The aim of this paper is to investigate the implementation of a molten carbonate fuel cell (MCFC) as a CO2 separator. By applying multi-objective optimization (MOO) using the genetic algorithm, the optimal values of operating load and the corresponding values of objective functions are obtained. Objective functions are minimization of the cost of electricity (COE) and minimization of CO2 emission rate. CO2 tax that is accounted as the pollution-related cost, transforming the environmental objective to the cost function. The results show that the MCFC stack which is fed by the syngas and gas turbine exhaust, not only reduces CO2 emission rate, but also produces electricity and reduces environmental cost of the system.
Cost of electricity including carbon dioxide tax/ ($· (kWh)−1)
CT
Carbon dioxide tax/ ($·t−1)
Theoretically achievable maximum reversible potential/V
Standard cell potential/V
Electric energy produced per year/ (kWh•a−1)
ER
Emission rate
Faraday’s constant (96487?C equiv.-1)
Molar flow rate of component i/ (mol·h−1)
Objective function
Fuel price in the first year/ ($· (kWh)−1)
The Gibbs free energy change/ (J·mol-1)
Enthalpy/ (kJ·kmol-1)
Current/A
Total investment cost in the first year/$
Iin
Specific investment cost of the installation for the MCFC/ ($•kW−1)
Inflation rate/ (%·a−1)
Specific cost of a stack for the MCFC/ ($·kW−1)
Current density/ (A·m-2)
Equilibrium constant
Separated carbon dioxide flow/ (t·h-2)
Year
Plant power/kW
Plant factor/ (h·a−1)
R
Resistance/ (Ω· m-2)
Ran
Irreversible losses at anode/ (Ω·m-2)
Rca
Irreversible losses at cathode/ (Ω·m-2)
Internal cell resistance/ (Ω·m-2)
The sum of irreversibility occurred at anode, cathode and electrode/ (Ω·m-2)
RTtot,1
Total reduced carbon dioxide tax in the first year/($·a−1)
Temperature/C
Cell voltage/V
Weight factor
Conversion degree
Greek letter
Voltage loss/V
Electrical efficiency
Subscripts
an
Anode
ca
Cathode
CO
Carbon monoxide
CO2
Carbon dioxide
e
Electric
elec
Electrical
H2
Hydrogen
H2O
Water vapor
i
Species
i, an
Species at anode
i, ca
Species at cathode
in
Installation
inf
Inflation
ir
Internal resistance
ne
Nernst
out
Outlet
OP
Operation
p
Plant
pr
Price
pry
Produced per year
RT
Reduced CO2 tax
si
Stack investment cost
tot
Total
Superscripts
0
Standard
max
Maximum
trans
Transformed
Abbreviations
GHG
Greenhouse gases
IRR
Internal rate of return
kWh
Kilo-Watt-hour
MCFC
Molten carbonate fuel cell
MOO
Multi-objective optimization
PBP
Payback period
1
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