molten carbonate fuel cell overview

7/26/2019 Molten Carbonate Fuel Cell Overview

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MCFC

Molten Carbonate Fuel Cells

Technology and Market

Overview


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1. Introduction Fuel cell converts chemical energy to electrical energy

A fuel cell is different than a battery in that it does not

store energy, but produces energy from the input materialssuch as Hydrogen and Oxygen

First fuel cell was invented in 1839 by Sir William Grove

Not adopted early on due to high cost and technology barriers

NASA used fuel cells to generate power for space missionswhich renewed interest in fuel cell research

Fuel cell technology has now advanced to the point where

various types have begun to enter the market place.

Pike Research has estimated that the stationary fuel cell marketwill reach 50,000 MW by the year 2020(Prabhu, Rahul R., Staitonary Fuel Cell Market, Jan. 2013)


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Molten Carbonate Fuel Cell History

Both Solid Oxide and Molten Carbonate fuel cell research began

together with a divergence in the technologies during the 1950s

a. Emil Baur, H. Preis experimented with high temperature,

solid oxide electrolytes in the 1930s

b. O.Davtyan conducted further experiments in the 1940s

c. G. Broers, J. Ketelaar continued the solid oxide research, but

solid oxides of the day prevented any short term progress.To forge ahead, they turned their attention to electrolytes

consisting of molten carbonate salts.

d. By 1960, Broers and Ketelaar had a fuel cell that ran for six

months using and electrolyte that was a mixture of lithium,sodium and potassium carbonate.

e. Mid 1960s, Texas Instruments made MCFC for the US Army

which ranged in size between 100W and 1kW


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1. Overview of Molten Carbonate Technology

Inputs : Hydrogen, Oxygen, and Carbon Dioxide

Outputs : Electrical Power, Water, and Heat

Applications are usually large stationary power plants


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Anode material is based on

porous Nickel.

Original designs used solid

Nickel, but due to hightemperature operation, the Nickel

would degrade (sintering)

Nickel is now stabilized using

chromium or aluminum

Cathode material is NiO

High temperature operation

causes the NiO to dissolve A limiting factor for Molten

Carbonate fuel cell lifetime


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Electrolyte is a molten mixture of

lithium and potassium or lithium

and sodium carbonates

High temperature operation ofaround 600C 700C forms a

highly conductive molten

electrolyte containing salts

formed by the carbonates A porous ceramic material LiAlO2

called the electrolyte matrix is

used in the electrolyte region

The stability of the LiAlO2 matrixis another limiting factor for fuel

cell lifetime. ( < 6 years )


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Chemical Reactions :Anode : H2 + CO3

2- -> H2O + CO2 + 2e- (oxidation)

Cathode : 1/2O2 + CO2 + 2e- -> CO3

2- (reduction)

Net Reaction : H2 + 1/2O2 + CO2(cathode) -> H2O + CO2 (Anode)

Carbonate Ions transfer from the Cathode to the Anode throughthe electrolyte ( ion transfer )

The Cell potential : (Nernst equation)

The cell potential depends upon the

partial pressures of O2

, H2

, and H2O

The CO2 partial pressure may be the

same (electrolyte is invariant) or

different (contributes to cell potential


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Cell voltages typically range from 0.6V to 1.1V Typical current densities range from 140 to 160 mA/cm^3

Fuels :

Hydrogen is input on the Anode side Oxygen is input on the Cathode side

Carbon Dioxide is a second input

on the Cathode side, but may be

recycled from the Anode output

CO2 may also be produced by

combusting the anode exhaust gas

which is mixed directly with thethe anode inlet gas

Outputs : Electrical Power, Water,

Heat, Cathode Gas


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Advantages :a. The high operating temperature improves chemical reaction

kinetics and so there is no need for noble metal catalysts (lower cost)

b. High temperature operation makes the MCFC resistant

to carbon monoxide contamination and as a result, mayuse alternate fuels such as natural gas or methane.

c. High efficiency, up to 60% electrical efficiency or when

used as combined heat and power (CHP) up to 80%

d. Clean energy and quiet operation

Disadvantages :

a. High temperature operation limits applications to stationary power

plants (slow startup time)b. Liquid electrolyte is difficult to work with

c. Short life span due to electrode and electrolyte degradation

d. Inject CO2 at cathode as carbonite ions consumed by anode reaction


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2. Types of Applications and Market Status

Primary application is stationary power plants

a. Electrical Utilities

b. Industrial and distributed power generationc. Military and Government (Post Office)

Large systems : typically 250kW to 3MW

Future application may include ship power plants

a. Navy and civilian shipping

Early stationary power plant installations

a. Miramar Marine Corps Air Station (San Diego, 1997)

operated a 250 kW MCFC prototype power plantb. Santa Clara, 1997, Energy Research Corp. operated a

2MW demonstration power plant (cosponsored by DOE)


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Molten Carbonate Fuel Cell (MCFC) Market Overview

The commercialization of MCFC technology is still in its infancy

US manufacturers : Fuel Cell Energy and GenCell Corp. (CT)

European manufacturers : MTU Friedrichshafen and CFC Solutions

Japanese manufacturer : Ishikawajima-Harima Heavy Industries

Korean manufacturers : KEPCO/ POSCO Power, Doosan HI

Total fuel cell market (all types) exceeded $1 billion in 2012

About half of fuel cell shipments have been stationary fuel cells, Since MCFC technology applications are large, stationary power

plants, the number of units shipped are low, but the equivalent power

generated is high. For example, when comparing number of units

shipped per year between various fuel cell technologies, MCFC is onthe order of tens of units shipped, but the annual power generation

capacity is around half of the total power capacity shipped for

stationary power plants.


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Number of fuel cell units shipped globally in 2013 was 50,050 units

PEMFC is leading fuel cell technology with 88.6% of total units shipped

and 48.6% of power capacity shipped (mobile and stationary)

Stationary applications account for 57% of total capacity in 2013

MCFC accounts for about half of the stationary market( Grand View Research, Inc. , 2014 ) (CAGR for MCFC ~ 56%, 2014 2020)

Molton Carbonate Fuel Cell shipments by Power (MegaWatts)

year MCFC Total FC Stationary Ratio

2009 18.00 35.40 0.51

2010 7.70 35.00 0.22

2011 44.50 81.40 0.552012 62.00 124.90 0.50

2013 91.90 186.90 0.49

0.00

20.00

40.00

60.00

80.00

100.00

120.00

140.00

160.00

180.00

200.00

2009 2010 2011 2012 2013

MCFC Yearly Shipments (MegaWatts)

MCFC Total FC Stationary

0.00

0.10

0.20

0.30

0.400.50

0.60

2009 2009 2010 2010 2011 2011 2012 2012 2013 2013 2014

Percentage of MCFC to Total FC shipped(Power Capacity)


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MCFC power plant installation cost ~ $ 4,000 / kW

About 2x the cost of Gas Turbine and 3x cost of Reciprocating Engine

Feasibility study by NREL compared installation costs of several

competing power generation technologies

3. Cost Targets

42454375

1896

1342

MCFC PAFC GAS TURBINE RECIPROCATING ENGINE

Installed Cost by Technology ( $ per kW )

Company Model Technology Installed Cost

FCE Direct Fuel Cell 1500 MCFC $4,245/kW

Doosan Power Pure Cell 400 PAFC $4,375/kW

Solar Mercury 50 gas turbine $1,896/kW

Caterpillar C3250 reciprocating engine $1,342/kW


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4. Key Challenges For MCFC technology to be competitive in the power generation market,

the installed cost per kilowatt will have to drop to under $2000/kW

Further research to increase the power density of MCFC technology

a. Increase the operating temperatureb. Increase ionic conductivity of the electrolyte

c. Decrease the polarization losses of the electrodes

Further research to increase the lifespan of Molten Carbonate fuel cells

a. Improve structural stability of Ni-base anodes

b. Reduce NiO dissolution of the cathode

c. Reduce particle growth in the LiAlO2 electrolyte matrix

d. Reduce electrolyte evaporation ratee. Improve electrolyte structure ( ~ 70% cell ohmic losses )

Cost reductions with volume manufacture

Doubling orders from suppliers may reduce costs ~ 20%


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Installation and Conditioning

After manufacture, the fuel cell must be conditioned. Under controlled

conditions, the fuel cell is brought up to temperature to melt the electrolyte

and condition the electrolyte matrix. Currently, this process takes about 2

weeks after which the fuel cell can be delivered to the customer.

The fuel cell is then assembled into the power plant at the customer site

after which operation is verified and the power plant is commissioned. The

total cost of this conditioning, installation, and commissioning process isestimated at $700/kW. At higher production volumes, it is estimated that

$200/kW could be saved on this process. Further cost reductions to this

process could make a significant contribution to MCFC feasibility.

molten carbonate fuel cell overview

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