Reducing oxides of nitrogen using hydrogen generated from engine fuel and exhaust

Either (a) the exhaust of an engine and/or (b) inlet air is sent to a hydrogen generator along with diesel fuel to produce hydrogen and carbon monoxide for either (c) mixing with the mainstream of exhaust fed to a catalytic converter or (d) regenerating a pair of NOx adsorption traps, thereby reducing oxides of nitrogen (NOx) to provide system exhaust which may have less than 0.20 grams/bhp/hr of NOx and 0.14 grams/bhp/hr of non-methane hydrocarbons. A water recovery unit may extract water from either the exhaust or the effluent of the NOx traps to humidify inlet air for mixture with fuel. Inlet air may be humidified in an air bubbling humidifier that receives water from a condenser that uses inlet air to cool NOx trap effluent.