ECONOMICAL ANALYSIS OF GASEOUS AND LIQUID HYDROGEN
STORAGE AND TRANSPORTATION
Zehra Yumurtacı* and Nur Bekiroglu**
* Yildiz Technical University Mechanical Engineering Faculty, TR 34349, Besiktas Istanbul
** Yildiz Technical University Electrical and Electronics Engineering Faculty, TR 34349,
Besiktas Istanbul
ABSTRACT
In this study, we studied production, storage and transportation costs of gaseous and liquid hydrogen. Sea water is
distilled by reverse osmosis for obtaining pure water, and then electrical energy is produced in small hydroelectric
power plants. By using this electrical energy in electrolysis system gaseous hydrogen is obtained. And by adding
liquefaction system to above system liquid hydrogen can be obtained. Costs of storage of gaseous and liquid
hydrogen in tanks, underground and within metal hydrid are calculated and results are compared. Storage of gaseous
hydrogen within metal hydrid gives the most appropriate result and storage of liquid hydrogen has been found the
most expensive way. Costs of transportation of gaseous and liquid hydrogen by highways, railways, sea and via
pipelines and cost of transportation of metal hydrid by highway and railway have been calculated. Transportation of
gaseous hydrogen by highway, liquid hydrogen by railway and metal hydrid by highway have been found the most
appropriate results. Finally all the obtained results are compared.
Keywords: Hydrogen Energy, Gaseous Hydrogen, Liquid Hydrogen, Economical Analysis
NOMENCLATURE
D
Storage capacity for GH2 (kg)
Ft
Annual production (kg/year)
E
Energy (kWh)
Sw
Cooling water (lt/h)
Ck
Compressor capital cost ($)
Ct
Tank capital cost ($)
Ctotal k
Ak
Ek
E ky
Total capital cost ($)
Amortization ($)
Energy cost ($)
Annual energy cost ($)
Sk
S ky
Cooling cost ($/h)
Annual cooling cost ($)
Ck
A bk
Total annual cost ($)
Unit capital cost ($/kg)
Eb
Unit energy cost ($/kg)
k
S bk
Unit cooling cost ($/kg)
C bk
Total unit cost ($/kg)
Tr n
Required train/wagon quantity
________________________________________________
Corresponding Author: Z.Yumurtacı
Phone: +90 212 2597070/2540
Fax: +90 212 2616659
e-mail:zyumur@yildiz.edu.tr
Cm
Cave capital cost ($)
Ch
a
Af
Hydrid capital cost ($)
Area (m2)
Current (kg/m2sn)
FB
CL
CD
D
T
Tı k
M
Ys
Boiling loss (kg/h)
Liquidities capital cost ($)
Tank capital cost ($)
Transportation way (km)
Annual total number of transportation
TIR capacity of gas hydrogen (kg)
Total distance (km)
Transportation duration (h)
Ss
Driving duration (h)
S yb
Loading/unloading duration (h)
S tı
TIR operation duration (h)
Tı n
Required TIR quantity
Drv n
Number of drivers required
S tr
Nre
Pg
C
r
Train operation duration (h)
Reynold's number
Input pressure (Pa)
Annual cost ($/year)
Discountratio(%)
Subscripts
SHP Small Hydroelectric Power Plant
EL
Electrolysis
DIS
Distillation
GH2 Gaseous Hydrogen
INTRODUCTION
Hydrogen is an ideal energy source that would
not pollute the environment, that would satisfy
energy requirements of developing technologies
from ovens to spacecrafts so it must be used as
soon as possible in all feasible application areas
[1]. Hydrogen has may advantages; it is relatively
easy to produce, is appropriate for transportation
sector, obtained energy can be transformed into
other energy forms without difficulty, has high
efficiency and does not pollute as it is recycled
into water [6].
Therefore in this paper we studied production,
storage and transportation costs of gaseous and
liquid hydrogen. In the first step, electrical energy
is produced in small hydroelectric power plant
and then sea water is distilled by reverse osmosis
for obtaining pure water. In the second step, by
using this electrical energy in electrolysis system
gaseous hydrogen is obtained. Storage methods
of gaseous hydrogen in compressed form,
underground and within metal hydrid have been
determined and cost calculations have been
obtained. Costs of transportation of gaseous
hydrogen by highways and railways have been
calculated.
By adding liquefaction system to above system
liquid hydrogen can be obtained. Costs of
storage of liquid hydrogen in tanks and
transportation of liquid hydrogen by highway,
railway, sea and via pipelines have been
calculated.
In addition transportation of metal hydrid by
highway and railway have been determined.
Finally all the obtained results are compared.
SYSTEM DESCRIPTION
In this study we assumed that the system has been
established nearly sea level because of shortening
the pipeline which has been lay down between
the sea and the system. So the cost of the system
can be decreased.
The block diagram of the system is shown in
Figure 1. Costs of storage and transportation for
gaseous and liquid hydrogen are obtained by
using this system.
LH2
c
m
e
Liquid Hydrogen
Investment
Operating and maintenance
Electricity
Sea Water
Distillation
Pure Water
Electrical
Small Hydroelectric Energy
Power Plants
Electrolysis
Gaseous Hydrogen
- Compressed
- Underground
- Metal Hydrid
Gaseous Hydrogen
Storage
Liquefaction
- Highway
- Pipeline
- Railway
Gaseous Hydrogen
Transportation
Liquid Hydrogen
Storage
Liquid Hydrogen
Transportation
- Highway
- Pipeline
- Railway
- Sea
Figure 1. The flow chart of the system
SIMULATION MODEL
The simulation model consists of the following
models:
- To calculate pure water cost from distillation
unit
- To calculate the electrical energy cost from
hydraulic power system
- To calculate gaseous and liquid hydrogen
production and cost from electrolyser system
- To calculate gaseous and liquid hydrogen
storage and transportation cost
- To determine product cost and economics
These models are reviewed in the following
section.
Hydrogen production by electrolysis
Hydrogen production by electrolysis of water is
the salt solution classical technique. As water is
stable under room temperature, its electrolysis
requires considerable energy. Hence, electrolysis
costs largely depend on energy costs. Water is the
most abundant raw material for hydrogen
production on this planet; 99% of it is salty and in
Polar Regions it is in ice form [1]. Use of an
electrolyte as sea water is important in the
context of cost reduction [2].
Distillation method for salty water
Because of the problems mentioned above, salty
water is distilled by reverse osmosis. Reverse
osmosis is a membrane process. It is based on the
behaviour of potable water and salty water on the
different sides of a semi-permeable membrane.
Pure water passes thru the membrane and
rarefies. Water behaves as it is under pressure
and this is called osmotic pressure. Osmotic
pressure is a function of the differences between
the salt concentration and solution temperatures.
By applying pressure to the salt solution, the
process can be reversed [4].
Small hydroelectric power plants (SHP)
As electrolysis and desalination systems require
large amounts of energy, a small hydroelectric
power plant is to be constructed in order to
reduce costs. Therefore, energy costs for SHP are
calculated. A SHP is described as having a total
power inferior to 10 MW, producing small
amounts of electricity by using one or more
turbine generator or a group of generators. SHPs
are appropriate for local consumption of
electrical energy [13].
Liquefaction of Hydrogen
In order to obtain liquid hydrogen, gas hydrogen
is compressed under high pressures, and then the
compressed gas is cooled with liquid nitrogen and
finally is dilated in turbines [9]. As liquefaction
process is realized by cooling the gas to the point
where it becomes liquid, compressors, heat
exchangers, turbine and reduction valves are
required. The simplest liquefaction process is
Linde Conversion or Joule-Thompson dilatation
conversion where the gas is compressed until the
pressure equals the atmospheric pressure, then it
is cooled in a heat exchanger and goes to a
reduction valve where a certain quantity of liquid
is obtained (Joule-Thompson dilatation comes
about). This liquid is extracted and cold gas is
sent back to compressor via heat exchanger.
However, gases such as azotes that are used in
Linde conversion get cooler under room
temperature beyond a certain dilatation point.
Hydrogen, on the other hand, becomes hotter
beyond that point. Hence, it is crucial to keep
hydrogen below the inversion temperature of 202
0
K. Modern hydrogen liquefaction processes, in
order to reach the desired temperature, hydrogen
temperature is cooled down to around 78 0K
before it reaches the first dilatation valve. This is
realized by Linde conversion with pre-cooling
where azotes is utilized.
HYDROGEN STORAGE
- Storage of compressed hydrogen gas: This is
storage method is the most applied and simplest
one as it only requires a compressor and
compression tank. On the other hand, high levels
of compression mean higher investment and
operation costs [3]. Storing small quantities of
hydrogen in compressed tanks is simple and low
cost but as the hydrogen quantity to be stored
increase, the costs increase as well; hence this is
not a cost effective method for storing large
quantities of hydrogen.
- Underground hydrogen storage: This is another
form of storing hydrogen in compressed gas state
and leads to lowest storage costs for high
quantities. Natural and man-made underground
caves can be used. Underground gas reservoirs
require a minimum investment cost but a 5% loss
in terms of gas volume is a disadvantage [7].
- Storing hydrogen within metal hydrid:
Hydrogen has capacity to be absorbed within
metals. Metal hydrids are formed in this manner.
This is an exothermic process and as hydrogen is
diffused from metal hydrid, a reverse process, i.e
an endothermic reaction occurs. Absorption and
diffusion of hydrogen depend on certain
parameters: hydrogen pressure, metal temperature
and hydrogen leaking proportion [5]. This storage
method consists of attaching hydrogen
chemically on metal, metalloid elements and
alloys. Metal hydrids consist of metal atoms with
cage-like structures and hydrogen atoms captured
in intervals within these cage-like structures.
- Storage of liquid hydrogen: Hydrogen becomes
liquid under a relatively low temperature of 200K.
Hence,
liquidification
process
requires
approximately 30% of hydrogen ignite energy in
electrical energy form. The main problem in the
production and storage of liquid hydrogen is loss
due to vaporization. As the capacity of the tank
where liquid hydrogen is stored increase, the
losses diminish. Vacuum is used for isolation
purposes between inner and outer walls of
tanks[12]. Liquid hydrogen can be stored in small
and large quantities but cylindrical tanks for
natural gas are not feasible as this leads to large
amounts of vaporization losses [14].
HYDROGEN TRANSPORTATION
Hydrogen can be transported under compressed
gas, liquid or solid (within metal hydrids) forms.
Transportation cost minimization depends on the
quantity to be transported and the distance of
transportation [3]. Transportation methods to be
examined in this present paper are: highway,
railways, sea and pipelines.
High pressure cylinders, tube trailers or pipelines
can be utilized for transportation. In order to
maximize tank capacity, very high levels of
compression are required. Liquid hydrogen
should be transported in special isolation tanks
that have two walls to minimize vaporization.
Some tankers have liquid nitrogen based heat
shields that cool the outer wall of their tanks in
order minimizes heat transfer [11]. TIR tanks'
capacity ranges from 360 to 4300 kg whereas
2300 to 9100 kg. of liquid hydrogen can be
transported in a single train wagon tank. For both
cases, daily vaporization losses vary between
0.3% and 0.6%. Tanker ships are suitable for long
distance transportation. Daily vaporization losses
for ships vary between 0.2% and 0.4%. Another
way of liquid hydrogen transportation is using
pipelines [15]. These are isolated lines and
contain super conductor wires. As liquid
hydrogen acts as a cooler for super conductor
wire, high levels of current loss in long distance
transmission as in the case of traditional power
lines is not a problem. The main problems are
special isolation requirements and pumping and
cooling losses [3].
Transportation costs for gaseous and liquid
hydrogen are obtained as following;
—Compressed gas hydrogen transportation by
highways
—Compressed gas hydrogen transportation by
railways
—Liquid hydrogen transportation by highways
—Liquid hydrogen transportation by railways
—Liquid hydrogen transportation by sea
—Liquid hydrogen transportation via pipelines
—Metal hydrid transportation by highways
—Metal hydrid transportation by railways
long distance energy transmission. The cost is
lower when hydrogen is transported via pipelines
[3]. Hence, producing hydrogen and transporting
it with pipelines to a location that requires heat or
electrical energy has a low cost as energy losses
are minimal [10].
Results of cost calculations for four hydrogen
storage methods are presented in Fig.2.
Calculated transportation costs are presented in
Fig. 3. Cost comparison among various methods
for liquid hydrogen transportation is presented in
Fig. 4. Cost comparison for metal hydrid
transportation methods are presented in Fig. 5.
1,48
1,6
1,4
1,2
1
$/kg 0,8
0,6
0,29
0,197
0,4
0,116
0,2
0
Compressed Gaseous Hydrogen
Underground Hydrogen
Within Metal Hydrid
Liquid Hydrogen
Figure 2. Storage costs per unit for different
forms of hydrogen storage
2,34
2,5
2
COST COMPARISON FOR HYDROGEN
ENERGY
Main factors affecting a transportation method
decision are application, quantity and the distance
between the production plant and the user. For
short distances and small quantities, compressed
gas form is the most appropriate [4]. If hydrogen
is required in liquid form, it must be transported
to application location in liquid form. When large
quantities are concerned, pipelines are the most
convenient in terms of cost. If oceans must be
crossed, tanker ships are the obvious choice.
Operational costs for pipelines are the lowest
when compared to other methods but capital
investment cost is very high. On the other hand,
operational costs are high but capital investment
cost, depending on hydrogen quantity and
transportation distance is low for liquid hydrogen.
Pipelines are not profitable for small quantities of
hydrogen as capital investment cost is very high.
Hence, a choice among compressed gas and
liquid forms of hydrogen depend solely on the
distance. For long distances, high liquidification
costs are prohibitive. For short distances and
small quantities, compressed gas form is the most
appropriate. Transportation cost of compressed
gas form for long distances exceed transportation
cost of liquid hydrogen including liquidification
costs. A special issue concerning hydrogen is
1,5
0,88
$/kg
1
0,5
0
Highway
Railway
Figure 3. Transportation cost of gas hydrogen for
highway and railways
3,2
3,5
3
2,5
2
$/kg
1,5
1
0,8
0,373
0,5
0
By highway
0,067
By railway
By sea
Via pipeline
Figure 4. Transportation costs of liquid hydrogen
0,927
1
0,9
0,8
0,7
0,6
$/kg 0,5
0,4
0,3
0,2
0,1
0
0,336
Highway
Railway
Figure 5. Metal hydrid transportation cost for
highway and railways.
CONCLUSION
In this present research, total cost of gas
hydrogen production is found to be about 0.35
$/kWh, total cost of liquid hydrogen production
is found to be 0.65 $/kWh. Compressed gas
hydrogen is obtained by electrolysis of
desalinated sea water. Three methods for storage
of gas hydrogen were chosen and cost analyses
were carried out. Storing hydrogen within metal
hydrid is the most cost effective form of storing
in terms of per unit costs (about 0.116 $/kg). Four
methods for transportation of gas hydrogen were
chosen and cost analyses were carried out. Metal
hydrid transportation by highways is the most
cost effective form of transportation in terms of
per unit costs (about 0.336 $/kg). However, the
crucial point is that the most cost effective form
of transportation depends on quantity and
distance and the requirements of the end user.
Four methods for transportation of liquid
hydrogen stored in tanks were chosen and cost
analyses were carried out. Railways are the most
cost effective form of transportation in terms of
per unit costs 0.067 $/kg. However, the crucial
point is that the most cost effective form of
transportation depends on quantity and distance
and the requirements of the end user. Hydrogen
energy has a high cost today but as it has many
advantages over traditional energy forms, further
research and development is necessary. By
replacing polluting energy forms, hydrogen
energy can lead to a safer/ healthier environment
for every occupant of this planet.
ACKNOWLEDGEMENTS
The transportation dataset for this paper by
Catoni Persa Ltd. Sti. is acknowledged.
REFERENCES
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Transporting Hydrogen, National Renewable
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1973.
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BatteryPowered
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for introducing hydrogen into transportation”
Energy Policy, Volume 31, Issue 13, October
2003,1357-1367.
APPENDIX 1
Values utilized for cost calculations [3,8]
Hydrogen
F
100 kg/h
Storage period
Operation pressure
Energy quantity spent by the compressor
Compressor pressure
Compressor cost
T
1 day
P
Ke
Kp
Km
20.10 Pa
2,2 kWh/kg (20 Mpa)
20 Mpa
1000 $/kW
Compressor power
Tank cost for gaseous hydrogen
Kg
Tm
4000 kW
1323 $/kg
Tank capacity for gaseous hydrogen
Compressor cooling
Underground storage capital cost
Tank pressure
Tp
Ks
Ym
Tp
227 kg
50 lt/h
9 $/kg
20 Mpa
Metal hydrid heat
Hk
23260 kj/kg
Metal hydrid cooling water
Hs
209 lt/kg
Metal hydrid cost
Steam cost
Power required for liquidification
Boiling rate
Liquidifier cost
Liquidifier capacity
Tank cost for liquid hydrogen
Tank capacity for liquid hydrogen
Compressor factor
Compressor pressure factor
Tank factor
Tank pressure factor
Lifespan for SHP
Cost of electrical energy
Liquidification factor
Tank factor for liquidification
Hm
B
Lp
BT
Lm
Ls
Dm
Ds




n
ge
2205 $/kg
3,79 $/Gj
9.9 kWh/kg
1%
44093$/kg
2205 kg/h
441$/kg/h
220 kg/h
0,80
0,18
0,75
0,44
22 years
0.08$/kWh
0,65
0,70
Transportation way
The capacity of GH2 for TIR
D
Tı k
200km
181 kg
Mean speed
Ht
80 km/h (for TIR),40 km/h (for train),16 km/h (for ship)
Loading/unloading duration per transport
Operation duration per day for TIR
Hydrogen capacity
T1s
T1a
Trk
Train hydrogen gas tank cost
Train carrier cost
Train lifespan
Cost of transportation by train
Daily vaporization rate
TIR hydrogen gas tank cost
TIR carrier cost
Ship hydrogen gas tank cost
Ship carrier cost
Ship lifespan
Cost of transportation by ship
Diameter
Viscosity
Roughness ratio
Friction coefficient
Cgtrain
Cctrain
ntrain
Ctrain
VR
CgTIR
CcTIR
Cgshir
Ccship
nship
Cship
r
Vi
Rr
f
2 hours
24 hours
453 kg (GH2 for train),4082 kg (LH2 for TIR)
9072 kg (LH2 for train),4082 kg (LH2 for ship)
200.000 $
100.000 $
15 years
400 $
0.3%
100.000 $
60.000 $
350.000 $
100.000 $
6 years
3000 $
0,25 m
8.62x10-6 kg/m.sec
0.000184
0.005


6
ge
C


 C m (t ) 1  r 
c (t )
n
 E 1  r 
APPENDIX 2
Formulas
t
F 
C L = Lm xLs  x  B 
 Ls 
t
 D 
(t )
t 1
D = F.t (kg)
F t = F x 360 x 24 (kg/year)
(The system is assumed to operate 24 hours a day
for 360 days)
  P 
 ln 

6

0
,
1
x
10


E = F x Ke x
(kWh)

6 


20
x
10
 ln 

  0,1x10 6  



  P 
 ln 

6
Sw = F x Ks x   0,1x10   (lt/h)

6 
 ln  20x10  
  0,1x10 6  

 

 E 
 P 

C k = ( Km x Kg) x   x 
 Kg 
Kp 

C t = (T m x T g ) x


 Tp
 Sx

P
 T
g








Ak =
 F 
T =  t 
 Tık 
M = T x D (km)
Ys =
D
Ht
(h)
S s = T x Y s (h)
S yb = T x Tı s (h)
St
S tı
Tı n =
Sdrv= Drv a x 360 (h)
($)

 Tp 
 

($)
Drv n =
St
S drv
Af =
E k = E x 0,08 ($)
E k y = E k x 24 x 360 ($)
S k = S su x 0,00000002 ($/h)
S k y = S k x 24 x 360 ($)
Y 
VR  s 
 2 
a=
F
a
 xr 2
Nre =
Pg =
Ak
Ft
Eb k =
S bk =
($/kg)
Ek
F
Sk
(m2)
4
r x Af
Vi
4 xfxD xA
E = F x Kg x
($/kg)
($/kg)
C b k = A b k + E b k +S b k ($/kg)




E = F x Hh
Sw= Fx Hw
C h = D x Hh
T p 

P 

($)
(kWh)
(lt/h)
($)

F B = F x 1  1  e 

1
2
f
BT



(kg/h)
x( RH 2 xTe )
r
 Pg
ln 
 0,1x10 6

 20 x10 6
ln 
 0,1x10 6

C k = (K m x K g ) x
F
C m = Ym x Dx
(kg)
(kg/m2sn)
Ck = A k + E k + S k ($)
A bk =
(The driver is assumed to work
for 12 hours a day for 360 days a year)
 F 
T=  t 
 Tr 
 k
Fd = Ft x e
($)

C D = Dm xDs  x   ($)
 Ds 

 P 
x  
($)
S tı = Tı a x 360 (h)

Ctotal = C k + C t ($)
Ctotal
n


 Pi 2
(Pa)


 ln  Pi
6


   0,1x10
6


 ln  20 x10

 0,1x10 6


 E

 Kg






 Pg
x 
 Pi











(kW)

($)