Compression Ignition of Low-Octane Gasoline: Life Cycle Energy Consumption and Greenhouse Gas Emissions

Significance Statement

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.

Compression Ignition of Low-Octane Gasoline Life Cycle Energy Consumption and Greenhouse Gas Emissions - Renewable Energy Global InnovationsFigure 1 Life cycle energy consumption and GHG emissions

Compression Ignition of Low-Octane Gasoline Life Cycle Energy Consumption and Greenhouse Gas Emissions - Fig 2 - Renewable Energy Global InnovationsFigure 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.

About the author

Prof. Fuquan (Frank) Zhao is the director of Tsinghua Automotive Strategy Research Institute (TASRI), the President of the International Federation of Automotive Engineering Societies (FISITA 2018-2020), and the member of Global Future Council on Mobility for the World Economic Forum.

Prof. Zhao joined Tsinghua University in 2013. Before, he worked more than 20 years in the automotive industry. He has been a leading author of more than 300 academic papers in English, Japanese and Chinese, written 5 books in English and Chinese, and led the development of about 20 vehicle models and 10 powertrain products.

His research is focus on strategy in fields of automotive industry development, corporate management and technology development roadmaps.

He holds Master and PhD degrees in Mechanical Engineering, Hiroshima University, Japan, and a Bachelor degree in Jilin University of Technology, China.

About the author

Dr. Hao is the assistant researcher in Tsinghua Automotive Strategy Research Institute (TASRI). He is the contributing author of Intergovernmental Panel on Climate Change (IPCC) the 5th Assessment Report, the member of editorial Committee of China Automotive Energy Outlook and the member of editorial committee of Sustainable Automotive Energy System in China.

Dr. Hao is the journal reviewers of the following SCI journals: Renewable & Sustainable Energy Reviews, Energy, Transportation Research Part A: Policy and Practice, Transportation Research Part D: Transport and Environment, Transport Policy, Energy Conversion and Management and Applied Mathematical Modeling.

His research field is mainly on automotive industry research, with focus on industrial development and planning, life cycle evaluation methods, technical strategy methodology, etc.

He holds Bachelor and PhD degrees in Department of Automotive Engineering from Tsinghua University.

About the author

Feiqi Liu is the doctoral candidate in Tsinghua Automotive Strategy Research Institute (TASRI). Her research interests are vehicle fleet carbon emissions and life cycle evaluation methods. She holds the Bachelor degree in School of Transportation Science and Engineering, Beihang University.

Journal Reference

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

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