The SW Summary: Cork for carbon reduction, record organic wine sales in the UK, and the environmental impact of barrel cleaning techniques

By Hanna Halmari

Reducing the carbon footprint of wine production with cork closures

Writing for The Ecologist, Nick Breeze praises cork for its sustainability impact. Closing a wine bottle with cork not only “significantly reduces the carbon footprint of wine packaging,” but also “helps sustain vital ecosystems,” he reports. Breeze refers to a study by PwC investigating the sustainability life-cycle impact of corks and screw-caps, which revealed that “cork closures showed a 24-fold advantage over aluminium screw-caps.” 

The shift from cork to screw-tops began around a decade ago, largely driven by cork taint, “where a bacteria – Trichloroanisol – gives wine a damp cardboard aroma and destroys the wine’s pleasurable characteristics.”  Breeze discusses the strides taken by the world’s largest cork product producer, Amorim, to develop sophisticated techniques that have significantly reduced such risks.

The leading company also recently hired Ernst & Young to carry out a study to assess the full carbon impact of cork closures. The findings revealed that “a single natural cork closure is proven to retain up to 309 grammes of CO2, while a sparkling wine stopper captures even more at 562 grammes,” reports Breeze. Using cork closures can therefore significantly reduce the carbon footprint of wine bottle production, which ranges between 300-500g of CO2. Furthermore, the earth’s 2.2 million hectares of cork forests are considered biodiversity ‘hotspots’, providing one of the highest levels of forest biodiversity. Given the fact that “over 70 percent of cork usage [goes] into wine closures,” Breeze suggests that “it could be argued that drinking wine sealed with cork has a material benefit in supporting this valuable carbon sink.” Read more here.

2019 organic wine sales reached record value in the UK, with growth expected to continue

So reports Lisa Riley in this article for Harper’s Bazaar. According to the Soil Association Certification Organic Market Report 2020, the UK organic wine market grew 4.5% in 2019, reaching a record value of £2.45bn. Already eight years strong, this growth trend is expected to carry on throughout 2020 as supermarkets continue to respond to eco-conscious consumer demands. Riley quotes Clare McDermott, business development director at Soil Association who says:

“Organic certification means people can be sure that what they are buying has been produced to the highest environmental and animal-welfare standards. The remarkable success of organic wine last year is proof that the demand for nature-friendly products is there, and that if retailers stock more organic, shoppers will buy it.”

The report estimates the total organic market to be worth £2.5bn at the end of 2020, predicting growth across all channels including home delivery, supermarkets, food service etc. Riley shares how 2019 saw the highest organic sales growth (11.2%) in online and home delivery, explaining how Soil Association “put the success of this channel – which includes organic veg box schemes and online retailers like Ocado – down to savvy shoppers turning to the internet to choose from the widest ranges of organic products available.”

Phoebe French, covering the report for The Drinks Business, similarly highlights the rising trend in organic consumption, with consumers spending “an average of £200 million on organic food and drink every month.”

Read more in Harper’s Bazaar here and The Drinks Business here.

“Wine is a luxury, non-essential product, so of all the farming practices, trying to be sustainable in growing grapes is one of the first places we should start”

So says Daniel Ham, founder of sustainable winery Offbeat Wine, in this article by Phoebe French for The Drinks Business. Despite a common belief that UK sustainable wine production “is really difficult because of disease pressure,” Ham believes that sustainable winegrowing can be a reality in the UK provided winegrowers adopt a “more coordinated approach to sustainability.” 

The UK has seen a recent increase in wine sustainability movements, including the creation of the Sustainable Wines of Great Britain initiative in 2019. However, as stated by French, as “a relative newcomer on the world wine scene, it is understandable that sustainable frameworks are less developed [in the UK].” 

Comparing initiatives in the UK to those in Champagne, Ham highlights the need for a “central push towards sustainability” in the UK. “Whereas here you’ve got individual producers doing it on their own, over [in Champagne] you’ve got central locations where they take all the winery wastewater to be treated. Grape pomace and final pressings get taken to a similar sort of location for processing where they make spirits,” he says. 

Read more about Ham’s story and Offbeat Wines here.

New study finds CO2 barrel cleaning technique to have the lowest environmental impact

Vineyards are increasingly shifting to more sustainable practices in efforts to reduce their overall carbon footprints. However, as Becca points out in this article in The Academic Wino, barrel cleaning doesn’t tend to jump out as the first focal point for improvement. Barrel cleaning is crucial in the wine production process, as in order to ensure that the wine “[takes] on the desired sensory characteristics of the wood” the barrels must be cleaned and disinfected adequately to remove the build up of solids that accumulate inside. However, many of the common cleaning techniques such as using pressurised hot water, high-pressure water vapour and, at times, chemical disinfectants rely on high water and energy expenditures.

The article draws attention to a study (García-Alcaraz et al., 2020) recently published in the Innovative Food Science and Emerging Technologies journal that analyses the environmental impact of the four most common wine barrel cleaning and disinfecting techniques. The study uses a Life Cycle Assessment (LCA) method, which Becca describes as “the most widely-used method for calculating environmental impact of a product or industry…[evaluating] the ‘cradle to grave’  for one unit of product.” The four barrel cleaning techniques assessed were:

  1. “Pressurized water + Sulfur dioxide (SO2) wick
  2. Water vapor + SO2
  3. Ozone
  4. Carbon dioxide (CO2) (using dry ice exposure)”
Factors Included in the LCA Analysis Factors Not Included
– “Electricity consumption of machinery used
– Transportation of the barrels during the cleaning process
– Products used in the cleaning/disinfecting
– Emissions produced by labor
– Consumption of materials and resources during cleaning
– Transportation of barrels
– Set-up of the machines used for cleaning
– Maintenance of the machines used for cleaning
– Storage of the barrels after cleaning was complete.”


The study found that the cleaning technique with the overall greatest environmental impact was the water vapour + SO2 method, whereas the CO2 cleaning technique produced the lowest overall environmental impact. As reported by Becca, “the authors of the study concluded that this is the order of overall environmental impact, from lowest to highest”:

CO2 > Pressurised water + SO2 > Ozone > Water vapour + SO2


Read more about the study in The Academic Wino article here or in the journal here.

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About the author

Hanna Halmari

Hanna Halmari is the editor at Sustainable Wine and the head of conferences at Innovation Forum. Hanna specialises in sustainability research and events across various industries. She holds an MSc in international development from Kings’s College London, where she developed a strong interest in political economy and post-communist transformation. Hanna speaks Finnish, Bulgarian and English. In her spare time she is a dedicated Radio Lollipop volunteer at Great Ormond Street Children’s Hospital, enjoys travelling, and tasting new wines.