Download - Al Water Summary r2
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SPLITTING ANY KIND OF WATER WITHGLOBAL-SCALE, EARTH-ABUNDANT, LIGHT,
RECYCLABLE METALS TO MAKEHYDROGEN, HEAT AND
POTABLE WATER ON DEMANDJerry M Woodall
National Medal of Technology Laureate
Epstein Distinguished Professor of ECE
Purdue University
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Why isnt there a global scale hydrogen energy economy?
Small volume energy density
High pressure gas and low temperature
liquid storage expensive and dangerous
Hydrogen transport dangerous and expensive
Solution: use a safe, cheap, earth-abundant high energydensity material for storage and transport that can
react with water to make hydrogen on demand
Is there such a material? Yes! Its ALUMINUM!
If aluminum could split water the chemistry would be:
2Al + 6H2O 3H2 + Al2O3:3H2O
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Aluminum has the highest volumetricenergy density ofanything on the chart
and a higher mass energy density than
ethanol, methanol or bituminous coal!
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Mass Energy Densities of Interest
As hydrogen from splitting water:
1 Kg H2: 142 MJ = 39.4 kWh combustible energy 1 Kg Al makes 111 g of H2 from 2 Kg of H2O = 4.4 kWh
1 gal (10 Kg) Al makes 44 kWh as hydrogen
1 gal. diesel: 37 kWh
1 gal. liquid hydrogen: 10 kWh
As heat from splitting water:
1 Kg Al: 4.4 kWh
Total energy, 1 Kg Al: 8.8 kWh (1Kg coal: 6.7 kWh!)Energy to electrolyze alumina to 1 Kg of Al: 12.9 kWh
Total energy efficiency: (8.8/12.9) x 100 = 68%
H2 energy efficiency: (4.4/12.9) x 100 = 34%
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Technology sustainability & large scale use
World Supply:
Al reserve in the planets crust: about 1013 Kg (as Al);
1.2 x 1012 Kg of H2 made by splitting water = 5 x 1013 kWhrs
of H2 energy
Current worldwide annual Al production: 32 billion Kg from
bauxite;
400 billion Kg of scrap impure elemental Al; amount
needed to supply 12% US annual energy consumption of
about 100 quad BTU. Since all Al that is converted to an
oxide can be recycled back to metallic Al via electricity
from any source, Al is a global scale alternative energy
storage material with almost no carbon footprint.
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WHAT CAN WE MAKE? Buy scrap or metallurgical grade, i.e. cheap, Al, melt itwith Ga and Sn, then cool it to make solid, bulk like Al
rich alloys up to 93 wt% solid Al grains, and 6.2 wt% Ga,and 0. 8 wt% Sn liquid in the grain boundaries that splitsany kind of liquid water, e.g. sea water, dirty water andpolluted water, at between 20 C and 100 C and make H2,heat, including superheated steam, on demand and
aluminum hydroxide powder Buy 95% Al, 5% Sn vendor alloy, contact with a liquidmixture of 7 wt% Ga and 1 wt% Sn, and then with water;this splits any kind of liquid water at temperatures
between 20 C and 100 C and make H2, heat, includingsuperheat steam, on demand and aluminum hydroxidepowder
Recover/separate inert Ga and Sn from hydroxidepowder and recycle indefinitely
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A sample of Al-GalInSn* splitting water
Using scrap Al and
recovering the GaInSncomponent, the cost/kWh of
our hydrogen/compared
to other fuels:
Coal: $0.004Natural Gas: $0.06
Al: $0.10
Gasoline: $0.09 (at $3.00/gallon)
Li ion battery: $4.00
*GaInSn is liquid at room temperature
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2Al(GaInSn) + 6H2O* 3H2 + 2Al(OH)3 + GaInSn
3H2 + 3/2O2 3H2O; we get back half the water when we use the H2;we get rest of the water + the Al back via smelting; the GaInSn is inert
* Including salt water
2 Al(OH)3 + heat Al2O3 + 3 H2O + electricity 2 Al
Bottom line: You get all the water back as potable water!
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Legend:
= Aluminum= Ga-In-Sn
= Hydroxide
= Hydrogen gas
Al-Ga
grain
Alloy Water
At room temperature, the Ga-In-Sn phase is liquid! The solid Al grains are able to dissolve into and move freely through the
liquid phase. Al near the surface contacts the water interface. The ensuing exothermic reaction produces hydrogen as the Al is
oxidized. This reaction proceeds until all the Al grains split the water into hydrogen gas and aluminum hydroxide
How it works!
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Abundance:Al: crustal abundance 8%Ga: crustal abundance 0.002%
Sn: crustal abundance 0.0002%
Sustainability:Al: annual production 32 billion kg
Ga: annual production 184 million kgSn: annual production 165 million kg
Therefore, as long as the Ga and the Sn arerecycled there is no Ga abundance or productionproblem
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Energy Source
(wind, solar, nuclear,
geothermal, etc)
(-12.9 kWh/kg-Al)
Application(fuel cell, combustion
engine)
Water
Aluminum
Alloy
Aluminum
Hydroxide
Heat
(+4.4 kWh/kg-Al)
Energy
Water
Reaction
Hydrogen
(+4.4 kWh/kg-Al)
The Aluminum-Hydrogen Cycle
CO2
Sequestered
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Example applications:
Replace batteries with a Ga-Al-H20/fuel cell
system for high energy density electric power applications:
emergency/stand-by power (AlGalCo)
electric wheel chairs, golf carts, utility vehicles
PDAs, Laptops, etc.
hybrid and fuel cell powered cars
Stirling engines
replace gasoline for HEVs (GM Volt)
liquid fuel multiplier, e.g. diesel enrichment
trains, boats, ships, subs, trucks large boats and other maritime applications
off-grid/remote power + desalinated/potable water!
integrated utilities with solar farms/wind turbines
Other applications:
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Enabling Wind or Solar as Base LoadElectricity Generation Capacity
Target cost: $0.10/kWhr, assuming 40x alloy
recyclingAll required technologies are known
Primarily an Engineering Development Project
Enables Environmentally Sound and Secure
Electricity
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reaction tank,
95-5 alloy, and
controlsH20
H2, 4.4 kWh/Kg-alloy
24/7 or on demand
Fuel Cell or Gas
Turbine/Generator
H20
Electricity
Heat, 4.4 kWh/Kg-alloy
24/7 or on demand
Steam Turbine
alumina,
Ga,In,Sn + H20
component separationH20
Ga,In,Sn recovery
alumina electrolysis
12.9 kW-Hrs/Kg Al
95-5 alloy
regeneration
intermittent
electrical power, e.g.solar or wind
Enabling Wind or Solar as Base Load
Electric Power Model Flow Diagram
CONSUMER
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CAN BE DONE FOR $1/GAL OF WATER AND $0.34/kWh OF ELECTRICITY
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ALUMINUM! A GLOBAL-SCALE, EARTH-ABUNDANT,HIGH ENERGY DENSITY STORAGE
MATERIAL FOR SPLITTING ANY KIND OFWATER TO MAKE HYDROGEN, HEAT ANDPOTABLE WATER ON DEMAND
ONCE YOU BUY IT, IT IS YOURS FOREVER;UNLIKE FOSSIL FUELS IT STAYS IN THE
ENERGY SYSTEM.
THE BOTTOM LINE: