The Rocky Road to The Rocky Road to a Hydrogen a Hydrogen EconomyEconomy

Presented By Rebecca Armstrong Presented By Rebecca Armstrong

April 18, 2008April 18, 2008

Advisor Boris KieferAdvisor Boris Kiefer

IntroductionIntroduction

•Why Hydrogen Economy•Current ideas •Our ideas •Future

97% Transportation Fuel Crude Oil

25% greenhouse emissions

Materials for hydrogen storage: current research trends and perspectivesAnnemieke W. C. van den Berg{a and Carlos Otero Area´n*b

About 75% of the materials we use for energy are conventional fossil fuels.

Hydrogen is much cleaner than fossil fuels

Hydrogen stores 2.6 times more energy per Hydrogen stores 2.6 times more energy per mass unit than gasolinemass unit than gasoline

Hydrogen-storage materials for mobile applicationsLouis Schlapbach*† & Andreas Züttel†

Mg2NiH4 LaNi5H6 H2 (liquid) H2 (200 bar)

CUTE (Clean Urban Transportation for Europe)

27 Hydrogen fuel cell buses

2015 – 170 fuel cell buses 73 Hydrogen

Materials for hydrogen storage: current research trends and perspectivesAnnemieke W. C. van den Berg{a and Carlos Otero Area´n*b

Conversion and Storage of Energy

http://dsc.discovery.com/news/2008/04/03/hydrogen-plane-zoom.html

TWO PROBLEMSTWO PROBLEMS

1.Fuel Cell – Solved

2.Storage - Unsolved

Other Ideas!Other Ideas!

• Hydrides

• Zeolites

• Nanotubes

We took a different route and came up with the following.

http://www.umass.edu/sbs/news_events/news_stories/nanotech.htm

http://www.chem.arizona.edu/courses/c518_2003/tgb518/public_html?N=D

http://www.flickr.com/photos/ghutchis/124782973/

Five commandments Five commandments of hydrogen storageof hydrogen storage

• (i) High storage capacity: minimum 6.5 wt %

• (ii) Tdec 60-120 °C.

• (iii) Reversibility of the thermal absorption/

desorption cycle: • (iv) Low cost.• (v) Low-toxicity of a nonexplosive and possibly

inert (to water and oxygen) storage medium.

Thermal Decomposition of the Non-Interstitial Hydrides for the Storage andProduction of Hydrogen Wojciech Grochala*,†,‡ and Peter P. Edwards*,§The School of Chemistry, The University of Birmingham, Edgbaston, Birmingham, B15 2TT U.K., The Department of Chemistry, The University ofWarsaw, Pasteur 1, 02093 Warsaw, Poland, and Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QR U.K.

ModelModel

• The Human Body

• Uses Iron to transfer oxygen throughout the body

• The transferring

molecule…

Hemoglobin

http://www.lipitor-online.com/imgs/cholesterol-human-body.jpg

Heme GroupsHeme Groups

http://www.chemistry.wustl.edu/~edudev/LabTutorials/Hemoglobin/MetalComplexinBlood.html#ChangeMovie

Hemoglobin: active site

Heat of FormationHeat of FormationA + B + … A + B + … C + D + … C + D + …

• ΔE = EP – ER < 0 exothermic reaction. energy is released. more stable state.

• ΔE = EP – ER > 0 endothermic reaction. energy is absorbed. less stable state.

Example: Formation of waterH2 (g) + ½ O2 (g) H2O(l) ΔE=-284 kJ/mole

EEReactantsReactants= E= EAA + E + EBB + … + … E ECC + E + EDD + …= E + …= EProductsProducts

Transition Metals - OTransition Metals - O22 Binding Binding

Fe + O2 and Fe + 2 O2

Stable

Hydrogen Storage: Replace O2 H2.

What transition metal to What transition metal to choose?choose?

Requirements:

• Adsorb H2, no chemical reaction.• Maximum number of adsorbed molecules.

need maximum number of unpaired electrons. Manganese.

Storage Capacities:Storage Capacities:

• Our mechanism: Maximum storage capacity : 15.3 wt% hydrogen. • (Li,Mg)NH2 : 5.2 wt%.

• LiBH4 : 5.4 – 9.6 wt%.

• Current DOE goal: 7.8 wt%.

http://www.hydrogen.energy.gov/pdfs/5037_h2_storage.pdf

Mn + H2 Mn-H2

Mn + 2H2 Mn-2H2

Compound has a stable geometry.But: product has a higher energy than the

reactants unlikely that transition provide efficient storage medium for H2.

Manganese and HydrogenManganese and Hydrogen

-1000

-800

-600

-400

-200

0

200

400

600

H2

- B

ind

ing

Ene

rgy

(kJ/

mo

l)

0 I II III IV

Oxidation State

CIV

Unstable

Stable H2 adsorption

MnIII

FeIII

CoIII

Li0

Mg0

Li C Na Mg Al Co Mn Fe

Mn0

Fe0

Co0

Hydrogen Adsorption EnergiesHydrogen Adsorption Energies• Li too stable(hydride).

• Mg too stable(hydride).

• Carbon - nanotubes?Likely low storage.

• Na: low storagecapacity.

• Other elements toostable?

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

10

H2

- B

ind

ing

En

erg

y (k

J/m

ol)

0 I II III IV

Oxidation State

Na: adsorption capacity too low

Mg, Mn too stable

Al too stable

C? 300 K

Hydrogen Adsorption EnergiesHydrogen Adsorption Energies• Li too stable(hydride).

• Mg too stable(hydride).

ConclusionConclusion

• Lots of ideas that are being worked on. None meeting more than a two commandments.

• Our idea does not bind, but through other ideas we might find something else

• Hydrogen as a fuel is possible, we just need to continue research on how to store it.

• We do not see according to our simplified model across

the periodic table elements do not bind H2.

It is a Rocky Road.It is a Rocky Road.

THE ENDTHE END