Effect of the addition of new biofuels on the aging of conventional fuels – BioACE
The lifespan of usual fuels is limited in time because they are transformed in contact with air (oxidation). New-generation biofuels have a shorter lifespan than these fuels, which is a barrier to their use, especially in air transport.
Experimental measurements and simulations of the impact of the addition of biofuels on the aging of conventional fuels.
Oil combustion currently accounts for the largest share of the European energy mix and EU Reference Scenario projections show that this will still be the case in 2050. This is explained by the energy consumption of certain sectors such as aviation or road freight, which rely on combustion engines that are very difficult, if not impossible, to replace with electric power. Of course, the use of fossil fuels in these engines is a major source of greenhouse gases. This is why the EU encourages the use of sustainable fuels produced from biomass (biofuels) which can be, in principle, carbon neutral, locally produced and operational in today’s engines. The potential biofuels that can be produced from different sources of biomass are numerous and the consequences of their addition on the aging (= oxidation of the liquid) of the usual fuels are often negative and remain unpredictable. This project aimed to study and understand the effect of adding different biofuels to a conventional fuel on its aging.
Experimental measurement of aging and detailed simulation of the phenomenon.
Experimental and modeling tools were used to understand the aging chemistry of (bio)fuel blends. The aging experiments were carried out in a heated autoclave to accelerate the aging phenomenon. To simulate the measured aging, models have been developed. These models contain thousands of reactions that describe the chemistry of aging at the molecular level. They will make it possible to simulate autoclave data and to understand the chemistry of aging. This represents a considerable challenge because no model for the aging of such mixtures is available in the literature. Indeed, this modeling has remained an unattainable goal for a long time in the literature: for each of the thousands of reactions and species that make up the model, data must be provided to calculate the rates and equilibria of the reactions that constitute the chemistry of aging. However, there are very few data in the literature and the values of these thousands of model data changes for each (bio)fuels and their mixtures! Tools based on theoretical chemistry and equations of state have been developed to meet this challenge.
Major results of the project
Biofuels of different families (different chemical structures) have been studied: alcohol, ketone and ether. We have shown that alcohol-type biofuels increase the resistance to aging of a typical fuel, unlike the other families which decrease this resistance. Tools based on equations of state and theoretical chemistry have made it possible to propose the only method in the literature for the high-frequency and precise calculation of thousands of data on the rate and equilibrium of chemical aging reactions. This approach has made it possible to simulate and understand the aging of biofuel/usual fuel mixtures at the molecular level.
Perspectives
The project has enabled the development of modeling tools capable of predicting the impact of different biofuels on the resistance of common fuels. The prospects for computer-aided development of antioxidants, capable of slowing down the aging process of biofuels, is one of the promising prospects of this work to promote the use of biofuels, particularly in the aviation sector. This project has also made it possible to initiate a European project These results have made it possible to build the European project ERC Consolidator Grant BioSCOPE which will examine the effect of the aging of (bio)fuels on the efficiency of engines and the pollutants emitted at the engine output . This potential source of additional pollutants remains totally unexplored in the literature.