This paper has addressed the long-term development of
emissions of GHG (Green House Gases) from commercial air
transportation operated by a conventional jet A and cryogenic
LH2 (Liquid Hydrogen) fuelled aircraft fleet. Based on an update of the author's previous research, the paper aimed to
further stimulate the academic/research, consultancy, and
professional community to continue to consider breakthrough solutions for mitigating these emissions, one of
which could be partially or fully using LH2 (Liquid Hydrogen)
instead of the currently exclusively used jet A fuel for commercial air transportation.
The developments so far have indicated that commercial
air transportation has contributed relatively modestly to the
total man-made emissions of GHG e only 2e3 percent. Thus,
compared to other transport modes and man-made activities,
its contribution to global warming and consequent climate
change has been also modest.
However, the prospective long-term growing demand is
expected to continue to drive the accumulation of emissions
of GHG (CO2 and NOx) by commercial air transport despite
applying different demand-affection and fuel efficiency
improvement technical/technological, operational, and economic/policy measures to the conventional jet A fuelled
Fig. 7 e Potential effects of implementing cryogenic aircraft on the cumulative emissions of GHG (CO2) by international
commercial air transportation (period 2010e2065).
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 9 ( 2 0 1 4 ) 1 6 4 2 6 e1 6 4 4 1 16439
aircraft fleet. An additional cause for growing emissions is
their long residence (life) time in the earth's atmosphere
causing their continuous long-term contribution to global
warming and climate change. Consequently, achieving “carbon-neutral” commercial air transportation would not be
possible under such conditions.
The implementation of a cryogenic LH2 fuelled aircraft
fleet on account of their conventional jet A fuelled counterparts as a breakthrough solution has shown promise in
mitigating the cumulative emissions of GHG (by 2065) under
the given conditions e ‘baseline’ and ‘all improvements’
development scenarios based on using exclusively the jet A
fuelled aircraft fleet. In particular, introduction of a cryogenic aircraft fleet even at a rather modest rate (1e3%/year)
could contribute to stabilization, stagnation, and then
reduction of the cumulative emissions of CO2. An introduction rate of 5% could immediately stop and then
continuously and sharply reduce these emissions by the end
of the observed period (2060/65) below the target (50% of the
emissions in 2006/10).
Thus “carbon-neutral” commercial air transportation
could be achieved implying unconstrained further long-term
growth of air transport demand without further increase in
the cumulative emissions of GHG (CO2) and consequent
contribution to global warming and climate change