The Briefing Room
General Category => Science, Technology and Knowledge => Energy => Topic started by: EC on March 16, 2017, 10:17:15 am
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A team of scientists have found a way to use solar power to generate a sustainable and relatively cheap fuel by using natural light to generate hydrogen from biomass.
Moritz Kuehnel, Ph.D., from the Department of Chemistry at the University of Cambridge and joint lead author, said that lignocellelose—the main component of plant biomass—can be used to harness hydrogen.
“Lignocellulose is nature's equivalent to armored concrete,” Kuehnel said in a statement. “It consists of strong, highly crystalline cellulose fibers, that are interwoven with lignin and hemicellulose which act as a glue. This rigid structure has evolved to give plants and trees mechanical stability and protect them from degradation and makes chemical utilization of lignocellulose so challenging.”
The technology relies on a simple photocatalytic conversion process where catalytic nanoparticles are added to alkaline water in which the biomass is suspended. This is then placed in front a light in the lab that mimics solar light to create a solution ideal for absorbing the light and converting the biomass into gaseous hydrogen that can then be collected from the headspace.
The hydrogen produced is free of fuel-cell inhibitors, such as carbon monoxide, which allows it to be used for power.
The nanoparticle is able to absorb energy from solar light and use it to undertake complex chemical reactions. In this experiment, it rearranges the atoms in the water and biomass to form hydrogen fuel and other organic chemicals, including formic acid and carbonate.
“There's a lot of chemical energy stored in raw biomass but it's unrefined, so you can't expect it to work in complicated machinery, such as a car engine,” joint lead author David Wakerley, Ph.D., of the Department of Chemistry, said in a statement. “Our system is able to convert the long, messy structures that make up biomass into hydrogen gas, which is much more useful.
“We have specifically designed a combination of catalyst and solution that allows this transformation to occur using sunlight as a source of energy. With this in place we can simply add organic matter to the system and then, provided it's a sunny day, produce hydrogen fuel.”
The research team used different types of biomass in their experiments including pieces of wood, paper and leaves that were placed in test tubes and exposed to solar light.
More: http://www.rdmag.com/article/2017/03/solar-power-harnessed-generate-hydrogen
One to watch.
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I bet it still costs more energy to make the hydrogen than you get out of burning it. That is the permanent downside to a hydrogen economy that makes it economically impossible. The energy necessary to crack the hydrogen-oxygen bonds in a water molecule are very strong.
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I bet it still costs more energy to make the hydrogen than you get out of burning it. That is the permanent downside to a hydrogen economy that makes it economically impossible. The energy necessary to crack the hydrogen-oxygen bonds in a water molecule are very strong.
Maybe, maybe not. You can generate hydrogen gas using a car battery, saltwater, and some electrodes at home. If the energy input is "free" like the sun, it could be viable.
Electrolysis is a well known way to remove rust.
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True - but it's a catalytic method. Catalysts, once formed, never need replacing (the chemical changes they go through during the reaction they catalyse result in them returning to the original state at the end of the process) but only cleaning once in a while. It's going to be a significantly lower cost method of obtaining hydrogen than electrolysis.
While there is still going to be an energy debt - always is - that is offset in my book by the conversion of useless biomass into portable fuel, just as methane digesters make that trade off (or alcohol stills, for that matter).
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Hydrogen the most abundant element in the universe. So dang hard to get.
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Hydrogen the most abundant element in the universe. So dang hard to get.
Existing, and existing in a useful format are two different things. We have lots of hydrogen in the ocean's water molecules; rather useless form for a heat engine or fuel cell. Just as needed is the oxygen as well.