Published on April 11th, 2017 | by James Ayre0
Use Of Alternative Jet Fuels Won’t Allow For Significant Emissions Reductions, Study Finds
April 11th, 2017 by James Ayre
The use of so-called alternative jet fuels — made from vegetative or waste feedstock — won’t allow for a significant reduction of the aviation sector’s carbon dioxide emissions, according to a new study on the matter.
The problems? Other than costs, the issues are: 1) when land use change effects are factored in, vegetable oil–based feedstocks usually have a higher carbon intensity than conventional jet fuel does, and 2) with regard to agricultural waste feedstocks, the supply simply isn’t there (and won’t be there) to offset significant amounts of conventional jet fuel use.
The study was performed with the intent of evaluating the possibility of the aviation sector achieving carbon-neutral growth by or after 2020 (despite the sector’s expectation of strong growth over the coming decades).
Here’s more on the study from the ICCT: “The feedstocks that provide the largest carbon reductions in AJFs are constrained in their supply and will likely also be in demand from competing sectors such as road transport. Estimates for maximum availability of sustainable AJF feedstocks reveal that it would be impossible to substitute total jet fuel consumption with AJF up to 2050 or attain carbon-neutral growth through AJF only. Although estimated demand for jet fuel amounts to 24–37 EJ in 2050, the absolute maximum amount of lignocellulosic biofuel that could be available for the aviation sector is around 4 EJ in 2050, resulting in emission reductions up to around 360 million tonnes CO2. The actual amount of low carbon AJF that will be available is likely much lower.”
“This study finds that the large-scale deployment of AJF and the ability of the aviation sector to mitigate emissions through their use will be limited by several factors, mainly: the sustainability and availability of feedstock, the production cost, and the extent to which those fuels will be commercialized. A literature review on estimated production costs of AJF for all pathways and feedstocks reveals that they are not commercially competitive with petroleum-derived jet fuel. Furthermore, the airlines’ price sensitivity relative to the road sector presents a possible disparity in terms of the aviation industry’s ability to support production costs as high as competing sectors.”
I’ll note here that I’m skeptical of the aviation sector’s expectation of strong growth over the coming decades. It seems more likely that economic problems (triggered by a variety of climate, resource, and overpopulation problems) will put a damper on continued growth in the sector, and in its corollary tourism — at least, in the US and Europe.
With regard to potential emissions reductions in the sector, it will likely be possible to transition many short-haul flights to hybrid and electric aircraft with a decade or two. While such an approach is technically possible, it remains unclear if widespread commercialization is in the cards. Considering that large firms such as Siemens are working towards the goal, though, it may well be the case.