|Preliminary Tank-to-Wheels CO2 emissions, including likely fuel options for China. Click to enlarge. Data: GM|
GM has begun the process of a Well-to-Wheels evaluation of alternative powertrains and fuels for light duty vehicles in the context of the Chinese market, with an emphasis on those alternative fuels that have the potential to play a major role in the country, including: M10, M85, E10, E85, DME, and CTL.
The preliminary assessment of the Tank-to-Wheels component is complete, accounting for energy consumption and greenhouse gas emissions—although not criteria pollutants— resulting from vehicle use. The Well-to-Tank component is underway.
Concerns about energy availability and climate change are becoming more prominent in China; the government adjusted the tax structure to provide a financial disincentive for the purchase of large-displacement vehicles: a 50% sales tax on engines greater than 4.0 liters, and a 27% tax on engines between 2.2 and 4.0 liters.
The Shanghai auto show was the venue for displays of advanced powertrain concepts (including hybrids and fuel cell vehicles) from domestic as well as international automakers, including Chery, SAIC and Chang'an Automobile Group.
A full life cycle analysis of powertrain/fuel combinations could prove useful in shaping policy and product planning there (as elsewhere). GM sponsored a similar W-t-W project in Europe in 2002, and EUCAR, CONCAWE and JRC have followed up with a more detailed and current W-t-W assessment for that region.
For the China study, GM used an Opel Zafira (minivan) type vehicle that is expected to be marketed in high volumes in China in the 2010-2015 timeframe. The baseline vehicle was configured with a gasoline engine and automated manual transmission. (The Zafira was also the baseline vehicle in the GM European study.) The researchers used GM’s proprietary Hybrid Powertrain Simulation Program (HPSP).
GM included the coal-derived fuels—methanol, Fischer-Tropsch diesel and dimethyl-ether—due to their likely presence in the Chinese market. The researchers noted:
The choice of fuel has a significant impact on the fuel consumption of [internal combustion engine] vehicles. Methanol, in M100 and M85 blended fuels, has the highest impact because its heating value is about 50% less that gasoline. However, the potential to produce methanol from coal, using CTL technologies, may provide China a national security advantage compared to using petroleum-based fuels. In this case, one should keep in mind that the T-t-W emissions of methanol-fueled vehicles are associated with higher tailpipe emissions of CO, NOx, formaldehyde and acetaldehyde.
|Fuel consumption in gallons of gasoline equivalent for the different fuels (non-hybrid, combustion-engine). Click to enlarge.|
Overall, the study found that incremental technology changes in combustion engines have the potential to reduce fuel consumption by up to 20% compared to baseline vehicles. Hybridization of those platforms can lead to an additional reduction in fuel consumption of up to 21%. Fuel cell vehicles are associated with the greatest improvement, with a 58% reduction in fuel consumption of the gasoline baseline vehicle, and no on the road CO2 emissions.
On the fuels side, M10 and E10 results in an “insignificant” reduction in CO2 emissions, while M85, E85 and M100 (CTL) can produce a 2%-7% reduction.
Tank-to-Wheels Preliminary Assessment of Advanced Powertrain and Alternative Fuel Vehicles for China (SAE 2007-01-1609)