In working with process equipment manufacturer Dalum Beverage Equipment, Edinburgh’s Stewart Brewing has invested in a sustainable, in-house CO2 solution that has turned CO2 waste into a valuable resource. This is how they did it.
For Edinburgh’s Stewart Brewing, a staple of the Scottish brewing scene for over two decades, sustainability has always been a core part of their identity.
Their commitment stems from founders Steve and Jo Stewart’s dedication to environmental sustainability. “Jo and I actually met on a Sustainable Development degree, so when we started Brewing, we always had an interest in brewing sustainably,” Steve Stewart shares.
Installing two Dalum CO2 Recovery Plants, respectively in 2022 and 2023, has led to complete CO2 self-sufficiency at Stewart Brewing. These plants transform a natural fermentation byproduct into a valuable resource and offer a strong model for craft breweries aiming to minimise environmental impact and improve business resilience.
Previously, Stewart Brewing purchased nearly 35 tonnes of CO2 annually for processes such as tank purging, packaging, and dispensing. This reliance brought escalating costs, with prices per tonne increasing from around £250 in 2016 to nearly £1,000 by 2021, a substantial expenditure of over £30,000 annually.
More critically, the volatile CO2 supply chain presented a severe threat. The crisis peaked in 2021 when, after navigating pandemic-related shifts towards packaged beer, breweries started to face acute CO2 shortages.
He recalls this huge business resilience issue for their brewery as a completely stressful time, which led them to focus their efforts on finding a sustainable, in-house CO2 solution.
Strategic CO2 Recovery
Driven by their net zero ambitions and the urgent need for supply security, Stewart Brewing looked into CO2 recovery options. Their previous fermentation process released approximately 70 tonnes of CO2 annually from their 20,000 hL production, a significant waste of resource.
“The question that we asked ourselves,” Stewart explains, “was how much of this released carbon dioxide can be recovered to offset against the purchase of CO2 into the business?” The solution had to be cost-effective and align with their business values.
They partnered with Dalum Beverage Equipment, a Danish expert in craft-scale CO2 recovery systems. “Dalum really understood our needs and worked with us to fully implement the technology,” he notes, also crediting a positive recommendation from Eddie Gadd of Ramsgate Brewery, the UK’s first DALUM CO2 Recovery Plant adopter.
Stewart Brewing installed two 15 kg/hr Dalum CO2 Recovery Plants. This dual-system approach provides crucial flexibility for varying fermentation batch sizes and makes it possible for them to run one or both machines as needed. This strategic choice, combined with neat installation and operator buy-in, boosted CO2 recovery potential.
“The system is well set-up for success” says production manager, Sam Russell, “it still requires the brewers and operators to begin capturing fermentations at the right time, understand the dynamics of the collection system and keep it clean, conduct checks, and look for opportunities, such as collecting from empty BBTs.
“The question that we asked ourselves was how much of this released carbon dioxide can be recovered to offset against the purchase of CO2 into the business?”
Steve Stewart, Stewart Brewing
The team have taken to this brilliantly; they’re proud to be harvesting and recycling CO2, especially as an early adopter of the technology on this scale. We also see the rewards in having high-quality, sustainable CO2 on tap.” The recovered CO2 is 99.99% pure and completely odour- and tasteless.
Resilience & Reduced Emissions
The Dalum system has been transformative for the brewery. Recovering 52 tonnes of CO2 annually, Stewart Brewing now far exceeds their internal demand of ~35 tonnes, achieves 100% CO2 self-sufficiency, and has successfully turned a former waste stream into a valuable asset.
The success has also created a new revenue opportunity: the brewery sells approximately 17 tonnes of their excess, sustainably produced biogenic CO2 to local pubs, bars, and restaurants.
The financial case for the £150,000 investment (covering plants, tank, and systems) is strong. Electrical costs for the CO2 recovery are roughly £177 per tonne, a stark contrast to the nearly £963 per tonne for commercial CO2 and yields annual savings of around £26,000.
“We were fortunate to obtain an RSA Grant of roughly £50,000,” Stewart mentions, “so, from the business point of view, it’s about a three-year payback.”
This comprehensive approach brings several advantages. Eliminating external CO2 deliveries and introducing a bulk system has streamlined operations and improved workplace safety and satisfaction. Crucially, independence from the volatile CO2 market protects production against price hikes and shortages and ensures a strong business resilience.
Furthermore, recovering 52 tonnes of CO2 annually prevents its direct release and significantly reduces their carbon footprint. The system is supported by their extensive solar infrastructure: 570 solar panels on the brewery roof generate an average of 163,152kWh annually (enough to power 45 homes).
A large portion of this renewable energy directly powers the CO2 recovery process, especially during peak recovery times on weekends.
The strong partnership with Dalum has been vital. “They’ve helped us with problem- solving, maintenance, support, and the utilisation of the machines,” Steve acknowledges.
Kim Dalum, Dalum founder and CEO, reflects on the collaboration: “Working with Steve, Sam, and the brewing team at Stewart Brewing has been fantastic. Their dedication to sustainability is inspiring.
“It’s incredibly rewarding to see them not only achieve CO2 self- sufficiency but also to become a local CO2 supplier. We were thrilled to support them with their new cylinder filling station and help them share their sustainably recovered CO2. It’s a great example of the technology’s positive influence for craft breweries.”
