Sustainability Assessment of Alternative Energy Fuels for Aircrafts—A Life Cycle Analysis Approach

Aviation is of crucial importance for the transportation sector and fundamental for the economy as it facilitates trade and private travel. Nonetheless, this sector is responsible for a great amount of global carbon dioxide emissions, exceeding 920 million tonnes annually. Alternative energy fuels (AEFs) can be considered as a promising solution to tackle this issue, with the potential to lower greenhouse gas emissions and reduce reliance on fossil fuels in the aviation industry. A life cycle analysis is performed considering an aircraft running on conventional jet fuel and various alternative fuels (biojet, methanol and DME), including hydrogen and ammonia. The comparative assessment investigates different fuel production pathways, including the following: JETA-1 and biojet fuels via hydrotreated esters and fatty acids (HEFAs), as well as hydrogen and ammonia employing water electrolysis using wind and solar photovoltaic collectors. The outputs of the assessment are quantified in terms of carbon dioxide equivalent emissions, acidification, eutrophication, eco-toxicity, human toxicity and carcinogens. The life cycle phases included the following: (i) the construction, maintenance and disposal of airports; (ii) the operation and maintenance of aircrafts; and (iii) the production, transportation and utilisation of aviation fuel in aircrafts. The results suggest that hydrogen is a more environmentally benign alternative compared to JETA-1, biojet fuel, methanol, DME and ammonia.