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A Review of Environmental Assessments on Liquid Biofuels in China
Available online at www.sciencedirect.com
ScienceDirect Energy Procedia 61 (2014) 2105 – 2108
The 6th International Conference on Applied Energy – ICAE2014
A review of environmental assessments on liquid biofuels in China Li Lua, Jingsong Zhoua* a
State Key Laboratory of clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
Abstract Liquid vehicle fuel from biomass is an effective alternative to relieve the intensive pressure of fossil energy depletion and greenhouse gas(GHG) emissions. To ensure optimal biomass-derived liquid fuels production, the environmental effects is necessary to be taken into account in regard to the production system. This paper provides a review of analysis of vehicle fuel in terms of two types of primary biofuels (bioethanol and biodiesel) in China via life cycle assessment (LCA) technique in China to ascertain material and energy flow. The methodology utilized was WTW (well to wheel) module and pathways including soybean, jatropha, waste oil, corn, cassava and sugar grass. Combined with energy utilization and GHG indicators, several recommendations of biofuel production and policy were proposed. © by Elsevier Ltd. This an open Ltd. access article under the CC BY-NC-ND license ©2014 2014Published The Authors. Published by isElsevier (http://creativecommons.org/licenses/by-nc-nd/3.0/). Selection and/or peer-review under responsibility of ICAE Peer-review under responsibility of the Organizing Committee of ICAE2014
Keywords: Bioethanol; Biodiesel; LCA; GHG emissions
1. Introduction The heavy dependence of fossil-based oil and growing crude oil price have forced many countries to pay attention to searching a renewable effective alternative to relieve the intensive pressure. As one of the indispensable parts of renewable energy, biomass is the potential precursor to produce biofuels due to its abundant resources and enormous potential which can be directly converted into carbon liquid fuels. Meanwhile, an amount of CO2 is absorbed during biomass growth process through photosynthesis, which makes a dramatic contribution to climate change mitigation. Conventional biofuel includes biodiesel (refers to vegetable oil such as rap oil, jatropha curcas oil and waste oil), bioethanol (from sugar crops and lignocellulosic materials), dimethyl ether (from woody crops),
* Corresponding author. Tel.: +86-571-87952041; fax: +86-571-87951616. E-mail address: Zhoujs@ zju.edu.cn.
1876-6102 © 2014 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/). Peer-review under responsibility of the Organizing Committee of ICAE2014 doi:10.1016/j.egypro.2014.12.086
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Li Lu and Jingsong Zhou / Energy Procedia 61 (2014) 2105 – 2108
pure plant oil (generally refers to rapeseed) and so on. Most of the present life-cycle analyses (LCA) researches on biofuel system were performed in America and European countries, while few relative studies were conducted in developing countries. However, different countries have unique resources and climatic environment, which causes essential data and GHG emissions unable to currently quote and consult. In China the majority of LCA researches on vehicle liquid biofuels had been developed in Tsinghua University, Tongji University, Shanghai Jiaotong University groups. This article summarizes the development of local LCAs of liquid biofuels in China. LCA of soybean biodiesel investigated by Dong [1], Jatropha and waste oil biodiesel studied by Xin [2], rapeseed and bark biodiesel reported by Hu [3] all reflected positive environmental influence on CO2 emissions. On the other hand, LCA of cassava bioethanol studied by Hu, corn bioethanol investigated by Zhang [4] and comprehensive analysis by Ou [5] demonstrated the potential of bioethanol as an alternative biofuel. Basic data in this research are cited reports above. 2. System boundary in this study In the field of vehicle fuel LCA analysis, the international common technology approached is WTW analysis which contains WTP (well to pump) stage and PTW (pump to wheel) stage. Both of the two stages comprehend EC (energy consumption) and GHG (greenhouse gas). The flow chart displayed in Fig.1 reveals a generic biofuel life cycle scheme [6]. E, C, X respectively means energy flow, carbon flow and emissions to the environment. WTP includes raw materials cultivation, storage, transportation, distribution and fuel production (stage A, B, C, D), while PTW includes downstream fuel combustion process in vehicle’s engine (stage E).
Figure 1.material flow and environmental interventions across the life cycle stages in a biofuel system
3. Key results from assessments 6 primary industrial routes are discussed below. The total fossil energy use and GHG emissions of each type of biodiesel and bioethanol are shown in the graphs as well as the proportions of 3 main substages including resource, fuel and vehicle stage. Because the assumption of low proportion bioethanol (E10) is infinitely similar to gasoline, as well as BD5 biodiesel fuel to traditional diesel, E85 bioethanol fuel utilized FFV (Flexible Fuel Vehicles) technology and BD20 biodiesel utilized DICI (Direct Injection Compression Ignition) technology were discussed. To high proportion of bioethanol E85 (Fig.2), the fossil energy consumption mainly depends on the
2107
Li Lu and Jingsong Zhou / Energy Procedia 61 (2014) 2105 – 2108
raw materials cultivation including stewing and fermentation. On the other hand, all biomass routes reveal undersized reduction in vehicle stage. To combine bioethanol and other vehicle fuel at the optimal ratio is considered as a good choice for a terrific benefit. In contrast to widespread belief, GHG emission of bioethanol exceeds traditional petroleum fuel. In spite of carbon fixation effect during biomass growth, massive CO2 and N2O emission owing to coal using in producing process and agricultural chemical fertilizer in China which offset a large proportion of fixation. vehicle stage fuel stage resource stage
3.0 2.5
vehicle stage fuel stage resource stage
250 200 geqCO2/km
MJ/km
2.0 1.5 1.0
150 100 50
0.5 0
0.0
0#diesel BD soybean BD jatrophaBD waste oil
0#diesel BD soybean BD jatrophaBD waste oil A
B
Figure 2.Biodiesel WTW (a) fossil energy use (b) GHG emissions per km
There is no directly petroleum consumption in the biodiesel production process, which leads to a conspicuous decline of fossil consumption. However, finite biodiesel proportion limits saving scale (Fig.3). Similar to bioethanol, GHG emission of biodiesel doesn’t reflect much predominance over traditional diesel route on account of N2O and the residue of oil extraction. In addition, considering biodiesel as an alternative to boiler fuel is a remarkable choice of GHG emission according to a higher substitution amount. vehicle stage fuel stage resource stage
4.0 3.5
300
3.0
250 geqCO2/km
2.5 MJ/km
vehicle stage fuel stage resource stage
350
2.0 1.5 1.0
200 150 100 50 0
0.5
-50
0.0 93#gasoline
BE corn
BE cassava BE sugar grass A
93#gasoline
BE corn
BE cassava BE sugar grass B
Figure 3.Bioethanol WTW (a) fossil energy use (b) GHG emissions per km
If unit yield of a certain route could be enhanced and consumptions in each stage (cultivation, fertilization, extraction) could be reduced, the energy input and output would be able to achieve a balance. Furthermore, by-products percentage improvement will lead to a similar result. The typical fossil energy use comparison of biodiesel between China and USA was 360kJ/MJ versus 190kJ/MJ, while that of GHG emissions was 32g/MJ to 18g/MJ, which reflected enormous difference [7]. When derived the avoided CO2 indicator of bioethanol relative to the land area used, China is the only
2108
Li Lu and Jingsong Zhou / Energy Procedia 61 (2014) 2105 – 2108
country which resulted in negative value compared to America and Britain (Fig.4). The dominating reason was unreasonable energy structure (coal dominated) and a high proportion of chemical fertilizer utilize in developing countries. avoided CO2
avoided CO2 (kg/ha.a)
4500 3000 1500 0 -1500 China corn
USA corn Britain wheat straw
Figure 4. Avoided GHG emissions for different bio-ethanol systems
4. Conclusion Current sustainable biofuel is an effective alternative to relieve the intensive pressure of fossil fuel supply (5.1%~21.4%) and a potential application of pollution reduction, especially for the countries with abundant coal and scarce petroleum. Environmental fertilizer technology would obviously promote biofuel competitiveness on account to N2O emission effect caused by fertilization especially nitrogenous fertilizer. Furthermore, specific yield enhancement would result in an improved scenario. Through increasing unit yield, decreasing consumptions in planting and chemical process and improving by-product percentage, the GHG emissions would acquire a superior manifestation. Acknowledgements The project is supported by the National Key Project of Fundamental Research on Biomass to Highgrade Fuel (2013CB228100). References [1] Dong Jinning, Ma Xiaoqian. Life cycle assessment on biodiesel production[J]. Modern Chem Industry, 2007, 27(9): 59-63. [2] Xing Aihua, Ma Jie, Zhang Yinghao, Wang Yao, Life cycle assessment of economy for biodiesel[J]. Journal of Tsinghua University (Sci&Tech), 2010, 50(6): 923-927 [3] Hu Zhiyuan, Tan Piqiang, Lou Diming, dong Yaoqing, Assessment of life cycle energy consumption and emissions for several kinds of feedstock based biodiesel [J]. Nuclear science and techniques, 2006, 22(11): 141-146 [4] Zhang Yanli, Gao Xinxing, Wang Aihua, Zhao lixin, Life-cycle assessment for Chinese fuel ethanol demonstration projects [J]. Renewable energy resources, 2009, 27(6):63-68 [5] Ou Xunmin, Zhang Xiliang, Chang Shiyan, Guo Wangfang, LCA of bio-ethanol and bio-diesel pathways in China[J]. Acta energia solaris sinica. 2010, 31(10):1246-1249 [6] Harro von Blottnitz, Mary Ann Curran. A review of assessments conducted on bio-ethanol as a transportation fuel from a net energy, greenhouse gas, and environmental life cycle perspective [J]. Cleaner Production, 15(2007):607-619 [7] Carraretto C, Macor A, Mirandola A, et al.. Biodiesel as alternative fuel: Experimental analysis and energetic evaluations[J]. Energy, 29 (2004): 2195~2211.
ScienceDirect Energy Procedia 61 (2014) 2105 – 2108
The 6th International Conference on Applied Energy – ICAE2014
A review of environmental assessments on liquid biofuels in China Li Lua, Jingsong Zhoua* a
State Key Laboratory of clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
Abstract Liquid vehicle fuel from biomass is an effective alternative to relieve the intensive pressure of fossil energy depletion and greenhouse gas(GHG) emissions. To ensure optimal biomass-derived liquid fuels production, the environmental effects is necessary to be taken into account in regard to the production system. This paper provides a review of analysis of vehicle fuel in terms of two types of primary biofuels (bioethanol and biodiesel) in China via life cycle assessment (LCA) technique in China to ascertain material and energy flow. The methodology utilized was WTW (well to wheel) module and pathways including soybean, jatropha, waste oil, corn, cassava and sugar grass. Combined with energy utilization and GHG indicators, several recommendations of biofuel production and policy were proposed. © by Elsevier Ltd. This an open Ltd. access article under the CC BY-NC-ND license ©2014 2014Published The Authors. Published by isElsevier (http://creativecommons.org/licenses/by-nc-nd/3.0/). Selection and/or peer-review under responsibility of ICAE Peer-review under responsibility of the Organizing Committee of ICAE2014
Keywords: Bioethanol; Biodiesel; LCA; GHG emissions
1. Introduction The heavy dependence of fossil-based oil and growing crude oil price have forced many countries to pay attention to searching a renewable effective alternative to relieve the intensive pressure. As one of the indispensable parts of renewable energy, biomass is the potential precursor to produce biofuels due to its abundant resources and enormous potential which can be directly converted into carbon liquid fuels. Meanwhile, an amount of CO2 is absorbed during biomass growth process through photosynthesis, which makes a dramatic contribution to climate change mitigation. Conventional biofuel includes biodiesel (refers to vegetable oil such as rap oil, jatropha curcas oil and waste oil), bioethanol (from sugar crops and lignocellulosic materials), dimethyl ether (from woody crops),
* Corresponding author. Tel.: +86-571-87952041; fax: +86-571-87951616. E-mail address: Zhoujs@ zju.edu.cn.
1876-6102 © 2014 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/). Peer-review under responsibility of the Organizing Committee of ICAE2014 doi:10.1016/j.egypro.2014.12.086
2106
Li Lu and Jingsong Zhou / Energy Procedia 61 (2014) 2105 – 2108
pure plant oil (generally refers to rapeseed) and so on. Most of the present life-cycle analyses (LCA) researches on biofuel system were performed in America and European countries, while few relative studies were conducted in developing countries. However, different countries have unique resources and climatic environment, which causes essential data and GHG emissions unable to currently quote and consult. In China the majority of LCA researches on vehicle liquid biofuels had been developed in Tsinghua University, Tongji University, Shanghai Jiaotong University groups. This article summarizes the development of local LCAs of liquid biofuels in China. LCA of soybean biodiesel investigated by Dong [1], Jatropha and waste oil biodiesel studied by Xin [2], rapeseed and bark biodiesel reported by Hu [3] all reflected positive environmental influence on CO2 emissions. On the other hand, LCA of cassava bioethanol studied by Hu, corn bioethanol investigated by Zhang [4] and comprehensive analysis by Ou [5] demonstrated the potential of bioethanol as an alternative biofuel. Basic data in this research are cited reports above. 2. System boundary in this study In the field of vehicle fuel LCA analysis, the international common technology approached is WTW analysis which contains WTP (well to pump) stage and PTW (pump to wheel) stage. Both of the two stages comprehend EC (energy consumption) and GHG (greenhouse gas). The flow chart displayed in Fig.1 reveals a generic biofuel life cycle scheme [6]. E, C, X respectively means energy flow, carbon flow and emissions to the environment. WTP includes raw materials cultivation, storage, transportation, distribution and fuel production (stage A, B, C, D), while PTW includes downstream fuel combustion process in vehicle’s engine (stage E).
Figure 1.material flow and environmental interventions across the life cycle stages in a biofuel system
3. Key results from assessments 6 primary industrial routes are discussed below. The total fossil energy use and GHG emissions of each type of biodiesel and bioethanol are shown in the graphs as well as the proportions of 3 main substages including resource, fuel and vehicle stage. Because the assumption of low proportion bioethanol (E10) is infinitely similar to gasoline, as well as BD5 biodiesel fuel to traditional diesel, E85 bioethanol fuel utilized FFV (Flexible Fuel Vehicles) technology and BD20 biodiesel utilized DICI (Direct Injection Compression Ignition) technology were discussed. To high proportion of bioethanol E85 (Fig.2), the fossil energy consumption mainly depends on the
2107
Li Lu and Jingsong Zhou / Energy Procedia 61 (2014) 2105 – 2108
raw materials cultivation including stewing and fermentation. On the other hand, all biomass routes reveal undersized reduction in vehicle stage. To combine bioethanol and other vehicle fuel at the optimal ratio is considered as a good choice for a terrific benefit. In contrast to widespread belief, GHG emission of bioethanol exceeds traditional petroleum fuel. In spite of carbon fixation effect during biomass growth, massive CO2 and N2O emission owing to coal using in producing process and agricultural chemical fertilizer in China which offset a large proportion of fixation. vehicle stage fuel stage resource stage
3.0 2.5
vehicle stage fuel stage resource stage
250 200 geqCO2/km
MJ/km
2.0 1.5 1.0
150 100 50
0.5 0
0.0
0#diesel BD soybean BD jatrophaBD waste oil
0#diesel BD soybean BD jatrophaBD waste oil A
B
Figure 2.Biodiesel WTW (a) fossil energy use (b) GHG emissions per km
There is no directly petroleum consumption in the biodiesel production process, which leads to a conspicuous decline of fossil consumption. However, finite biodiesel proportion limits saving scale (Fig.3). Similar to bioethanol, GHG emission of biodiesel doesn’t reflect much predominance over traditional diesel route on account of N2O and the residue of oil extraction. In addition, considering biodiesel as an alternative to boiler fuel is a remarkable choice of GHG emission according to a higher substitution amount. vehicle stage fuel stage resource stage
4.0 3.5
300
3.0
250 geqCO2/km
2.5 MJ/km
vehicle stage fuel stage resource stage
350
2.0 1.5 1.0
200 150 100 50 0
0.5
-50
0.0 93#gasoline
BE corn
BE cassava BE sugar grass A
93#gasoline
BE corn
BE cassava BE sugar grass B
Figure 3.Bioethanol WTW (a) fossil energy use (b) GHG emissions per km
If unit yield of a certain route could be enhanced and consumptions in each stage (cultivation, fertilization, extraction) could be reduced, the energy input and output would be able to achieve a balance. Furthermore, by-products percentage improvement will lead to a similar result. The typical fossil energy use comparison of biodiesel between China and USA was 360kJ/MJ versus 190kJ/MJ, while that of GHG emissions was 32g/MJ to 18g/MJ, which reflected enormous difference [7]. When derived the avoided CO2 indicator of bioethanol relative to the land area used, China is the only
2108
Li Lu and Jingsong Zhou / Energy Procedia 61 (2014) 2105 – 2108
country which resulted in negative value compared to America and Britain (Fig.4). The dominating reason was unreasonable energy structure (coal dominated) and a high proportion of chemical fertilizer utilize in developing countries. avoided CO2
avoided CO2 (kg/ha.a)
4500 3000 1500 0 -1500 China corn
USA corn Britain wheat straw
Figure 4. Avoided GHG emissions for different bio-ethanol systems
4. Conclusion Current sustainable biofuel is an effective alternative to relieve the intensive pressure of fossil fuel supply (5.1%~21.4%) and a potential application of pollution reduction, especially for the countries with abundant coal and scarce petroleum. Environmental fertilizer technology would obviously promote biofuel competitiveness on account to N2O emission effect caused by fertilization especially nitrogenous fertilizer. Furthermore, specific yield enhancement would result in an improved scenario. Through increasing unit yield, decreasing consumptions in planting and chemical process and improving by-product percentage, the GHG emissions would acquire a superior manifestation. Acknowledgements The project is supported by the National Key Project of Fundamental Research on Biomass to Highgrade Fuel (2013CB228100). References [1] Dong Jinning, Ma Xiaoqian. Life cycle assessment on biodiesel production[J]. Modern Chem Industry, 2007, 27(9): 59-63. [2] Xing Aihua, Ma Jie, Zhang Yinghao, Wang Yao, Life cycle assessment of economy for biodiesel[J]. Journal of Tsinghua University (Sci&Tech), 2010, 50(6): 923-927 [3] Hu Zhiyuan, Tan Piqiang, Lou Diming, dong Yaoqing, Assessment of life cycle energy consumption and emissions for several kinds of feedstock based biodiesel [J]. Nuclear science and techniques, 2006, 22(11): 141-146 [4] Zhang Yanli, Gao Xinxing, Wang Aihua, Zhao lixin, Life-cycle assessment for Chinese fuel ethanol demonstration projects [J]. Renewable energy resources, 2009, 27(6):63-68 [5] Ou Xunmin, Zhang Xiliang, Chang Shiyan, Guo Wangfang, LCA of bio-ethanol and bio-diesel pathways in China[J]. Acta energia solaris sinica. 2010, 31(10):1246-1249 [6] Harro von Blottnitz, Mary Ann Curran. A review of assessments conducted on bio-ethanol as a transportation fuel from a net energy, greenhouse gas, and environmental life cycle perspective [J]. Cleaner Production, 15(2007):607-619 [7] Carraretto C, Macor A, Mirandola A, et al.. Biodiesel as alternative fuel: Experimental analysis and energetic evaluations[J]. Energy, 29 (2004): 2195~2211.