S.Francisco, California October 12-15, 2003 GASIFICATION TECHNOLOGIES 2003 COAL POWER PLANTS WITH CO2 CAPTURE: THE IGCC OPTION J.Davison - IEA Greenhouse Gas R&D Programme L.Bressan - R.M.Domenichini - Foster Wheeler Italiana
Summary Scope of the Study Bases of the Study Alternative IGCC Processing Schemes Performance Data Investment Cost Data Production Costs Conclusions 2020 IGCC
Scope of the Study The study investigates alternative power plants plant designs, based on coal gasification, with and without capture of the produced CO2 in order to determine the increase of the cost of the electricity due to the capture of the CO2. The primary purpose of this study is the evaluation of the tecnologies that can be used in these complex power generation schemes to optimize efficiency and capital cost and reduce, at the same time, emissions to the atmosphere.
Bases of the Study The reference plant has a capacity of 800 MWe Nominal and is fed with a typical coal having a low heating value (LHV) equal to 25870 kj/kg and a sulphur content equal to 1.1 % wt (dry ash free). The study is based on commercially available technologies and developing technologies close to commercialization, evaluating costs and performances of plants which can be presently engineered and built. After a preliminary evaluation where several alternatives have been considered, the study investigated 13 alternatives designs of the power generation plant, which differ for the gasification technology, the gasification pressure, the presence or not of shift step, the acid gas removal process. The site is a green field located in the NE coast of the Netherlands; with an average air temperature of 9 C and an average sea water temperature of 12 C.
Bases of the Study For each of the alternatives considered, the IGCC design capacity has been fixed to match the appetite of the selected gas turbines which are two General Electric frame 9FA. These gas turbines are representative of the current state of the art of large commercial gas turbines suitable for use with IGCC fuel gas. The IGCC complex main product is electric energy. By-products are: Sulphur (either liquid or solid) Carbon Dioxide for the alternatives recovering CO2 Solid by-products: slag, fly ash and filter cake, depending on gasification technology
Bases of the Study The overall gaseous emissions from the IGCC Complex referred to dry flue gas with 15% volume O2 shall not exceed the following limits: NOx (as NO2) : <= 80 mg/nm3 SOx (as SO2) : <= 10 mg/nm3 Particulate : <= 10 mg/nm3 CO : <= 50 mg/nm3 These limits are lower than those defined by the applicable European Directive and are set in order to minimize the emissions without penalize significantly the plant efficiency and the investment cost.
Bases of the Study ASU. The state of the art plants are based on cryogenic air separation. In most cases, 50% of the compressed air for the air separation unit (ASU) is extracted from the gas turbine during normal full load operation and the remaining 50% is provided by a separate electrically driven compressor. Pressurized nitrogen from the ASU is fed to gas turbine trough a booster compressor, to maximize the loading of the gas turbine and improve NOx reduction. For each case evaluated the integration degree has been optimized. Cases with CO2 capture assume CO2 compression at 110 bar but do not include transport and storage of CO2. Costs of CO2 storage depend greatly on local factors, such transport distance, the pipeline diameter and the type of storage reservoir.
Description of the process alternatives Gasification process Gasification pressure CO Shift CO2 capture AGR process a1 DFG-WHB low (36) no no MDEA a2 DFG-WHB high (61) no no MDEA b1 DFG-WHB low (36) sour yes Selexol b2 DFG-WHB low (36) clean yes Selexol b3 DFG-WHB low (36) sour yes(+h2s) MDEA b4 DFG-WHB high (61) sour yes Selexol c1 SFG-WQ high (65) no no Selexol c2 SFG-WQ high (65) sour no Selexol c3 SFG-WQ low (38) no no MDEA+AGE d1 SFG-WQ high (65) sour yes Selexol d2 SFG-WQ high (65) sour yes(+h2s) Selexol d3 SFG-WQ high (65) sour yes(low) Selexol d4 SFG-WQ low (38) sour yes Selexol
Performance Data Gasification process Coal (t/h) Cold Gas Efficienccy Gross Power Output (MWe) Aux.Consumpt ions (MWe) Net Power Output (MWe) Net Electrical Efficiency (%) a1 DFG-WHB 250,6 83,5 909,8 133,9 775,9 43,1 a2 DFG-WHB 252,1 83,0 895,0 146,7 748,3 41,3 b1 DFG-WHB 273,1 83,5 896,2 220,0 676,2 34,5 b2 DFG-WHB 274,6 83,5 875,0 223,7 651,3 33,0 b3 DFG-WHB 271,4 83,5 883,3 200,0 683,3 35,0 b4 DFG-WHB 271,9 83,5 879,2 240,3 638,9 32,7 c1 SFG-WQ 303,0 70,5 988,7 162,2 826,5 38,0 c2 SFG-WQ 327,6 70,5 1012,8 152,2 860,6 36,6 c3 SFG-WQ 300,9 71,0 954,3 154,4 799,9 37,0 d1 SFG-WQ 323,1 70,5 972,8 242,5 730,3 31,5 d2 SFG-WQ 323,2 70,5 979,9 237,6 742,3 32,0 d3 SFG-WQ 323,1 70,5 978,7 234,4 744,3 32,1 d4 SFG-WQ 320,4 71,0 942,1 237,1 705,0 30,6
Investment Costs The overall investment cost (+/- 25% accuracy) includes: direct materials including equipment and bulk materials construction, including mechanical erection, instrument and electrical installation, civil works and, where applicable, buildings and site preparation other costs, including temporary facilities, solvents, catalysts, chemicals, training, commissioning and start-up costs, spare parts, etc.. EPC services including Contractor s home office services and construction supervision land purchase, surveys technology fees contingencies (average 6,5%) The project is in accordance to the International and EU Standard Codes
Investment Cost Data Gasification process Air Separation MAIN IGCC SECTIONS INVESTMENT COSTS Process Units CO2 Compression Power Island Utilities Offsites Total Investment 10^6 Euro Specific Investment Euro/kW 10^6 Euro 10^6 Euro 10^6 Euro 10^6 Euro 10^6 Euro a1 DFG-WHB 106,0 480,0 0,0 365,0 113,0 1064,0 1372,0 a2 DFG-WHB 112,0 557,0 0,0 361,0 113,0 1143,0 1528,0 b1 DFG-WHB 112,0 636,0 23,0 363,0 124,0 1258,0 1860,0 b2 DFG-WHB 113,0 642,0 25,0 359,0 124,0 1262,0 1937,0 b3 DFG-WHB 112,0 561,0 26,0 361,0 121,0 1180,0 1726,0 b4 DFG-WHB 118,0 695,0 25,0 358,0 122,0 1317,0 2061,0 c1 SFG-WQ 128,0 360,0 0,0 363,0 130,0 981,0 1187,0 c2 SFG-WQ 131,0 400,0 0,0 366,0 135,0 1032,0 1199,0 c3 SFG-WQ 125,0 335,0 0,0 360,0 140,0 960,0 1200,0 d1 SFG-WQ 131,0 424,0 27,0 362,0 147,0 1092,0 1495,0 d2 SFG-WQ 131,0 382,0 27,0 362,0 147,0 1050,0 1414,0 d3 SFG-WQ 131,0 429,0 25,0 362,0 148,0 1095,0 1471,0 d4 SFG-WQ 129,0 455,0 27,0 359,0 147,0 1117,0 1585,0
Production Costs The following table provides the cost of electricity (C.O.E.) and the cost of the CO2 recovery associated for the cases designed for the capture of CO2. The following assumptions have been made: cost of coal: 1,5 Euro/GL (38,8 Euro /t) 7446 equivalent operating hours of IGCC fed by syngas at 100% capacity total investment cost as given above 10% discount rate on the investment cost over 25 operating years ratio Euro versus US dollar equal to 1 130 operators sulphur price 103 Euro/t working capital (30 days for coal and chemicals storage) insurance and local taxes 2% of installed costs
Production Costs The CO2 removal cost is calculated as follows: Delta Electric Power Cost Euro = Delta Specific CO2 Emission ton of CO2 captured Delta Electric Power Cost means the electric power cost of the alternative with CO2 capture minus the electric power cost of the corresponding alternative without the CO2 capture. The unit of measurement is Euro/kWh Delta Specific CO2 Emission means ratio (CO2 emission/power production) of the alternative with CO2 capture minus the ratio (CO2 emission/power production) of the corresponding alternative w/o CO2 capture. The unit of measurement is t CO2/kWh.
Cost of Electric Power Production Gasification process C.O.E (DCF=10%) cent/kwh Cost of CO2 (DCF=10%) Euro/t a1 DFG-WHB 4,8 ---- b1 DFG-WHB 6,3 24,2 b3 DFG-WHB 6,0 19,0 c1 SFG-WQ 4,5 ---- d1 SFG-WQ 5,6 16,5 d2 SFG-WQ 5,4 13,5 d3 SFG-WQ 5,3 15,2
Conclusions IGCC is a complex combination of different technologies. The primary purpose of the study was the evaluation of the technologies that can be used in an IGCC in order to optimize capital cost and efficiency and reduce, at the same time, emissions to the atmosphere. Efficiency and investment cost DFG-WHB based IGCC displays a superior coal to power efficiency The efficiency penalty for the CO2 capture is lower in the SFG-WG gasifier plant SFG-WQ based IGCC requires a lower investment given in Euro per kw In the calculation of cost of production of electricity, the SFG-WQ advantage in investment more than compensates the DFG-WHB advantage in efficiency resulting, at the conditions specified for the study, in a cost for electricity and a cost for CO2 recovery marginally inferior for the SFG-WQ
Conclusions However, it should be noted that the DFG-WHB technology based plant emits and capture less CO2 per kwh of electricity. To maintain the same absolute amount of CO2 emissions the SFG-WQ shall be designed for higher recovery which in turn will increase both plant and CO2 disposal costs. Nevertheless SFG-WQ is still likely the lowest cost option unless CO2 disposal is a major environmental concern Gasification pressure high pressure for the SFG-WQ technology low pressure for the DFG-WHB technology Shift conversion without CO2 capture there is no advantage to introduce a shift converter in an IGCC without CO2 capture unless a retrofit is foreseen in the near future
Conclusions Production of combined CO2 and H2S stream no doubt the common production of both CO2 and H2S is economically favoured. Only a disposal problems can change the situation. It s worthwhile to mention CO2 sour streams are already injected to enhance oil recovery. Sour shift versus clean shift the nature of the SFG-WQ makes the sour shift a must for the DFG-WHB technology the sour shift is still the most economical solution Environmental performance Th environmental performance of IGCC technology is far superior than of any other power producing technology known today based on fossil fuels. Further the impact on environment of IGCC is independent from the quality of feedstock, which permits to process in the IGCC the worst coals or residues and still meet the most severe limits
2020 IGCC with CO2 capture The 2020 plant should have the following features: dry feed, 2 stages entrained flow gasification product gas quench sour shift conversion physical solvent scrubbing acid gas removal 2020 gas turbine (G or H) once-trough supercritical HRSG ion transfer membrane air separation
ACKNOWLEDGEMENTS CHEVRONTEXACO (Slurry Feed Gasification with Water Quench) DOW (MDEA Technology) GENERAL ELECTRIC (9FA Gas turbines) JOHNSON MATTHEY CATALYSTS (Shift catalyst technology) SHELL (Dry Feed Gasification with Waste Heat recovery Boiler) SUD CHEMIE (Shift catalyst technology) UOP (Selexol technology)