A review on low carbon fuels for road vehicles: The good, the bad and the energy potential for the transport sector

The increased energy demand of the modern society has striven researchers to explore various alternatives to generate power without worsening the greenhouse gas (GHG) emissions. In the road transport sector, this has led to a progressive change towards the preference for the electrification of powertrains in replacement of the in-ternal combustion engine (ICE). Nonetheless, providing options to reduce the GHG coming from ICEs in the short-and medium-term will still be fundamental in fulfilling the global emission targets while the phasing-out of the combustion vehicle takes place or in places where the change to electric powertrains could represent a potential risk in the energy supply. Low carbon fuels (LCF) can serve as such alternative if carbon neutrality or carbon offsetting is achieved. In addition, these fuels could serve as intermediate energy storage for renewable energy sources during instances of low demand and high generation, where they can later be utilized to generate electricity for any application or electric vehicles. The current review paper will provide an overview of the advantages, drawbacks, and energy potential for LCF in the framework of the light-duty compression ignition engine for road transportation. The paper highlights how LCFs, biofuels and synthetic fuels, require sustainable production adhering to regulations to avoid harm to biodiversity and ensure GHG reductions. In addition it is discussed how LCFs can offer advantages in fuel consumption and emissions reduction, contingent on fuel characteristics and combustion processes, which might affect hardware performance and scalability depending on the type of fuel.