A natural gas fuelled 10 kw electric power unit suitable for distributed energy conversion based on an automotive internal combustion engine

The paper discusses the concept and the overall performance of an auxiliary power unit, suitable for distributed energy conversion, based on a wide-spread automotive supercharged Diesel internal combustion engine. The latter has been converted into a spark ignition methane/natural gas unit by Istituto Motori CNR of Italy and it has been specifically chosen among many other engines as a reliable, high efficiency, cost effective unit, suitable for energy conversion systems (such as microcogeneration for residential or commercial applications). The paper starts by defining the ratio which leaded to the adoption of an automotive four cylinders, Diesel internal combustion engine, in order to produce the above mentioned electric power. This is followed by a explanation of the main modifications adopted to convert the former Diesel engine in a spark ignited stoichiometric unit, with a discussion over the most significant element and technical solution that could give the system a high efficiency, low gaseous emissions and long endurance. The unit has been coupled with a liquid cooled induction generator and then tested as an electricity and heat production system, ready for grid connection and to become a base for a future microcogeneration system, thanks to a new designed management/control system. During field test a complete report of its running behavior has been reported.