NOVELTY - A spark-ignited gas engine (1) consists of an exhaust gas duct (6) and a compressor (2) for loading a combustion chamber (1.1) with an air-gas-mixture. The compressor is driven using a motor (15), and has a thermal reformer (3) for converting higher hydrocarbons containing carbon atoms and hydrogen atoms into hydrogen. The reformer is connected to one or more portions of the exhaust gas duct for supplying the reformer with heat. The conversion of higher hydrocarbons into hydrogen involves forming hydrogen and carbon monoxide by reacting hydrocarbon and water.    USE - Spark-ignited gas engine (claimed) e.g. Otto engine.    ADVANTAGE - The spark-ignited gas engine has high overall engine efficiency, and enables the efficient conversion of higher hydrocarbons into hydrogen with desired specific energy, by driving the compressor with electric motor rather than exhaust gas through an endothermic process.    DETAILED DESCRIPTION - A spark-ignited gas engine consists of exhaust gas duct and one or more compressor for loading a combustion chamber with an air-gas-mixture. The compressor is driven using a motor, and has a thermal reformer for converting higher hydrocarbons containing n carbon atoms and m hydrogen atoms into hydrogen. The reformer is connected to one or more portions of the exhaust gas duct for supplying the reformer with heat. The conversion of higher hydrocarbons into hydrogen involves forming m/2+n amount of hydrogen and n amount of carbon monoxide by reacting hydrocarbon (CnHm) and n amount of water, forming m/2 amount of hydrogen and n amount of carbon monoxide by reacting hydrocarbon (CnHm) and n/2 amount of oxygen, or forming m/2 amount of hydrogen and 2n amount of carbon monoxide by reacting hydrocarbon (CnHm) and n amount of carbon dioxide. An INDEPENDENT CLAIM is included for spark-ignited gas engine running procedure.    DESCRIPTION OF DRAWING(S) - The drawing shows the schematic view explaining the supply chain of spark-ignited gas engine with air-gas mixture and exhaust system.    Spark-ignited gas engine (1)    Combustion chamber (1.1)    Compressor (2)    Reformer (3)    Exhaust gas duct (6)    Motor (15)