In order to reduce the consolidated CO2 emission balance stemming from the operation of internal combustion engines, application of new alternative fuels out of renewable sources can deliver a major contribution in the future. For this paper, several fuels were selected which can be produced out of biomass or with hydrogen which is generated directly via electrolysis with electricity from renewable sources. All fuels are compared to conventional diesel fuel and two diesel surrogates. It is well known that there can be a large effect of fuel properties on mixture formation and combustion, which may result in a completely different engine performance compared to the operation with conventional diesel fuels. Mixture formation and ignition behavior can also largely affect the pollutant formation. The knowledge of the combustion behavior is also important to design new engine geometries or implement new calibrations for an existing engine. The fuel properties of the investigated fuels comprise a large range, for example in case of derived cetane number from below 30 up to 100. Different optical diagnostics are used simultaneously to monitor the behavior of these fuels. Measurements have been taken in a high pressure vessel at in-cylinder conditions relevant to modern diesel engines. To investigate the ignition and the lift-off length, high-speed detection of OH*-radicals was applied. In case of mixture formation analysis, Mie-scatterlight was used to detect the liquid penetration length and for the gas-phase, a schlieren method was used. For both measurement techniques, a high speed camera was set up. By combining these optical measurement technics, different amounts of premixed combustion have been observed for the different fuels. This can affect strongly the pollutant formation in an engine.