Fuel Cell-Gas Turbine Hybrid System

The main advantage of combining the fuel cell with a classic power plant system is that one can create a binary system which can potentially achieve ultra-high efficiencies (see Fig. 5.46). This task is frdfiUed through the other system using the fuel cell exhaust heat. 

A typical Solid Oxide Fuel Cell-Gas Turbine Hybrid System (SOFC-GT) consists of the following elements  

The SOFC-M is not the only power souree in the SOFC-GT hybrid system (additional power is produeed by the gas turbine subsystem). SOFC-GT hybrid system effieieney is defined by the following relationship  

SOFC-GT hybrid systems ean be elassified based on fuel cell module operational pressure. Systems in which the gases leaving the fuel cell are comparable to atmospheric pressure are called atmospheric SOFC systems. The second group consists of systems in which the pressure of the exhaust gas leaving the fuel cell is significantly higher than atmospheric those kinds of systems are called systems with pressurized SOFC. 

This classification determines the location of the fuel cell in a power system. Generally, the fuel cell can perform a similar function in the system to that of a combustion chamber, i.e. to oxidize fuel supplied to the system, which results in relatively large quantities of electricity being taken from the fuel cell itself. The combustion chamber works with lower amounts of fuel and does not require a large excess of air in order to reduce the temperature of gas getting to the turbine. 

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Plans are underway for a field test of a megawatt class fuel cell/gas turbine hybrid system on an Environmental Protection Agency site at Ft. Mead, Maryland. This system is expected to exhibit an efficiency of about 60 % (LHV) depending on the turbine and the inverter selected. Operation is expected in the second half of 2002. 

Liese E.A., Gemmen R.S. (2005) Performance comparison of internal reforming against external reforming in a solid oxide fuel cell, gas turbine hybrid system. ASME Journal of Engineering for Gas Turbines and Power 127, 86-90. 

Fuel cells are currently being developed for distributed generation most are for applications under 1 MW. Some solid oxide fuel cell/gas turbine hybrid systems are being developed for 5 MW applications. Aside from fuel cells used... 

J., Jabbari, F., Brouwer, )., and S., Samuelsen (2010) Design, simulation and control of a 100 MW-class solid oxide fuel cell gas turbine hybrid system. 

Samuelsen, S. (2004) Fuel Cell/Gas Turbine Hybrid Systems, ASME International Gas Turbine Institute, Norcross, GA. 

Van Osdol, )., liese, E., Tucker, D., Gemmen, R., and James, R. (2010) Scaling of a solid oxide fuel cell gas turbine hybrid system to meet a range of power demand. J. Fnd CeU Set. Technol., 7, 015001. 

Performance characteristics of a solid oxide fuel cell/gas turbine hybrid system with various part-load control modes./. Power Sources, 166, 155-164. 

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