Liquid hydrocarbon fuels are an essential component of our energy system.  They have unprecedented volumetric density of energy, roughly 32 MJ/liter for gasoline, compared to a lithium ion battery at 2.4 MJ/liter.  This means that for activities requiring high or sustained power delivery such as flying and shipping there are no current alternatives.  Compared to electric motors, internal combustion engines have significantly lower efficiency, and the recent improvements in the electric vehicle sector suggest that at least for light vehicle duty their use is not essential.  However, despite significant government action to promote electrification of the light duty fleet, there will still be a period of transition that could last well over a decade as the developing world increases its consumption of transportation services and the world builds the capacity to electrify personal transportation.  Therefore, there is an urgent need to develop pathways to produce renewable liquid hydrocarbon fuels as part of the energy transition to low carbon energy systems.