A close look at what carbon-14 analysis reveals for biofuel blends

October 29, 2018 |

By Haley Gershon, Beta Analytic
Special to The Digest

Biofuels maintain an important role in the fuel industry as environmental and human health concerns ignite the transition from using fossil fuels to more eco-friendly options. Alongside environmental benefits, biofuels also offer an opportunity for manufacturers to qualify for tax credits and other financial incentives. This article highlights how in order to receive reliable data to demonstrate biogenic carbon content of biofuels, third-party verification through carbon-14 testing under ASTM D6866 is necessary. Results from carbon-14 analysis are then able to provide proof that biofuel manufacturers are meeting biogenic content thresholds required under program standards and regulations.

Biofuels: a zero carbon footprint alternative to fossil fuels

Biofuels in liquid form are transportation fuels processed from biomass sources such as plant or animal fats.1Biofuels release carbon-neutral carbon dioxide when combusted since plants absorb carbon dioxide through the process of photosynthesis, removing the carbon from the atmosphere, and then once the biofuel is burned, the carbon is released back into the atmosphere. Therefore, burning of biofuels overall has no effect on the net level of carbon dioxide in the atmosphere and are often viewed as advantageous alternatives to petrochemical-derived fuels which contribute to the increase of carbon dioxide levels.2

As support for environmental-friendly fuel flourishes, the global biofuels market is expected to undergo rapid growth from USD 100.76 billion in 2016, forecasted to reach USD 132.67 billion in 2023.3Continuous growth of the biofuel industry has triggered the development of several different types of renewable transportation fuels such as bio-ethanol and biodiesel. With growing popularity and manufacture of biofuels, third-party verification is a necessary step to ensure accurate labeling and sale of blends. Laboratory analysis through the ASTM D6866 test method is widely used.

ASTM D6866 to distinguish between biogenic & synthetic fuel origin

Carbon-14 testing, which is standardized by ASTM D6866, is capable of analyzing multiple types of biofuel blends to determine the biogenic carbon content of fuel. Since biofuels are mostly processed from photosynthetic plants containing the radioactive isotope carbon-14, the analysis can accurately distinguish between biogenic and fossil fraction of fuels.4Carbon-14 testing can prove a certain percentage of biogenic or renewable carbon content within a blend.

Carbon-14 analysis is frequently used to identify the origin of ethanol, which is produced from either renewable sources, known as bio-ethanol, or from petrochemical origin, termed synthetic ethanol. Although bio-ethanol and synthetic ethanol are the same compound, C2H5OH, and are chemically indistinguishable, the isotopic composition of carbon atoms comprising bio-ethanol differs from the isotopic composition of synthetic ethanol.5Therefore, by measuring the relative amount of carbon-14 in an ethanol sample, ASTM D6866 verifies the origin of the ethanol sample, since bio-ethanol contains carbon-14 whereas petroleum-derived ethanol does not contain the radioactive isotope.

In addition, carbon-14 analysis can distinguish the amount of bio-ethanol present in blends that are mixtures of renewable and petroleum-derived material. E85 ethanol is a popular blend that is often comprised of 85 percent bio-ethanol and 15 percent synthetic-derived fuel.6Laboratories, such as ISO-17025 accredited Beta Analytic, act as a third-party verification to analyze the accuracy of biofuel blends in which the biogenic carbon content of biofuels is reported as a percentage that ranges between 0% and 100% biobased. In the case of the E85 ethanol blend exemplified above, carbon-14 analysis results yield 85% biobased.

Biofuel blends are increasingly used by manufacturers in order to qualify for financial incentives and to meet necessary regulation standards. Carbon-14 analysis is extremely vital as tax credits received for biofuel gasoline blends may tempt unscrupulous manufacturers or distributors to fraudly represent petroleum-derived fuel as renewable fuels. Data from carbon-14 analysis therefore enables manufacturers to obtain proof that their biofuels contain a certain amount of biogenic content.

Biofuel regulations and how to receive financial incentives

Worldwide, many initiatives encourage the use of biofuels as a substitute to fossil fuels. The United States Environmental Protection Agency (EPA) Renewable Fuel Standard (RFS), which aims to reduce greenhouse gas emissions, requires the use of carbon-14 analysis for biofuel producers to determine the biogenic fraction of renewable transportation fuel.7For fuels produced or imported in the U.S., the EPA sets a minimum national volume requirement of renewable fuels blended into transportation fuels on an annual basis. For example, the 2018 final volume requirements include 288 million gallons for cellulosic biofuel, 2.1 billion gallons for biomass-based diesel, 4.29 billion gallons for advanced biofuel, and 19.29 billion gallons for renewable biofuel.In order for individual parties to comply with the program, the national volume requirements are converted into individual targets for producers.

The EPA tracks compliance of the RFS program requirements through the Renewable Identification Number (RIN) system, assigning a specific RIN to each gallon of renewable fuel.9The individual volume obligations for fuel producers determine the amount of RINs of each type of renewable fuel that must be obtained by the producer to comply with the requirements. Biofuel producers who use separated municipal solid waste as feedstock are able to generate RINs for their products.10This acts as a financial incentive for manufacturers since biofuel producers generating RINs can use them as credits for compliance, allowing them to avoid purchasing RINS to meet the requirements.


On a global level, preference of environmental-friendly fuel fosters the growth of the biofuels market. In order to ensure accuracy of biofuel blends as development within the industry advances, carbon-14 testing is a popular method for measuring the biogenic content. Carbon-14 analysis allows biofuel producers to demonstrate compliance of program requirements such as the U.S. EPA Renewable Fuel Standard, and further aids biofuel producers to steer clear of financial penalties applied if failing to meet program requirements.


1 Biofuel.Org.UK. Biofuels: What are they? [Internet]. United Kingdom: Biofuel.Org.UK. [date unknown]. [cited 2018 Sept 26].

2 Carbon Neutral Earth, Inc. Biofuels – A Way To Reduce Your Carbon Footprint. [Internet]. [place unknown]. Carbon Neutral Earth, Inc. [date unknown]. [cited 2018 Sept 26].

3 Statista. Biofuels market size worldwide in 2016 and 2023 (in billion U.S. dollars). [Internet]. New York: Statista. 2017 Dec. [cited 2018 Sept 26].

4Beta Analytic. Measuring Biobased Carbon Content of Fuels through ASTM D6866. [Internet]. Miami: Beta Analytic. [date unknown]. [cited 2018 Sept 26].

5Beta Analytic. Distinguishing Between Bio-ethanol and Petroleum Ethanol. [Internet]. Miami: Beta Analytic. [date unknown]. [cited 2018 Sept 26].

6 U.S. Energy Information Administration. Biofuels: Ethanol & Biodiesel. [Internet]. Washington, D.C: U.S. Energy Information Administration. 2018 Aug. [cited 2018 Sept 26].

7 United States Environmental Protection Agency. Overview for Renewable Fuel Standard. [Internet]. Washington, DC: United States Environmental Protection Agency. 2017 June. [cited 2018 Sept 26].

8  United States Environmental Protection Agency. Proposed Volume Standards for 2019, and the Biomass-Based Diesel Volume for 2020. [Internet]. Washington, DC: United States Environmental Protection Agency. 2018 July. [cited 2018 Sept 26].

9 Alternative Fuels Data Center: Renewable Fuel Standard. [Internet]. [place unknown]. Alternative Fuels Data Center. 2018 March. [cited 2018 Sept 26].

10 United States Environmental Protection Agency. Renewable Identification Numbers (RINs) under the Renewable Fuel Standard Program. [Internet]. Washington, DC: United States Environmental Protection Agency. 2017 March. [cited 2018 Sept 26].

About the Author. Haley Gershon is a Marketing Specialist with Beta Analytic, more about the company here.





Print Friendly, PDF & Email

Category: Thought Leadership

Thank you for visting the Digest.