What do you prefer for your wine – a cork or a screw cap? Who would have thought the medium to close a bottle of wine could cause such debate, or warrant any air time at all for that matter.
But it does, and once again the humble wine seal has made headlines.
Because a recent Ernst & Young Lifecycle Assessment study found that a wine bottle sealed with cork can have half the carbon footprint of a wine bottle sealed with a screw top.
For an industry that struggles with its carbon footprint, this is revelatory.
Carbon footprint of wine and sustainable wine
But this isn’t just good news for the wine industry, this is great for all eco-conscious wine drinkers keen to play their part by choosing products that are not just environmentally friendly, but sustainable too.
Yes, it might seem tough to summon the energy to care passionately about whether your bottle of wine is sealed with a cork or a cap, but if you want sustainable wine, then you need to look at the whole wine production process, not just the grape part, but the bottling part too.
Because it’s all good and well imbibing natural wine – a wine that is sustainably produced from organic or biodynamic vineyards, but if that wine is then cased in standard glass bottles and sealed with a foil cap, you’re giving to the environment with one hand and taking away with the other.
Learn more about pet nat wine, a popular natural sparkling wine.
Emissions in the wine industry
You might think that wine production is a carbon-capturing industry – what with all those billions of vines photosynthesising during their growing seasons. But it’s not as cut and dry as that.
Winemaking, the process of turning the grapes to wine, releases emissions – fermentation, for example, wild fermentation or regular, both produce an inordinate volume of CO2. Then there are the glass bottles the wine comes in.
The glass bottle alone makes up HALF of the wine’s overall carbon footprint. Half? That’s right.
The problem with glass
With all the furore surrounding plastic and the impact of plastic on marine pollution, glass is usually favoured as the more environmentally friendly packaging option. But when you take into consideration the life cycle of glass, it can oftentimes come out worse than plastic.
The green credentials of glass are not as clear-cut as we think.
The impact on the environment from the production of glass (the furnaces used to forge glass bottles are never switched off for example), its distribution (the weight of the glass and therefore the fuel required to transport it), its use and its end-of-life, can all be devastating.
But one way the wine industry can reduce the carbon footprint of wine bottles is through lightweight bottles, such as the ones used by Villa Wolf.
Lightweight wine bottles are essentially the same design as heavier bottles – they’re also strong and fit for purpose. But by reducing the weight of the bottles, this has a positive impact all along the line. It makes for easier filling in the bottling plant, lighter loads for transportation (reducing emissions), as well as reducing the volume of glass to be processed at the end of a wine bottle’s life.
But if you then top that glass bottle with a screw cap (screw caps aren’t carbon negative as producing them releases carbon into the atmosphere) and you’re back at square one.
Find out how long does wine last once you opened it.
The shift to screw caps
The switch to screw caps began over 10 years ago when it was believed that the incidence of cork taint* was between 7-8% of all cork-sealed bottles of wine.
Not to mention it was thought that it was better for the environment to use foil over the cork. Campaigners said that the water usage required to grow the cork trees had a detrimental impact on the environment.
But now it transpires that cork is ‘carbon negative’. The cork trees themselves cause a net capture of CO2 (i.e. they capture carbon from the atmosphere) and despite the process to manufacture corks for wine bottles, using a cork still reduces a bottle of wine’s carbon footprint, rather than adding to it.
In the Ernst & Young study, the researchers found that using natural cork to seal a bottle of wine captured up to 309g of CO2 (an average bottle of wine has a carbon footprint of up to 1200g).
Cork or cap?
So, which do you prefer? Here at PTC, we retail both, just in case. Also, we know many ways how to get a cork out.
*What is cork taint?
A corked wine doesn’t have tiny bits of corking floating in it, it actually means the wine has become contaminated – not by the presence of the cork but by a chemical compound – TCA (2,4,6- trichloroanisole).
TCA is formed when fungi (which reside in the cork) come into contact with wine sanitation/sterilisation products such as bleach. If the winery then goes on to use these infected corks, the wine itself can become tainted.
The discovery of this reaction between bleach and fungi is only a recent one – in the 1990s and as a result, most wineries have stopped using these chlorine-based cleaning products. But the incidence was enough to cause a significant uptake in screw cap usage as a result.