAPCOA guidelines. The ARB's web page contains information on risk assessment.

New Source Review Guidance

New Source Review (NSR) is a title applied to programs regulating the new construction of and / or modifications to, industrial sources that emit air pollutants. The permits resulting from this process are termed NSR, Prevention of Significant Deterioration (PSD), Minor New Source Review (Minor NSR), and / or Nonattainment Area Permits (NAA) depending on the issuing agency, area designation for state and National Ambient Air Quality Standards, and the amount and type of pollutants that the source will emit. By going to the website, you can find information on local air district, State, and federal NSR / PSD, Emission Reduction Credit (ERC) banking, and offset program rules and regulations; alerts of NSR / PSD program changes; offset cost data; and related hot-links.

A concern in siting a new project is its impact on air quality. The benchmarks of acceptable air quality are normally State and federal ambient air quality standards. Section 42301(a) of the California Health and Safety Code requires that district permit systems ensure that new permits will not be issued for emission units that will prevent or interfere with the attainment or maintenance of any applicable air quality standard. For this reason, air quality impacts should be evaluated for each State and national ambient air quality standard potentially impacted by emissions from a project. Any evaluation of air quality impacts should be conducted with a model approved by the U.S. EPA and the ARB. District NSR rules and regulations employ both best available control technology (BACT) and offset requirements to reduce the impact on air quality from new or modified stationary sources.

Air Pollution Credits, Incentives & Grants
Permitting Activities