The past two years have seen huge advances in electric propulsion. However, battery weight is a major barrier to scaling up the technology to become commercially viable for anything larger than small general aviation aircraft. Is hydrogen then the breakthrough power source that will allow the industry to transition towards zero-net-carbon? Perhaps, but, again, developments are still in their infancy. Our expert panel will discuss whether hydrogen, electric, or hybrid-electric propulsion represents the best bet for a sustainable future for aviation.