Alkalinebattery
5 ct / Wh
Li-SOCl2battery
60 ct / Wh
NaH(η = 0.45)
16 ct / Wh
Diesel(η = 0.15)
0.1 ct / Wh
Methanol(η = 0.40)
0.05 ct / Wh
MgH2
(η = 0.45)
12 ct / Wh
LiH(η = 0.45)
11 ct / Wh
Electric energy density
Wh / kg Wh / ℓ
0
1000
2000
3000
4000
191
760
1259
1890
2240 2295
3800
478
12201450
15721774
2607
2371
F R A U N H O F E R I N S T I T U T E F O R m A N U F A c T U R I N g T E c H N O l O g y
A N d A d vA N c E d m AT E R I A l S I F A m , b R A N c H l A b d R E S d E N
ON-SITE hydrOgEN gENEraTION vIa hydrOlySIS Of mgh2
1 Hydrolysis demonstrator
2 Hydrolysis reaction of a MgH2 pellet
3 Electric energy densities and costs of
various energy storage materials
Fraunhofer Institute for
manufacturing Technology
and Advanced materials IFAm
branch lab dresden
Winterbergstrasse 28
01277 Dresden | Germany
Contact
Dr. rer. nat. Lars Röntzsch
Phone +49 351 2537 411
Email: Lars.Roentzsch
@ifam-dd.fraunhofer.de
Dr. rer. nat. Marcus Tegel
Phone +49 351 2537 413
Email: Marcus.Tegel
@ifam-dd.fraunhofer.de
www.h2materials.de
www.ifam-dd.fraunhofer.de
2 3
Introduction to hydrolysis
Hydrogen is an environmentally friendly
energy carrier with a very high gravimet-
ric energy density. Its chemical energy can
be readily converted to electrical energy
by means of fuel cells. However, direct
storage of pressurized H2 is difficult as it
involves expensive, heavy and bulky tanks
as well as saftey fittings, which go far
beyond the requirements for many porta-
ble and mobile applications. In low pow-
er, long term storage applications espe-
cially, hydrogen losses rule out any
storage of elemental hydrogen.
However, hydrogen can be directly gene-
rated on-site by the reaction of certain
metal hydrides with water. As light-
weight, compact, non-volatile, safe and
reasonably priced compounds, these hyd-
rides can thus serve as energy sources si-
milar to conventional or special batteries
(e. g. Li-SOCl2) but with a gravimetric and
volumetric energy density at least one or-
der of magnitude higher.
Applications
• Backup / emergency power supplies
• Standalone radiocommunication
• Beacons
• Sensors
• Probes
Advantages of mgH2 for
hydrolysis reactions
Research at Fraunhofer IFAM has shown that
MgH2 as hydrogen storage material for hyd-
rolysis reactions has a variety of advantages
over other materials:
• Optimal and balanced gravimetric and
volumetric energy density
• Inexpensive, readily available
• Easy to handle (even in air)
• Direct reaction with water is possible
• Reaction kinetics can be tailored for
specific applications
• High reaction and product safety
• Non-toxic and environmentally friendly
21
Hydrolyse_Flyer_2013.indd 1 02.04.2013 17:46:01
Fig. 1 Time-dependent hydrogen generation for commercial and activated MgH2 (catalysts developed and tested at Fraunhofer IFAM).
1
2
1 Specialized lab-scale testing
equipment for hydrolysis
reactions
2 Outline of a hydrolysis reactor
in combination with a fuel cell
detailed information
MgH2 + 2 H2O 2 H2 + Mg(OH)2
When MgH2 is hydrolyzed, both the total
amount of released hydrogen and the
reaction kinetics strongly depend on a
number of factors:
- Active surface area
- pH
- Presence of buffers
- Salinity of water
- Water temperature
Beyond that, the reaction has to be
catalyzed by the addition of certain Lewis
acids. At Fraunhofer IFAM, special materials
and processing routes have been developed
to make the hydrolysis of MgH2 highly
efficient and controlled.
Fraunhofer R&d Services
• Development of storage materials with
regard to specific requirements, e.g.
- Suitable kinetics
- High energy density
- Environment-related aspects
• Development of materials processing
technologies
• Specialized water treatment (e.g.
for sea water applications)
• Construction, test and evaluation of
metal hydride cartridges suitable for
hydrolysis
• Safety and reliability tests
• System development and testing
• System integration with fuel cells
• Software development
Metal Hydride Pellets
Water
Hydrolysis Reactor
Recuperation of Water
Exhaust (H2O)
Air (O2)
e−
H+
H2
Fuel Cell1 2
0 15 30 45 60
Time (min)
Hyd
roge
n co
nver
sion
(%)
75
Activated MgH2 + Catalyst I*)
Activated MgH2 + Catalyst II**)
Activated MgH2 (without catalyst)
MgH2 (commercial)
0
20
40
60
80
100
*) Catalyst developed at Fraunhofer IFAM **) Most efficient catalyst according to literature
All measurements were performed with de-ionized water at pH[t0] = 7; T[t0] = 20 °C (weight ratio 1:150) and equimolar amounts of catalyst.
Hydrolyse_Flyer_2013.indd 2 02.04.2013 17:46:06
Top Related