A transient analysis of a hybrid SOFC-GT system for isolated islands

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A transient analysis of a hybrid SOFC-GT system for isolated islands

P. Boutikos, P. Iliadis, K. Atsonios, P. Grammelis Centre for Research and Technology Hellas, Chemical Process Engineering Research Institute

CERTH CENTRE FOR RESEARCH &

9th Global Conference on Global Warming Virtual conference

Groatia, 1 – 4 August 2021

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Population growth Rapid industrial and technological advancement Improvement of living standards

Energy consumption (↑2.9% in 2019) . Greenhouse gas emissions Global warming, climate change Health issues

Fossil Fuels (Oil, Coal, Natural gas)

Carbon-free & environmental friendly economy

Energy Sources Sustainable, efficient and cleaner Intermittent and fluctuate with production not in sync with demand The lack of access to electricity especially in non-interconnected islands

Electrocatalytic technologies Fuel Cell technology leads to the production of H 2 .

Clean energy carrier Abundant (water) Fuel in fuel cell & ICE

Introduction

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Introduction

High efficienc y (up to 70%) Low CO 2 emissions Fuel flexibility : NG, LNG, H 2 , biogas Assembly in existing power plants (1kW – 10 MW) Cogeneration possibility (domestic hot water, district heating, desalination, etc ). Exhaust gas utilization at a bottomed thermodynamic cycle (e.g. Rankine, Brayton).

Fuel Cell Fuel  Electricity

SOFCs: Solid Oxide Fuel Cells

Hybrid SOFC-GT

Overall hybrid cycle efficiency can be >70%.

Anode Cathode Air (1/2 0,) Fuel Water and Electrolyte

A.G. Olabi, T. Wilberforce, M.A. Abdelkareem, Energy 214 (2021) 118955. F. Calice, M. Dentice d’Accadia, A. Palombo, L. Vanoli, Energy 31 (2006) 3278.

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Aim

Αποτέλεσμα εικόνας για coal power plant clipart

OIL OIL

CO 2

Αποτέλεσμα εικόνας για coal power plant clipart

CO 2

LNG

Αποτέλεσμα εικόνας για coal power plant clipart

SOFC

Current status

Future scenario

G GT

Dependence on oil fuel High electricity cost High CO 2 emissions Technical difficulties for RES development

Dependence on NG High efficient electricity production Low CO 2 emissions

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Solid Oxide Fuel Cell - Gas Turbine Model

Model Development

Assumptions The reformer and the SOFC are treated as a zero dimensional (0D). Uniform distribution of gas concentration, temperature and current density in the fuel cell. Only H 2 is electrochemically oxidized. All gases are assumed to be ideal.

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Model Development

J. Xu and G.F. Froment, AIChE J. 35 (1989) 88 – 96. K ang , Y.-W., Li, J., Cao, G.-Y., Tu, H.-Y., Li. J., Yang, J., J. Power Sources 188 (2009), 380 – 392.

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Model Development

Akkaya, A.V ., J. Energy Research 31 (2007), 79 – 98 . Zhao, Y., Sadhukhan, J., Lanzini, A., Brandon, N., Shah, N ., J. of Power Sources 196 (2011), 9516 – 9567.

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Model Development

The design parameters of the reformer and fuel cell were obtained by literature 1,2,3 . The model was implemented in Matlab version 8.2.0 (R2013b).

Operational Parameters Fuel flow rate (kmol/h) 7 Air flow rate (kmol/h) 240 Pressure (bar) 3 Fuel Composition (%) 93% CH 4 , 3% C 2 H 6 , 1% CO 2 , 3% N 2 Compressor efficiency (%) 89 Gas Turbine efficiency (%) 91 Reformer temperature ( 0 C ) 650 SOFC temperature ( 0 C) 910 Current density (A/m 2 ) 1.000 – 3.000

Campanari S., Iora P., J. Power Sources 132 (2004), 113 – 126. Costamagna P., Magistri L., Massardo A.F., J. Power Sources 96 (2001), 352 – 368. Georgis D., Jogwar S.S., Almansoori A.S., Daoutidis P., Computers and Chem. Eng. 35 (2011), 1691 – 1704.

Design Parameters m cat (g) 0.6 ρ cat (kg/m 3 ) 2335 Cp cat (J.kg -1 .K -1 ) 444 Bed voidage 0.4 Reactor Volume (m 3 ) 3.10 -3 ρ SOFC (kg/m 3 ) 4200 Cp SOFC (J.kg -1 .K -1 ) 640

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Atsonios et al. model 1 This work Voltage (V) 0.68 0.692 Current density (mA/cm 2 ) 183 170 SOFC Stack power output (MW) 1 1 Fuel Utilization factor (%) 85 63 Anode outlet composition 50.9% H 2 O, 24.9% CO 2 , 11.6% H 2 , 7.4% CO 46.68% H 2 O, 35.43% CO 2 , 9.75% H 2 , 8.04% CO Pre-reformer outlet temp. (°C) 536 534 Stack exhaust temperature (°C) 838 816

Model Validation

Atsonios, K., Samlis, C., Manou, K., Nikolopoulos, A., Sfetsioris, K., Mitsotakis, A., Grammelis, P., J. Hydr. Energy 46 (2021), 4827 .

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Results

Effect of current density (T SOFC = 910 0 C)

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Results

Effect of Cell temperature (current density = 1700 A/m 2 )

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Results

Effect of molar flow rate ( T SOFC = 910 0 C, current density = 1700 A/m 2 )

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Results

Operation load of the hybrid SOFC-GT system in an isolated island during a year and during a whole day. The island includes 8.85 MW wind turbines and 5.17 MW photovoltaics.

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Conclusions

A zero-dimensional model was developed in Matlab in order to investigate the full-load and partial-load operation performance of a hybrid SOFC-GT system. The dynamic model predicts very well the numerical results of a literature model under steady-state operation. The cell voltage decreases with the current density increasing, whereas the power of the system increases until it reaches a maximum and then it starts decreasing. The system power increases until the cell temperature reaches at 850 o C after which it decreases slowly. The efficiency of the system presents a similar behavior. The fuel flow rate has a negative effect on the efficiency of the system. The hybrid system presents medium fluctuations in power demand with the penetration of wind turbines and photovoltaic cells .

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Thank you for your attention

www.sunies-fuelcell.eu

Acknowledgements This work has been carried out in the framework of the Greek-German Research Project “SUstainable and Novel fuel cell applications for Island Energy - SUNIES”.