Understanding Biofuel Standards

By Angela Fivga and Zsuzsa A. Mayer (Lee Enterprises Consulting, Inc./Biofuels Digest) The analysis and standardization of biofuels are in constant development, therefore in many studies they follow a historic view or borrow unsuitable methods from fossil fuel analysis. An overview of the current standards helps to achieve better results.

Due to historic reasons the most common way of grouping biofuels is based on the feedstock (food crops, agriculture waste, algae etc.), generations (1^st generation, 2^ndgeneration etc.) or technology (chemical, thermochemical or biological). However, there are strong arguments for grouping biofuels in categories like oils (e.g. biodiesel consisting methyl esters) or alcohols (e.g. bio-ethanol consisting ethyl alcohol), as the chemical composition of the fuel limits or determines the applications rather than the three above mentioned categories.

Biofuels are also challenging in analysis and standardization. When compared to fossil fuels (mixture of hydrocarbons, relatively easy to analyze or predict their characteristics), they have significantly different chemical composition. This means different physical and fuel properties.

Hydrocarbon fuels also have a very extensive system of industrial standards and testing laboratories, while biofuel tests are constantly adapting to the development of the latest technologies.

There are a large number of synonyms and trade names in use for the same chemical compounds. For example, ethanol is known by many names: ethane monoxide, ethyl hydrate, ethylol, methylcarbinol etc. Regulatory bodies and industry need to standardize and prefer to use an internationally recognized and unique numeric identifier called CAS Registry Number. The CAS number of bioethanol is the same as for ethanol (64-17-5); for Biodiesel 100 it is the same as for methyl esters of C₁₄-C₂₄ fatty acid (67784-80-9). CAS Registry also integrates chemical and substance information from patent and non-patent sources under the supervision of the American Chemical Society.

The EU is responsible for issuing mandatory environmental directives, concerning fuel quality, and the European Standards Organization (CEN) is responsible for developing industrial standards to comply with those directives. The CEN’s mission is “to promote voluntary technical harmonization in Europe in conjunction with worldwide bodies and its European partners”.^[1]

CEN developed two standards for automotive fuel quality in 1993, the EN 590 for diesel and the EN 228 for gasoline (petrol). Although the application of those standards was voluntary, they were widely adopted by all fuel suppliers in Europe. The first mandatory environmental regulations concerning fuel quality were introduced by the EU in 1998 (Directive 98/70/EC), which were revised in 2003 (Directive 2003/17/EC) and again in 2009 (Directive 2009/30/EC). To comply with these directives, the fuel properties in the CEN standards were updated. These changes included the lead and sulphur content for gasoline, cetane number, sulphur content, and FAME (Fatty Acid Methyl Esters) biodiesel content for diesel. The 2009 directive also developed sustainability criteria for biofuels to ensure that they fulfil their greenhouse gas intensity reduction obligation.

The first American standard for biodiesel, was developed by the American Society for Testing & Materials (ASTM), for biodiesel (B100) blend stock, for distillate fuels (ASTM D6751). The standard was adopted in 2002, and covers the use of biodiesel (B100) as a blending component with petroleum diesel fuels. Unlike the EU standards which allow the use of both neat biodiesel, and biodiesel as a blending component, this standard was not applicable to neat biodiesel when used as an automotive fuel. The USA standard for petroleum diesel was then updated to include blends of up to 5% biodiesel, in 2008.^[4] This standard was then updated in 2012 to define two grades of biodiesel; grade 2-B (identical to biodiesel defined by earlier versions of the standard); and grade 1-B with tighter controls on monoglycerides and cold soak filterability.

In 2008, the ASTM published a new Biodiesel Blend Specification, the ASTM D7467. This standard covers fuel blends from 6% to 20% biodiesel with the remainder being a light middle or middle distillate diesel fuel, respectively designated as B6 to B20. The biodiesel and petroleum diesel used in these blends need to comply with the ASTM D6751 and ASTM D975 standards, respectively.

Biodiesel standards in the USA allow the use of both fatty acid methyl esters (FAME) and fatty acid ethyl esters (FAEE), in contract with the EU which only allows the use of FAME.

The United States Environmental Protection Agency (EPA)^[5] is responsible for regulating fuel quality as it relates to emissions, under the authority of the Clean Air Act Amendments of 1990. The environmental goals set by the Act, led to the development of two bioethanol standards, by ASTM, the ASTM D 4806 and the ASTM D 5798.

The first standard for bioethanol was a denatured fuel ethanol specification.^[6]

The second standard, released in 1999 was developed to allow for an ethanol blend to be used in specially designated vehicles as a gasoline substitute.^[7] This standard allowed the blend of 75 to 85 volume % denatured fuel ethanol and 25 to 15 additional volume % hydrocarbons for use in ground vehicles with automotive spark-ignition engines.

Due to its later adoption as a transport fuel in Europe, the first standard for bioethanol arrived in 2007.^[8] This first standard was a bioethanol specification to allow blending with gasoline. The EN 228, European standard for gasoline specification, was updated to allow blends up to 5% bioethanol, in 2008. This is now aligned with the 2009 directive (2009/30/EC), allowing up to 10% bioethanol in gasoline.

CEN/TC 19/WG 41 is currently developing standards for fast pyrolysis oils, in response to EC mandate M/525 (2013), since there is currently no standardization in the EU. These will include specifications for using pyrolysis oils as heavy fuel oil, light fuel oil, and for use of bio-oils in stationary combustion engines. In contrast, the USA has developed the ASTM D7544, which covers the specification of pyrolysis liquid produced from biomass, for use in various types of fuel-burning equipment. READ MORE