The Rocky Road to a Hydrogen Economy Presented By Rebecca Armstrong April 18, 2008 Advisor Boris Kiefer

Introduction Why Hydrogen Economy Current ideas Our ideas Future

97% Transportation Fuel Crude Oil 25% greenhouse emissions Materials for hydrogen storage: current research trends and perspectives Annemieke 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 mass unit than gasoline Hydrogen-storage materials for mobile applications Louis Schlapbach*† & Andreas Züttel† Mg 2 NiH 4 LaNi 5 H 6 H 2 (liquid) H 2 (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 perspectives Annemieke W. C. van den Berg{a and Carlos Otero Area´n*b Conversion and Storage of Energy TWO PROBLEMS 1.Fuel Cell – Solved 2.Storage - Unsolved

Other Ideas! Hydrides Zeolites Nanotubes We took a different route and came up with the following

Five commandments of hydrogen storage (i) High storage capacity: minimum 6.5 wt % (ii) T dec °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 and Production 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 of Warsaw, Pasteur 1, Warsaw, Poland, and Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QR U.K.

Model The Human Body Uses Iron to transfer oxygen throughout the body The transferring molecule… Hemoglobin

Heme Groups Hemoglobin: active site

Heat of Formation A + B + …  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 water H 2 (g) + ½ O 2 (g)  H 2 O(l) ΔE=-284 kJ/mole E Reactants = E A + E B + …  E C + E D + …= E Products

Transition Metals - O 2 Binding Fe + O 2 and Fe + 2 O 2 Stable Hydrogen Storage: Replace O 2  H 2.

What transition metal to choose? Requirements: Adsorb H 2, no chemical reaction. Maximum number of adsorbed molecules.  need maximum number of unpaired electrons.  Manganese.

Storage Capacities: Our mechanism: Maximum storage capacity: 15.3 wt% hydrogen. (Li,Mg)NH 2 : 5.2 wt%. LiBH 4 : 5.4 – 9.6 wt%. Current DOE goal: 7.8 wt%.

Mn + H 2  Mn-H 2 Mn + 2H 2  Mn-2H 2 Compound has a stable geometry. But: product has a higher energy than the reactants  unlikely that transition provide efficient storage medium for H 2. Manganese and Hydrogen

Hydrogen Adsorption Energies Li too stable (hydride). Mg too stable (hydride).

Carbon - nanotubes? Likely low storage. Na: low storage capacity. Other elements too stable? Hydrogen Adsorption Energies Li too stable (hydride). Mg too stable (hydride).

Conclusion 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 H 2. It is a Rocky Road.

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