Carbon-14 Analysis of Waste-Derived Fuels and CO2 Emissions

  • UK gas and electricity market regulator OFGEM approves the use of the Carbon-14 method to measure renewable energy content of flue gases generated by combusting waste-derived fuels
  • Facilities can use the Carbon-14 technique to apply for Renewable Obligation Certificates (ROCs)
  • By providing high-quality Carbon-14 analysis, Beta Analytic helps waste-to-energy companies obtain incentives under the Renewables Obligation

Carbon-14 Analysis of Post-Combustion Flue Gases

renewable carbon analysis
According to the UK Office of of Gas and Electricity Markets (OFGEM), Carbon-14 analysis can be used to accurately determine the renewable energy content of gases from the combustion of waste-derived fuels. This conclusion is based on independent reports commissioned by OFGEM and the Renewable Energy Association (REA).

OFGEM commissioned an independent report to review the science behind the carbon-14 technique and to check the accuracy of the method compared to the sampling procedures currently used by Renewable Obligation Certificates (ROCs) accredited electricity generators. The report commissioned by REA supports the conclusions of the OFGEM-commissioned report.

OFGEM will consider, on a case by case basis, the fuel measurement and sampling procedures using carbon-14 analysis to determine the renewable carbon analysis of fuels. OFGEM clarifies that ROCs accredited generators are not required to use the carbon-14 analysis and will continue to consider proposals using the existing methods used by industry.

Carbon-14 analysis involves measuring the ratio between carbon-12 / carbon-13 and carbon-14 isotopes in flue gases. Materials from biomass contain carbon-14. Fossil materials only have carbon-12 and carbon 13 in them. Thus the carbon-14 measured from the gases is easily correlated to the biomass portion of the waste feedstock. The data is used in calculating renewable energy content.

See OFGEM Announcement Here

Determination of Biomass Energy Content of Waste-Derived Fuels

The REA recommends the carbon 14 analysis described in a 2007 study by Fichtner Consulting Engineers UK. The described method addresses the difficulties encountered when analyzing the biomass fractions of heterogeneous fuels.

Under the UK Renewables Obligation, electricity generated from mixed wastes and from biomass qualifies for certain incentives; energy-from-waste plant operators are required to determine the fraction of the energy content of the fuel that is derived from biomass.

Most of the methods for determination of the biomass content of fuels are suitable for homogenous fuels but can be very difficult and costly for plants using heterogeneous fuels like refuse-derived fuels and solid recovered fuels. The Fichtner study proposed an alternative method wherein carbon 14 analysis is done on the mixed fuel’s combustion gases and not on the solid fuel.

The following are pertinent excerpts obtained from the report regarding carbon 14 dating and its accuracy and precision when compared to other methods such as selective dissolution and manual sorting:

“The study shows that the C14 method can be used to determine the biocarbon percentage in a solid sample by analyzing the combustion gases from that sample and that the accuracy is reasonable” – Pg.4 ln.9-11

“It is possible to combine the calculations with the C14 measurement of the biomass carbon percentage in the fuel to determine the biomass energy in the mixed fuel.” – Pg.8 ln.9-10

“For waste fuels derived from mixed wastes, this method (carbon 14 dating) is likely to be more accurate than the alternatives including: a) solid fuel sampling for analysis by selective dissolution; b) solid fuel sampling for manual sorting; c) solid fuel sampling followed by C14 analysis.” – Pg.2 ln.14-16

“From the above assessment, it is clear that the proposed method of flue gas sampling for C14 analysis is likely to be the most accurate method compared to the available solid fuel sampling alternatives for fuels derived from mixed wastes.” – Pg.13 ln.29-31

The study entitled “C14 Determination of Biomass Energy Content of Fuels” incorporated carbon 14 results from a Columbia University report.

About OFGEM

OFGEM regulates the UK’s gas and electricity industries. One of its role is the administration of the ROCs program, under which green certificates are issued to accredited generators for eligible renewable electricity generated within the UK and supplied to customers within the country by a licensed electricity supplier. In general, one ROC is issued for each megawatt hour (MWh) of eligible renewable output generated.

About REA

London-based Renewable Energy Association was established in 2001 to represent renewable energy producers in the UK and promote the use of sustainable energy in the country. Called the Renewable Power Association until October 2005, the REA represents a wide variety of organizations that include generators, project developers, fuel and power suppliers, equipment producers, and service providers.

Beta Analytic in the UK

Beta Analytic, Inc., is an ISO/IEC 17025:2005-accredited radiocarbon dating lab based in Miami, Florida. The company has an office in London, UK, to provide clients a more convenient and cheaper option than shipping samples directly to the US. Beta Analytic is a world leader in Carbon-14 analysis and its industrial applications ASTM D6866 and Testing for Solid Recovered Fuels.