Drop-in replacement biofuels and electrofuels can provide net-zero CO2 emissions
with dramatic reductions in contrail formation. Biofuels must transition to
second-generation cellulosic feedstocks while improving land and soil
management. Electrofuels, or "e-fuels,” require aggressive cost reduction in
hydrogen production, carbon capture, and fuel synthesis. Hydrogen has great
potential for energy efficiency, cost reduction, and emissions reduction;
however, its low density (even in liquid form) combined with it’s extremely low
boiling temperature mean that bulky spherical tanks will consume considerable
fuselage volume. Still, emerging direct-kerosene fuel cells may ultimately
provide a superior zero-emission, energy-dense solution.
Decarbonized Power Options for Civil Aviation discusses the current
challenges with these power options and explores the economic incentives and
levers vital to decarbonization. Until common and enforceable global carbon
pricing arrives, targeted national measures (e.g., mandates, price support, and
finance) will be required.