1. SINTEF Energy Research Power cycles with CO 2 capture – combining solide oxide fuel cells and gas turbines Dr. ing. Ola Maurstad

2. SINTEF Energy Research Outline of the presentation A technology status for power plants with CO 2 capture (efficiencies, capture costs, timeframes) A hybrid SOFC/GT power cycle with CO 2 capture

3. SINTEF Energy Research Commercial power cycles The dominating technology for new power generation plants based on natural gas: the combined cycle (CC) It combines a gas turbine cycle with a steam turbine and achieves electrical efficiencies close to 60 % (LHV) The specific investment cost is around $500/kWe Compared to coal fired power plants the emissions of CO 2 is only around 50 % per kWh electricity (due to the higher efficiency and the lower carbon content of natural gas)

4. SINTEF Energy Research Gas fired power plants with CO 2 capture To fulfill the Kyoto agreement Norwegian emissions of CO 2 must be reduced The electricity consumption is increasing yearly Norway has large reserves of natural gas We also have geological structures under the sea with great storage capacity for CO 2 The less costly alternative would be to use CO 2 for enhanced oil recovery (EOR) Therefore, one option in reducing the emissions are gas fired power plants with CO 2 capture Other options include renewable energy, energy efficiency and energy modesty

5. SINTEF Energy Research 1: Post-combustion principle 2: Pre-combustion principle 3: Oxy-fuel principle = direct stoichiometric combustion with oxygen Principles for power plants with CO 2 capture

6. SINTEF Energy Research 65 Efficiency potential incl. CO 2 compression (2%-points) Year 123456789101112131415 Time until commercial plant in operation given massive efforts from t=0 43 45 47 49 51 53 55 57 59 61 63 Combined Cycle Post-combustion amin-absorption Pre-combustion, NG reforming Chemical Looping Combustion AZEP Oxy-fuel Combined Cycle SOFC+CO 2 capture

7. SINTEF Energy Research Post-comb. amin-abs. 0.40.81.21.62.02.42.83.23.64.04.44.85.25.6.. CC Pre-comb. NG reform. AZEP Combined Cycle additional cost €-cent/kWh el Chemical Looping Combustion Oxy-fuel Combined Cycle Low Medium High SOFC+CO 2 capture Risk for not succeeding 2.4 (Norway)

8. SINTEF Energy Research Risk for not succeeding Post-comb. amin-abs. 123456789101112131415 CC Pre-comb. NG reform. AZEP Chemical Looping Combustion Oxy-fuel Combined Cycle Low Medium High SOFC+CO 2 capture Time until commercial plant in operation given massive efforts from t=0 Year

9. SINTEF Energy Research Working principle of a SOFC Source: http://www.seca.doe.gov/

10. SINTEF Energy Research Anode Cathode Electrons Electrolyte ZrO 2 Oxygen ions Fuel Air Reforming Water/gas shift 900-1000 °C The solide oxide fuel cell (SOFC)

11. SINTEF Energy Research Technology status of SOFCs The major developers of SOFCs is Siemens Westinghouse, but several others The cost of the SOFCs is the major barrier for market introduction SECA – Solid State Energy Conversion Alliance A 10-year program led by Dept. of Energy, USA to accelerate the commercialization of SOFCs Cost target for 3-10 kW module by 2010: $ 400/kW Projected costs assuming mass production of existing cell designs are $1500-4500 SECA yearly budget is around 20 million $

12. SINTEF Energy Research ~ Heat exchanger SOFC with internal reforming Natural gas Vann Air Compressor Turbine Exhaust Combustor Scale 250 kW-10 MW Efficiency (net AC/LHV) ~60-70% Anode Cathode Electrons Electrolyte ZrO 2 Oxygen ions Fuel Air Reforming Water/gas shift 900-1000 °C Combining SOFCs and gas turbines

13. SINTEF Energy Research Benefits of SOFC/GT systems Electrical efficiencies as high as those for combined cycle plants at much smaller scale (1/1000) Very low emissions of NO x, SO x

14. SINTEF Energy Research Technology status SOFC/GT system 220 kWe demonstration system in operation at NFCRC, USA Designed and fabricated by Siemens Westinghouse (operational in 2000) 53 % electrical efficiency (net AC/LHV) achieved Conceptual designs by SW have shown electrical efficiencies approaching 60 % (300 kW to 20 MW systems) More complex and/or expensive systems in the literature promise much higher efficiencies (e.g. 70 %) Other planned demonstration systems have not always appeared on schedule...

15. SINTEF Energy Research Adding CO 2 capture to the process The SOFC is especially well suited for capture of CO 2 CO 2 is present only in the anode exit stream (not mixed with nitrogen), and at high partial pressure The afterburner oxidizes the rest of the fuel so that the exhaust consists only of CO 2 and H 2 O The water vapor is then condensed by cooling and removed => resulting in a pure stream of CO2, ready for compression Source: Shell Technology Norway AS

16. SINTEF Energy Research Simplified system description Efficiency (net AC/LHV): 65 – 68 %

17. SINTEF Energy Research The SOFC unit with recirculation

18. SINTEF Energy Research Afterburner solutions Several solutions are possible (both mature and unmature technologies) Cryogenic separation Chemical absorption Second SOFC Oxygen permeable membrane Hydrogen permeable membrane

19. SINTEF Energy Research

20. Technology status SOFC/GT with CO 2 capture No demonstration system exists Aker Kværner and Shell are working with the technology in cooperation with Siemens Westinghouse A demonstration system for an atmospheric SOFC with CO 2 capture was planned operational in Kollsnes, Norway before 2004 – has not appeared Specific investment cost for a SOFC/GT system with CO 2 capture based on today’s equipment has been estimated to $5000-8000/kWe

21. SINTEF Energy Research Technological challenges Development of low-cost and reliable SOFC (and afterburner) units Component matching and system integration Development of suitable micro gas turbines for small scale solutions Development of new power converters

22. SINTEF Energy Research Thank you for your attention!