טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentElitzur Shani
SubjectParametric Investigation of Hydrogen Supply for a Fuel Cell
from Aluminum-Water Reaction
DepartmentDepartment of Aerospace Engineering
Supervisors Professor Emeritus Alon Gany
Dr. Valery Rozenband
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


Abstract

This thesis presents a parametric experimental investigation of a novel method of in-situ hydrogen production, safely and compactly, from the chemical reaction between activated aluminum and water. It further studies its application in PEM fuel cells in order to generate green electric energy, with only water as a byproduct.

Hydrogen is the most attractive alternative fuel because of its outstanding reaction energy and its environmental friendly products (water or water vapor). Hydrogen energy will be widely used only after overcoming the challenges of hydrogen storage and transportation due to its very low density and safety problems resulting from its high reactivity.

The stoichiometric reaction between aluminum and water, Al2OAl(OH)3(3/2)H2, yields theoretically 11% hydrogen mass compared to the aluminum mass (equivalent to over 1.2 liter of hydrogen per gram of aluminum), making the concept very efficient for hydrogen storage.

A thermo-chemical process of aluminum activation, using a small fraction of lithium based activator (typically 2.5%), developed at the Fine Rocket Propulsion Center of the Faculty of Aerospace Engineering of the Technion, modifies the protective properties of the oxide or hydroxide film on the aluminum particle surface, and enables a spontaneous and sustained reaction between activated aluminum and water, at regular conditions.

The influence of different parameters on the reaction rate and efficiency was tested: water/aluminum mass ratio, fraction of activator, size and shape of the aluminum particles, initial water temperature, type of water, and high pressure conditions.

It was found that the reaction is faster for lower water/aluminum ratio, higher initial water temperature, and higher specific surface particles. A maximum efficiency of 80% was demonstrated, while flakes give lower efficiencies than powder. It was also observed that different types of water (tap water, sea water, or purified water) can be used.

Application of the hydrogen produced by this method in PEM fuel cells for electricity generation was investigated using Horizon H-30 fuel cell with a rated power of 30W.

The specific electric energy storage that can be received using hydrogen produced by the aluminum-water reaction is 2200 Wh/kg Al compared to 120 Wh/kg for lithium-ion batteries.  

The best application for this method of electric energy generation using the aluminum-water reaction may be in marine and underwater vehicles that can use water from the ambience. Other applications may be for battery replacements and in electric cars.