By: Dr. Richard Smart
What is the difference between a winery and a power plant burning fossil fuel to generate electricity? Both release carbon dioxide (CO2) into the atmosphere – a major cause of global warming and climate change. The difference is one of timing, and scale. Wineries mainly discharge CO2 for a few months of the year during vintage, power plants continually. Power plants also release much, much more CO2 than wineries.
Environmentally-conscious wine consumers would be aghast to know that wineries release CO2 into the atmosphere during fermentation, since increasing atmospheric levels of CO2 and other “greenhouse” gases are known to be the cause of climate change.
In grape juice fermentation one molecule of sugar yields two molecules of ethanol and two molecules of CO2. This CO2 can be a hazard to winery workers, and so precautions are taken to vent it to the atmosphere. I call this treating the atmosphere like a sewer.
Wine makers may say that we have always done this, since wine was first made. Perhaps so, but times have changed. Climate scientists the world over are worried about global warming caused by increasing CO2 content of the atmosphere; they say we need to dramatically reduce emissions to avoid catastrophic climate events in the next 30 years. Even small contributors, like from wine fermentation, should cease.
Europeans are generally more environmentally aware than winemakers in the rest of the world. There are several companies in Europe producing equipment to capture fermentation CO2, clean and compress it for re-use or for re-sale. Such systems are commercially available now, for example from Enomet (Italy). Such systems are more common in breweries, and are even available for microbreweries (Earthly Labs, USA).
Château Smith Haut Lafitte of Bordeaux is using a process developed by the French firm Alcion Environnement to capture fermentation CO2 as bicarbonate of soda (sodium bicarbonate). The Wine Council of Bordeaux, the CIVB (Conseil Interprofessionnel du Vin de Bordeaux), is showcasing the initiative as a good example of how to lower CO2 emissions from fermentation.
The Wine Industry as a Carbon Polluter
It is common now for various industries to calculate their carbon footprint, using agreed protocols called Life Cycle Analyses. This has been done for the grape and wine sectors in several countries. Such a study in in Australia has shown that the wine industry is around 7% of the carbon emission of civil aviation. The grape and wine industry is not a large contributor in society but neither is it insignificant.
The grape and wine industry is especially sensitive to weather and climate, so it is in the industry’s best interest to do what it might to mitigate climate change. And yet, we hear little about this. For all the industry talk about “sustainability” one hears very little about carbon footprints.
LCA studies show that grapegrowing and winemaking are not major contributors to the carbon footprint of wine production and sale. The production of glass bottles and transport make up the great majority of wines carbon footprint.
How can the Grape and Wine Sector Minimize Carbon Pollution?
The standard 750ml glass bottle is the main villain for wines carbon footprint, being weighty, volume demanding and energetically expensive to manufacture and recycle and transport. A wander around supermarkets shows there are many other lighter packaging alternatives for liquids. Lower value wines are infrequently cellared nowadays, being generally purchased for immediate consumption, and comprise around 50% of wine sales in several markets. Expensive containers like glass bottles, designed for storage seem unnecessary, as well as being environmentally most undesirable. Perhaps 750 ml glass will be replaced by 1 L cardboard or paper cartons, as for many other food liquids.
The grape and wine sectors can take heart that some modern research, machinery and process developments are available to minimise carbon footprints. For vineyards, these could involve use of biofuels, electric tractors, improved irrigation efficiency, and reductions in agricultural chemical use. Solar and wind energy are being employed by some businesses.
Vineyards and wineries are generally slower than other agricultural industries in considering waste products as biomass fuel for heat and electricity generation. Electricity production remains largely dependent on fossil fuels, and winery demands for heating/cooling and lighting are major contributors to the carbon footprint. European studies suggest that pomace, stalks and prunings as renewable energy sources can contribute significantly as electricity alternatives. Prunings can be baled in the vineyard, easily collected and air-dried, then chipped before use as a fuel.
An important recent development has been in pyrolysis units to convert biomass into electricity. Large municipal facilities have problems of biomass supply, because of low biomass value for cartage over longer distances. Newer developments of small, portable units can be located at the source of biomass as for the winery; they can produce syn-gas, wood vinegar, biochar and bio-oil. Bio-oil and syn-gas can be used to produce electricity, and wood vinegar when dilute is a natural plant growth stimulant, and when concentrated is a herbicide. Bio char is very stable. It can be used as a soil amendment, and is a means of sequestering carbon.
Some carbon accounting methods deliberately exclude CO2 emissions from fermentation. The “justification” for this is to label such emissions as “biogenic”; that is, this CO2 source does not need to be accounted for since it is balanced by the annual growth cycle of the vine in capturing CO2 by photosynthesis, the so-called “short term” carbon cycle. One wonders why there is the mandatory exclusion of fermentation CO2 in some LCA models. Is it to do with wanting to avoid legislative interest in such emissions? There are laws governing disposal of waste water, why not fermentation CO2? By way of comparison, the OIV (2017) carbon calculator allows for the optional inclusion of fermentation CO2.
There appears no valid reason why wineries should continue to treat the atmosphere as a sewer for CO2. The means are available to avoid this, admittedly at a cost.
I conclude with a question: How long before an environmentally sensitive wine consumer is able to purchase an alternate package of wine bearing the label “During the fermentation of this wine no carbon dioxide was released into the atmosphere, or perhaps using the attached logo?
Dr Richard Smart is an experienced viticultural scientist and consultant. He can be contacted using firstname.lastname@example.org, and is available for internet consulting, in your office or in the field.