By now, pubs and homes are well stocked with booze for Christmas but, given the time of year that’s in it, few give a thought to what to do with the huge amount of waste from the brewing process.
Studies show that for every pint of beer that’s brewed, about two porridge bowls’ worth of spent grain is produced. The average Irish drinker quaffs about 400 pints yearly,according to the OECD. Just add that up!
Some people, including researchers at Queen’s University Belfast (QUB) and celebrity chef Jamie Oliver, have been looking at constructive ways of using brewery waste, which has traditionally been fed to cattle and pigs.
Despite a drop in alcohol consumption in Ireland, beer sales are rising and account for 45% of the drinks market. We’ve also seen growth in micro-breweries producing craft beers and now have around 75 such breweries.
In QUB, scientists have developed a low-cost technique to convert left over barley from breweries into carbon which could be used as a renewable fuel for homes in winter, charcoal for barbecues or water filters in poorer countries. Breweries in the EU throw out around 3.4m tons of unspent grain every year, weighing the equivalent of 500,000 elephants.
Using just 1kg of the grain, Ahmed Osman from the School of Chemistry and Chemical Engineering, QUB, has been able to create enough activated carbon to spread across 100 football pitches.
The results have been published in the Journal of Chemical Technology and Biotechnology. Dr Osman said there are only a few steps in their low-cost and novel approach. They first dry out the grain and follow this with chemical and heat treatment.
“Across the globe there is a real demand for carbon as it is used to create fuel for households, parts for water filters and charcoal for barbecues,’’ he explained.
"It could really help to solve global waste and energy problems.”
In making beer, malted barley is soaked and mashed to extract protein, sugar and nutrients, leaving behind the spent grain. And we have Jamie Oliver’s word that this by-product is totally edible. What’s more, he says, it has a delicious and nutty flavour.
Jamie has given the UK-based Good Things Brewing Co as an example of how spent grain from their beer can be turned into a tasteful malted flour, high in protein and fibre. He uses the grain to make Irish soda bread as well as a pasta dough.
“So much more complex and delicious than usual,” he says.