Reducing Aircraft Emissions Using Biofuels

by Laura Thomson (AZO Cleantech) Many strategies and solutions have been developed to enforce sustainable development in aviation and to limit the negative impact on the environment. This article looks at recent research exploring the use of biofuels to reduce the impact of aircraft emissions.

The adoption by the International Civil Aviation Organization (ICAO) of standards for aviation emissions of NO_x, CO₂, PM, and nvPM, and the formation of a new CO₂ Compensation and Reduction System for International Aviation (CORSIA), are among the most significant legislative measures enacted during the 1990s, whose main goal has been to maintain a net-zero increase in CO₂ emissions in civil international aviation since 2021, in comparison to emissions from 2019–2020.

The use of hydrogen as a fuel or as admixtures to hydrocarbon fuels, in particular, appears to be interesting in terms of enhancing the fuel’s heating value while lowering CO₂ emissions. Studies on the usage of fuels created from marine algae or jatropha are the most promising in terms of bio-derived fuels.

Algae are extremely efficient in producing biomass. An efficient algae biofuel production system needs a variety of resources, including suitable land and climate, long-term water resource management, extra carbon dioxide (CO₂), and other nutrients (e.g., phosphorus and nitrogen). Algae may be an appealing feedstock in a variety of situations because of their diversity, which allows for high potential biomass production in a variety of climates and environments.

The hydroprocessing of Jatropha curcas yields another interesting alternative to conventional jet fuel. Because of its quick growth ability, high energy content, and resistance to harsh temperatures and poor soil conditions, this plant is regarded as a viable source for supplying a large amount of future jet biofuel production.

The lifetime GHG emissions of jatropha jet biofuel (JBF) range from 22 to 54 (gCO₂e/MJ), representing a decrease of up to 75% compared to Jet-A. JBF from Jatropha reduces GHG emissions more than palm oil and less than algae while remaining comparable to rapeseed, soybean, and salicornia feedstocks.

The main issue for the jatropha JBF sector is to bring production costs down to a level that is competitive with traditional Jet-A while maintaining a high and consistent crop yield.

The aim of the research presented in this paper is to see if plant-derived fuels may minimize pollutant emissions in the exhaust.

The research was based on the Airbus A340-200 aircraft, which was equipped with four Snecma CFM56-5C engines and flew between Paris and Vancouver airports.

The largest mass variations in CO₂ emissions (from 7.6 to 11.7 tons) were found in the case of changes in CO₂ emissions, which is a significant figure considering that the acquired data are reported for only one case study (a particular aircraft and a particular route).

The research given in this article suggests that using biofuels, such as algae and jatropha, can enhance the aircraft’s environmental performance. However, over the cruising range, the reduction in CO₂ and NO_x emissions is offset by an increase in fuel consumption. The usage of the assessed biofuels necessitates the addition of 4.6 tons of algae fuel and 3 tons of jatropha fuel to the mix.

Laboratory testing of alternative fuels and their blends with kerosene or hydrogen to achieve the same heating value as kerosene should be the focus of future studies. Furthermore, testing should be carried out on a test bench. READ MORE

Pawlak, M. and Kuźniar, M. (2022) The Effects of the Use of Algae and Jatropha Biofuels on Aircraft Engine Exhaust Emissions in Cruise Phase. Sustainability, 14(11), p.6488. Available Online: https://www.mdpi.com/2071-1050/14/11/6488/htm.