The high need for control of greenhouse gas emissions is of importance due to the adverse effect it poses on health and environment. This is not far-fetched as the transport industry, despite its rule plays in society has contributed immensely to greenhouse gas emissions.
An improved vehicle technology which uses low-octane gasoline on the gasoline compression ignition engines offer various advantages compared with other vehicle technologies. It offers a lower ratio of octane compared with conventional gasoline engine, and in terms of energy efficiency and resourcefulness, a higher thermal efficiency compared to the conventional gasoline spark ignition engine and a demand balance between gasoline and diesel can also be achieved. Also, the ease in refinery process due to the use of low-octane gasoline is worthy to notice.
As various researches highlights the significant improvement of low-octane gasoline on gasoline compression ignition engines, a life cycle assessment of energy consumption and greenhouse gas emissions in view of this vehicle technology would also give details on the impacts achieved during the refinery process.
Researchers led by Professor Fuquan Zhao from the State Key Laboratory of Automotive Safety and Energy at Tsinghua University in China reported a life-cycle assessment on the application of low-octane gasoline on the gasoline compression ignition engines in view of finding its effect on energy consumption and greenhouse gas emissions, followed by a comparison study with the conventional gasoline-spark ignition engines. The research work is now published in Applied Energy.
The authors considered a system boundary, well-to-wheel concept. The well-to-wheel concept had two phases; well-to-tank phase and tank-to-wheel phase coupled with evaluations on energy consumption and greenhouse gas emissions related with crude oil extraction, transportation, petroleum refining, products transportation for the former and vehicle use for the latter, based on relevant data. They also made use of a mass-based method for allocation of energy consumption and greenhouse gas emissions in the refinery process.
At the well-to-tank phase, lower energy consumption and greenhouse gas emissions occurred in the refining process of the low-octane gasoline compared to the conventional gasoline. This was due to the non-existence of the isomerization and catalytic reforming units.
With consideration of vehicle fuel consumption rate of related data, low energy consumption and greenhouse gas emissions was also attained for low-octane gasoline and its application on the gasoline compression ignition engine when observed in both phases of the well-to-tank and tank-to-wheel respectively.
Figure 1 Life cycle energy consumption and GHG emissions
Figure 2 The contributions of the WtT and TtW phases in reducing energy consumption and GHG emissions
Outcomes from the life cycle assessment indicated a lesser energy consumption and greenhouse gas emissions by 24.6% and 22.8% for the low-octane gasoline on the gasoline compression ignition system compared to the conventional gasoline on spark ignition system, as Figure 1 shows. The WtT phase contributes to 29% of energy consumption reduction and 34% of GHG emissions reduction. The other 71% of energy consumption reduction and 66% of GHG emissions reduction are attributed to the TtW phase, as Figure 2 shows. The results indicate that both WtT and TtW phases play essential roles in realizing reductions in energy consumption and GHG emissions. Relatively, the TtW phase makes larger contributions.
The authors were able to show that low-octane gasoline on gasoline compression ignition engines would definitely lessen energy consumption and greenhouse gas emissions and provide a major improvement in vehicle technology.
Hao, H., Liu, F., Liu, Z., Zhao, F. Compression ignition of low-octane gasoline: Life cycle energy consumption and greenhouse gas emissions, Applied Energy 181 (2016) 391–398.
State Key Laboratory of Automotive Safety and Energy, Tsinghua University, Beijing 100084, China