“By 2050 the cheapest type of fuel will be synthetic fuel from biomass, produced with nuclear-generated (fission or fusion) electricity.”

Nuclear is the cheapest, safest, lowest CO2 emission power source we know of (when taking a long view and discounting ideologically motivated subsidies and meddling), and synthfuel from biomass can be a carbon sink while using existing infrastructure. As the climate deteriorates the externalities should start showing up in the price of most other options.