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