Fuel Cell and Hydrogen Energy Systems Overview

Fuel Cell and
Hydrogen Energy Systems
Loh Kee Shyuan
Puri Pujangga
Universiti Kebangsaan Malaysia (UKM)
National University of Malaysia
18 June 2014
7th Asian School on Renewable Energy
Fuel Cell Institute, UKM

Loh Kee Shyuan
7th Asian School on Renewable Energy, Puri Pujangga UKM, Malaysia, 16th-20th June 2014
Outline
• Introduction
• Types of fuel cells and hydrogen production
systems
• Basic performance and cost
• Applications
• Future prospects
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Loh Kee Shyuan
Chronology of Fuel Cell Development
• 1839 - Sir William Grove, first electrochemical H2/O2
reaction to generate energy
• 1950s - GE developed the solid-ion exchange H2 fuel cell
used by NASA
• 1960s- GE produced the fuel cell-based electrical power
system for NASA Gemini and Apollo space capsules
• 1960s other fuel cells discovered – phosphoric acid, SOFC,
molten carbonate
• 1970s – Vehicle manufacturers began to experiment FCEV.
• 1990 – The California Air Resource Board introduced the
Zero Emission Vehicle (ZEV) Mandate.
• 2000 – Fuel cell buses were deployed as part of the
HyFleet/CUTE project
• 2007 – fuel cell started to be sold commercially as APU
• 2008 – Honda begins leasing the FCX fuel cell electric
vehicle.
• 2009 – Large scale of residential CHP programme in Japan.
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What is Fuel Cell?
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How does fuel cell work?
• In a typical fuel cell, gas (hydrogen) is fed
continuously to the anode compartment and an
oxidant (e.g. oxygen from the air) is fed
continuously to the cathode (positive electrode)
compartment. Electrochemical reactions take
place at the electrodes to produce electric
current.
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How does fuel cell work?
• At the anode:
H2  2H+ + 2e-
• At the cathode:
½ O2 + 2H+ + 2e-  H2O
• Overall:
H2 + ½ O2  H2O
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Fuel Cell Main Components
• Electrode: a thin catalyst layer pressed between the ionomer membrane and
porous, electrically conductive substrate.
• Electrolyte: A chemical compound that conducts ions from one electrode to
the other inside a fuel cell.
• Catalyst: A substance that causes or speeds a chemical reaction without itself
being affected.
• Bipolar plates: connecting the anode of one cell to the cathode of the
adjacent cell.
• Gas diffusion layer: a layer between the catalyst layer and bipolar plates, also
called electrode substrate or diffusor/current collector.
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Fuel Cell Main Components
9
Endplate
Bipolar plate

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Schematic overview of the three phase boundary
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Fuel Cell vs Battery
• Converting chemical energy to electrical energy.
• Works like a battery but does not run down or
need recharging.
• Produce electricity as long as fuel is supplied.
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Comparison of Fuel Cells with Internal Combustion Engines
12
Chemical energy of fuels Electrical Energy
Thermal Energy Mechanical Energy
Fuel Cell
ICE-1
ICE-2
ICE-3
Schematic of energy conversion in Fuel cells and Internal
Combustion Engines (ICE)

Loh Kee Shyuan
Fuel Cell as Power Alternative
13
ICEs
- operate by burning fuel to create heat, heat is converted into
mechanical energy and then electric power.
- the efficiency of this conversion process is greatly affected by
losses of waste heat and friction.
- In contrast, fuel cells efficiently convert fuel directly into
electricity via an electrochemical reaction
- Like an ICE, fuel cells conveniently use fuel from and they
operate continuously as long as fuel is supplied.
- However, fuel cells do not burn fuel and therefore do not
produce the air pollutants resulting from combustion.
Batteries
- energy storage devices; they can only produce power
intermittently as they must be recharged.
- recharging process is lengthy, inconvenient, and shifts pollution,
efficiency and cost issues up the power line to central electrical
power plants.
- Batteries and fuel cells are both electrochemical (no combustion)
devices that have high efficiency and quiet operation.
- A battery stores its energy in its electrodes. Electricity is released
as the stored energy is consumed.

Loh Kee Shyuan
High energy-conversion efficiency
14
Thermodynamic efficency for fuel cells and Carnot efficiency for heat
engines.

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Overview of fuel cell types
• They are usually differentiated by the
type of fuel used, operating pressure
and temperature, area of application.
• Fuel cells can be distinguished by the
type of electrolyte material used as a
medium for the internal transfer of
ions (protons).
• The type of electrolyte determines
the operating temperature on which
the type of catalyst depends.
• The choice of fuel and oxidant for any
FC depends on their electrochemical
activity, cost, and easiness of fuel and
oxidant delivery and removal of
reaction by-products.

Loh Kee Shyuan
Overview of fuel cell types
17
Fuel Cell Electrolyte Qualified
Power (W)
Working
Temperature
(◦C)
Electrical
Efficiency
Status
Alkaline fuel cell Aqueous alkaline solution
(e.g., potassium hydroxide)
10 kW to 100
kW
60-120 35-55 Commercial/Rese
arch
Direct methanol
fuel cell
Polymer membrane
(ionomer)
100 kW to 1
mW
arch
Phosphoric acid
fuel cell
Molten phosphoric acid
(H3PO4)
up to 10 MW 150-220 40 Commercial/Rese
arch
Molten
carbonate fuel
cell
Molten alkaline carbonate
(e.g., sodium bicarbonate
NaHCO3)
100 MW 600-650 >50 Commercial/Rese
arch
Solid oxide fuel
cell
O
2-
-conducting ceramic oxide
(e.g., zirconium dioxide,
ZrO2)
up to 100
MW
700–1000 >50 Commercial/Rese
arch
Proton exchange
membrane fuel
cell
Polymer membrane
(ionomer) (e.g., Nafion® or
Polybenzimidazole fiber)
100 W to
500 kW
arch

Loh Kee Shyuan
Characteristics of Fuel Cells
18
Fuel Cells Attractive Attributes Undesirable Attributes
Phosphoric Acid
Fuel Cell (PAFC).
-Low temperatures suitable for portable
device applications
-Ability for variable power output
-Broad fuel choice
-Uses expensive platinum as a
catalyst.
-Electrolyte is poor conductor at low
temperatures
Proton Exchange
Membrane Fuel Cell
(PEM).
-Low operating temperature suitable for
transportation and portable devices
-High power density
-Uses expensive platinum as a
catalyst
-Sensitivity to fuel impurities
Molten Carbonate
Fuel Cell (MCFC)
-High operating temperature improves
efficiency for base load power plants.
-Not suitable for small-sized
applications
Solid Oxide Fuel Cell
(SOFC)
-High operating temperature improves
efficiency for base load power plants.
-Solid electrolyte improves conductivity
- Electrolyte is made from ceramics
and solid zirconium oxide that is a
rare mineral
Alkaline Fuel Cells
(AFC)
-Low temperature and high fuel-to-
electricity efficiency
-Requirement of pure hydrogen and
allergic to carbon dioxide
Direct Methanol
Fuel Cells (DMFC).
-Eliminates need for fuel reformer drawing
hydrogen directly from the anode
-Low temperatures suitable for portable
devices
-Fuel crossing from anode to cathode
without producing electricity

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Fuel cell Basic Chemistry & Thermodynamics
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21
T (K) ΔH ΔG ΔS Eth (V)
298.15 -286.02 -237.34 -0.16328 1.23
333.15 -284.85 -231.63 -0.15975 1.20
353.15 -284.18 -228.42 -0.15791 1.184
373.15 -283.52 -225.24 -0.15617 1.167
Change of enthalpy, Gibbs Free Energy, and Entropy of hydrogen/oxygen fuel cell reaction with temperature and resulting
theoretical cell potential

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22
• Effect of pressure
 For the H2/O2 fuel cell reaction, the Nernst equation
becomes:
 By introducing Eq (1),
 Therefore, cell potential is higher at higher reactant
pressures.

Loh Kee Shyuan
Fuel Cell Electrochemistry
• Electrode kinetics
 Electrochemical reactions involve transfer of electrical charge and change of Gibbs
energy.
 The rate of electrochemical reaction is determined by an activation energy barrier
that the charge overcome in moving from electrolyte to electrode or vice versa.
 Faraday’s Law: current density is proportional to the charge transferred and the
consumption of reactant per unit area:
 i = nFj
 The consumption of the reactant species is proportional to their surface
concentration. For the forward reaction, the flux is:
 jf =kfCOx and jb = kbCRd
 The net current generated is the difference between the electrons released and
consumed:
 i =nF (kfCOx − kbCRd)
 At equilibrium, the net current should equal zero because the reaction will proceed
in both directions simultaneously at the same rate.
 The rate which reaction proceed at equilibrium is called the exchange current
density.
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• Exchange current density
– The exchange current density is analogous to the rate constant chemical
reaction.
– i0 is concentration dependent, is a function of temperature, also a function
of catalyst loading and catalyst specific surface area.
– The effective exchange current density at any temperature and pressure is
given as:
24



















ref
c
ref
r
cc
ref
T
T
RT
E
P
Laii 1exp
Pr
00

Where
i0
ref = reference exchange current density (at
ref T, P) per unit catalyst surface are,Acm-2
Pt.
ac = catalyst specific area.
Lc = catalyst loading.
Pr = reactant partial pressure, kPa.
Pr
ref = reference pressure, kPa.
γ = pressure coefficient (0.5 to1.0).
Ec = activation energy (66 kJ/mol for O2
reduction on Pt).
R = gas constant, 8.314 Jmol-1K-1
T = temperature, K.
Tref = reference temperatire. 298.15 K

Loh Kee Shyuan
• Voltage Losses
 Activation polarization
 Internal Currents and crossovers losses
 Ohmic (resistive) losses
 Concentration polarization
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26
• Voltage different from equilibrium is
need to get the electrochemical
reaction going – activation
polarization













 
aacc
rcell
aactcactraccell
i
i
F
RT
i
i
F
RT
EE
VVEEEE
,0,0
,,
lnln

• each H2 molecule that diffuse results
in fewer electrons that travel to the
external circuit
• the losses are minor during fuel cell
operation, BUT significant when fuel
cell operates at low current densities,
or it is at open circuit voltage.







0
, ln
i
i
F
RT
EE
loss
rOCVcell


Loh Kee Shyuan
27
• Ohmic losses occur due to the
resistance of the flow of ions in the
electrolyte and resistance to the flow
of electrons.
• Concentration polarization occur
when a reactant is rapidly consumed
at the electrode by the
electrochemical reaction so that
concentration gradients are
established.cieiiii RRRR ,,, 








ii
i
nF
RT
V
L
L
conc ln

Loh Kee Shyuan
• Three types of losses in
fuel cell.
• Activation losses are by far
the largest losses at any
current density.
• The cell voltage is
therefore:
28
ohmcconcactaconcactrcell VVVVVEV  )()(
i
aL
aL
cL
cL
aoacoc
PTrcell iR
ii
i
nF
RT
ii
i
nF
RT
i
i
F
RT
i
i
F
RT
EE 



 )ln()ln()ln()ln(
,
,
,
,
,,
,,


Loh Kee Shyuan
Fuel Cell Polarization Curve
• A polarization curve is the most important characteristic of a fuel
cell and its performance.
• It would be useful to see what effect each of the parameters has
on the polarization curve shape.
29

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Sensitivity of parameters in polarization curve
• Effect of transfer coefficient/Tafel slope
• Effect of exchange current density
• Effect of H2 crossover and internal current loss
• Effect of internal resistance
• Effect of limiting current density
• Effect of operating pressure
• Air vs oxygen
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Sensitivity of parameters in polarization curve
Effect of transfer coefficient on fuel cell performance
α =0.5
α =1.5
α=1
Effect of exchange current density on fuel cell polarization
curve.
Effect of cell internal resistance on its polarization curve. Effect of operating pressure on fuel cell polarization curve

Loh Kee Shyuan
Theoretical Fuel Cell Efficiency
• Assuming that all of the Gibbs free energy can be converted into
electrical energy, the maximum possible efficiency of a fuel cell is:
η= ΔG/ ΔH = 237.34/ 286.02 = 83%
• Maximum theoretical fuel cell efficiency:
η= ΔG/ ΔHLHV = 228.74/ 241.98 = 94.5%
• If both ΔG/ ΔH are divided by nF, the fuel cell efficiency may be
expressed as a ratio of two potentials:
η= (ΔG/nF)/ (ΔH/nF)HHV = 1.23/1.482 = 0.83
• The fuel cell efficiency is always proportional to the cell potential.
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Basic performance of fuel cell
• The overall performance of fuel cell may be evaluated on the basis of the
current-voltage diagram.
Journal of Power Sources 113 (2003) 37–43
Effect of cell temperature on performance. E-TEK 20% Pt/C; Pt =0:12 mg/cm2.

Loh Kee Shyuan
Basic performance of fuel cell
Journal of Power Sources 113 (2003) 37–43
Effect of Pt loading on performance for electrodes made using E-TEK 20% Pt/C, 35/45/45 ˚C.

Loh Kee Shyuan
Implication and Use of Fuel Cell Polarization Curve
• Fuel cell polarization curve may be used for
diagnostic purposes, as well as for sizing and
control of a fuel cell.
• From potential-current relationship, other
information about the fuel cell may also become
available just by rearranging the potential-
current data.

Loh Kee Shyuan
Use of polarization curve for fuel cell sizing
• H2/air fuel cell polarization curve is given with
the followings parameters:
α = 1, i0 = 0.001 mAcm-2, Ri = 0.2Ωcm-2
Operating conditions: T =60˚C, P=101.3 kPa
Operating point is selected at 0.6 V. Active area is
100 cm2.
(a) Calculate nominal power output.

Loh Kee Shyuan
Solution
• Power output is
Wel = Vcell x i x A
Vcell = 0.6 V
A =100 cm2
i = ???
• Current density must be determined from the polarization curve. Because no H2 crossover and
internal current losses and no limiting current are given, the fuel cell polarization curve may b
calculated from:
Where
Er = 1.482-0.000845T + 0.0000431T ln(PH2PO2
0.5)
= 1.482-0.000845 (333.15) + 0.0000431 (333.15) ln (0.21)0.5
=1.189 V
R=8.314 Jmol-1K-1
T=333.15K
α =1
n = 2
F =96485 C mol-1
Io = 0.001 mAcm-2
Ri = 0.2 Ωcm2
Current cannot be explicitly calculated from the previous equation.
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Solution
( b) The engineers improved fuel cell performance by improving internal
resistance to Ri = 0.15 Ohm-cm2.calculate power gain at 0.6 V
• From the new polarization curve, the current density is:
I = 1.25 Acm-2
Power output is, Wel = 0.6 x 1.25 x 100 = 75.0 W
Power gain is ΔW = 75.0 – 58.2 = 16.8 W or 28.9%

Loh Kee Shyuan
Solution
(c) The engineer found out that there was not enough air flow to operate
this fuel cell at a higher current density. Calculate the power and efficiency
gain if the improved fuel cell is to be operated at the original current
density.
Vcell = 1.189 – (8.314x333.15)/(1x96485) ln (970/0.001) – 0.97 x 0.15
= 0.648 V
New power output is, Wel = 0.648 x 0.97 x 100 = 62.9 W
Power gain is, ΔW 62.9 -58.2 = 4.7 W or 8%
The efficiency before improvement was:
η=Vcell/1.482 = 0.6/1.482 =0.405
The efficiency after improvement is:
η=Vcell/1.482 =0.648/1.482 = 0.437

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Solution
Fuel cell power output is
58.2 = Vcell x i x 100
Another Vcell-i relationship is obtained from
the polarization curve:
Vcell = 1.189 – (8.314x333.15)/(1x96485) ln
(i/0.001) – i x 0.15
Again, by iteration or graphically the solution
is:
Vcell = 0.666 V
i = 875 mACm-2
Noted that point “a” and “d” lay on two
different polarization curve but in the
same constant power line.
The new efficiency is
η = Vcell/1.482 = 0.666/1.482 = 0.449
(d) The engineer realized that there is no need for additional power. Calculate the
efficiency gain if the improved fuel cell is to be operated at the original power output.

Loh Kee Shyuan
Cost expectations-Fuel cell costs
• The US Department of Energy (DOE) had aimed (in 2007)
to demonstrate fossil fuelled PEMFC CHP systems for
under $750/kW by 2011 and under $450/kW by 2020.
• These targets were recently revised to $1200/kW by 2015
and $1000/kW by 2020, for a complete 2 kW natural gas
fuelled PEMFC system.
• The DOE’s SECA programme established cost targets for
3-10 kW stationary SOFC systems, initially starting at
$800/kW by 2005, then falling to $700/kW by 2008 and
$400/kW by 2010.
• Their cost reduction efforts now aim to demonstrate fuel
cell stacks for $175/kW and complete systems for
$700/kW

Loh Kee Shyuan

Loh Kee Shyuan
Type of fuel cells application?
46
There are many different uses of fuel cells being utilized right now. Some of these
uses are…
•Power sources for vehicles such as cars, trucks, buses and even boats and submarines
•Power sources for spacecraft, remote weather stations and military technology
•Batteries for electronics such as laptops and smart phones
•Sources for uninterruptable power supplies.

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Type of fuel cells application?

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Fuel cell vehicles by various automakers

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Layout of Honda FCX Powertrain

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Specification of several fuel cell vehicles

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Hydrogen stations
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Toyota FCHV-BUS at FC Expo
52
•90 kW PEFC Fuel cell stack: twice
•Motor: AC synchronous 80 kW twice
•Hydrogen tank: Compressed hydrogen gas
35 MPa / 150 liter, five (version 2002) or
seven (version 2005)
•Passenger capacity: 63 (included 22 seats)

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Residential Fuel Cell
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Fuel Cell Technologies Forging Cross-industry Collaboration
• Google, one of the pilot customers, has a 400-
kilowatt installation at its main campus. Over 18
months, the project delivered 3.8 million kilowatt
hours of electricity.
• Wal-Mart has installed two 400 KW systems at retail
locations in Southern California.
• Bank of America is putting in a 500 KW installation at
a call center in Southern California.
• Coke too is putting in a 500 KW installation, at its
Odwalla plant in Dinuba, Calif. That fuel cell will run
on re-directed biogas and provide up to 30 percent
of the plant’s electricity needs.
• Cox Enterprises is putting in a 400 KW installation at
its KTVU TV station in Oakland, Calif.
• E-commerce giant e-Bay is using a 500 KW
installation at its San Jose, Calif., facility that will run
on biogas.
• FedEx has installed five 100 KW Bloom boxes at its
package sorting facility in Oakland.
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Alternative Energy
56
• Increasing of energy demand
• Depletion of fossil fuel in near future
• Reducing negative impact on
environmental
Renewable Energy 31 (2006) 719–727

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What is our choices?
• Pressing need to find alternative renewable,
sustainable and clean energy source.

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Alternative energy
• Sustainable – ability of an energy source to
continue providing energy for a long period of
time
• Renewable – energy that comes from resources
which are continually replenished
• Clean ‐ does not pollute the atmosphere when
used/produced

Loh Kee Shyuan
Hydrogen properties
• Gaseous, odorless, colorless, tasteless,
flammable, explosive
• Bonds with many other elements
• Seldom found in pure form in nature
• Liquid at -253 ˚C (20 K)
• Not an energy source, it is an energy
carrier/store

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Hydrogen safety
• Hydrogen Vehicle Safety.
– The Ford Motor Company, in their report to the US
Department of Energy included this statement:
“Overall, we judge the safety of a hydrogen
FCV system to be potentially better than the
demonstrated safety record of gasoline or
propane, and equal to or better than that of
natural gas.”
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Hydrogen safety
61
Hydrogen Vehicle Gasoline Vehicle Hydrogen Vehicle Gasoline Vehicle Hydrogen Vehicle Gasoline Vehicle
One minute after ignition; hydrogen
fire nearly extinguished
The pictures below were taken 3
seconds after ignition
The following pictures compare
hydrogen and gasoline fires from an
experiment conducted at the
University of Miami.
The car on the left contained high pressure hydrogen tanks with 175,000 btu of energy and the
car on the right had a conventional gasoline tank with just five pints of gasoline or about 70,000
btus of energy. Spark plugs were installed outside both vehicles to ignite a leaking hydrogen
tank and a leaking gasoline line.

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Hydrogen Production Paths
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Hydrogen production methods
• Main methods
-Thermal
-Electrochemical
-Biological
• Others
-Chemical reaction
-etc
Primary method Process Source/Feed
stock
Energy
Thermal Stream reforming Natural gas High temperature steam
(autothermal)
Thermochemical
water splitting
Water High temperature heat from
nuclear reactor
Gasification Coal, Biomass High temperature (&
pressure) steam & oxygen
Pyrolysis Biomass Moderately high
temeprature
Electrochemcal Electrolysis Water Electricity from solar, wind,
hydro & nuclear
Photoelectrochemi
cal
Water Direct from sunlight
Biological Photobiological Water & algae
strains
Direct sunlight
Anaerobic/ferm
entation
Biomass &
microorganis
m
Food source
Anaerobic
degistion
Biomass High temperature heat
Fermentative
microorganisms
Biomass High temperature heat

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Hydrogen production technologies
Steam methane reforming :
• widely used in the chemical and refining industries.
• Considered the cheapest way of producing hydrogen.
• Reforming involves the reaction of desulphurized natural gas with high-
temperature steam over a Ni-based catalyst.
• This produces syngas-mainly a mixture of H2 and CO.
• The CO is then converted to H2 and CO2 via a water gas shift reaction.
• High purity (up to 99.99%) H2 is separated using pressure swing adsorption
method.

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Coal gasification:
• well-established commercial technology
• competitive with SMR only where oil and/or
natural gas are expensive.
• coal could replace natural gas and oil as the
primary feedstock for hydrogen production, since
it is so plentiful in the world.

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Electrolysis of water :
• Water molecules can be separated using electricity. But we use
electricity to produce hydrogen to produce electricity again.
• Pure water is in many places a scarce resource.
• The electricity for the electrolysis needs to be produced and the
water needs to be purified (soft de-ionized water is needed).
• Reaction:
• Electricity can be obtained at a large scale from nuclear reactors
but the hydrogen needs to be stored and transported, and nuclear
fuel is not a renewable source of energy.
• At a VERY small scale wind or solar power can be used, but this
energy is available only when there is wind or sunlight.

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Biomass gasification and pyrolysis:
• Provide two ways to produce H2 from biomass.
• The processes can be adapted to a range of feedstock:
switch grass, plant scraps, garbage, willow, sugar cane
waste.
• Both techniques are followed by a reforming stage.
• Gasifier may be heated indirectly and directly.
• With pyrolysis, biomass is rapidly heated in the absence
of O2, the vapors are then condensed to form pyrolysis
oil.
• This pyrolysis oil can be used as feedstock for H2
production.

Loh Kee Shyuan
Conversion of Biomass
Pyrolysis
Gasification
Combustion
No oxygen
With oxygen
(partial oxidation)
With oxygen
(complete oxidation)
Organic material + heat -> charcoal +oil +gases
Organic material + O2 +H2O-> H2 +CO2 +CO+ others
Organic material + O2-> CO2 +H2O
Slow &Low (<450ºC)
-Max char 35%wt
Intermediate (450-500ºC)
-Typical 10-15% has. 20-30% char,
45-65% oil
Fast & high (>500ºC)
-(>550ºC – mas oil 70%)
-(>600ºC - max gas 80%)
High (>800ºC)
Low (start 200‐300ºC)
(>1000ºC)
Gas-Syngas
CO2
H2O
CO
CH4 etc
Heat
Solid-char
Liquid-oil
Hydrogen
Transfrom

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Hydrogen Storage Alternatives
• Compressed Gas Storage
• Solid State Storage
• Liquid Hydrogen Storage

Loh Kee Shyuan
Compressed Gas Storage

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High Pressure Gas
• High-pressure hydrogen is stored in cylinders.
• Conventional cylinders – cylindrical shaped
sidewall section with hemispherical end
domes.
• Conformal Cylinders – Use multiple cylinders
in tandem and distort the cylindrical shape in
order to increase the usable volume.

Loh Kee Shyuan
Hydrogen Cylinders

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Metal Hydrides
• Principle used is that some metals readily
absorb gaseous hydrogen under conditions of
high pressure and moderate temperature to
form metal hydrides
• These metal hydrides release the hydrogen
gas when heated at low pressure and
relatively high temperature

Loh Kee Shyuan
Metal Hydrides
• There are many types of specific metal
hydrides
• Primarily they are based on metal alloys of
magnesium, nickel, iron and titanium
• They are divided into:
• high hydrogen desorption temperature
• low hydrogen desorption temperature

Loh Kee Shyuan
Metal Hydrides
• High hydrogen desorption temperature
• Less expensive
• Holds more hydrogen
• Requires significant amount of heat to release
hydrogen
• Low hydrogen desorption temperature
• Heat from an engine is sufficient to release hydrogen
• Sometime in this case it releases hydrogen at
ambient temperatures
• It needs to be pressurized to overcome this problem

Loh Kee Shyuan
Metal Hydrides

Loh Kee Shyuan
Metal Hydrides
Advantages
• Hydrogen becomes part of the chemical
structure of the metal itself and therefore
does not require high pressures or cryogenic
temperatures for operation
• Since hydrogen is released from the hydride
for use at low pressure, hydrides are the most
intrinsically safe of all methods of storing
hydrogen

Loh Kee Shyuan
Metal Hydrides
Disadvantages
• They have low mass energy density
• Best metal hydrides contain only 8% hydrogen by
weight
• very heavy and expensive
• Metal hydride storage systems can be up to 30
times heavier and ten times larger than a gasoline
tank with the same energy content
• They must be charged with only very pure hydrogen
• If they become contaminated there is loss of
capacity

Loh Kee Shyuan
Liquid Hydrogen Storage
Liquid hydrogen storage tank (850,000 gallons) at NASA KSC

Loh Kee Shyuan
Liquid Hydrogen
• The storage of liquefied cryogenic gases is a
proven and tested technology.
• Hydrogen was first liquefied by J. Dewar in
1898.
• In liquid form, hydrogen can only be stored
under cryogenic temperatures.

Loh Kee Shyuan
Advantages
• Liquid hydrogen: high energy/mass ratio, three times
that of gasoline.
• It is the most energy dense fuel in use (excluding
nuclear reactions fuels), which is why it is employed in
all space programs
• Compared with compressed hydrogen, liquid hydrogen
has much lower storage pressure  the risk caused by
high pressure may be reduced to some extent.
• Liquid hydrogen (LH2) tanks can store more hydrogen in
a given volume than compressed gas tanks.

Loh Kee Shyuan
Disadvantages
• Requires extremely low temperatures of -423 F/-
2520
C.
• Boil-off losses / vaporization of hydrogen due to
heat leakage constitute a major disadvantage.
• A highly sophisticated and expensive production
and processing system is necessary in order to
minimize losses caused by diffusion, evaporation
and impurity.
• Evaporation losses on todays tank installations
are between 0.3 and 3% per day.

Loh Kee Shyuan
Summary of H2 Storage

Loh Kee Shyuan
Cost expectations-Hydrogen production costs
• H2 production from natural gas by steam reforming
methods is well established.
• At low (pipeline) pressure, it is about 1.0 US$kg-1 (based
on inexpensive natural gas, assumed at 1.5 US$ GJ-1).
• Simbeck and Chang (2002) estimate the delivered H2 cost
from biomass waste is about 2.5 US$kg-1.
• Conventional small-scale electrolyzer H2 cost have been
estimated as 8-12 US$kg-1.
• Larger unit using surplus wind power may attain a cost
down to 2 US$kg-1
• The H2 cost based on coal gasification is estimated as over
12 US$kg-1

Loh Kee Shyuan
Cost and performance characteristics of various hydrogen production
Process
Energy Required
(kWh/Nm3)
Ideal
Energy Required
(kWh/Nm3)
Practical
Status of Tech.
Efficiency
[%]
Costs Relative
to SMR
Steam methane reforming
(SMR)
0.78 2-2.5 mature 70-80 1
Methane/ NG pyrolysis R&D to mature 72-54 0.9
H2S methane reforming 1.5 - R&D 50 <1
Landfill gas dry reformation R&D 47-58 ~1
Partial oxidation of heavy oil 0.94 4.9 mature 70 1.8
Naphtha reforming mature
Steam reforming of waste oil R&D 75 <1
Coal gasification (TEXACO) 1.01 8.6 mature 60 1.4-2.6
Partial oxidation of coal mature 55
Steam-iron process R&D 46 1.9
Chloralkali electrolysis mature by-product
Grid electrolysis of water 3.54 4.9 R&D 27 3-10
Solar & PV-electrolysis of
water
R&D to mature 10 >3
High-temp. electrolysis of
water
R&D 48 2.2
Thermochemical water
splitting
early R&D 35-45 6
Biomass gasification R&D 45-50 2.0-2.4
Photobiological early R&D <1
Photolysis of water early R&D <10
Photoelectrochemical
decomp. of water
early R&D
Photocatalytic decomp. of
water
early R&D

Loh Kee Shyuan
Cost of various hydrogen production technologies
Technology Cost range (US$
(2000)/GJH2
Additional cost
of CO2 capture
Comments
SMR, large-scale
(>1000MW)
SMR, small-scale
(<5MW)
5.25-7.26
11.50-40.40
$7.26 cost
increases to
$8.59/GJ with
CCS Prohibitive
Cost highly dependent
on natural gas prices.
Transitional
technology. Cost highly
dependent on natural
has prices, plant size
and purity of H2
required.
Coal gastification 5.4-6.8 Average of 11% Coal price more stable
and predicatable than
natural gas.
Biomass
gasification
(>10MW)
7.54-32.61
(av.14.31)
Not given (with
CCS technology,
would become
carbon
negative)
Size ranges from 25 to
303 MW and affects
cost.

Loh Kee Shyuan
Cost of various hydrogen production technologies
Technology Cost range (US$
(2000)/GJH2
Additional cost of
CO2 capture
Comments
Biomass pyrolysis
(>10MW)
6.19-14.98 Not given (with CCS
technology would
become carbon
negative)
Size ranges form 36
to 150MW; cost
redued by sale of
co-products
Electrolysis, Large
scale (>1MW)
11-75 Emissions (and CCS
options) depend on
source of electricity
Size ranges from 2
to 376MW, but
little effect on cost;
cost very
dependent on
assumed price of
electricity
Electrolysis, small-
scale (<1MW)
28-133 Emissions (and CCS
options) depend on
source of electricity
Size ranges from
0.03 to 0.79MW,
cost very size-
dependent.

Loh Kee Shyuan
Wind/ Hydrogen Projects
• Greece
 RES2H2 Project
• Spain
 RES2H2 Project
 ITHER Project
• Canada
Ramea Island
Prince Edward Island
• United Kingdom
HARI Project
PURE Project
• United Stated
 Basin electric, Wind-to-Hydrogen Energy Pilot Project
 National RE Lab and Xcel Energy, Wind-to-Hydrogen Project

Loh Kee Shyuan
PURE Project
• The project aims to demonstrate how wind power and hydrogen
technology can be combined to meet the energy needs of a remote
rural industrial estate.
• PURE was conceived to test and demonstrate safe and effective
long-term use and storage of hydrogen produced by renewable
energy using wind-powered electrolysis of water, and to regenerate
the stored energy into electric energy with a fuel cell.
• The key components of the system are:
 Wind turbines: Two 15 kW (Proven Ltd)
 Electrolyzer: 15 kW alkaline operating at 55 bar (AccaGen SA)
 Hydrogen storage: 44 Nm3 in H2 cylinders
 PEM fuel cell: 5 kW (Plug Power).
• The electrolyzer section consists of an AccaGen electrolyzer unit
assembled with advanced cells specifically designed and
manufactured by AccaGen SA for wind application, capable of
operating up to 55 bar.

Loh Kee Shyuan
Basin Electric, Wind-to-Hydrogen Energy Pilot Project
• this project was to research the application of hydrogen
production from wind energy, allowing for continued wind
energy development in remote wind-rich areas and
mitigating the necessity for electrical transmission
expansion.
• The report completed on August 2005 found that the
proposed hydrogen production system would produce
between 8,000 kg and 20,000 kg of hydrogen annually.
• The cost of the hydrogen produced ranged from $20 to
$10 per kilogram.
• The hydrogen-production system utilizes a bipolar alkaline
electrolyzer nominally capable of producing 30 Nm3/h (2.7
kg/h).

Loh Kee Shyuan
Future energy landscape
91

Loh Kee Shyuan
Furture Energy Landscape

Loh Kee Shyuan
7th Asian School on Renewable Energy, Puri Pujangga UKM, Malaysia, 16th-20th June 2014 93
THANK YOU
ksloh@ukm.edu.my

Fuel Cell and Hydrogen Energy Systems Overview

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