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October 30, 2021updated 09 Jun 2023 11:46am

Wine’s carbon footprint: Counting the cost of production

By Jamie Goode

As the world’s politicians gather for COP26 in Glasgow, Jamie Goode begins a three-part series investigating wine’s carbon footprint and how it can be reduced with an inventory of vineyard and winery emissions.

Vineyards are sensitive to climate. The very basis of what makes wine interesting—the diversity of grape varieties, and the way they express themselves differently in different locations—hinges on small climatic differences. Of course, vines don’t see climate, which is an average of weather over many years. Rather, they see the specific weather of the year. A good vintage is one that avoids calamitous events, and where the weather doesn’t deviate too much from the climatic averages—unless of course a grape variety has been planted in the wrong place, and flourishes with exceptional cool or hot vintages.

It’s because of the sensitivity of vines to climatic changes that winegrowers worldwide are deeply concerned about climate chaos, which seems to be bringing extreme vintages and also calamitous weather events. For this reason the wine industry really ought to be doing a self-inventory of its carbon footprint and how it can be reduced. In a three-part series, I’ll be looking at how things are going in (1) the vineyard and winery; (2) logistics and packaging; and (3) some of the hero wineries and producers who are leading the way.

In the vineyard: The problem of tractors

In the vineyard the key impact in terms of carbon footprint is burning diesel for tractor passes through the vineyard. The less time spent driving up and down the rows in a tractor, the lower the footprint. This is a highly relevant topic because there’s a conflict here between farming in a green way and carbon footprint. The lowest number of tractor passes will be with herbicides for weed control and systemic fungicides for disease control. But if herbicides are eliminated, then manual weed control requires a lot of tractor work. And organics and biodynamics requires the use of less effective contact fungicides sulfur and copper which require repeated application, and reapplication after rain. So farming well may increase the carbon footprint of vineyard operations, although there is also the issue of carbon sequestration in soils that have a high organic content, and which aren’t tilled. More on this later.

Some wineries use biodiesel to power their tractors. Calculating the carbon footprint of biodiesel is complex for a number of reasons (it’s problematic with some land use changes), but it seems to cut the carbon footprint of running a tractor by at least 50%. Alternatively, some wineries are considering the use of electric tractors. Monarch in the USA are leading the way with their new driverless electric tractors, which are being trialled by some wineries. As long as the electricity used to charge them comes from a renewable source, this has massive potential to reduce vineyard carbon footprint.

Sprays, water, and soils

Other sources of carbon footprint include the sprays themselves (their manufacture), the dynamization of biodynamic sprays, pumping water for irrigation, and also wastewater treatment processes that are part of being a good environmental steward. Frost protection involving the use of propellers, burners, or helicopters is likely to be a rare event but involves some level of footprint.

As with other plants, vines use carbon dioxide in photosynthesis and then lock this carbon up into organic compounds (these contain carbon, taken from atmospheric carbon dioxide). Whether or not some or all of this is released or not back to the atmosphere depends on how the prunings are dealt with. If they are burnt, then this becomes carbon dioxide again; if they are composted then as long as the composting is done well (without releasing the greenhouse gas methane), then this locks the carbon in, and it can end up adding to the soil organic matter when it is applied. The sugar in the grapes (which contains carbon, of course) releases carbon dioxide during fermentation. Some wineries are considering ways of capturing this, which I will describe later in this piece.

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One way that vineyards can make a big difference to carbon footprint is through the potential of soils to lock in atmospheric carbon dioxide, in addition to the carbon that is stored in the growing woody parts of the vine, and also the root system. If there are cover crops or a permanent vegetative cover in the vineyard, this can also sequester carbon, but the key thing is that it remains in the soil. One problem with tillage is that it leads to the oxidation and loss of soil organic material, especially if regularly practiced. Using regenerative farming and permaculture approaches, however, has the ability to sequester a lot of carbon in the soil. It also reduces the fuel burnt in practicing tillage, which can be significant. Another way of reducing carbon footprint in the vineyard is by using animals for weed control, such as sheep.

Power hungry

Modern wineries can be power hungry, and the greatest need for power is usually for cooling both the facility itself, and also in chilling tanks during fermentation, settling, and for stabilization. Pumping also requires power, as do presses, sorting tables, destemmers, and forklifts, when they are used. There are two main ways of reducing this footprint. The first is to have a well-designed facility that has sufficient insulation that it doesn’t need lots of power to cool it, or warm it in those places where the winters are really cold. One way of doing this is sinking large parts below ground, making use of the cool, stable subterranean temperatures. Another is making use of cool night air, where this is a possibility. If possible, the winery should be passively cooled.

The second way wineries can reduce their footprint is to make sure that any electricity used is generated renewably. For many wineries, using solar power or wind power to generate their own electricity is a possibility, and this can be coupled with lithium battery storage where generation capacity is out of step with peak demand. Looking at more efficient ways of cooling tanks is going to help with carbon footprints. Many fermentations take place at low temperatures. At various stages in winemaking, significant cooling of large volumes of wine is necessary, for example, during cold stabilization. Techniques being developed to carry out stabilization of white wines without chilling to very low temperatures could result in reduction of winery footprint.

Carbon capture

Finally, we have the challenge of capturing carbon dioxide produced during fermentation. In some ways, this is the low hanging fruit: we have a high concentration of carbon dioxide being released from a fermenting tank, and this is toxic to winery employees anyway. The issue is that if expensive equipment is needed, it will only be used for a few weeks in a year. Different solutions have been proposed. One is to use the carbon dioxide to feed algae and then catch the carbon this way. Another is to catch it and form calcium carbonate. And there is also an alternative from a company called Exytron, whose method involves transforming carbon dioxide to methane via the Sebatier reaction, which then can be used as a biogas. None of these solutions are totally straightforward, but they are being worked on.

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