Biomethane CNG hybrid: A reduction by more than 80% of the greenhouse gases emissions compared to gasoline

Recent results of GDF SUEZ Research and Innovation Division (RID) activities on Compressed Natural Gas (CNG) vehicles are depicted in this paper: The prototype "Toyota Prius II Hybrid CNG Vehicle", developed with IFP Energies Nouvelles, combines a natural gas thermal engine with a hybrid electric motorization. After optimization, CO2 emissions, measured on chassis dynamometer, were 76 g/km on NEDC cycle. The use of raw biogas in CNG Vehicle has been explored. These tests have shown that raw biogas (not upgraded) can be used as a fuel, if blended with natural gas. In fact, the use of raw biogas can be envisaged in dedicated CNG engines, if new engine technologies (lean CNG combustion) are developed. In such a case natural gas can be blended with up to 70% volume of not upgraded biogas. The potential reduction of greenhouse gases (GHG) emissions related both to the optimization of the CNG vehicle and to the use of biomethane as a vehicle fuel has been evaluated. GHG emissions from CNG vehicles (mono-fuel and hybrid) may be significantly lower than emissions of gasoline vehicles: around 17% lower in the case of dedicated CNG Vehicle and up to 51% lower in the case of hybrid CNG vehicles. In addition, biomethane (from the anaerobic digestion of waste) brings the GHG emission levels, over the course of the life cycle, down to more than 80% compared to a gasoline vehicle. Emission levels are lowered by 87% in the case of the Toyota Prius CNG Hybrid prototype fuelled by biomethane produced from waste (in comparison to a gasoline vehicle). Thus, biomethane allows a reduction of GHG emissions far below the minimum required by the European Directive on the Promotion of Renewable Energy Sources (2009/28/EC). These results have shown that the combination of optimized and innovative engines with the use of biomethane as a fuel permits to significantly reduce the GHG emissions. (C) 2011 Published by Elsevier B.V.