1. Introduction - Firenze University Press

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There are many alternatives for hydrogen production from liquid and gaseous hydrocarbons such as thermo-catalytic cracking, steam reforming and plasma arc decomposition [6]. Moreover, from solid feedstocks, H2 can be produced through the gasification of coal, biomass, petroleum coke, or solid waste. Nearly 50% of the global hydrogen is generated through natural gas reforming, 30% from oil/naphtha reforming, 18% from gasification, 3.9% from water electrolysis and 0.1% from other sources [6]. Coal gasification is a promising way to obtain H2 because the production techniques have achieved maturity and are commercially available. Moreover, the relatively high global resources of coal and its widespread availability worldwide make his resource a promising option [8]. In addition, this process has environmental advantages: 1) SOX can be processed into a marketable by-product, 2) ash can be liquefied into a slag that passes toxicity issues, 3) CO2 can be held and recovered in the loops of gasifiers for remediation/reuse, and 4) gasifiers can be modified such that wide product flexibility is easily obtained [9]. The steam-oxygen gasification (SOG) process is the only commercialized method of gasification used to manufacture several chemicals from coal. The Wabash River Coal Gasification Repowering Plant, near to West Terre Haute, Indiana (USA), has proven since November of 1995 the successful application of H2 production by coal gasification. This plant uses H2, from SOG process, in a gas combustion turbine generator to produce electricity. It generates around 292 MW of electric power. With this production, this plant is one of the largest single-train gasification combined cycle plants operating commercially in the world [10]. Table 1. Ultimate and proximal analysis of Guaduas Formation’s coal (HHV = 30,634 kJ kg -1 ) data taken from [11] w/w (%) Proximate analysis Moisture 4.12 Ash 5.61 Fixed carbon 67.8 Volatiles Ultimate analysis* 22.4 Carbon 70.7 Hydrogen 5.29 Nitrogen 1.58 Chloride 2.35 Sulfur 1.57 Ash 5.61 Oxygen 7.91 *dry basis Two thirds of the total fuel fossil reserves in the world are coal and will last for more than 150 years [12]. Coal is in fact one of the main resources in Colombia. It is estimated that 0.7% of the world proved coal reserves, which corresponds to 6.7 Pg (6700 Mt), are in Colombian territory [11]. Colombia has several coal formations over its territory. The main ones are: Cerrejón, Los Cuervos, Guaduas, Umir, Cerrito, and Amagá. The Guaduas formation’s coal, located in the center of Colombia, is characterized by a bituminous coal with high volatiles and low sulfur and ash content (Table 1). which is advantageous for a gasification use [13]. Therefore, coal from Guaduas formation was selected for this study. Aspen Plus® has been widely employed to simulate chemical processes in a wide number of fields including but not limiting to the petroleum industry, chemical processes and biomass gasification. It also can be used to model steady state processes handling solid carbons materials in multiple unit operations. Therefore, many coal and biomass conversion processes have been simulated using Aspen Plus as integrated coal gasification combined cycle (IGCC) power plant [14], biomass 341
gasification [15], hybrid biomass gasification [16], hydrogen production from biomass gasification [17], and coal combustion [18]. Additionally, proximate and ultimate analysis properties of solid coal are specified to provide a fairly rigorous simulation of the gasifier performance [19]. The purpose of this study is to simulate and analyze through Aspen Plus the coal gasification process and subsequent processing for the hydrogen-rich syngas production, using the most commercialized and referenced available technologies. A sensitive analysis of the variables with high impact over the key process parameters is performed to identify important process efficiency improvements (yield and energy) and environmental performance. 1.1. Gasification Technologies There are three main types of coal gasification technologies: fixed-bed, fluidized-bed, and entrained-flow gasification. Table 2 summarizes key parameters for these gasification technologies. Among these processes, entrained-flow gasification is the commercially preferred technology due to its versatility and lower environmental impact [4, 13, 14, 20] . Table 2. Main features of industrial gasifiers Gasifier type Main features Entrained-flow Particle size below 0.1 mm High operating temperature (> 1473 K) High operating pressure (3 to 12 MPa) High oxidant demand Short residence time (0.5 to 10 s) Ash is removed as molten slag Fluidized-bed Particle size between 6 and 10 mm Uniform temperature distribution High operating temperature (1073 to 1323 K) Lower carbon conversion Ash is removed as slag or dry Fixed-bed Coarse particles (6 to 50 mm) Low operating temperature (698 to 1088 K) Low oxidant demand Resident time above 600 s Ash is removed as slag or dry Many commercial technologies in entrained-flow gasification reactors are available nowadays such as: GE/Texaco, Shell, and ConocoPhillips. GE/Texaco and Shell entrained-flow gasification reactors are used in about 75% of the gasification plants throughout the world [13]. In this study, the GE/Texaco gasifier has been selected because: 1) it is profusely discussed in the literature, 2) high coal conversion is reported, and 3) the resulting syngas is free of tars, phenols and paraffins. Additionally, the GE/Texaco gasifier is leader worldwide with 145 reactors in commercial operation and 85 in planning, engineering, or under contract agreements in 15 different countries [21]. 2. Process Description In the SOG process, coal-water slurry is gasified with O2 from the air separation unit (ASU) to produce a gas mainly composed by CO and H2. It is necessary to increase the H2 concentration by a 342
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Proceedings e report 90
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ECOS 2012 : the 25 th International
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Advisory Committee (Track Organizer
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The 25 th ECOS Conference 1987-2012
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VOLUME VI CONTENT VI. 1 CARBON CAPT
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-----------------------------------
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» Personal transportation energy c
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» Excess enthalpies of second gene
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VOLUME IV IV . 1 - FLUID DYNAMICS A
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» Exergy analysis and genetic algo
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» Optimal lighting control strateg
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» Stability and limit cycles in an
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PROCEEDINGS OF ECOS 2012 - THE 25 T
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Fig. 2. The exergy destruction of M
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ineffectiveness of the catalyst, in
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[ P EXmth EX SNG] ESR F where EXm
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Fuel inputkW 728221 203771 237719 3
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Not only at desined Rc (the ratio o
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4. DISCUSSION The graphic exergy an
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Figure 9(a) illustrates the energy
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Engineering Technical Conferences &
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generally there are four kinds of m
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However, even under the off-design
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Fig. 3. 600MW supercritical coal-fi
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CO2 rich loading(molCO2/molMEA) 0.4
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Net efficiency (%) 40.28 30.29 26.4
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Fig. 11. Schematic diagram of heat
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28.67%. In addition, through heat i
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Applied Thermal Engineering 2010;30
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Abstract: PROCEEDINGS OF ECOS 2012
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Fig. 1. Solution diagram of „four
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K ~ K 1 eK 1a p K 1a iK mK
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Oxygen recovery rate, % 105 95 85 7
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Calculated optimal compressor press
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The net amount of the flue gas leav
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Figure 3. Idea for lignite drying b
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Energy efficiency, % 34,00 33,00 32
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points efficiency increase related
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Figure A1b. Thermoflex flow sheet o
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Figure A3a. Thermoflex flow sheet o
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Figure A4. Thermoflex flow sheet of
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2.1. Life Cycle Assessment 2.1.1. G
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these factors. A sensitivity analys
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methane slip contributes to 13% of
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As can be seen in Fig. 5 the impact
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References [1] Eurobserv’er, The
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in which CO2 is separated from H2,
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dimensions of water droplets and wa
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Temperature (°C) 8 7 6 5 4 3 2 1 0
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4. Conclusions In the present paper
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penalty, but without separate captu
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0.5 - 0.7 kg/kg, resulting typicall
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3.3 - Utilising waste heat All exis
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4.5 - Suomusjärvi olivine deposits
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material will change from a few % t
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Fig. 5 Schematic diagram of the PFB
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8. Combined SO2 capture and CO2 min
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Fig. 10 Carbonate- (left) and sulph
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[13] Ekdahl, E., Idman, H. Statemen
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HEAT Fig. 1. Scheme and main reacti
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(raw) materials pre-heating and AS
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Fig 3- Aspen Plus® model 110
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Table 4. Elemental and XRD analysis
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the ÅA CSM route. The content of M
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moisture - 0,2237 ash - 0,0876 LHV
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2.2 CFB plant For the current momen
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The CO2 emission factor which indic
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The CO2 emission factor calculated
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Appendix A Fig A.1. Simulation mode
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(b) Fig. A.2. Simulation model of C
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Table A.1. Calculated parameters at
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References [1] Pfaff I., Oexmann J.
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with a CC installation could be avo
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2.3. Basic CHP plant indices. The b
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3. Off-design calculations The main
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Fig. 6. CHP plant efficiency Fig. 7
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amount of steam delivered to the he
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[5] Lukowicz H., Mroncz M.: Analysi
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water removal is feasible by coolin
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Figure 2. Sketch of the suggested P
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a b Figure 5. a) Exergy balance of
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The basis of comparison of each met
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Figure 7a. Impact of S/CATR on PCU
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However, more energy duty is requir
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3.1. JACOBIAN-ASPEN Interface ASPEN
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Fig. 3. Triple Pressure Bottoming S
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As seen from Table 1, the mass flow
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4. Conclusion Fig. 5. Partial Emiss
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[19] Yantovski E., Shokotov M., Sho
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investigation and the developing of
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University of L’Aquila and German
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hydrogen combustion technology at d
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eversibility of a pre-treated synth
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Fig. 1. TG curves collected for spe
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(see Fig 5). Carbon dioxide uptake
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period is reduced to the first 15 c
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CO2 capture capacity up to 150 th c
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the way for biogas utilisation is t
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projectand is described in the foll
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4. Pilot plant tests In order to de
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Concerning the absorption reaction,
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with Regeneration (AwR), consists i
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[25] Aspen Plus 2004.1. Cambridge,
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systems for fuel drying waste strea
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heated in a heat exchanger placed i
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Fig. 2. Lower heating value of fuel
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Acknowledgements The results presen
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large amount of CO2 [1,5-7]. APCr a
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N 1 i ( x x i n 1 m ) 2.3. Carbon
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DTA analysis of the untreated APCrs
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Table 4. Relative Error (%) of the
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CaO HCl CaCl H O 193kJ / mol (
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[1] M. Fernández Bertos, S.J.R. Si
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2. Process development 2.1. Backgro
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to dissolve the chloride salts prec
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The remaining 25% (5 ml/min) of the
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Table 6. Experimental conversions o
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p p 1 1. 5 p H 1 1. 5 2O p mi
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Calculating from the Aspen Plus mod
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[11] Mattila, H.-P., Experimental s
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Mg2SiO4(s) + 2CO2(g) →2MgCO3(s) +
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(Mg/Fe) of the mineral rock, Mg-sil
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Figure 2. Effect of Mg/Fe ratio of
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Figure 4 shows that an increase in
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Figure 5. Process flow diagram of M
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2. Only cold utility is needed belo
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extraction process at 400 °C (~ 62
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Table A2. Extraction equations and
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[13] Teir S, Kuusik R, Fogelholm CJ
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In the area of coal technologies al
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Tabel 1. Characteristics quantities
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N m eT 4a ~ T cp T4a 1 ( K
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Auxiliary power rate of ASU, % 40 4
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[8] Buhre B.J.P., Elliott L.K., She
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1.1 - Cement Manufacturing The ceme
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2. Numerical model The purpose of t
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-0.309x15.77x2 2.085x3 240x4 12.53x
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Table 4 - Results of the optimizati
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1. Define the studied system (in th
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cycle) or a lignin extraction plant
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limiting factor for the maximum siz
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Table 5. Key data for the four ener
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Global CO 2 emissions [ktonnes/yr]
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for biofuels and the investment cos
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The possibility to capture CO2 from
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[17] Berglin N, Andersson L. Proces
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Therefore NL Agency (an agency of t
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1. Introduction - Firenze University Press

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