Recent development in studies of alternative jet fuel combustion: Progress, challenges, and opportunities

Abstract

With the growing air transport demand and concerns about its environmental impacts, alternative jet fuels derived from non-conventional sources have become an important strategy for achieving a sustainable and green aviation. In the past ten years, governments around the world along with aviation industry have invested significant efforts into exploring all sorts of alternative jet fuels that can be used to power aircraft engines. Among all the alternative jet fuels explored, the aviation sector has agreed that hydrocarbon-based ‗drop-in' replacement fuels, which are fully interchangeable and compatible with current conventional jet fuels, would be the best choice in the near future, as they can be used without any modifications to today's aircraft or fuel infrastructure. This paper reviews the current state of development of ‗drop-in' alternative jet fuels including various Fisher-Tropsch synthetic jet fuels and bio-jet fuels. Recent advances in research activities on alternative jet fuels, including fuel property evaluations, combustor component tests, engine tests, and flight tests, are highlighted. Furthermore, basic research needs for understanding the combustion characteristics of alternative jet fuels are underlined and discussed by reviewing recent fundamental combustion studies on ignition, extinction, flame

A Study on Electrofuels in Aviation

“…The storage problem is a challenge specifically for CH 4 and specifically problematic for hydrogen. Toxicity is problematic for NH 3 and CH 3 OH, but also, the common fuel so far is not fully free of this issue. The combustion properties contain the reactivity and stability.…”

“…However, this would require major modifications of the combustor, which is considered a negative issue in the drop-in capability with respect to combustion. For the turbine, three criteria are listed with the turbine power output always being very good, specifically for H 2 and NH 3 . With the increase in engine speed, however, a clear cost was also identified, as the turbine geometry would require significant adaptations.…”

“…Assuming the ground-based "storage process" of energy in the fuel to have no emission of greenhouse gases (essentially CO 2 ) or other emissions, which, at least ideally, might be possible by the use of renewable power sources like wind-or solar-based electricity, such electrofuels could be seen as CO 2 -neutral. This is evident for such energy-carrying fuels without carbon content (e.g., H 2 or NH 3 ), but is valid (at least ideally) even for electrofuels based on the hydro-carbon structure. For the former group, no direct CO 2 will be emitted with combustion in-flight, while the latter will have such emissions, but as the carbon is taken out of the atmosphere during the production process of this fuel, it still can be seen as CO 2 -neutral.…”

“…The option to use "drop-in" fuels is commonly seen as the first possible step on the path toward electro-based sustainable aviation. An overview of the recent development of conventional drop-in fuels can be found in [3]. If radically different fuels were to be used, also the combustion engines would need to be redesigned.…”

Impact of a Jet A-1/HEFA blend on the performance and emission characteristics of a miniature turbojet engine

“…Scientific and technological advances related to the existing pathways to produce biojet and future implementation of a sustainable production chain for renewable aviation fuel were reviewed by Gutierrez-Antonio et al 2017. A review of the most important achievements of the last 10 years in the scope of studies conducted on alternative fuels for aircraft turbine engines was presented by Zhang et al 2016. Many experiments executed both, on different types of real aircraft engines, as well as with the use of different alternative fuels were presented in the field of engine studies.…”