This week the International Renewable Energy Agency (IRENA) released a brief this week on biojet, noting that developing and promoting it will be essential to reduce carbon emissions from commercial aviation but wider adoption is constrained right now by cost. The aviation sector is one of the largest emitters of GHGs in the world, at 2% of the human-induced total. IRENA says that if the sector were a country, aviation would rank number 8 in GHG emitters. The sector’s transition to sustainable, renewable fuels, IRENA says, is crucial to meet the international climate targets set forth in the 2015 Paris Agreement. The following figure shows GHG emissions and reduction targets set by industry, including where biojet fits in.
Some highlights and findings in the brief include the following:
- Biojet fuels can potentially reduce GHG emissions compared to fossil-based jet fuel, according to a well-to-wheel life-cycle analysis (and shown in the figure above). However, the emissions-reduction potential of different feedstocks may differ significantly, with values ranging from 50% to 95% of the claimed potential reduction when compared with fossil jet fuel.
- Achieving the GHG emissions reduction targets proposed by the aviation industry and organizations such as the International Civil Aviation Organisation (ICAO) will require a significant increase in biojet production and consumption. The exact volumes required to achieve specific goals are not clear because of factors such as the aviation sector’s future fuel consumption, the extent of emissions reductions achieved through offsets, and the specific emissions-reduction potential of various options for making biojet fuels, which are called pathways…Fuel consumption for international aviation could be as high as 852 million tonnes (Mt) by 2050, and could require 426 Mt of biojet to meet the GHG emissions-reduction goals. Current production, however, is currently very limited, at less than 0.1% of global total consumption of all types of jet fuels, according to IRENA.
- One of the main reasons such small amounts of biojet are currently used is the high cost of production. This is a major challenge, IRENA says, because fuel accounts for about 30% of the total expense of operating an airline. Hydroprocessed Esters and Fatty Acids (HEFA) biojet has historically cost more than fossil-derived jet fuels, and potential feedstocks for HEFA-biojet alone often cost more than traditional jet fuel, with the cost of converting them into HEFA-biojet adding to the price gap from there. In January 2016, for example, the cost of palm oil was USD 0.45/L, while the price of jet fuel was USD 0.25/L. Pricing for advanced biojet fuels based on lignocellulosic feedstocks is less clear as these technologies are still in the demonstration phase and not yet commercially available. Even when oil prices were considerably higher than their current level of about USD50 per barrel (USD 0.36/L), biojet is significantly more expensive: generally in a range from two to seven times more than fossil derived jet fuel, according to IRENA. The table below shows a summary of technologies, status and estimated capital costs by conversion process.
- Alternative feedstocks that are considered more sustainable will likely suffer from a lack of availability, preventing significant production increases. They include used cooking oil (UCO), tallow, tall oil, and non-edible crops such as camelina. Some time would also be needed to develop and optimize yields and new supply chains for crop feedstocks. As well, the potential is finite to increase the supply of other oleochemical feedstocks, such as those just mentioned or from residues from palm-oil processing and other industries. Another challenge is that any of these options will put bio-jet in direct competition with the current biodiesel industry, where there is more demand and more-developed supply chains. This suggests that there won’t be enough biojet to achieve GHG-reduction goals unless at least one of the lignocellulose-to-biojet pathways, such as SIP or ATJ, are commercialized.
- Without specific interventions and incentives directed towards biojet production and use, current policies in jurisdictions such as the U.S. will favor the production of renewable diesel over biojet.