Scientists have shown how sunlight and a cheap catalyst can unlock significant amounts of hydrogen from fescue grass.
The method, now demonstrated for the first time, could potentially lead to a sustainable way of producing hydrogen, which has enormous potential in the renewable energy industry due to its high energy content and the fact that it does not release toxic or greenhouse gases when it is burned.
“This really is a green source of energy,” says coauthor Michael Bowker, a professor at the Cardiff Catalysis Institute. “Hydrogen is seen as an important future energy carrier as the world moves from fossil fuels to renewable feedstocks, and our research has shown that even garden grass could be a good way of getting hold of it.”
Hydrogen exists in enormous quantities all over the world in water, hydrocarbons, and other organic matter. The challenge for researchers has been devising ways of unlocking hydrogen from these sources in a cheap, efficient, and sustainable way.
A promising source of hydrogen is the organic compound cellulose, which is a key component of plants and the most abundant biopolymer on Earth.
In their study, the team investigated the possibility of converting cellulose into hydrogen using sunlight and a simple catalyst—a substance which speeds up a chemical reaction without getting used up.
This process is called photoreforming or photocatalysis and involves the sunlight activating the catalyst, which then gets to work on converting cellulose and water into hydrogen.
The researchers studied the effectiveness of three metal-based catalysts: palladium, gold, and nickel.
Nickel was particularly interesting to the researchers, from a practical point of view, as it is a much more earth-abundant metal than the precious metals, and is more economical.
In the first round of experiments, the researchers combined the three catalysts with cellulose in a round bottom flask and subjected the mixture to light from a desk lamp. At 30 minutes intervals the researchers collected gas samples from the mixture and analyzed them to see how much hydrogen was being produced.
To test the practical applications of this reaction, the researchers repeated the experiment with fescue grass, which came from a domestic garden.
“Up until recently, the production of hydrogen from cellulose by means of photocatalysis has not been extensively studied,” adds Bowker. “Our results show that significant amounts of hydrogen can be produced using this method with the help of a bit of sunlight and a cheap catalyst.
“Furthermore, we’ve demonstrated the effectiveness of the process using real grass taken from a garden. To the best of our knowledge, this is the first time that this kind of raw biomass has been used to produce hydrogen in this way. This is significant as it avoids the need to separate and purify cellulose from a sample, which can be both arduous and costly.”
The team, which also includes researchers from Queen’s University Belfast, report the findings in the journal Proceedings of the Royal Society A.
Source: Cardiff University