Research into the use of a lean burn and a stoichiometric heavy duty engine fuelled with a blend of hydrogen and natural gas

Abstract

Energy sustainability implies the increase of share of renewable sources, as well as the reduction of inefficiencies during generation and distribution. However, a large use of renewable intermittent energy sources, such as solar and wind, in power plants and in small generators distributed could complicate the electrical grid. An important aspect of the impact of electrical networks operating on the distribution system concerns the regulation of voltage. In the case of surplus of electricity decentralized production, energy storage could be a viable solution. In this scenario the production of hydrogen by electrolysis as energy carrier, with oxygen as a byproduct, can become appealing. Hydrogen in urban areas could easily be used in blends with natural gas in urban vehicle fleets. This solution is flexible regarding the amount of hydrogen available and in any case natural gas is the best choice for the internal combustion engine for urban fleets. The use of natural gas in stoichiometric or lean burn engines guarantees a very low level of toxic emissions and zero particulate matter without the need of a trap, even after the vehicle has accumulated a considerable mileage. In particular, only the NOx emissions are harmful, since the emission of hydrocarbons are mainly composed of methane, which is not toxic to human health. In this paper the effect of the addition of hydrogen to natural gas, in the amount of 15% by volume, on the emission of a stoichiometric and a lean burn heavy duty engine was studied. The tests were carried out on the European transient cycle. The results show that with the stoichiometric engine no special attention must be put in the supply change while with the lean burn engine the problem of poor NOx control suggests adjusting the calibration of ignition; with the aim of not compromising the engine emission. © 2012 WIT Press.