Life-Cycle Analyses of Energy Consumption and GHG Emissions of Natural Gas-Based Alternative Vehicle Fuels in China

Tsinghua life-cycle analysis model (TLCAM) has been used to examine the primary fossil energy consumption and greenhouse gas (GHG) emissions for natural gas- (NG-) based alternative vehicle fuels in China. The results show that (1) compress NG- and liquid NG-powered vehicles have similar well-to-wheels (WTW) fossil energy uses to conventional gasoline- and diesel-fueled vehicles, but differences emerge with the distance of NG transportation. Additionally, thanks to NG having a lower carbon content than petroleum, CNG- and LNG-powered vehicles emit 10–20% and 5–10% less GHGs than gasoline- and diesel-fueled vehicles, respectively; (2) gas-to-liquid- (GTL-) powered vehicles involve approximately 50% more WTW fossil energy uses than conventional gasoline- and diesel-fueled vehicles, primarily because of the low efficiency of GTL production. Nevertheless, since NG has a lower carbon content than petroleum, GTL-powered vehicles emit approximately 30% more GHGs than conventional-fuel vehicles; (3) The carbon emission intensity of the LNG energy chain is highly sensitive to the efficiency of NG liquefaction and the form of energy used in that process