Krajcar Bronić, Ines; Barešić, Jadranka; Horvatinčić, Nada
Application of 14C method for biogenic component determination in waste and liquid fuels.
In: ESIR Isotope Workshop XIII (20 September 2015 - 24 September 2015) Zadar, Hrvatska.
Increase of CO2 concentration in the atmosphere during 20th century is a consequence of intensive use of fossil fuels. The increase of CO2 concentration can be slowed down by the use of biogenic materials for energy production and/or transport. One of the method for determination of the fraction of the biogenic component in any type of fuel or waste is the 14C method, which is based on different content of 14C in biogenic (reflects the modern atmospheric 14C activity) and in fossil component (no 14C present). The method can be applied to various types of fuels used in waste-to-energy plants (such as solid communal waste, used car tyres), to liquid fuels, even to the CO2 produced by combustion of various fuels. Any measuring technique used in 14C dating laboratories could be used. Here we present comparison of characteristics (precision, complexity, price) of various techniques (sample preparation and measurement) for biogenic fraction determination by the 14C method. A case of liquid fuels will be specially discussed. According to the EU Directive 2009/28/EC all (liquid) fuels have to contain at least 10 % of bio-fuel, i.e., blend of biogenic origin, by 2020. A technique of direct measurement in liquid scintillation counters of the 14C content in liquid fuel is simple and fast but has a main disadvantage: different liquid colours cause different quenching and thus changes in the measurement efficiency. We propose a new data evaluation technique that uses liquids of different colours to construct calibration curves for modern and background samples . The technique depends neither on the fossil matrix or the biogenic additive type. Lowest detectable biogenic fraction is 0.5 %.  Krajcar Bronić I, Barešić J, Horvatinčić N, Krištof R, Kožar-Logar J. In: Proc. 10th symposium of the Croatian Radiation Protection Association, Šibenik, 15 – 17 April 2015. CRPA, Zagreb, 2015. p. 360-365.
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