Hundreds of thousands of unused kegs of Guinness have been repurposed to fertilise Christmas trees during the coronavirus lockdown.

The forestry project is one of several environmentally friendly disposal routes the famous Irish brewery employed as it brought back millions of litres of stout, beer and ale from closed pubs and bars.

At the start of the lockdown in Ireland, Guinness reduced operations at its St James’s Gate brewery in Dublin to the minimal level required to keep its yeast stocks alive.

It was the first time that had happened since the 1916 Easter Rising rebellion in the city.

Now production has ramped up once again as pubs and bars across Ireland, the UK and beyond prepare to start welcoming customers back.

Anticipating the challenges the drinks industry is set to encounter in the era of social distancing, Guinness owner Diageo has announced a 100 million US dollar ‘Raising the Bar’ fund to help pubs pay for new hygiene and safety measures – 14 million euro of which is being made available on the island of Ireland.

The PA news agency has been behind the scenes at St James’s Gate to witnesses the scaling up of operations.

Aidan Crowe, the director of operations at the brewery, said Guinness decided in the early days of lockdown to support its on-trade customers by retrieving the kegs that were set to go undrunk due to the closure of hospitality outlets.

“It’s been a tough time in the brewery but it’s been a much tougher time if you’re trying to run on-trade outlets in this part of the world,” he told PA.

“That’s why it was very, very important right from the start of the lockdown to support the on-trade as much as we could. That’s why we took the decision to bring back all of the beer from the on-trade.”

He added: “Basically what we do is we take all the keg beer back and we decant it and we disperse the product through a number of environmentally sustainable routes.

“The vast majority of the beer goes to willow and Christmas tree plantations, it’s used as nutrients in those farms.

“We’ve also diverted some product through to anaerobic digesters, where it produces a bio-gas.

“Actually, we’re quite optimistic that, in the long term, that bio-gas can be a suitable fuel source for us to use here in the brewery.

“And then we’ve also diverted some of the product for composting.

“So it’s an unprecedented problem for us to have and we wanted to ensure that in terms of how we manage that and manage the beer it was environmentally sustainable, because that’s so critically important, not just for our business, but obviously for the country as a whole as well.”

Asked how many litres had been returned, Mr Crowe said: “You’d probably make me cry if I started to add it all up, but it’s hundreds of thousands of kegs and we’ve still got some products to decant and we’ve still got some markets that haven’t finished returning their beer to us. So a lot of beer and a lot of kegs.”

The main brew house at St James’s Gate produces 7.2 million hectolitres (720 million litres) a year.

That amounts to 39 pints a second all year round.

Ordinarily, St James’s brews 2.5 million pints of Guinness every day and 1.5 million pints of other beer and stout.

But all that was scaled back in the last two weeks of March and first week of April.

“Our biggest job really over that period of time was just managing what was an unprecedented downturn,” said Mr Crowe.

“Probably going back to 1916, actually, is the last time we had such a dramatic short-term change.

“Now, thankfully, we’re on the other side of that, we’re ramping up very, very strongly through the months of June and July.”

St James’s Gate’s three largest markets are Great Britain, Ireland and North America but overall it distributes to 130 countries worldwide.

All stout, beer and ale produced at the height of lockdown was used only for canned products.

So while the kegging operation at St James’s Gate ground to a near halt, canning and bottle operations in Belfast and Runcorn actually stepped up production, to meet the added demand from the off-sales trade.

Mr Crowe said the biggest challenge the brewery now faces is the uncertainty about what demand will look like in the first few months of eased restrictions.

“We’ve got to be prepared for different eventualities,” he said.

“If it’s slower than we expect, we’ve got to be ready for that. If it’s significantly busier than we expect, we’ve got to be ready for that too. And we are ready, we will be ready.

“It’s a much nicer set of challenges to be trying to manage than the challenges that we had back in March when everything was being ramped down.”