Leftover grain from breweries could be converted into fuel for homes


Breweries in the EU throw out around 3.4 million tons of unspent grain every year, weighing the equivalent of 500,000 elephants. 

Using just 1kg of the grain, Dr Ahmed Osman from the School of Chemistry and Chemical Engineering has been able to create enough activated carbon to spread across 100 football pitches, which could be used as a renewable fuel for homes in winter, charcoal for summer barbecues or in parts for water filters. 

The results have recently been published in the Journal of Chemical Technology and Biotechnology.

Barley waste (also known as brewer’s spent grain) is an abundant form of biomass waste and comprises a significant portion of brewery by-product. Conventionally, this waste has uses as an animal feedstock, but its short shelf life of less than 48 hours renders its use as such problematic. Landfill disposal of this waste leads to the production of methane, a greenhouse gas which exerts more significant effects on the climate in comparison to CO2 - therefore conversion into more stable, valuable forms of carbon is hugely desirable.

Dr Osman explains: “There are only a few steps in our low cost and novel approach – drying the grain out and a two-stage chemical and heat treatment using phosphoric acid and then a potassium hydroxide wash, both of which are very low cost chemical solutions. This then leaves us with activated carbon and carbon nanotubes – high value materials which are very much in demand.

Liquid forms of carbon are normally shipped to the UK from the Middle East, and solid biocarbon, in the form of wood pellets is shipped from the US and elsewhere.  Using this new technique, we can utilise more locally produced resources, reduce emissions linked with the agriculture sector, and we are also creating a high-value product.

Across the globe, there is a real demand for carbon, as it is used to create fuel for households, parts for water filters, and even charcoal for barbecues. If we are able to take something that would otherwise be a waste and turn it into a useful biofuel, it can only be a good thing for our planet. It could really help to solve global waste and energy problems.”

“The synthesis of value-added products from waste is also a prime example of the circular economy, which benefits the environment and society through economic and social opportunities.”

Ahmed Osman
Ahmed Osman博士

The project was funded by EPSRC and The Bryden Centre at Queen’s. It was an international collaboration between Queen’s University Belfast, South West College and Sultan Qaboos University in Oman.

David Rooney, Director of the Bryden Centre and Professor of Chemical Engineering at Queen’s said: “We often underestimate the value and usefulness of natural carbon resources which we have readily available to us. Sustainability is a key focus of our research here in the School of Chemistry and Chemical Engineering at Queen’s and it is great to see our undergraduate students, research staff, and partners from across Northern Ireland and the world work together to deliver the types of solutions needed to support future generations and realise the potential of a truly sustainable society."

Dr Osman is hoping to explore opportunities for the commercialisation of the method in creating activated carbon and carbon nanotubes.

Queen’s University's work on biofuels from waste will be featured in the upcoming major Engineering the Energy Transition Conference, from 26 to 28 February 2020 in Belfast.

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