ASTM Standards for Ethanol & Ethanol Blends
Ethanol has been widely used in the United States for many years as a gasoline extender and octane enhancer. Ethanol is currently blended into 46 percent of all gasoline and is an essential component of the U.S. motor fuel market. The use of ethanol and other renewable fuels are expected to significantly increase in the future.
In the late 1970s and early 1980s, in response to the Arab oil embargo, gasoline producers blended up to 10 volume percent ethanol with 90 percent gasoline (a product known as gasohol) to extend gasoline supplies and increase octane as a result of U.S. Environmental Protection Agency regulations phasing out the use of lead. The Clean Air Act Amendments of 1990 further stimulated ethanol’s growth by mandating the use of oxygenated fuels in certain areas of the country during the winter to reduce carbon monoxide emissions, and by requiring the use of reformulated gasoline to reduce ozone levels in the nation’s most severe ozone non-attainment areas.
In August 2005, U.S. President George W. Bush signed into law the Energy Policy Act of 2005 (Public Law 109-58). This comprehensive energy legislation establishes a renewable fuels standard, mandating the use of 7.5 billion gallons [28 million m3] of renewables (including ethanol and biodiesel) by 2012. Several states have also mandated the use of ethanol and other renewable fuels. In his Jan. 23, 2007, State of the Union address, the president called for a 20 percent reduction in gasoline consumption by 2017 (“Twenty in Ten”). The president’s plan includes a fuels standard to dramatically increase the use of renewable and alternative fuels to 35 billion gallons [132 million m3] by 2017 nearly five times the 2012 level required under the Energy Policy Act of 2005. Under the president’s plan, 35 billion gallons [132 million m3] of renewable and alternative fuels can displace 15 percent of projected annual gasoline use in 2017.
ASTM International Committee D02 on Petroleum Products and Lubricants and Subcommittee D02.A0 on Gasoline and Oxygenated Fuels have established several standards governing the use of ethanol and ethanol blended fuels, and a research report on reformulated gasoline. These are:
• ASTM D 4806, Specification for Denatured Fuel Ethanol for Blending with Gasolines for Use as Automotive Spark-Ignition Engine Fuel: Covers a fuel-grade ethanol that is suitable for blending with gasoline in levels up to 10 volume percent ethanol.
• ASTM D 4814, Specification for Automotive Spark-Ignition Engine Fuel: Covers gasoline and gasoline-oxygenate blends for use in automotive spark-ignition engines including gasoline-ethanol blends containing up to 10 volume percent ethanol.
• ASTM D 5798, Specification for Fuel Ethanol (Ed75-Ed85) for Automotive Spark-Ignition Engines: Covers a fuel blend, nominally 75 to 85 volume percent denatured fuel ethanol and 25 to 15 additional volume percent hydrocarbons for use in ground vehicles with automotive spark-ignition engines.
• ASTM Research Report D02:1347 Research Report on Reformulated Spark-Ignition Engine Fuel: Provides information on the requirements of reformulated gasoline for ground vehicles equipped with the spark-ignition engines that are required by federal and state reformulated gasoline programs.
This article discusses federal and state initiatives impacting the use of ethanol and other renewables, ASTM standards applicable to ethanol fuels, and the future outlook for ethanol use.
Clean Air Standards: Oxygenated Fuels and Reformulated Gasoline
Under the Clean Air Act, oxygenates have been used as an emission control strategy to reduce carbon monoxide in winter oxygenated fuel programs, and as a required component in federal reformulated gasoline programs to help reduce ozone. The Clean Air Act Amendments of 1990 require states with areas that exceed the national ambient air quality standard for carbon monoxide to implement programs requiring the sale of oxygenated gasoline containing a minimum of 2.7 weight percent oxygen during the winter months.
The Clean Air Act also requires the use of reformulated gasoline in certain areas in order to reduce emissions of toxic and ozone-forming compounds. Section 211(k)(1) of the Clean Air Act prohibits the sale of conventional gasoline (gasoline that has not been certified as reformulated) in the nine largest metropolitan areas with the most severe summer ozone levels. Additional areas have voluntarily opted in to the reformulated gasoline program or have been required by the U.S. EPA to use reformulated gasoline.
Energy Policy Act of 2005: Renewable Fuels Standard
On Aug. 8, 2005, President Bush signed into law the Energy Policy Act of 2005. This energy legislation makes significant revisions to the federal reformulated gasoline program, including the elimination of the 2.0 weight percent oxygen requirement in reformulated gasoline, and establishes a renewable fuels standard requiring the use of renewable fuels beginning in 2006. Congress mandated the use of 4 billion gallons [15 million m3] of renewable fuels in 2006 (including ethanol and biodiesel), increasing to 7.5 billion gallons [28 million m3] by the year 2012 (see table).
EPA is required to establish rules implementing the Energy Policy Act of 2005. For the first year of the program, EPA issued a rule allowing that the 4 billion gallons [15 million m3] of renewable fuel required to be sold in 2006 could be met on a national basis, rather than requiring compliance by individual refiners. EPA is planning to issue a final rule by early spring 2007 implementing the renewable fuels standard and credit trading provisions for 2007 and later. While the Clean Air Act originally required a minimum 2.0 weight percent oxygen in reformulated gasoline, that provision was repealed under the Energy Policy Act of 2005. EPA issued a final rule eliminating the minimum oxygen content in reformulated gasoline effective April 24, 2006, for California, and May 5, 2006, for the rest of the nation.
ASTM Specification for Denatured Ethanol as a Blending Component in Gasoline
ASTM D 4806, Specification for Denatured Fuel Ethanol for Blending with Gasolines for Use as Automotive Spark-Ignition Engine Fuel, is the current ASTM standard for denatured fuel ethanol as a blending component in gasoline. The latest version of D 4806 was approved Nov. 1, 2006, and published in December 2006. This specification covers nominally anhydrous denatured fuel ethanol intended to be blended with unleaded or leaded gasolines at 1 to 10 volume percent for use as a spark-ignition automotive engine fuel. This specification is the standard specification used in commerce governing the sale of ethanol for use in gasoline.
A proposed Specification for Denatured Fuel Ethanol to be Blended with Gasoline for Use as an Automotive Spark-Ignition Engine Fuel was first issued as a joint ballot item of ASTM Committees D02 and E44 on Solar, Geothermal and Other Alternative Energy Sources in December 1984. After further development, the specification was formally approved in May 1988 as D 4806 with the same title. Over the years, in order to keep the specification current, the D 4806 standard has been updated and new requirements added as applicable. The Fuel Oxygenates Task Force under ASTM Subcommittee D02.A0 has responsibility for recommending changes to D 4806 as well as other fuel oxygenate standards.
D 4806 establishes performance requirements on ethanol content, methanol content, solvent-washed gum, water content, denaturants, inorganic chloride, copper, acidity, pHe, sulfur and sulfates. Denaturant and sulfur limits were added to harmonize the standard with the Internal Revenue Service; the Alcohol, Tobacco, Tax and Trade Bureau; and EPA requirements. The most recent property change was the addition of a maximum four ppm sulfate content limit and the addition of three test method annexes to measure sulfate content. The three test methods have been approved as standard test methods and will be balloted to replace the current annexes in D 4806. ASTM recently established an interlaboratory crosscheck quality assurance program on fuel ethanol to assess the measurement of ten denatured fuel ethanol properties.
ASTM Specification for Automotive Spark-Ignition Engine Fuel
ASTM D 4814 covers gasoline and gasoline-oxygenate blends for use in automotive spark-ignition engines, including gasoline-ethanol blends containing up to 10 volume percent ethanol. The majority of ethanol sold in the United States today is marketed as a blend of up to 10 volume percent ethanol with gasoline, as EPA regulations presently limit the maximum amount of ethanol in a gasoline blend to 10 volume percent. Gasoline containing 10 volume percent ethanol can be used in the current vehicle population without any vehicle modifications; all automobile manufacturers approve the use of ethanol blends containing up to 10 volume percent ethanol.
Under Section 211(f) of the Clean Air Act, the U.S. EPA regulates the sale of new fuels and fuel additives that may be used in gasoline. In 1978, EPA issued a gasohol waiver, permitting blends of 10 volume percent denatured anhydrous ethanol to be marketed in commerce. In 1982, under an interpretive rule, EPA extended the gasohol waiver to apply to blends of less than 10 volume percent.
Early in 1978, Subcommittee D02.A0 began to address whether ASTM D 439, Specification for Automotive Gasoline (now D 4814), appropriately covered gasohol. In May 1981, a Proposed Specification for Gasohol and Leaded Gasohol was issued. An information document on Gasohol (Motor Fuel Containing 10% Volume of Denatured Ethanol in Gasoline) was also developed to provide information on differences between hydrocarbon-only gasoline and gasohol.
Rather than establishing a standalone specification for gasohol, in 1988 ASTM adopted D 4814, which covers the requirements of automotive fuels for ground vehicles equipped with spark-ignition engines. The spark-ignition engine fuels covered are gasoline and its blends with oxygenates, including gasoline-ethanol blends. Over the years, ASTM D 4814 has been modified to respond to federal EPA regulations and technology changes.
ASTM D 4814 sets limits on the various technical properties of gasoline by season and region of the country, including volatility, copper strip corrosion, silver strip corrosion, solvent-washed gum, sulfur content, lead content, and oxidation stability; it also includes test methods to measure such limits. The most recent change related to ethanol blends was a modification of the driveability index equation to add an ethanol adjustment term, based on programs conducted by the Coordinating Research Council. Another recent change was removing the water tolerance requirement and moving the information on water tolerance to an appendix until a workable test method can be developed.
ASTM Specification for Fuel Ethanol (Ed75-Ed85)
ASTM D 5798 covers a fuel blend, nominally 75 to 85 volume percent denatured fuel ethanol and 25 to 15 additional volume percent hydrocarbons for use in ground vehicles with automotive spark-ignition engines. In mid-1993, the National Conference on Weights and Measures asked ASTM to develop a specification for E85 fuel ethanol. ASTM D 5798 was first published by ASTM in 1996. The specification was reapproved in 2004 without any modifications.
Ethanol can be used either as a blend of up to 10 percent ethanol in gasoline, or in concentrations of 85 percent ethanol and 15 percent gasoline for use in specially designed flexible fuel vehicles. EPA permits the use of E85 in vehicles certified by EPA to operate on the fuel. While current market penetration of E85 is relatively small, its use is expected to grow. At present, there are approximately 6 million flexible fuel vehicles on the road capable of using E85. U.S. automakers General Motors, Ford, and DaimlerChrysler have announced their intention to make 50 percent of their new vehicles flexible fuel-capable by 2015.
In response to federal and state initiatives to encourage the use of renewable energy, an E85 Task Force was formed in 2006 by ASTM Subcommittee D02.A0 to update and recommend changes to the specification as necessary. The first concern being addressed is the analytical procedures for determining properties. Subcommittee D02.A0 has asked several property subcommittees to develop new test methods or to modify existing test methods to cover E85 in their scopes and to provide test precision for E85 fuel ethanol. In addition, the CRC was asked to conduct a cold-start and warm-up driveability test program to assess the importance of vapor pressure and gasoline content. The results of this program will be used as technical support for any changes in volatility property limits for E85.
ASTM Research Report on Reformulated Gasoline
Subcommittee D02.A0’s Task Force on Reformulated Gasoline has produced Research Report D02: 1347 Research Report on Reformulated Spark-Ignition Engine Fuel, which provides information on the requirements of reformulated gasoline for ground vehicles equipped with spark-ignition engines required by federal and state reformulated gasoline programs. This document includes information on the federal reformulated gasoline program; the Energy Policy Act of 2005 provisions dealing with reformulated gasoline and the renewable fuels standard; state reformulated gasoline programs; and EPA, California Air Resources Board, and ASTM test methods for reformulated gasoline. This report is continually updated to include new developments affecting reformulated gasoline at both the federal and state levels. It is available on the ASTM D02 Web site free of charge.
State Adoption of ASTM Standards
ASTM specifications are consensus standards that have been adopted by the federal government and states as minimum quality standards. Specification D 4814 (or D 439) is referenced by the federal government in the substantially similar rule and in a number of oxygenate waivers. According to a survey conducted by Herman & Associates, 35 states and two counties have adopted Specification D 4814 as the standard specification for automotive spark-ignition engine fuel. Nine states have adopted their own fuel specifications, some of which are based on ASTM D 4814. Pipeline companies have also adopted specification D 4814, which results in most states receiving Specification D 4814 product even though not required by state law.
While specification D 4814 is designed to cover ethanol blends, the U.S. Environmental Protection Agency allows gasoline-ethanol blends containing 9 to 10 volume percent ethanol to have a 1.0 psi [6.89 kPa] higher vapor pressure than the summer maximum vapor pressure limit for conventional gasoline. In addition, certain states and local jurisdictions that have established more stringent vapor pressure standards than EPA for a particular ozone nonattainment area may also allow a 1.0 psi [6.89 kPa] higher vapor pressure for gasoline-ethanol blends during the summer vapor pressure period.
At the present time, over 30 states provide a volatility waiver from ASTM specifications for ethanol blended fuels. Most of these states allow ethanol blends to have a 1.0 psi [6.89 kPa] higher vapor pressure than that established for gasoline, but some states also waive distillation limits and vapor-liquid ratio limits as well. Twenty-two states have adopted Specification D 4806 as a minimum quality standard for denatured fuel ethanol and 18 states have adopted specification D 5798 as a minimum quality standard for E85 fuel ethanol. During the next year, many states are likely to revise their existing fuel specifications to include new standards for alternative fuels.
Future Outlook for Ethanol Fuel
Current and projected U.S. ethanol production capacity and use are far outpacing the levels required under the Energy Policy Act of 2005. According to the Energy Information Administration, in 2006 the United States produced 5.3 billion gallons [20 million m3] of ethanol. By the end of 2009, the ethanol industry expects an additional 6 billion gallons [23 million m3] of production capacity to be in operation.
In the future, it is likely that Congress and states will enact additional legislation to accelerate and/or expand the existing renewable fuels standard. The president has announced a goal of 35 billion gallons [132 million m3] of renewable and alternative fuels by 2017. In addition, many members of Congress have introduced legislation setting aggressive targets for an increased renewable fuels standard and for reducing U.S. reliance on imported oil. Certain states and jurisdictions have mandated the use of ethanol and other renewable fuels. In light of national security concerns, the federal government and states will continue to take action to increase the use of renewable energy.
The commercialization of cellulosic ethanol will be a critical factor in enabling increased production and utilization of ethanol fuels. The majority of ethanol produced in the U.S. today is almost exclusively derived from corn. The National Corn Growers Association projects that approximately 15 billion gallons [57 million m3] of ethanol can be produced from corn without significantly disrupting other corn markets. The production of ethanol from cellulosic feedstocks such as switch grass, wood chips, and agricultural waste will be necessary to expand ethanol supplies. Many companies are working to commercialize cellulosic ethanol production. The U.S. Department of Energy recently announced the selection of six cellulosic ethanol plants for federal funding to help contribute to the president’s goal of reducing U.S. gasoline consumption by 20 percent in 10 years.
ASTM Subcommittee D02.A0 will continue to address new issues as they emerge and update ASTM ethanol fuel standards as necessary to facilitate the increased use of ethanol and other renewable fuels. //