A Detailed Well to Wheel Analysis of CNG Compared to Diesel Oil and Gasoline for the French and the European Markets 2007-01-0037

Pollutants emissions from transportation have become a major focus of environmental concerns in the last decades. Many alternative fuels are under consideration, among which Natural Gas as fossil resource offering an advantageous potential to reduce local emissions. The European Commission has set an objective of 10% of Natural Gas consumption for the transport sector by 2020. In a sustainable development view, both vehicle emissions and energy supply chain analysis from well to wheel must be addressed. Even if the main focus today is on CO₂ emissions, it is interesting to evaluate the pollutant emissions of the whole Well to Wheel chain. Besides, as the potential of reducing pollutant emissions of vehicle (due to the improvement of engines and severization of norms), looking at pollutant emissions of the Well to Tank part of the chain could show the possible further improvements.

Former studies exist, comparing Natural Gas to conventional and non conventional fuels. This paper presents in the first part results from major studies. Then the study conducted by IFP in partnership with AFGNV (French Vehicle Natural Gas Association) is highlighted. This study deals with a comparative Life Cycle Analysis of Natural Gas, diesel oil and gasoline fuels looking at the French and the European situation.

For the “Tank to Wheel” study, new data for vehicle emissions have been used based on a French medium-class sedan vehicle, both measured and modeled. For the “Well to Tank” part of the study, a detailed modeling of the energy consumption and air emissions has been set along the whole supply chain. The results concern WTW non renewable energy consumptions, GHG emissions and local pollutant emissions. Local pollutant have a lower impact in the Natural Gas pathway than in the gasoline or diesel oil pathways. The relative contribution of upstream (well to tank) and downstream (tank to wheel) parts depends on the pathway. Finally a sensitivity analysis is presented and uncertainties are evaluated. The more sensitive parameters are losses during Natural Gas transport and energy consumption at different steps.

As a conclusion, the potential GHG emissions reduction derived from the European objective of 10% contribution of Natural Gas in the energy mix for transport sector is investigated. Related GHG emissions reduction could reach 4,5 Mt CO₂ equivalent in 2010 in France, which represents around 30% of target of the total GHG emissions reduction supposed to be achieved in France in the transport sector by 2010.