A team of researchers from the Polytechnic University of Madrid (UPM) and the University of Castilla-La Mancha (UCLM) has used residues from the fruit industry to extract orange oil and analyzed its potential as a fuel for bioreactors. “The results obtained demonstrate that said oil is a viable alternative to be mixed by up to 15% with jet fuel, without any significant inconvenience to its performance, and complying with all the requirements of the aviation standards. This biofuel has been treated to reduce its tendency to form soot, so its use would help reduce pollutant emissions from current fuels,” the UPM stated.
“The fruit industry and, in particular, the orange juice industry generates up to 30 million tons of by-products and waste a year, which need to be managed to avoid serious economic and environmental problems. This waste has a high content of terpenes, which can be transformed to obtain biofuels suitable to be mixed with conventional fuels, both for aviation and cars. Among these residues, orange peels contain orange oil, which can be extracted by pressing or by using solvents.”
Orange oil, mainly made up of D-limonene, could be used as a biofuel for aviation and cars thanks to its excellent density, calorific value (together, they indicate the amount of energy stored in the vehicle's tank), and cold flow properties (that is, the behavior of the biofuel at low temperatures), the UPM added. However, the high soot-formation tendency of orange oil during its combustion makes it necessary to transform it through the chemical process of hydrogenation.
“The main advantage of this process is that the complete hydrogenation of the fuel allows reducing its soot emission by 55%, as we have verified in our study,” stated David Donoso, researcher at the Std of Industrial Engineering of the University of Castilla-La Mancha.
“Orange oil derived from the juice industry could replace 0.1% or 0.02% of the kerosene and diesel consumed in Spain in 2019, respectively. Clearly, the incorporation of orange oil into the biofuel market would not be enough to meet the objectives of reducing polluting emissions to mitigate the effects of climate change, but it would help.