Liquefied Natural Gas for Civil Aviation

Abstract

The growth in air transport and the ambitious targets in emission reductions set by advisory agencies are some of the driving factors behind research towards new fuels for aviation. Liquefied Natural Gas (LNG) could be both environmentally and economically beneficial. However, its implementation in aviation has technical challenges that needs to be quantified. This paper assesses the application of LNG in civil aviation using an integrated simulation and design framework, including Cranfield University’s aircraft performance tool, Orion, and engine performance simulation tool Turbomatch, integrated with an LNG tank sizing module and an aircraft weight estimation module. Changes in tank design, natural gas composition, airframe changes, and propulsion system performance are assessed. The performance benefits are quantified against a Boeing 737–800 aircraft. Overall, LNG conversion leads to a slightly heavier aircraft in terms of the operating weight empty (OWE) and maximum take-off weight (MTOW). The converted aircraft has a slightly reduced range compared to the conventional aircraft when the maximum payload is considered. Compared to a conventional aircraft, the results indicate that although the energy consumption is increased in the case of LNG, the mission fuel mass is decreased and CO2 emissions are reduced by more than 15%. These benefits come with a significant reduction in fuel cost per passenger, highlighting the potential benefits of adopting LNG for aviation.

Electric Aircraft Fueled by Liquid Hydrogen and Liquefied Natural Gas

“…Preliminary studies show that the total CO2 emissions of future electric aircraft can be reduced by using cryogenic fuels such as LH2, LNG, and liquefied bio-methane [4]. LH2, when cleanly produced has the potential to create a zero-carbon emission transport system [14].…”

“…Cryogenic fuels have a high gravimetric energy density, but a low volumetric energy density compared to conventional fuels, as shown in Fig. 1 [4]. That means more space is needed to store the fuel.…”

“…Although a 20-25% decrease is expected in the fuel burn of the aircraft due to engine improvements over the next 2 decades, it is not sufficient to meet the anticipated targets [3]. Due to the limitations of IOP Publishing doi:10.1088/1757-899X/1241/1/012035 2 height underwing, drag, and weight of the engine, further significant improvements are not possible with the conventional fuselage and wing-type designs [4]. There is a need for new progressive designs for achieving the emission reduction targets that have been set.…”

“…Another alternative solution to achieve the target emission reduction requirements is the use of low carbon alternative high energy-dense fuels [4]. For the alternative fuel to be a viable solution, it should have several key properties.…”

“…The fuel must be commercially available on a large scale, have a competitive price relative to the current AV gas, be energy-dense (both volumetric and gravimetric), be safe to ship and store, and it must be clean not only to burn but also to produce. The current AV gas meets some of the listed criteria but is not suitable in the long run due to its environmental impact in both production and burning in the engines [4].…”