Renewable and sustainable fuels (based on electricity) will play a key role in future scenarios for power supply. Enabling storage and distribution of local and temporal fluctuations of renewable energies, different e-fuels with varying production processes and characteristics get interesting for different locations. For reconversion of the chemical energy, a fuel-flexible internal combustion engine with a High Pressure Dual Fuel (HPDF) combustion process is suitable for different e-fuels. As the combustion process is the main influence on emissions, combustion behavior of the studied fuels hydrogen, methane, methanol and ammonia, ignited by the pilot fuels Fischer-Tropsch diesel and polyoxymethylene dimethyl ethers (OME), is investigated in varying fuel pairings. In addition, a review of production efficiencies and important characteristics like toxicity and storage method is given. Afterwards, the application of the investigated fuels in HPDF-combustion is investigated. The investigations are conducted with a numerical 3D-CFD model of a large bore high speed single cylinder research engine. The differences in ignition and combustion when using diesel or OME as pilot fuel are shown and a comparison of the emissions for the used main fuels is given.