NOVELTY - Diesel engine fuel composition (A) comprises: methanol at a level of at least 20 wt.% of the fuel; water at a level at least 20 wt.% of the fuel; and one or more additives (at least 0.1 wt.%), where the: ratio of water to methanol is 20:80 to 80:20; and total amount of water and methanol is at least 60 wt.% of the fuel composition; the level of sodium chloride, if present as an additive, is 0-0.5 wt.% of the fuel; and the level of flavorant, if present as an additive, is 0-1.5 wt.% of the composition.    USE - The diesel fuel composition is useful: in the process for powering a compression ignition engine, or power generation system (claimed); and in internal combustion engine.    ADVANTAGE - The diesel fuel composition reduces emissions and avoids an adverse impact on fuel efficiency and/or engine performance. (I) provides seamless options for efficient biomass co-processing to reduce carbon dioxide; provides waste heat to local communities by a hot water loop cooling down the exhaust and exchanging this major source of heat energy with local demand centers for heat, for heating or refrigeration purposes; provide pH neutral irrigation water for direct use by local communities; and provide a water washed exhaust which neutralizes acids and removes particulates down to low levels.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a process for powering a compression ignition engine using a fuel comprising methanol and water, including: pre-heating an intake air stream, introducing the pre-heated air into a combustion chamber of the engine and compressing the pre-heated air; and introducing the fuel into the combustion chamber and igniting the fuel/air mixture to drive the engine;    (2) a power generation system, where the power is generated by a process (A) comprising: powering a compression ignition engine using a methanol-water fuel to generate power; preheating an inlet air stream of the compression ignition engine, and/or fumigating the inlet air stream with an ignition enhancer; and treating engine exhaust gas to recover exhaust heat and/or water from the engine, and redirecting the heat and/or water for further use;    (3) a method of transporting a two-part pre-fuel composition comprising methanol and ether, including transporting the pre-fuel from a first location to a second location remote from the first location, and separating the ether from the methanol to yield a first fuel part comprising methanol, and a second fuel part comprising ether; and    (4) a pre-fuel composition comprising methanol and up to 10 wt.% of an ether.