Total Life Cycle Analysis of CNG and Hydrogen Enriched CNG Powered Vehicles: A Comparative Evaluation

Vehicles consume energy and release harmful emissions throughout their life period from the manufacturing stage of raw materials to the vehicle scrapyard. The current Green-House Gas (GHG) emissions from diesel and petrol vehicles are reported to be 164 g CO₂/km and 156 g CO₂/km respectively. Thus, enormous research studies are been carried out for low-carbon alternative fuel-powered vehicles to reduce the overall GHG emissions. Numerous research on hydrogen as a transportation fuel has demonstrated the potential of reduced vehicular emissions compared to conventional fuels. Life cycle assessment (LCA) is a comprehensive methodology used for estimating the overall environmental impact of vehicles. In this present work, a comparative LCA is conducted between Compressed Natural gas (CNG) powered vehicles and H-CNG powered vehicles. The effect of the two alternative vehicles is assessed from various points in their lifetime using the GREET model software. The analysis is done in two stages namely, well to pump and pump to the wheel. The obtained results of the analysis reveal that the H-CNG fuel exhibits a favorable reduction in CO emissions by 3% and CO₂ emissions by 5%. It is also found that there is no significant reduction in NO_X emissions. The H-CNG refueling sites are equipped with on-board small scale reformers for producing hydrogen, which is blended with CNG and then pressurized on-site for vehicle fueling. The proposed H-CNG production process is cheaper than the conventional physical blending process and thus paving way for the potential usage of H-CNG fuel.