Research School for Socio-Economic and
Natural Sciences of the Environment
Research School for Socio-Economic and
Natural Sciences of the Environment

Flying on biofuel for just a few extra euros

Sierk de JongThe aviation sector accounts for 1.5% of global greenhouse gas emissions. By 2050, emissions produced by the sector are expected to increase by three to six times. In his doctoral thesis, SENSE PhD candidate Sierk de Jong (UU) argues that we can limit a large part of this growth by using biojet fuels, if we produce the fuel sustainably, develop new production technologies and introduce adequate policy incentives. De Jong also makes recommendations for policymakers and the aviation sector. De Jong defended his doctoral thesis in the University Hall of Utrecht University on 15 June 2018.

Air traffic is responsible for 1.5% of the worldwide greenhouse gas emissions. In order to limit global warming to two degrees, as agreed upon in the Paris Agreement, emissions will need to be 40% to 70% lower in 2050 than in 2010. In the same period however, emissions from the aviation sector are expected to increase by three to six times. While the use of biojet fuel remains the best technological alternative to help structurally reduce the emissions of the aviation sector, they are currently sparsely used.

Cost reductions

PhD candidate Sierk de Jong quantified the future production of biojet fuels and calculated the corresponding emission reductions, focusing primarily on production costs and environmental impact. “At the moment, it costs two to three times more to produce biojet fuels than it does to produce fossil jet fuel. However, by gaining more experience, using new production technologies and optimising the production chains, we can cut the cost of biojet fuels by nearly half in the coming decade,” he explains. “By taking this approach we can increase the use of biojet fuels in Europe to 4 to 6* million tonnes by 2030 for just a few extra euros per passenger – sufficient to neutralise almost three-quarters of the forecast growth in emissions in the sector.”

Focus on environmental gains

In his doctoral thesis, De Jong lists several pre-conditions to facilitate the sustainable growth of biojet fuel consumption. Firstly, it is important that the focus is solely on biofuels that offer environmental gains, such as those produced from forestry residues, straw or – as is already the case – used cooking oil. De Jong: “Our results show that in many cases, biojet fuel can reduce emissions of greenhouse gases by at least 70% compared to fossil jet fuel.” Secondly, support for the development of new production technologies is essential to increase production and lower costs.

Incentives and commitment are essential

Policy incentives are vital to increase biojet fuel consumption in the aviation sector. De Jong: “The issue demands immediate action and a long-term vision, as it takes time to build up this industry. The relevant authorities also need to continue ensuring that biofuels are produced according to robust sustainability criteria.”

In light of the limited options open to the aviation sector to structurally reduce its CO2 emissions, De Jong recommends that more airlines and airports commit itself to biojet fuels. “It is also essential that the environmental benefits of biojet fuel are clearly communicated to increase public support. This support is important, mainly because a contribution of just a few euros per plane ticket can avoid a large part of the emission growth.”

* Was 12 to 19, but these numbers appeared to be incorrect. However, 'almost three-quarters of the forecast growth in emissions' is still correct.

Source: website Utrecht University (

Tuesday 19 June 2018