A process of powering a compression ignition engine using a main fuel comprising methanol and water, including: fumigating an intake air stream with a fumigant comprising an ignition enhancer; introducing the fumigated intake air into a combustion chamber in the engine and compressing the intake air; introducing the main fuel into the combustion chamber; and igniting the main fuel/air mixture to thereby drive the engine. Also provided a fuel for use in the process, a two-part fuel for use in the process, and associated power generation systems.