Clean Cities Technical Response Service (TRS) Archived Questions of the Month



What notable changes to federal alternative fuel conversion regulations resulted from the U.S. Environmental Protection Agency’s (EPA) final rulemaking?

Answer: On March 29, 2011, EPA announced the final rulemaking to adopt changes to the regulations in Title 40 of the Code of Federal Regulations, part 85, subpart F. These regulations apply to manufacturers of alternative fuel conversion systems for light-duty vehicles and heavy-duty highway vehicles and engines. The Clean Air Act prohibits anyone from altering a vehicle or engine from its certified configuration, and EPA is responsible for ensuring that all vehicles and engines sold in the United States meet federal emissions standards. This new approach simplifies and streamlines the process by which alternative fuel conversion systems manufacturers may demonstrate compliance with these emissions requirements and gain a regulatory exemption from potential tampering charges. 


Age-based Categories

Previous regulations required all vehicle and engine conversion systems to be covered by a Certificate of Conformity (Certificate) in order to be exempt from federal tampering prohibitions. The amendments are based primarily on EPA’s determination that it is appropriate to treat conversions differently based on the age of the vehicle or engine being converted. All conversion manufacturers seeking an exemption must demonstrate compliance, but the demonstration requirements differ among categories. A summary of each age-based category and the associated compliance requirements is as follows: 


New and Relatively New Vehicles and Engines

  • Includes vehicles/engines less than about two years old. More specifically, the date of the conversion is in a calendar year that is not more than one year after the original model year of the vehicle/engine.
  • Notification and demonstration requirements are very similar to previous practice, including a certification application that includes testing and on-board diagnostics (OBD) requirements. The demonstration requirement for new vehicles/engines is certification.
  • EPA issues a Certificate if all requirements are satisfied.
  • Once certified, annual recertification is no longer required to maintain the tampering exemption.


Intermediate Age Vehicles and Engines

  •   Includes vehicles/engines that are no longer “new and relatively new” (see above), but still fall within EPA’s definition of full useful life.
    • The definition of full useful life varies among different vehicle and engine regulations. Useful life is expressed as a threshold age in years, mileage, and/or number of hours of operation.·      
  • Notification and demonstration requirements include testing and data submission to show that the converted vehicle or engine meets applicable emission standards and an OBD scan tool report.
  • EPA does not issue a Certificate but will publically list the conversion systems as having satisfied the demonstration and notification requirements.
  • Converters of intermediate age vehicles and engines may voluntarily choose to satisfy the new vehicle/engine demonstration requirement (certification) instead of the intermediate age demonstration requirement, in which case they would receive a Certificate.
  • Annual recertification is not required to maintain the tampering exemption. 


Outside Useful Live Vehicles and Engines

  • Includes vehicles/engines that are outside EPA’s definition of useful life.·       Notification and demonstration requirements include submission of a technical description, other information and data, and an OBD scan tool report.
  • EPA does not issue a Certificate but will publically list the conversion systems as having satisfied the demonstration and notification requirements.
  • Annual recertification is not required to maintain the tampering exemption.  


Additional Information

The rule has been published in the Federal Register and is now in effect, as of April 8, 2011.

EPA also finalized several technical amendments related to exhaust and evaporative emissions testing requirements for gaseous-fueled vehicles, in addition to other technical changes to provide consistency and clarity. 

Refer to EPA’s Alternative Fuel Conversion website ( for more information about the regulations, including full text of the final rule, response to comments received on the proposed rule, and compliance information.  

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What are the average greenhouse gas (GHG) emissions from all-electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs)? How do these emissions compare to conventional vehicles?

Answer: In addition to reducing petroleum consumption, EVs and PHEVs have the potential to reduce pollutant emissions, resulting in environmental and human health benefits. Vehicle emissions can be characterized as:
  • Upstream: Emissions from the production of the vehicle fuel (e.g., electricity).
  • Tailpipe: Emissions produced by a vehicle while operating.
  • Well-to-wheel: The combination of upstream and tailpipe emissions.


EV Emissions

EVs are often referred to as “zero emission vehicles,” meaning they do not emit any tailpipe emissions. Therefore, the well-to-wheel GHG emissions associated with EV operation are entirely dependent on the source that is used to produce the electricity that powers the vehicle. Emissions from electricity production depend on the efficiency of the power plant and the types of fuel sources used. Based on the U.S. average electricity production fuel mix, the GHG emissions are lower for an EV using electricity generated from power plants than a vehicle running on gasoline or diesel. If electricity is generated from nonpolluting, renewable sources, EVs have the potential to produce no well-to-wheel GHG emissions. On the other hand, EVs powered by electricity generated using coal have the potential to produce more well-to-wheel GHG emissions than gasoline vehicles, depending on the power source. To determine your region’s specific fuel mix, as well as the emissions rates of electricity based on your zip code, see the U.S Environmental Protection Agency’s Power Profiler ( While factors such as the time of day and season can affect which specific power plant (and fuel mix) provides the vehicle’s electricity, these average emissions rates help approximate the impact of these vehicles. 


PHEV Emissions

PHEVs typically operate either in all-electric mode or using an internal combustion engine (ICE) and electric drivetrain in a manner similar to a hybrid electric vehicle (HEV). The emissions vary based on the percent of time that the vehicle is in each operating mode. When operating in all-electric mode, emissions are considered from the source that produced the electricity. When the vehicle’s ICE is running, both the upstream and tailpipe emissions must be taken into account. The tailpipe emissions will vary depending on vehicle efficiency.


Comparing EV and PHEV Emissions to ICE Vehicle Emissions

The following table estimates the well-to-wheel GHG emissions associated with a 100-mile trip in four comparable compact sedans, based on the national average for electricity production emissions. 

Vehicle GHG Emissions (pounds of CO2 equivalent)
EV 54 lb CO2e
PHEV 62 lb CO2e
HEV 57 lb CO2e
Conventional Gasoline 87 lb CO2e

 The Alternative Fuels & Advanced Vehicle Data Center (AFDC) Compare Electricity Sources and Annual Vehicle Emissions tool ( allows users to determine an estimate for annual well-to-wheel GHG emissions for an EV, PHEV, HEV, and conventional gasoline vehicle based on the electricity production fuel mix in their area.  


In addition, and EPA’s Green Vehicle Guide ( provide annual emissions estimates for individual vehicle models.

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What are the factors that determine the price of gasoline?

Answer: Gasoline price increases tend to emphasize the need for increased fuel supply or reduced fuel demand through the use of fuel-efficient vehicles, alternative fuels, and other strategies that reduce petroleum consumption. The final price of a gallon of gasoline is a product of many factors that can be complicated and constantly changing, but it comes down to the concept of supply and demand.


Currently, the average price of regular gasoline in the United States, including all taxes, is $3.78/gallon, as compared to $2.40/gallon in October 2010. According to the U.S. Energy Information Administration
(EIA,, the current cost of gasoline can be broken down into the following components:

  • Crude oil price (as purchased by refiners): 69%
  • Refining costs and profits: 16%
  • Taxes (including federal and state): 10%
  • Distribution and marketing costs and profits: 5%


Of these components, changes in the cost of crude oil have the greatest impact on gasoline prices. As crude oil prices increase, they become a larger percentage of the overall cost of gasoline at the pump. Between 2000 and 2008, the average retail price of gasoline was $2.06/gallon and crude oil prices only made up 51% of the overall price, as compared to the breakdown above. 


Crude oil prices are affected by economic, environmental, and political factors. As with most finite resources, the economics of oil are driven by supply and demand. Oil suppliers price their products based on actual and expected demand for petroleum products relative to current and projected short- and long-term supply of oil. When supply is low and/or demand is high, gasoline prices tend to increase. When supply is high and/or demand is low, gasoline prices tend to decrease.  


The demand for petroleum products is largely determined by the world economy. For instance, after the gasoline price spike in 2008, the economic situation led to a decline in global petroleum consumption and, therefore, a decrease in gasoline prices. Conversely, the recent rise in gasoline prices can be tied, in part, to the gradual improvement in the economy.  


The global oil supply tends to be more difficult to predict. Environmental factors, such as weather events, can affect the supply of oil. For instance, hurricanes in the Gulf of Mexico in the mid-2000s (e.g., Hurricane Katrina in 2005) shut down U.S. crude oil production and negatively affected refinery and pipeline operations, causing several spikes in oil and gasoline prices. In addition, global supply of oil can be affected by geopolitical issues. For example, the recent rise in gasoline prices can be partially attributed to political events outside our borders.  


For additional information on gasoline prices, please refer to:


In addition, the following publications related to gasoline prices and Clean Cities portfolio items may be of interest:

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How do I navigate the terminology associated with aftermarket vehicle and engine conversions?

Answer: The conversion vocabulary can sometimes be difficult to understand, particularly because the terms are not always used consistently. Below is a glossary of terms related to alternative fuel and advanced vehicle and engine conversions, broken down into categories. Please note that this information is meant to be a general Clean Cities reference guide; other agencies and organizations may define these terms differently.  


Aftermarket Conversion

  • Aftermarket conversion – An aftermarket conversion is a vehicle or engine which is modified to allow it to operate using a different fuel or power source than the one for which it was originally designed and certified to use. An aftermarket conversion can also be referred to as a retrofit or an upfit.


Key Players

  • Conversion manufacturer - An entity that produces and sells aftermarket conversion systems. A conversion manufacturer may have technicians that install the conversion system or may work with a qualified system retrofitter (QSR) to complete the installation.
  • QSR – An entity that operates independently of, but works closely with, conversion manufacturers to perform aftermarket conversions. QSRs are also commonly referred to as upfitters or installers.
  • Original equipment manufacturer (OEM) An entity that produces new vehicles and engines “off the assembly line.” Some OEMs produce vehicles and engines that are prepped for conversions, meaning they include components that are compatible with certain alternative fuels.

Aftermarket Conversion Types

  • Non-engine fuel type Involves changes to the vehicle components (not including the powertrain) to enable the engine to operate on an alternative fuel, but does not involve significant changes to the vehicle’s OEM-certified engine.
  • RebuildInvolves modifying the original engine to be powered by a different fuel type.
  • RepowerInvolves replacing the existing engine with a new, rebuilt, or remanufactured engine powered by a different fuel type.
  • Powertrain – Involves changes to the vehicle powertrain, and could involve installing an additional electric motor.


Resulting Vehicle Fuel Configuration

  • Dedicated –Vehicles that operate exclusively on an alternative fuel.
  • Bi-fuel and Dual-fuel – Vehicles that can operate on a combination of alternative and conventional fuel. The terms bi-fuel and dual-fuel are often used interchangeably and are defined differently by various agencies and organizations, but may include:
    • Vehicles that operate on a blend of an alternative fuel and a conventional fuel stored in one fuel tank; commonly called flexible-fuel vehicles.
    • Vehicles that operate on an alternative fuel or conventional fuel stored in separate tanks, using one fuel at a time.
    • Vehicles that operate on an alternative fuel and use a conventional fuel for ignition assist. These vehicles automatically switch over completely to an alternative after the engine has warmed up. 

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What is the status of E15 implementation now that the U.S. Environmental Protection Agency (EPA) has granted the recent Clean Air Act (CAA) waivers?

Answer: In March 2009, EPA received a formal CAA waiver request from the ethanol industry to raise the allowable ethanol content in gasoline for conventional passenger vehicles from 10% (E10) to 15% (E15). In October 2010, after an extensive evaluation, EPA granted a partial waiver for the use of E15 in Model Year (MY) 2007 and newer light-duty vehicles. In January 2011, EPA granted a second partial waiver for the use of E15 in MY 2001 and newer light-duty vehicles.  


So when will I see E15 at my local gas station?

The EPA waivers were just the first step in the process of bringing E15 to the market. State and federal agencies have begun to tackle the many additional issues that must be addressed. In the last two months, EPA has made the following announcements:

  • E15 Labeling and Other Requirements.  On June 27, EPA finalized new requirements to help ensure that E15 is properly labeled and used once it enters the market. Specifically, this rule outlined a label that must appear on all E15 fueling pumps to alert customers that the fuel may only be used in certain vehicles. In addition, the rule officially prohibits misfueling MY 2000 and older conventional gasoline vehicles with E15 and sets other requirements for E15 producers, distributors, and sellers. For more information, refer to the final rule in the Federal Register:
  • Underground Storage Tank Guidance.  On July 5, EPA finalized guidance for owners and operators of underground storage tanks (USTs) containing ethanol blends greater than E10. The guidance will assist these entities in demonstrating compliance with federal regulations requiring USTs to be compatible with the fuel stored. For more information, refer to the final guidance in the Federal Register:


What else must be done?

Before any fuel can be sold in the United States, manufacturers must register it with EPA’s Fuel and Fuel Additives program ( As of August 10, 2011, E15 had not yet been fully registered with EPA. Other federal regulations must also be addressed. In addition, state laws and regulations limiting sale of E15 must be amended before the fuel can be sold in certain states. These state provisions include ethanol blend cap restrictions, biofuels mandates, and technical fuel specification standards.  


Supplemental Information and Resources

It will no doubt take time to update laws and regulations to allow the sale of E15, and address other barriers. An exact timeframe is not known. For more information on the EPA partial waivers and to stay up-to-date on new developments related to E15, please reference the following resources:


In addition, the U.S. Government Accountability (GAO) Office recently published a report, Biofuels: Challenges to the Transportation, Sale, and Use of Intermediate Ethanol Blends (, which identifies three additional key challenges to the retail sale of E15 and other intermediate ethanol blends:

  • Compatibility.  Intermediate ethanol blends may degrade or damage some materials used in existing UST systems and dispensing equipment, potentially causing leaks. Studies that test fuel storage and dispensing components and equipment are needed to fully understand the effects of intermediate ethanol blends.
  • Cost.  New storage and dispensing equipment that is compatible with intermediate ethanol blends may be needed to sell the fuel at retail outlets. Currently, according to the GAO, the total cost of installing a compatible single-tank UST system and fuel dispenser is estimated to be more than $120,000. Costs will range widely depending on equipment replacement needs.
  • Liability.  Many fuel retailers are concerned about potential liability issues if consumers misfuel their MY 2000 or older automobiles or non-road engines with E15. This issue was partially addressed by the recent E15 labeling rule, but concerns may still exist.

The GAO report identifies several ongoing EPA and U.S. Department of Energy studies that are addressing these and other challenges.

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What are the top 10 resources for reliable and unbiased information about alternative fuels, advanced vehicles, and other petroleum reduction strategies?


  1. Alternative Fuels & Advanced Vehicles Data Center (AFDC): 
    The AFDC is a comprehensive clearinghouse of data, publications, tools, and information related to alternative fuels, advanced vehicles, idle reduction, fuel economy, and other petroleum reduction strategies. The AFDC Tools page ( is a one-stop-shop for links to tools, database searches, calculators, and interactive maps available through the AFDC, including the Alternative Fueling Station Locator, Vehicle Searches, Incentives and Laws Search, and Publications Search. 

  2. Clean Cities:

    The national Clean Cities website includes links to relevant news, events, and publications; program and coalition contacts; financial opportunities; and Coordinator Toolbox resources.

  3. allows users to search for fuel economy information for light-duty vehicle models through the Find and Compare Cars tool. In addition, the website includes a search tool for cars that don’t use gasoline, verified gas mileage tips, and the Your MPG fuel economy tracking tool.

  4. U.S. Energy Information Administration (EIA)’s Alternatives to Traditional Transportation Fuels:
    EIA collects, analyzes, and disseminates information about energy production and use in the United States. On an annual basis EIA publishes their Alternatives to Traditional Transportation report, which summarizes data on the number of alternative fuel vehicles supplied and in use, and the amount of alternative fuel consumed. Please note that the data published is generally two-years delayed; 2010 data will be available in the spring of 2012. EIA also publishes data on conventional fuel prices and production, as well as other topics of interest.

  5. DOE’s Energy Policy Act (EPAct) Information 

  6. DOE National Laboratories 
    The DOE national labs perform research, implement programs, and publish documents related to alternative fuels and advanced vehicles. A full list of labs and technology centers is available on the DOE website: The labs involved with Clean Cities include Argonne National Laboratory, Idaho National Laboratory, National Energy Technology Laboratory, and National Renewable Energy Laboratory.  

  7. Clean Cities Coalitions 
    Coalitions around the country are deploying alternative fuels and advanced vehicles, educating their stakeholders and the public, and engaging their communities. The coalition websites and coordinator contact information listed on DOE’s Clean Cities website ( are great resources for information and case studies. You may also reach out to the coordinator listserv with specific questions. 

  8. U.S. Environmental Protection Agency (EPA): 
    EPA administers a number of different programs aimed at reducing vehicle emissions. For example, the EPA website features information on the following:
  9. Other Federal Government Agencies
    Several other federal government agencies implement programs and regulations related to alternative fuels and advanced vehicles. These agencies include the U.S. Department of Transportation’s Federal Highway Administration and National Highway Traffic Safety Administration; U.S. Department of Agriculture; and U.S. Internal Revenue Service. The AFDC Incentives & Laws database provides information and links for additional information about federal incentives, laws, regulations, and programs by agency at the following website:  

  10. State and Local Government Agencies 
    State and local government agencies are great resources for information about regulations and programs in your area. The National Association of State Energy Officials maintains a list of state and territory energy office websites and contacts ( Likewise, the EPA posts a list of state and territorial environmental agency websites (  In addition, many state agency contacts are listed on the AFDC State Incentives and Laws website ( 


Industry associations and nonprofit organizations can also provide useful information specific to certain fuel or technology types or issue areas. For example, NAFA Fleet Management Association ( and ICLEI – Local Governments for Sustainability ( can be helpful resources.

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