The most effective way to transition from fossil fuels is to make an alternative more economical. For example, there is the “methanol economy”, in which solar

The most effective way to transition from fossil fuels is to make an alternative more economical. For example, there is the “methanol economy”, in which solar or nuclear energy is used to create syngas from water and CO2. The syngas is then transformed into methanol or other higher energy density fuels. When they are burned, you get the CO2 and water back - it’s a closed cycle, like a battery in an electric car. But, it is practical for air transport propulsion.