*Article* **An Overview of Promising Alternative Fuels for Road, Rail, Air, and Inland Waterway Transport in Germany**

**Janos Lucian Breuer 1,2,\* , Juri Scholten <sup>3</sup> , Jan Christian Koj <sup>4</sup> , Felix Schorn 1,2 , Marc Fiebrandt <sup>3</sup> , Remzi Can Samsun <sup>1</sup> , Rolf Albus <sup>3</sup> , Klaus Görner <sup>3</sup> , Detlef Stolten 2,5 and Ralf Peters <sup>1</sup>**


**Abstract:** To solve the challenge of decarbonizing the transport sector, a broad variety of alternative fuels based on different concepts, including Power-to-Gas and Power-to-Liquid, and propulsion systems, have been developed. The current research landscape is investigating either a selection of fuel options or a selection of criteria, a comprehensive overview is missing so far. This study aims to close this gap by providing a holistic analysis of existing fuel and drivetrain options, spanning production to utilization. For this purpose, a case study for Germany is performed considering different vehicle classes in road, rail, inland waterway, and air transport. The evaluated criteria on the production side include technical maturity, costs, as well as environmental impacts, whereas, on the utilization side, possible blending with existing fossil fuels and the satisfaction of the required mission ranges are evaluated. Overall, the fuels and propulsion systems, Methanol-to-Gasoline, Fischer–Tropsch diesel and kerosene, hydrogen, battery-electric propulsion, HVO, DME, and natural gas are identified as promising future options. All of these promising fuels could reach near-zero greenhouse gas emissions bounded to some mandatory preconditions. However, the current research landscape is characterized by high insecurity with regard to fuel costs, depending on the predicted range and length of value chains.

**Keywords:** Power-to-Gas; Power-to-Liquid; hydrogen; transport; future mobility concepts; LCA; environmental impacts; synthetic fuels; synthetic natural gas; technology readiness level
