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Life-cycle assessment of Fischer–Tropsch products from biosyngas
Renewable Energy 59 (2013) 229e236
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Renewable Energy journal homepage: www.elsevier.com/locate/renene
Life-cycle assessment of FischereTropsch products from biosyngas Diego Iribarren a, *, Ana Susmozas a, Javier Dufour a, b a b
Systems Analysis Unit, Instituto IMDEA Energía. 28935 e Móstoles, Spain Department of Chemical and Energy Technology, ESCET, Rey Juan Carlos University. 28933 e Móstoles, Spain
a r t i c l e i n f o
a b s t r a c t
Article history: Received 6 August 2012 Accepted 1 April 2013 Available online 30 April 2013
This article addresses the life-cycle assessment of an energy conversion system for the coproduction of fuels and electricity from a gasification-based biosyngas feedstock via FischereTropsch synthesis coupled with a combined-cycle process. Inventory data obtained mainly through process simulation are used to evaluate the environmental performance of the system in terms of abiotic depletion, global warming, ozone layer depletion, photochemical oxidant formation, land competition, acidification, and eutrophication. Furthermore, the cumulative non-renewable energy demand of the system is quantified and used in the calculation of the life-cycle energy balance of the system, which is found to be positive. Biosyngas generation arises as the main source of impact, with a much higher contribution than the rest of processes (production of catalysts, waste treatment, etc.). Electricity, diesel, gasoline and surplus hydrogen are the products of the system. The environmental profiles of these bioproducts are calculated and compared with those of fossil diesel, rapeseed biodiesel, soybean biodiesel, fossil gasoline, corn bioethanol, steam-methane reforming hydrogen, and the EU electrical grid. Overall, the bioproducts from the evaluated system are found to be promising alternatives to current energy products from a life-cycle environmental perspective. Ó 2013 Elsevier Ltd. All rights reserved.
Keywords: Biofuel Electricity Environmental impact Process simulation Syngas
1. Introduction Current research in the energy field aims at conceiving and developing sustainable processes and systems that lead to a favourable performance from a combined economic, social and environmental perspective. In this sense, environmental sustainability should be understood as a step towards economic profitability and as a response to the growing social concern on the environmental impact generated by anthropogenic activities. The energy sector is considered to be one of the main sources of environmental impact. This applies to both the transport subsector and the electricity subsector. Increased efforts are required to find alternative energy sources due to environmental concerns, energy insecurity, the continuous increase in fossil fuel prices, and the growing energy demand [1]. In the future, renewable energy sources are expected to play a leading role in dealing with these issues [2,3]. Research on renewable energy systems focuses not only on the development of new systems but also on the sustainable application of well-known processes. For instance, while the Fischere
* Corresponding author. Tel.: þ34 91 7371119. E-mail addresses: [email protected], [email protected] (D. Iribarren). 0960-1481/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.renene.2013.04.002
Tropsch (FT) synthesis was developed in the 1920s as a chemical process for the production of liquid hydrocarbons from a mixture of CO and H2 called syngas, the interest in this process has recently increased since it is considered to be a promising biofuel generation pathway that can be coupled with combined-cycle strategies to coproduce electricity from renewable resources [4,5]. The syngas used in FT systems for the coproduction of bioelectricity and biofuels comes from renewable sources and it is often called biosyngas. Lignocellulosic biomass gasification is one of the main processes studied for biosyngas generation. It is the thermochemical conversion of lignocellulosic biomass at elevated temperature (500e1400 C) in a gasification medium such as air, oxygen and/or steam to produce a gaseous fuel (biosyngas) which can be used to produce electricity and/or heat as well as in the synthesis of various products such as ammonia, methanol, hydrogen, and FT fuels [6,7]. However, the use of a biosyngas feedstock does not guarantee an advantageous environmental performance of FT systems from a life-cycle perspective. In this respect, comprehensive analyses are needed to evaluate the environmental suitability of a system. LifeCycle Assessment (LCA) is a well-defined methodology to assess the environmental aspects and potential impacts associated with a product [8,9]. The use of LCA for the evaluation of energy conversion systems has been highly encouraged because of its holistic nature [10].
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Fig. 1. Simplified block diagram of the FT system (dotted arrows indicate intermediate flows).
This article undertakes the LCA of a reference FT system for the coproduction of biofuels and bioelectricity through FT synthesis coupled with a combined-cycle process. The present study addresses the environmental characterization of this FT system and the comparison of the environmental profiles of the FT products with those of alternative products. 2. Material and methods 2.1. Goal and scope The goal of this study is to environmentally characterize an FT system for the coproduction of synthetic biofuels and
electricity. The FT system evaluated is shown in Fig. 1. The hypothetical plant considered in this study annually processes 9.4$108 N m3 of biosyngas to produce diesel, gasoline, electricity and a surplus of hydrogen, corresponding to the processing of 1500 dry metric tonnes of lignocellulosic biomass per day in a gasification plant. A cradle-to-gate approach is followed for the LCA of the FT system. The generation of the biosyngas feedstock is assumed to take place as described by Jungbluth et al. [11] for the production of synthetic gas from mixed wood chips using a fluidized-bed gasifier. The molar composition of the biosyngas is 50.4% N2, 13.7% H2O, 5.6% H2, 14.0% CO, 12.5% CO2, 3.1% CH4, and 0.7% other hydrocarbons. Capital goods are excluded from the analysis.
Fig. 2. Simplified diagram of the FT plant.
D. Iribarren et al. / Renewable Energy 59 (2013) 229e236 Table 1 Main inventory data of the FT system (FU: 10,000 N m3 of biosyngas). Inputs
Outputs
From the technosphere
To the technosphere
Biosyngas 10,000.00 WGS catalyst 0.02 FT catalyst 0.27 Water 6380.07 From the environment
N m3 kg kg kg
Products FT biodiesel FT biogasoline FT biohydrogen FT bioelectricity
Air
t
Wastes to treatment Wastewater 504.19 WGS catalyst 0.02 FT catalyst 0.27 To the environment
17.27
Emissions to water Water Emissions to air Biogenic CO2 Water Oxygen Nitrogen
98.90 41.83 0.34 1.21
kg kg kg MWh kg kg kg
1211.97
kg
5772.91 6478.66 1813.20 19,650.86
kg kg kg kg
The functional unit (FU) of the LCA of the system is 10,000 N m3 of biosyngas fed to the plant. The main operations carried out in the FT plant are shown in Fig. 2. In the plant, the biosyngas feedstock is conditioned. First, it is heated and compressed to 200 C and 30 bar [12]. Thereafter, a fraction of the biosyngas undergoes a one-stage water gas shift (WGS) process to increase the H2/CO molar ratio of the FT reactor input to approximately 2 [13], while the remaining fraction by-passes the WGS process. After the WGS reactor, which uses a CueZn catalyst, the resulting stream is cooled and used to produce hydrogen in a pressure swing adsorption (PSA) unit with 85% efficiency (32 C and 28.5 bar) [12]. The hydrogen produced is partly used in the refining area. At the end of the conditioning stage, the PSA off-gas, the biosyngas fraction which by-passed the WGS process and the required hydrogen are mixed to feed the FT reactor. In the FT reactor, CO and H2 react to produce a hydrocarbon mixture according to the following simplified reaction:
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nCO þ (n þ m/2)H2 / CnHm þ nH2O. This tubular fixed-bed reactor uses a Co catalyst and operates at 200 C and 25 bar [13]. Because the FT process is highly exothermic, the reactor is cooled using water so that steam is produced and used later for power generation. The hydrocarbon products involve two streams: wax (C20þ) and FT raw products (unconverted syngas and C1eC20 hydrocarbons). The latter is cooled to 40 C in order to condense the C5þ fraction. This fraction and the wax stream are processed in the refining area, which is operated similarly to a conventional refinery, producing diesel, gasoline and fuel gas (C1eC4). The unreacted syngas and the fuel gas are completely combusted in a gas turbine for power generation (39 MW). The hot gas stream leaving the gas turbine is used in a heat recovery steam generator (HRSG) linked to a steam cycle (18 MW) with three pressure levels (87/31/2.4 bar) [14]. This combined cycle makes the plant energetically self-sufficient [5].
2.2. Data acquisition Table 1 presents the main inventory data of the system. These data derive from a process simulation in Aspen PlusÒ [15]. A tubular fixed-bed FT reactor with 40% CO conversion is considered. For simulation purposes, the product from the FT reactor is assumed to consist only of paraffins [12]. The refining area is modelled according to literature data [12]. Fig. 3 shows the simulation diagram of the whole FT plant. Data regarding the generation of the biosyngas feedstock and data for background processes are taken from the ecoinvent database [11,16]. Background processes include waste management [17] and the production of chemicals [18] and energy carriers [19]. As presented in Table 1, the FT system produces diesel, gasoline, surplus hydrogen, and electricity. When evaluating this type of multifunctional systems, an allocation approach has to be followed in order to distribute the life-cycle inventory data and environmental burdens among the different products [20]. Due to the different nature of the products (material/energy) and the commercial nature of the system, an allocation approach based on economic values is used in this study. Economic data are taken from
Fig. 3. Simulation diagram of the FT plant.
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Table 2 Calculation of economic allocation factors.
Table 4 Characterized results per process (FU: 10,000 N m3 of biosyngas).
Product
Amount per FU
V/FU
Economic factor
FT FT FT FT
98.90 kg 41.83 kg 0.34 kg 1.21 MWh
147.42 81.08 2.72 260.63
0.30 0.16 0.01 0.53
biodiesel biogasoline biohydrogen bioelectricity
available literature [1,7,21]. Table 2 shows the calculation of the allocation factors used in the LCA of the FT system. 3. Results and discussion 3.1. Environmental characterization and life-cycle energy balance The life-cycle inventory of the FT system is implemented into SimaPro 7 [22]. Seven environmental impact potentials are evaluated: abiotic depletion (ADP), global warming (GWP), ozone layer depletion (ODP), photochemical oxidant formation (POFP), land competition (LC), acidification (AP), and eutrophication (EP). They are evaluated using the CML method [23]. Additionally, the cumulative non-renewable fossil and nuclear energy demand (CED) of the system is quantified according to Hischier et al. [24]. Table 3 presents the results of the environmental characterization of the FT system and the distribution of the environmental impacts among the products according to the economic allocation factors calculated in Section 2.2. The CED indicator of the total system (6655 MJ/FU in Table 3) is used as the energy input value in the calculation of the life-cycle energy balance of the FT system [1,6,7]. The energy output is estimated as the sum of the bioelectricity output (1.21 MWh/FU in Table 1, i.e., 4356 MJ/FU) and the biofuel output based on the lower heating values of gasoline, diesel and hydrogen [1,6]. The total biofuel output is 6130 MJ/FU (4232 MJ/FU for diesel, 1857 MJ/FU for gasoline and 41 MJ/FU for hydrogen). Thus, the energy output is 10,486 MJ and the life-cycle energy balance (energy balance ¼ energy output energy input) results in 3831 MJ/FU. This positive result indicates a favourable life-cycle energy performance of the FT system. In order to assess the origin of the impacts, Table 4 presents separately the contribution of biosyngas production and the contribution of the remaining processes (production of chemicals, waste management, direct emissions, etc.). The production of the biosyngas feedstock is found to be the main source of impact, with contribution percentages above 97% in all categories. Hence, improvement actions to enhance the environmental performance of the FT system should focus on biosyngas generation. According to a previous study on biomass gasification [6], efforts should be made in order to minimize the biomass feedstock demand, improve the logistical planning for biomass supply and optimize the electricity demand of the syngas cleaning stage.
ADP (kg Sb eq) GWP (kg CO2 eq) ODP (kg CFC-11 eq) POFP (kg C2H4 eq) LC (m2a) AP (kg SO2 eq) EP (kg PO3 4 eq) CED (MJ eq)
Biosyngas production
Rest of processes
Total system
2.06 296.23 3.43 105 0.10 3131.81 2.16 0.66 6592.94
0.02 3.70 2.32 107 1.00 103 0.32 0.03 0.02 62.25
2.08 299.93 3.46 105 0.10 3132.14 2.19 0.68 6655.19
Biosyngas production has to be excluded from the assessment when special attention is to be paid to the rest of the processes involved in the FT system. Fig. 4 shows the contribution of the different processes to each of the categories when taking into account all processes except biosyngas production. In such case, the production of the FT catalyst (useful life of the catalyst: 3 years) dominates all impact potentials except POFP and CED, with percentage contributions ranging from 35% (EP) to 66% (AP). Water production arises as the main source of POFP (52%) and CED (49%), also contributing significantly to the remaining categories. Additionally, wastewater treatment is found to be a relevant contributor to EP (32%) and ODP (7%), and the production of the WGS catalyst (useful life: 3 years) contributes significantly to EP (9%), POFP (7%), and AP (6%). Research in the field of FT catalysts could secondarily result in an enhanced environmental performance of the FT process. 3.2. Comparison of the environmental profiles This section compares the environmental performance of the FT bioproducts with that of alternative products. The objective of this section is to give insights on the environmental suitability of the FT products from a life-cycle perspective. In addition to GWP, which is the most commonly evaluated indicator [25], the following impact potentials are compared [23,24]: ADP, OPD, POFP, LC, AP, EP, and CED. The environmental profile of FT biodiesel is compared with that of conventional low-sulphur diesel from crude oil [26] and rapeseed and soybean biodiesel fuels produced via vegetable oil transesterification [11]. The comparison is performed on the basis of 1 GJ of potential energy supply. A well-to-wheels approach is followed, including not only fuel production but also fuel use [27]. The emissions from the fuel use phase are taken into account according to EMEP/EEA [28]. As can be observed in Fig. 5, FT biodiesel is found to be the best option in terms of GWP and POFP. Furthermore, its ADP, ODP and CED results are clearly lower than those of conventional fossil diesel, and its EP is better than that of soybean and rapeseed biodiesel fuels. LC arises as the only category for which FT biodiesel shows the worst performance, due to high land requirements for the considered lignocellulosic biomass feedstock
Table 3 Characterized results of the system and breakdown per product (FU: 10,000 N m3 of biosyngas).
ADP (kg Sb eq) GWP (kg CO2 eq) ODP (kg CFC-11 eq) POFP (kg C2H4 eq) LC (m2a) AP (kg SO2 eq) EP (kg PO43 eq) CED (MJ eq)
FT biodiesel
FT biogasoline
FT biohydrogen
FT bioelectricity
Total system
0.62 89.98 1.04$105 0.03 939.64 0.66 0.20 1996.56
0.33 47.99 5.53$106 0.02 501.14 0.35 0.11 1064.83
0.02 3.00 3.46$107 0.00 31.32 0.02 0.01 66.55
1.10 158.96 1.83$105 0.05 1660.03 1.16 0.36 3527.25
2.08 299.93 3.46$105 0.10 3132.14 2.19 0.68 6655.19
D. Iribarren et al. / Renewable Energy 59 (2013) 229e236
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Fig. 4. Process contribution to the environmental impacts (biosyngas generation excluded).
[11]. A more favourable LC performance would be attained if the lignocellulosic feedstock came from short-rotation plantations [6]. A well-to-wheels perspective is also followed to compare the environmental profiles of FT biogasoline, conventional fossil gasoline [26] and corn bioethanol (biological conversion) [11] on the basis of 1 GJ of energy supply. In this case, in addition to the lower heating value of each fuel, the efficiency of the engines is considered: 35% for flexible-fuel vehicles using 100% bioethanol (E100) and 30% for gasoline vehicles [7]. As can be observed in Fig. 6, FT biogasoline shows the best performance in terms of ODP, GWP, ADP, and CED. However, conventional fossil gasoline results in lower
impacts regarding EP, AP and, especially, LC. Corn bioethanol is recommended only in terms of POFP. The Directive 2009/28/EC on the promotion of the use of energy from renewable sources establishes sustainability criteria for biofuels [29,30]. In particular, from 1 January 2018, the greenhouse gas (GHG) emission saving from the use of biofuels shall be at least 60% for biofuels and bioliquids produced in installations in which production started on or after 1 January 2017 [29]. When compared to the corresponding conventional fossil fuels, GHG emission savings of 74% and 70% are estimated for FT biodiesel and biogasoline, respectively. Hence, these FT biofuels are found to meet the 60% criterion.
Fig. 5. Relative comparison of the well-to-wheels environmental impacts of different diesel fuels.
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Fig. 6. Relative comparison of the well-to-wheels environmental impacts of FT biogasoline, conventional fossil gasoline and corn bioethanol.
Hydrogen is another biofuel derived from the FT system under study. However, it should be noted that the system is not oriented towards hydrogen production, but towards the coproduction of electricity and synthetic biofuels (gasoline and diesel), with surplus hydrogen as a minor product from the system (rather than a target product). In Fig. 7, the environmental profile of FT biohydrogen is compared with that of conventional hydrogen produced through steam-methane-reforming (SMR) [31]. While FT hydrogen is found to be a good choice in terms of ADP, GWP, ODP and CED, SMR hydrogen shows more favourable results for the remaining
categories (LC, EP, AP and POFP). When compared to conventional SMR hydrogen, a GHG saving of 32% is calculated for FT biohydrogen. Lastly, the environmental profile of FT bioelectricity is compared with that associated with the EU electrical grid [19]. As can be observed in Fig. 8, FT bioelectricity leads to much more favourable results than the EU electrical grid for all impact categories, with the exception of LC (linked to higher land requirements for biomass production). The absolute values used for all the comparisons made in this section are provided in the Appendix. Overall, the FT bioproducts
Fig. 7. Relative comparison of the environmental impacts of FT biohydrogen and SMR hydrogen.
D. Iribarren et al. / Renewable Energy 59 (2013) 229e236
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Fig. 8. Relative comparison of the environmental impacts of FT bioelectricity and the EU electrical grid.
evaluated herein are found to be promising alternatives to current energy products.
4. Conclusions An LCA study was conducted to assess the environmental performance of an energy conversion system for the coproduction of biofuels and electricity from biosyngas through FT synthesis coupled with a combined-cycle process. The environmental characterization of the system led to identify biosyngas generation as the main contributor to the selected environmental impacts. Furthermore, from a life-cycle energy perspective, the FT system was found to be feasible (positive life-cycle energy balance). The FT system under study produces electricity, diesel, gasoline and a surplus of hydrogen from a gasification-based biosyngas feedstock. The environmental profiles of these FT bioproducts were compared with those of alternative energy products (viz., fossil diesel, rapeseed biodiesel, soybean biodiesel, fossil gasoline, corn bioethanol, SMR hydrogen, and the EU electrical grid). The environmental suitability of the FT products was found to depend on the impact categories evaluated. In particular, significantly high GHG savings were found for each of the FT products. On the other hand, they presented more detrimental results for LC, due to high land requirements for biomass production. Overall, FT products are expected to contribute favourably to the future renewable energy system.
Acknowledgements This research has been supported by the Regional Government of Madrid (S2009/ENE-1743), the Spanish Ministry of Economy and Competitiveness (CTQ2011-28216-C02-02), and Fundación Iberdrola (II Research Grants in Energy and the Environment).
Appendix A Table A.1 provides the characterized results calculated for the comparison among FT biodiesel, conventional fossil diesel, rapeseed biodiesel, and soybean biodiesel. Similarly, Table A.2 presents the values used in the environmental comparison among FT biogasoline, conventional fossil gasoline, and corn bioethanol. The values used when comparing the environmental impacts of FT biohydrogen and SMR hydrogen and of FT bioelectricity and the EU electrical grid are shown in Tables A.3 and A.4, respectively.
Table A.1 Well-to-wheels environmental profile of different diesel fuels (1 GJ of potential energy output).
ADP (kg Sb eq) GWP (kg CO2 eq) ODP (kg CFC-11 eq) POFP (kg C2H4 eq) LC (m2a) AP (kg SO2 eq) EP (kg PO3 4 eq) CED (MJ eq)
FT biodiesel
Fossil diesel
Rapeseed biodiesel
Soybean biodiesel
0.15 21.29 2.45 106 9.05 103 222.04 0.30 0.08 471.78
0.54 83.34 1.06 105 9.85 103 0.01 0.26 0.05 1235.67
0.23 56.89 3.64 106 2.81 102 109.00 0.47 0.31 518.78
0.12 23.55 1.67 106 4.68 102 158.31 0.28 0.29 251.54
Table A.2 Well-to-wheels environmental profile of FT biogasoline, conventional fossil gasoline and corn bioethanol (1 GJ of energy supply).
ADP (kg Sb eq) GWP (kg CO2 eq) ODP (kg CFC-11 eq) POFP (kg C2H4 eq) LC (m2a) AP (kg SO2 eq) EP (kg PO3 4 eq) CED (MJ eq)
FT biogasoline
Fossil gasoline
Corn bioethanol
0.60 87.92 9.93 106 0.18 899.43 1.04 0.30 1911.12
1.82 294.53 3.48 105 0.18 0.03 0.95 0.16 4153.18
0.94 200.24 1.75 105 0.02 266.34 1.28 1.47 2140.48
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Table A.3 Environmental profile of FT biohydrogen and SMR hydrogen (1 GJ of potential energy output).
ADP (kg Sb eq) GWP (kg CO2 eq) ODP (kg CFC-11 eq) POFP (kg C2H4 eq) LC (m2a) AP (kg SO2 eq) EP (kg PO3 4 eq) CED (MJ eq)
FT biohydrogen
SMR hydrogen
0.51 73.50 8.47 106 2.47 102 767.55 0.54 0.17 1630.90
0.91 107.65 1.24 105 5.00 103 0.08 0.08 0.02 1886.10
Table A.4 Environmental profile of FT bioelectricity and the EU electrical grid (1 GJ).
ADP (kg Sb eq) GWP (kg CO2 eq) ODP (kg CFC-11 eq) POFP (kg C2H4 eq) LC (m2a) AP (kg SO2 eq) EP (kg PO3 4 eq) CED (MJ eq)
FT bioelectricity
EU electrical grid
0.25 36.49 4.21 106 1.23 102 381.09 0.27 0.08 809.74
0.99 133.26 5.62 106 2.34 102 1.27 0.60 0.39 2713.46
References [1] Iribarren D, Peters JF, Dufour J. Life cycle assessment of transportation fuels from biomass pyrolysis. Fuel 2012;97:812e21. [2] International Energy Agency. World energy outlook. Paris: OECD/IEA; 2011. [3] Serrano DP, Dufour J, Iribarren D. On the feasibility of producing hydrogen with net carbon fixation by the decomposition of vegetable and microalgal oils. Energ Environ Sci 2012;5:6126e35. [4] Larson ED, Jin H, Celik FE. Large-scale gasification-based coproduction of fuels and electricity from switchgrass. Biofuel Bioprod Bior 2009;3:174e94. [5] Liu G, Larson ED, Williams RH, Kreutz TG, Guo X. Making FischereTropsch fuels and electricity from coal and biomass: performance and cost analysis. Energ Fuel 2011;25:415e37. [6] Iribarren D, Susmozas A, Petrakopoulou F, Dufour J. Environmental and exergetic evaluation of hydrogen production via lignocellulosic biomass gasification. Biomass Bioenerg, submitted for publication. [7] González-García S, Iribarren D, Susmozas A, Dufour J, Murphy RJ. Life cycle assessment of two alternative bioenergy systems involving Salix spp. biomass: bioethanol production and power generation. Appl Energ 2012;95:111e22. [8] ISO 14040:2006. Environmental management e life cycle assessment e principles and framework. International Organization for Standardization; 2006. [9] ISO 14044:2006. Environmental management e life cycle assessment e requirements and guidelines. International Organization for Standardization; 2006. [10] Dufour J, Iribarren D. Life cycle assessment of biodiesel production from free fatty acid-rich wastes. Renew Energ 2012;38:155e62. [11] Jungbluth N, Chudacoff M, Dauriat A, Dinkel F, Doka G, Faist Emmenegger M, et al. Life cycle inventories of bioenergy. ecoinvent report no. 17, v2.0. Dübendorf: Swiss Centre for Life Cycle Inventories; 2007.
[12] Swanson RM, Satrio JA, Brown RC, Platon A, Hsu DD. Techno-economic analysis of biofuels production based on gasification. National Renewable Energy Laboratory, US Department of Energy. Available from:; 2010. [13] Hamelinck CN, Faaij APC, den Uil H, Boerrigter H. Production of FT transportation fuels from biomass; technical options, process analysis and optimisation, and development potential. Utrecht University. Available from: ; 2003. [14] Spath P, Aden A, Eggeman T, Ringer M, Wallace B, Jechura J. Biomass to hydrogen production detailed design and economics utilizing the Battelle Columbus Laboratory indirectly-heated gasifier. National Renewable Energy Laboratory, US Department of Energy. Available from: ; 2005. [15] Aspen Technology, Aspen PlusÒ. Available from: [accessed 13 April 2012]. [16] Frischknecht R, Jungbluth N, Althaus HJ, Doka G, Heck T, Hellweg S, et al. Overview and methodology, ecoinvent report no. 1, v2.0. Dübendorf: Swiss Centre for Life Cycle Inventories; 2007. [17] Doka G. Life cycle inventories of waste treatment services, ecoinvent report no. 13, v2.0. Dübendorf: Swiss Centre for Life Cycle Inventories; 2007. [18] Althaus HJ, Chudacoff M, Hischier R, Jungbluth N, Osses M, Primas A. Life cycle inventories of chemicals, ecoinvent report no. 8, v2.0. Dübendorf: Swiss Centre for Life Cycle Inventories; 2007. [19] Dones R, Bauer C, Bolliger R, Burger B, Faist Emmenegger M, Frischknecht R, et al. Life cycle inventories of energy systems: results for current systems in Switzerland and other UCTE countries, ecoinvent report no. 5, v2.0. Dübendorf: Swiss Centre for Life Cycle Inventories; 2007. [20] Ekvall T, Finnveden G. Allocation in ISO 14041 e a critical review. J Clean Prod 2001;9:197e208. [21] Spanish Ministry of Industry, Energy and Tourism. Available from: [accessed 16 April 2012]. [22] Goedkoop M, de Schryver A, Oele M, Durksz S, de Roest D. Introduction to LCA with SimaPro 7. the Netherlands: PRé Consultants; 2010. [23] Guinée JB, Gorrée M, Heijungs R, Huppes G, Kleijn R, de Koning A, et al. Life cycle assessment e an operational guide to the ISO standards. Leiden: Centre of Environmental Science; 2001. [24] Hischier R, Weidema B, Althaus HJ, Bauer C, Doka G, Dones R, et al. Implementation of life cycle impact assessment methods, ecoinvent report no. 3, v2.2. Dübendorf: Swiss Centre for Life Cycle Inventories; 2010. [25] Pereira de Souza S, Pacca S, Turra de Ávila M, Borges JLB. Greenhouse gas emissions and energy balance of palm oil biofuel. Renew Energ 2010;35:2552e61. [26] Jungbluth N. Erdöl, ecoinvent report no. 6-IV, v2.0. Dübendorf: Swiss Centre for Life Cycle Inventories; 2007. [27] Brinkman N, Wang M, Weber T, Darlington T. Well-to-wheels analysis of advanced fuel/vehicle systems e a North American study of energy use, greenhouse gas emissions, and criteria pollutant emissions. Argonne’s Transportation Technology Research and Development Center, US Department of Energy. Available from: ; 2005. [28] EMEP/EEA air pollutant emission inventory guidebook; 2009. Available from: . [29] Directive 2009/28/EC of the European Parliament and of the Council of 23 April 2009 on the promotion of the use of energy from renewable sources and amending and subsequently repealing Directives 2001/77/EC and 2003/30/EC. Off J Eur Union. Available from: ; 5 June 2009. [30] Thamsiriroj T, Murphy JD. The impact of the life cycle analysis methodology on whether biodiesel produced from residues can meet the EU sustainability criteria for biofuel facilities constructed after 2017. Renew Energ 2011;36:50e63. [31] Dufour J, Serrano DP, Gálvez JL, Moreno J, García C. Life cycle assessment of processes for hydrogen production e environmental feasibility and reduction of greenhouse gases emissions. Int J Hydrogen Energy 2009;34:1370e6.
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Life-cycle assessment of FischereTropsch products from biosyngas Diego Iribarren a, *, Ana Susmozas a, Javier Dufour a, b a b
Systems Analysis Unit, Instituto IMDEA Energía. 28935 e Móstoles, Spain Department of Chemical and Energy Technology, ESCET, Rey Juan Carlos University. 28933 e Móstoles, Spain
a r t i c l e i n f o
a b s t r a c t
Article history: Received 6 August 2012 Accepted 1 April 2013 Available online 30 April 2013
This article addresses the life-cycle assessment of an energy conversion system for the coproduction of fuels and electricity from a gasification-based biosyngas feedstock via FischereTropsch synthesis coupled with a combined-cycle process. Inventory data obtained mainly through process simulation are used to evaluate the environmental performance of the system in terms of abiotic depletion, global warming, ozone layer depletion, photochemical oxidant formation, land competition, acidification, and eutrophication. Furthermore, the cumulative non-renewable energy demand of the system is quantified and used in the calculation of the life-cycle energy balance of the system, which is found to be positive. Biosyngas generation arises as the main source of impact, with a much higher contribution than the rest of processes (production of catalysts, waste treatment, etc.). Electricity, diesel, gasoline and surplus hydrogen are the products of the system. The environmental profiles of these bioproducts are calculated and compared with those of fossil diesel, rapeseed biodiesel, soybean biodiesel, fossil gasoline, corn bioethanol, steam-methane reforming hydrogen, and the EU electrical grid. Overall, the bioproducts from the evaluated system are found to be promising alternatives to current energy products from a life-cycle environmental perspective. Ó 2013 Elsevier Ltd. All rights reserved.
Keywords: Biofuel Electricity Environmental impact Process simulation Syngas
1. Introduction Current research in the energy field aims at conceiving and developing sustainable processes and systems that lead to a favourable performance from a combined economic, social and environmental perspective. In this sense, environmental sustainability should be understood as a step towards economic profitability and as a response to the growing social concern on the environmental impact generated by anthropogenic activities. The energy sector is considered to be one of the main sources of environmental impact. This applies to both the transport subsector and the electricity subsector. Increased efforts are required to find alternative energy sources due to environmental concerns, energy insecurity, the continuous increase in fossil fuel prices, and the growing energy demand [1]. In the future, renewable energy sources are expected to play a leading role in dealing with these issues [2,3]. Research on renewable energy systems focuses not only on the development of new systems but also on the sustainable application of well-known processes. For instance, while the Fischere
* Corresponding author. Tel.: þ34 91 7371119. E-mail addresses: [email protected], [email protected] (D. Iribarren). 0960-1481/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.renene.2013.04.002
Tropsch (FT) synthesis was developed in the 1920s as a chemical process for the production of liquid hydrocarbons from a mixture of CO and H2 called syngas, the interest in this process has recently increased since it is considered to be a promising biofuel generation pathway that can be coupled with combined-cycle strategies to coproduce electricity from renewable resources [4,5]. The syngas used in FT systems for the coproduction of bioelectricity and biofuels comes from renewable sources and it is often called biosyngas. Lignocellulosic biomass gasification is one of the main processes studied for biosyngas generation. It is the thermochemical conversion of lignocellulosic biomass at elevated temperature (500e1400 C) in a gasification medium such as air, oxygen and/or steam to produce a gaseous fuel (biosyngas) which can be used to produce electricity and/or heat as well as in the synthesis of various products such as ammonia, methanol, hydrogen, and FT fuels [6,7]. However, the use of a biosyngas feedstock does not guarantee an advantageous environmental performance of FT systems from a life-cycle perspective. In this respect, comprehensive analyses are needed to evaluate the environmental suitability of a system. LifeCycle Assessment (LCA) is a well-defined methodology to assess the environmental aspects and potential impacts associated with a product [8,9]. The use of LCA for the evaluation of energy conversion systems has been highly encouraged because of its holistic nature [10].
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Fig. 1. Simplified block diagram of the FT system (dotted arrows indicate intermediate flows).
This article undertakes the LCA of a reference FT system for the coproduction of biofuels and bioelectricity through FT synthesis coupled with a combined-cycle process. The present study addresses the environmental characterization of this FT system and the comparison of the environmental profiles of the FT products with those of alternative products. 2. Material and methods 2.1. Goal and scope The goal of this study is to environmentally characterize an FT system for the coproduction of synthetic biofuels and
electricity. The FT system evaluated is shown in Fig. 1. The hypothetical plant considered in this study annually processes 9.4$108 N m3 of biosyngas to produce diesel, gasoline, electricity and a surplus of hydrogen, corresponding to the processing of 1500 dry metric tonnes of lignocellulosic biomass per day in a gasification plant. A cradle-to-gate approach is followed for the LCA of the FT system. The generation of the biosyngas feedstock is assumed to take place as described by Jungbluth et al. [11] for the production of synthetic gas from mixed wood chips using a fluidized-bed gasifier. The molar composition of the biosyngas is 50.4% N2, 13.7% H2O, 5.6% H2, 14.0% CO, 12.5% CO2, 3.1% CH4, and 0.7% other hydrocarbons. Capital goods are excluded from the analysis.
Fig. 2. Simplified diagram of the FT plant.
D. Iribarren et al. / Renewable Energy 59 (2013) 229e236 Table 1 Main inventory data of the FT system (FU: 10,000 N m3 of biosyngas). Inputs
Outputs
From the technosphere
To the technosphere
Biosyngas 10,000.00 WGS catalyst 0.02 FT catalyst 0.27 Water 6380.07 From the environment
N m3 kg kg kg
Products FT biodiesel FT biogasoline FT biohydrogen FT bioelectricity
Air
t
Wastes to treatment Wastewater 504.19 WGS catalyst 0.02 FT catalyst 0.27 To the environment
17.27
Emissions to water Water Emissions to air Biogenic CO2 Water Oxygen Nitrogen
98.90 41.83 0.34 1.21
kg kg kg MWh kg kg kg
1211.97
kg
5772.91 6478.66 1813.20 19,650.86
kg kg kg kg
The functional unit (FU) of the LCA of the system is 10,000 N m3 of biosyngas fed to the plant. The main operations carried out in the FT plant are shown in Fig. 2. In the plant, the biosyngas feedstock is conditioned. First, it is heated and compressed to 200 C and 30 bar [12]. Thereafter, a fraction of the biosyngas undergoes a one-stage water gas shift (WGS) process to increase the H2/CO molar ratio of the FT reactor input to approximately 2 [13], while the remaining fraction by-passes the WGS process. After the WGS reactor, which uses a CueZn catalyst, the resulting stream is cooled and used to produce hydrogen in a pressure swing adsorption (PSA) unit with 85% efficiency (32 C and 28.5 bar) [12]. The hydrogen produced is partly used in the refining area. At the end of the conditioning stage, the PSA off-gas, the biosyngas fraction which by-passed the WGS process and the required hydrogen are mixed to feed the FT reactor. In the FT reactor, CO and H2 react to produce a hydrocarbon mixture according to the following simplified reaction:
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nCO þ (n þ m/2)H2 / CnHm þ nH2O. This tubular fixed-bed reactor uses a Co catalyst and operates at 200 C and 25 bar [13]. Because the FT process is highly exothermic, the reactor is cooled using water so that steam is produced and used later for power generation. The hydrocarbon products involve two streams: wax (C20þ) and FT raw products (unconverted syngas and C1eC20 hydrocarbons). The latter is cooled to 40 C in order to condense the C5þ fraction. This fraction and the wax stream are processed in the refining area, which is operated similarly to a conventional refinery, producing diesel, gasoline and fuel gas (C1eC4). The unreacted syngas and the fuel gas are completely combusted in a gas turbine for power generation (39 MW). The hot gas stream leaving the gas turbine is used in a heat recovery steam generator (HRSG) linked to a steam cycle (18 MW) with three pressure levels (87/31/2.4 bar) [14]. This combined cycle makes the plant energetically self-sufficient [5].
2.2. Data acquisition Table 1 presents the main inventory data of the system. These data derive from a process simulation in Aspen PlusÒ [15]. A tubular fixed-bed FT reactor with 40% CO conversion is considered. For simulation purposes, the product from the FT reactor is assumed to consist only of paraffins [12]. The refining area is modelled according to literature data [12]. Fig. 3 shows the simulation diagram of the whole FT plant. Data regarding the generation of the biosyngas feedstock and data for background processes are taken from the ecoinvent database [11,16]. Background processes include waste management [17] and the production of chemicals [18] and energy carriers [19]. As presented in Table 1, the FT system produces diesel, gasoline, surplus hydrogen, and electricity. When evaluating this type of multifunctional systems, an allocation approach has to be followed in order to distribute the life-cycle inventory data and environmental burdens among the different products [20]. Due to the different nature of the products (material/energy) and the commercial nature of the system, an allocation approach based on economic values is used in this study. Economic data are taken from
Fig. 3. Simulation diagram of the FT plant.
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Table 2 Calculation of economic allocation factors.
Table 4 Characterized results per process (FU: 10,000 N m3 of biosyngas).
Product
Amount per FU
V/FU
Economic factor
FT FT FT FT
98.90 kg 41.83 kg 0.34 kg 1.21 MWh
147.42 81.08 2.72 260.63
0.30 0.16 0.01 0.53
biodiesel biogasoline biohydrogen bioelectricity
available literature [1,7,21]. Table 2 shows the calculation of the allocation factors used in the LCA of the FT system. 3. Results and discussion 3.1. Environmental characterization and life-cycle energy balance The life-cycle inventory of the FT system is implemented into SimaPro 7 [22]. Seven environmental impact potentials are evaluated: abiotic depletion (ADP), global warming (GWP), ozone layer depletion (ODP), photochemical oxidant formation (POFP), land competition (LC), acidification (AP), and eutrophication (EP). They are evaluated using the CML method [23]. Additionally, the cumulative non-renewable fossil and nuclear energy demand (CED) of the system is quantified according to Hischier et al. [24]. Table 3 presents the results of the environmental characterization of the FT system and the distribution of the environmental impacts among the products according to the economic allocation factors calculated in Section 2.2. The CED indicator of the total system (6655 MJ/FU in Table 3) is used as the energy input value in the calculation of the life-cycle energy balance of the FT system [1,6,7]. The energy output is estimated as the sum of the bioelectricity output (1.21 MWh/FU in Table 1, i.e., 4356 MJ/FU) and the biofuel output based on the lower heating values of gasoline, diesel and hydrogen [1,6]. The total biofuel output is 6130 MJ/FU (4232 MJ/FU for diesel, 1857 MJ/FU for gasoline and 41 MJ/FU for hydrogen). Thus, the energy output is 10,486 MJ and the life-cycle energy balance (energy balance ¼ energy output energy input) results in 3831 MJ/FU. This positive result indicates a favourable life-cycle energy performance of the FT system. In order to assess the origin of the impacts, Table 4 presents separately the contribution of biosyngas production and the contribution of the remaining processes (production of chemicals, waste management, direct emissions, etc.). The production of the biosyngas feedstock is found to be the main source of impact, with contribution percentages above 97% in all categories. Hence, improvement actions to enhance the environmental performance of the FT system should focus on biosyngas generation. According to a previous study on biomass gasification [6], efforts should be made in order to minimize the biomass feedstock demand, improve the logistical planning for biomass supply and optimize the electricity demand of the syngas cleaning stage.
ADP (kg Sb eq) GWP (kg CO2 eq) ODP (kg CFC-11 eq) POFP (kg C2H4 eq) LC (m2a) AP (kg SO2 eq) EP (kg PO3 4 eq) CED (MJ eq)
Biosyngas production
Rest of processes
Total system
2.06 296.23 3.43 105 0.10 3131.81 2.16 0.66 6592.94
0.02 3.70 2.32 107 1.00 103 0.32 0.03 0.02 62.25
2.08 299.93 3.46 105 0.10 3132.14 2.19 0.68 6655.19
Biosyngas production has to be excluded from the assessment when special attention is to be paid to the rest of the processes involved in the FT system. Fig. 4 shows the contribution of the different processes to each of the categories when taking into account all processes except biosyngas production. In such case, the production of the FT catalyst (useful life of the catalyst: 3 years) dominates all impact potentials except POFP and CED, with percentage contributions ranging from 35% (EP) to 66% (AP). Water production arises as the main source of POFP (52%) and CED (49%), also contributing significantly to the remaining categories. Additionally, wastewater treatment is found to be a relevant contributor to EP (32%) and ODP (7%), and the production of the WGS catalyst (useful life: 3 years) contributes significantly to EP (9%), POFP (7%), and AP (6%). Research in the field of FT catalysts could secondarily result in an enhanced environmental performance of the FT process. 3.2. Comparison of the environmental profiles This section compares the environmental performance of the FT bioproducts with that of alternative products. The objective of this section is to give insights on the environmental suitability of the FT products from a life-cycle perspective. In addition to GWP, which is the most commonly evaluated indicator [25], the following impact potentials are compared [23,24]: ADP, OPD, POFP, LC, AP, EP, and CED. The environmental profile of FT biodiesel is compared with that of conventional low-sulphur diesel from crude oil [26] and rapeseed and soybean biodiesel fuels produced via vegetable oil transesterification [11]. The comparison is performed on the basis of 1 GJ of potential energy supply. A well-to-wheels approach is followed, including not only fuel production but also fuel use [27]. The emissions from the fuel use phase are taken into account according to EMEP/EEA [28]. As can be observed in Fig. 5, FT biodiesel is found to be the best option in terms of GWP and POFP. Furthermore, its ADP, ODP and CED results are clearly lower than those of conventional fossil diesel, and its EP is better than that of soybean and rapeseed biodiesel fuels. LC arises as the only category for which FT biodiesel shows the worst performance, due to high land requirements for the considered lignocellulosic biomass feedstock
Table 3 Characterized results of the system and breakdown per product (FU: 10,000 N m3 of biosyngas).
ADP (kg Sb eq) GWP (kg CO2 eq) ODP (kg CFC-11 eq) POFP (kg C2H4 eq) LC (m2a) AP (kg SO2 eq) EP (kg PO43 eq) CED (MJ eq)
FT biodiesel
FT biogasoline
FT biohydrogen
FT bioelectricity
Total system
0.62 89.98 1.04$105 0.03 939.64 0.66 0.20 1996.56
0.33 47.99 5.53$106 0.02 501.14 0.35 0.11 1064.83
0.02 3.00 3.46$107 0.00 31.32 0.02 0.01 66.55
1.10 158.96 1.83$105 0.05 1660.03 1.16 0.36 3527.25
2.08 299.93 3.46$105 0.10 3132.14 2.19 0.68 6655.19
D. Iribarren et al. / Renewable Energy 59 (2013) 229e236
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Fig. 4. Process contribution to the environmental impacts (biosyngas generation excluded).
[11]. A more favourable LC performance would be attained if the lignocellulosic feedstock came from short-rotation plantations [6]. A well-to-wheels perspective is also followed to compare the environmental profiles of FT biogasoline, conventional fossil gasoline [26] and corn bioethanol (biological conversion) [11] on the basis of 1 GJ of energy supply. In this case, in addition to the lower heating value of each fuel, the efficiency of the engines is considered: 35% for flexible-fuel vehicles using 100% bioethanol (E100) and 30% for gasoline vehicles [7]. As can be observed in Fig. 6, FT biogasoline shows the best performance in terms of ODP, GWP, ADP, and CED. However, conventional fossil gasoline results in lower
impacts regarding EP, AP and, especially, LC. Corn bioethanol is recommended only in terms of POFP. The Directive 2009/28/EC on the promotion of the use of energy from renewable sources establishes sustainability criteria for biofuels [29,30]. In particular, from 1 January 2018, the greenhouse gas (GHG) emission saving from the use of biofuels shall be at least 60% for biofuels and bioliquids produced in installations in which production started on or after 1 January 2017 [29]. When compared to the corresponding conventional fossil fuels, GHG emission savings of 74% and 70% are estimated for FT biodiesel and biogasoline, respectively. Hence, these FT biofuels are found to meet the 60% criterion.
Fig. 5. Relative comparison of the well-to-wheels environmental impacts of different diesel fuels.
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Fig. 6. Relative comparison of the well-to-wheels environmental impacts of FT biogasoline, conventional fossil gasoline and corn bioethanol.
Hydrogen is another biofuel derived from the FT system under study. However, it should be noted that the system is not oriented towards hydrogen production, but towards the coproduction of electricity and synthetic biofuels (gasoline and diesel), with surplus hydrogen as a minor product from the system (rather than a target product). In Fig. 7, the environmental profile of FT biohydrogen is compared with that of conventional hydrogen produced through steam-methane-reforming (SMR) [31]. While FT hydrogen is found to be a good choice in terms of ADP, GWP, ODP and CED, SMR hydrogen shows more favourable results for the remaining
categories (LC, EP, AP and POFP). When compared to conventional SMR hydrogen, a GHG saving of 32% is calculated for FT biohydrogen. Lastly, the environmental profile of FT bioelectricity is compared with that associated with the EU electrical grid [19]. As can be observed in Fig. 8, FT bioelectricity leads to much more favourable results than the EU electrical grid for all impact categories, with the exception of LC (linked to higher land requirements for biomass production). The absolute values used for all the comparisons made in this section are provided in the Appendix. Overall, the FT bioproducts
Fig. 7. Relative comparison of the environmental impacts of FT biohydrogen and SMR hydrogen.
D. Iribarren et al. / Renewable Energy 59 (2013) 229e236
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Fig. 8. Relative comparison of the environmental impacts of FT bioelectricity and the EU electrical grid.
evaluated herein are found to be promising alternatives to current energy products.
4. Conclusions An LCA study was conducted to assess the environmental performance of an energy conversion system for the coproduction of biofuels and electricity from biosyngas through FT synthesis coupled with a combined-cycle process. The environmental characterization of the system led to identify biosyngas generation as the main contributor to the selected environmental impacts. Furthermore, from a life-cycle energy perspective, the FT system was found to be feasible (positive life-cycle energy balance). The FT system under study produces electricity, diesel, gasoline and a surplus of hydrogen from a gasification-based biosyngas feedstock. The environmental profiles of these FT bioproducts were compared with those of alternative energy products (viz., fossil diesel, rapeseed biodiesel, soybean biodiesel, fossil gasoline, corn bioethanol, SMR hydrogen, and the EU electrical grid). The environmental suitability of the FT products was found to depend on the impact categories evaluated. In particular, significantly high GHG savings were found for each of the FT products. On the other hand, they presented more detrimental results for LC, due to high land requirements for biomass production. Overall, FT products are expected to contribute favourably to the future renewable energy system.
Acknowledgements This research has been supported by the Regional Government of Madrid (S2009/ENE-1743), the Spanish Ministry of Economy and Competitiveness (CTQ2011-28216-C02-02), and Fundación Iberdrola (II Research Grants in Energy and the Environment).
Appendix A Table A.1 provides the characterized results calculated for the comparison among FT biodiesel, conventional fossil diesel, rapeseed biodiesel, and soybean biodiesel. Similarly, Table A.2 presents the values used in the environmental comparison among FT biogasoline, conventional fossil gasoline, and corn bioethanol. The values used when comparing the environmental impacts of FT biohydrogen and SMR hydrogen and of FT bioelectricity and the EU electrical grid are shown in Tables A.3 and A.4, respectively.
Table A.1 Well-to-wheels environmental profile of different diesel fuels (1 GJ of potential energy output).
ADP (kg Sb eq) GWP (kg CO2 eq) ODP (kg CFC-11 eq) POFP (kg C2H4 eq) LC (m2a) AP (kg SO2 eq) EP (kg PO3 4 eq) CED (MJ eq)
FT biodiesel
Fossil diesel
Rapeseed biodiesel
Soybean biodiesel
0.15 21.29 2.45 106 9.05 103 222.04 0.30 0.08 471.78
0.54 83.34 1.06 105 9.85 103 0.01 0.26 0.05 1235.67
0.23 56.89 3.64 106 2.81 102 109.00 0.47 0.31 518.78
0.12 23.55 1.67 106 4.68 102 158.31 0.28 0.29 251.54
Table A.2 Well-to-wheels environmental profile of FT biogasoline, conventional fossil gasoline and corn bioethanol (1 GJ of energy supply).
ADP (kg Sb eq) GWP (kg CO2 eq) ODP (kg CFC-11 eq) POFP (kg C2H4 eq) LC (m2a) AP (kg SO2 eq) EP (kg PO3 4 eq) CED (MJ eq)
FT biogasoline
Fossil gasoline
Corn bioethanol
0.60 87.92 9.93 106 0.18 899.43 1.04 0.30 1911.12
1.82 294.53 3.48 105 0.18 0.03 0.95 0.16 4153.18
0.94 200.24 1.75 105 0.02 266.34 1.28 1.47 2140.48
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Table A.3 Environmental profile of FT biohydrogen and SMR hydrogen (1 GJ of potential energy output).
ADP (kg Sb eq) GWP (kg CO2 eq) ODP (kg CFC-11 eq) POFP (kg C2H4 eq) LC (m2a) AP (kg SO2 eq) EP (kg PO3 4 eq) CED (MJ eq)
FT biohydrogen
SMR hydrogen
0.51 73.50 8.47 106 2.47 102 767.55 0.54 0.17 1630.90
0.91 107.65 1.24 105 5.00 103 0.08 0.08 0.02 1886.10
Table A.4 Environmental profile of FT bioelectricity and the EU electrical grid (1 GJ).
ADP (kg Sb eq) GWP (kg CO2 eq) ODP (kg CFC-11 eq) POFP (kg C2H4 eq) LC (m2a) AP (kg SO2 eq) EP (kg PO3 4 eq) CED (MJ eq)
FT bioelectricity
EU electrical grid
0.25 36.49 4.21 106 1.23 102 381.09 0.27 0.08 809.74
0.99 133.26 5.62 106 2.34 102 1.27 0.60 0.39 2713.46
References [1] Iribarren D, Peters JF, Dufour J. Life cycle assessment of transportation fuels from biomass pyrolysis. Fuel 2012;97:812e21. [2] International Energy Agency. World energy outlook. Paris: OECD/IEA; 2011. [3] Serrano DP, Dufour J, Iribarren D. On the feasibility of producing hydrogen with net carbon fixation by the decomposition of vegetable and microalgal oils. Energ Environ Sci 2012;5:6126e35. [4] Larson ED, Jin H, Celik FE. Large-scale gasification-based coproduction of fuels and electricity from switchgrass. Biofuel Bioprod Bior 2009;3:174e94. [5] Liu G, Larson ED, Williams RH, Kreutz TG, Guo X. Making FischereTropsch fuels and electricity from coal and biomass: performance and cost analysis. Energ Fuel 2011;25:415e37. [6] Iribarren D, Susmozas A, Petrakopoulou F, Dufour J. Environmental and exergetic evaluation of hydrogen production via lignocellulosic biomass gasification. Biomass Bioenerg, submitted for publication. [7] González-García S, Iribarren D, Susmozas A, Dufour J, Murphy RJ. Life cycle assessment of two alternative bioenergy systems involving Salix spp. biomass: bioethanol production and power generation. Appl Energ 2012;95:111e22. [8] ISO 14040:2006. Environmental management e life cycle assessment e principles and framework. International Organization for Standardization; 2006. [9] ISO 14044:2006. Environmental management e life cycle assessment e requirements and guidelines. International Organization for Standardization; 2006. [10] Dufour J, Iribarren D. Life cycle assessment of biodiesel production from free fatty acid-rich wastes. Renew Energ 2012;38:155e62. [11] Jungbluth N, Chudacoff M, Dauriat A, Dinkel F, Doka G, Faist Emmenegger M, et al. Life cycle inventories of bioenergy. ecoinvent report no. 17, v2.0. Dübendorf: Swiss Centre for Life Cycle Inventories; 2007.
[12] Swanson RM, Satrio JA, Brown RC, Platon A, Hsu DD. Techno-economic analysis of biofuels production based on gasification. National Renewable Energy Laboratory, US Department of Energy. Available from: