High efficiency carbonate fuel cell/turbine hybrid power cycle

This paper describes how a hybrid power cycle which includes direct carbonate fuel cells operating at near atmospheric pressure, a gas turbine and a steam system, is capable of generating power at a net LHV efficiency above 70%. The performance is relatively insensitive to ambient temperature and site elevation. This new power cycle requires a high temperature heat exchanger to transfer heat from the fuel cell system to the gas turbine. Studies of the hybrid power cycle for a 200 MW power plant, in which the system includes advanced heat exchanger technology indicate an efficiency of 70%. Required heat exchanger development is a design that operates at 1094 °C and 400 psi. The additional development of a fuel cell anode exit recycle compressor would result in a plant efficiency of73%. Emissions from the plant are expected to be well below existing or proposed standards. The NO_x emission level is 75% below the level from a combined cycle. A 200 MW plant with a hybrid power cycle is competitive with a gas turbine combined cycle for installations where the fuel cost is above $5.8/MMBTU. Technical challenges include verifcation of fuel cell performance at the system conditions chosen, development of a high temperature heat exchanger and an anode recycle blower. In addition, design integration of the cycle gas turbine is required