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Carbon Footprint: Is Saving The Planet Worth A Corked Wine?

Cork may lose out on the taint issue but its carbon footprint is far lighter than that of screwcaps. But, asks JAMIE GOODE, do consumers care?

The closures debate has taken a rather tortuous route over the last few years. It used to be simple. Cork was tolerated, since it was the only closure for wine bottles, but increasing grumbling over its reliability, chiefly via taint, led to the search for alternatives. Then, via the introduction of screwcaps and other closures, we began to realise that the amount of oxygen the closure transmits has an important effect on wine development after bottling. So we’ve had the debate about taint; we’ve had the debate about oxygen. Now there’s a new front emerging in the battle over who gets to seal the wine bottle: sustainability, the environment and the industries carbon footprint.

Green Issues

Green issues have suddenly become topical thanks to a headlong rush among retailers to prove they are the most ecologically minded, and perhaps also because cork companies are keen to deflect attention away from taint issues. Tesco, the UK’s leading supermarket, has initiated an ambitious programme that will soon see all its food and drink products labelled not only with nutritional information, but also their carbon footprint, including that of the packaging. It also has a commitment to reducing packaging waste by 25% from its 2006 figures by 2010. ‘As a business we want to achieve a 50% reduction in energy usage by 2010,’ says Tesco’s Andy Gale. ‘We want to lead consumers in a green consumption revolution.’ Not to be outdone, rival Sainsbury’s has just released two own-label wines in the standard bottle size of 75cl, but in PET (polyethylene terephthalate), a plastic which weighs in at one-eighth the weight of a typical glass bottle and is a third smaller, thus reducing transport-related emissions. In addition, these wines –one a New Zealand Sauvignon, the other an Australian rosé, at £4.99 and £3.99 respectively – are bottled in the UK from bulk-shipped wine, a practice being talked up as a way to further cut emissions.


French company Oeneo has led the way in initiating the carbon footprint debate on the green credentials of wine bottle closures. It is the firm behind one of the new generation of wine closures, Diam. This ‘technical cork’ is made from small pieces of ground-up cork combined with synthetic microspheres to form what looks and feels like a natural cork, but is more regular, with a grainy sort of complexion. The significant detail is that the cork particles are rendered taint-free by washing them in carbon dioxide.


Oeneo commissioned a report examining the environmental impact of a range of closures in terms of the carbon emissions generated during manufacture. Its motivation is clear: as a taint-free alternative to natural cork, the main competitor is probably screwcap, although it should be pointed out that Oeneo does manufacture and sell a screwcap as part of its closures portfolio. The report, carried out by French consultancy Cairn Environment, used an accepted method (Bilan Carbone) for assessing greenhouse gas emissions. Three closures were examined: natural cork, screwcap and Diam. The impact of the bottles’ capsules was also considered. The results show that natural cork has the lowest carbon footprint, and screwcaps the worst, and Diam somewhere between. No figures are yet available for synthetic closures, but they are likely to fit somewhere between Diam and screwcap in terms of carbon footprint.

The facts

Let’s put these figures in perspective. One million glass bottles, averaging 500g each, have a carbon footprint of 183 tonnes – a figure which includes the energy used to manufacture them, and which takes into account the use of a proportion of recycled glass. So if a screwcap has a footprint of 35.9 tonnes per million units, this is around a fifth of the impact of the glass bottle.

Other factors contributing to the carbon footprint of the bottle will include transport issues (remember, sea freight has much less impact than road freight) and the energy used in the production of the wine itself (some wineries are now announcing that they are carbon neutral). But before we get too carried away, it needs to be noted that there’s some debate about these sorts of figures. Where does the footprint start and stop?And now that this debate has been initiated, it’s likely that we’ll see a lot of companies jumping on the bandwagon, releasing their own figures and making their own claims.

The second survey, released in July 2007, was carried out by Amorim, the world’s largest cork producer. With regard to global warming, the report highlights the positive impact of natural cork forests in retaining CO2; the role of corks as a carbon dioxide sink (absorbing CO2) during the product life cycle; the fact that Amorim supplies 46% of its energy needs from vegetal biomass, including cork dust; and the way Amorim uses maritime transport for its products where possible. The report also touches on the significance of cork forests as sustainable development, balancing ecosystem conservation, creation of wealth and social development. ‘By providing environmentally sound jobs to farming communities,’ states the report, ‘cork forests not only foster biodiversity but also provide the means to sustain and retain populations on the land.’ This sounds like bad news for screwcaps. But how significant will these sorts of data prove in the real world?


Consumers are unlikely to let these carbon footprint considerations affect their wine-buying habits overnight. It is also unlikely that influential retailers will specify natural cork as a closure type on the basis of environmental impact alone. More significantly, quibbling over small amounts of carbon emissions is a moot point. New Zealand winemaker Steve Smith MW of Craggy Range argues that with the cost savings he makes by buying screwcaps over more expensive alternatives, such as Diam, he can more than offset the extra carbon footprint. ‘The increased carbon footprint of a screwcap works out at 0.00679kg CO2 per unit. To put that into perspective, it is equivalent to driving 18 metres in a 2,000cc car.’ Smith points out that in New Zealand there are programmes such as EBEX 21 ( ‘ E m i s s i o n s / B i o d i v e r s i t y Exchange in the 21st century) that use carbon credits to establish r e g e n e r a t i n g, permanent CO2 sinks on private property that otherwise would not be funded. ‘This is a professional, audited system that not only provides an opportunity to develop carbon sinks, but also will leave a wonderful legacy of new native forests for future generations. This would not have happened without the funding gained from carbon trading,’ he says. There is an almost overwhelming trend in the world today to develop marketing strategies using “carbon footprint” as a justification for supporting one product at the expense of others,’ says Smith. ‘The debate on food miles as a justification for buying local uses flawed conclusions to establish trade protection. It is likely that a case of NZ wine sent by container ship to London uses less carbon than sending a case of wine to London from Bordeaux by truck.’

Do the data on closure carbon footprints mean winemakers should use cork, with its known problems, simply because it combats global warming? Should consumers shrug their shoulders when they open a corked bottle of wine, and take one for the environment? I reckon winemakers are within their rights to insist on using closures that meet certain quality standards, and only then consider the closure carbon footprint. One thing is for sure: we’ll be hearing a lot more about carbon footprints over the next few years.

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