Orange peel as biofuel

The team from the Polytechnic University of Madrid and Castilla-La Mancha indicates in a study that orange peel as a biofuel emits 55% less soot, which would mean “a promising step forward in reducing emissions in both aviation and the automotive sector”.

Currently, there is a worrying need to look for sustainable alternatives to replace fossil fuels, especially in the transport sector, whose dependence on these non-renewable fuels exceeds 97% in the European Union.

A team of researchers from the Polytechnic University of Madrid (UPM) and the University of Castilla-La Mancha (UCLM) used waste from the fruit industry to extract orange oil and analyze its potential as fuel for bioreactors.

The results were published in Renewable energyand demonstrate that said oil is a viable alternative to be mixed up to 15% with aviation kerosene, without any significant inconvenience to its performance, and meeting all the requirements of aeronautical standards.

The biofuel has been treated to reduce its tendency to form soot, so that its use would contribute to reducing polluting emissions from current fuels.

An industry with a lot of waste

The fruit industry, and specifically the orange juice industry, generates a large amount of by-products and waste, reaching 30 million tons annually, which must be properly managed to avoid serious economic and environmental problems.

These residues have a high terpene content, whose transformation makes it possible to obtain suitable biofuels to be mixed with conventional fuels, both in aviation and in the automotive industry. Among these residues, orange peels contain orange oil, which can be extracted by pressing or using solvents.

Orange oil, mainly composed of D-limonene, could be used as a biofuel in aviation and automotive due to its excellent density and calorific value (together they indicate the amount of energy stored in the vehicle’s tank) and cold flow properties. (that is, the behavior of biofuel at low temperatures).

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However, the high tendency of orange oil to form soot during its combustion makes it necessary to transform it through the chemical process of hydrogenation. “The main advantage of this process is that complete hydrogenation of the fuel makes it possible to reduce soot emissions by 55%, as we verified in our study.”, points out David Donoso, a researcher at the Industrial Engineering ETShe from UCLM.

new market

The introduction of orange oil (and other terpenes derived from citrus fruits) into a new market, such as transport fuels, is of particular interest.”, says David Bolonio, researcher at the ETSI for Mines and Energy from UPM, another member of the team that carried out the study.

Orange oil derived from the juice industry could replace 0.1% or 0.02% of kerosene and diesel consumed in Spain in 2019, respectively. Clearly, the incorporation of orange oil into the biofuels market would not be enough to meet the targets for reducing polluting emissions to mitigate the effects of climate change, but it would help. “In the future energy scenario, multiple sources of biofuels will have to be used to replace fossil fuels.”, conclude the researchers.


Donoso, D. et al. “Hydrogenated orange oil: a waste-derived drop-in biojet fuel”. Renewable energy (2022)


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