Summers are growing hotter, storms more violent, wildfires more frequent and ocean levels are rising. It is becoming increasingly obvious that burning fossil fuels containing millions of years worth of trapped carbon is altering our atmosphere and climate.
Hydrogen is a promising alternative to fossil fuels. It’s abundant, clean burning and has a high mass energy density. With modification it can be used in heating, vehicle engines or fuel-cells as a replacement for carbon-based fuels such as natural gas (CH4) gasoline (C8H18) or diesel fuel (C12H23).
Hydrogen doesn’t have the long-term environmental flaws of fossil fuels. But it is not yet a simple replacement for hydrocarbons. Extracting green or grey hydrogen takes a considerable amount of energy and geologic hydrogen hasn’t yet been found in commercial quantities.
Hydrogen also has a low volumetric energy density. This means even though one kilogram of hydrogen can provide two to three times the energy of one kilogram of diesel fuel, at standard atmospheric pressure a hydrogen fuel tank requires about 5000 times the volume of a diesel fuel tank in order to provide the same energy and range.
Pressurizing the hydrogen to about 10,000 pounds per square inch improves this so that hydrogen only requires about 7 times the volume of diesel fuel. This pressure is almost twice as high as that which imploded the Titan submersible underwater earlier this year while hunting for the Titantic wreckage.
So while hydrogen is a promising fuel, storage and transport is challenging. If only we could efficiently generate hydrogen near where it is used. A Canadian research team may have the answer in aluminium.
It takes up to 63 kilowatt-hours to extract one kilogram of aluminium from its bauxite ore. Much of that energy remains trapped in the chemistry of Aluminium in the same way coal and gasoline trap the energy of ancient sunlight. In fact burning aluminium produces almost twice the energy of burning an equivalent mass of coal.
According to the U.S. Environmental Protection Agency the energy embedded in a single soda can could power a 14 watt light bulb for 60 hours or a television for two hours. By tuning the particle size and chemistry, the energy embedded in this metal can be used to extract hydrogen from water.
Reza Kholghy, PhD, is research chair in Particle Technology and Combustion Engineering at Carlton University in Ottawa Canada. Dr. Kholghy was kind enough to provide Green Prophet with some insight on this promising new technology.
GreenProphet (GP): How do you use aluminium to produce hydrogen?
Dr. Kholghy: Aluminium powder is mixed with water and combusts through a high temperature oxidation process. This way, Aluminium takes the oxygen molecule in water and turns into alumina (aluminium oxide) and releases the hydrogen in water molecules.
GP: What is the efficiency compared to other methods of recycling Aluminium?
Dr. Kholghy: This is not a method to recycle aluminium. By combusting it with water, we can get 100% yield, meaning that all of the aluminium will be converted to alumina and for every kg of Aluminium, roughly 1 kg of water is consumed releasing around 111 gr of hydrogen.
GP: What is the volume and mass energy density compared to hydrogen fuel cell technology?
Dr. Kholghy: The reactor is very compact, a 2 MW reactors only need a footprint of around 300 to 400 sq sq ft and cogenerate heat, hydrogen and alumina.
GP: Why weren’t we doing this 100 years ago?
Dr. Kholghy: This reaction has been used in a variety of application including green rocket propellant where Aluminium nanoparticles are used. However, the unique feature of our work is finding a way to burn large Aluminium particles
GP: What is the best scale for an Aluminium hydrogen generator? (car, house, utility…)
Dr. Kholghy: Utility, from 1 MegaWatt and higher.
GP: What would you tell someone who is sceptical?
Dr. Kholghy: This is just a pice of puzzle towards transitioning to zero carbon energy production. This technology offers off grid solutions for cogeneration of heat, hydrogen as well as valuable high purity alumina that is used in batteries.
GP: Are you working with other researchers or corporations?
Dr. Kholghy: We are working with a Company called GH Power to develop this technology.
GP: What is the next step?
Dr. Kholghy: Our industrial partner is working with us to demonstrate the full scale reactor.
GP: How are impurities removed?
Dr. Kholghy: For hydrogen generation, there is no need to remove impurities. We get similar hydrogen yield no matter if recycled Aluminium with low purity or high purity Aluminium is used. The purity of alumina is similar to the purity of the Aluminium fuel used and we have developed a proprietary process to remove impurities from the produced alumina if needed.
