“Carbon capture during fermentation could turn wine into a negative emission industry”


Few industries bear witness to climate change more closely than the world of wine.

I was born in Napa Valley and moved to Burgundy after graduating from UC Davis in 2001. Together with my husband, Jeremy Seysses, his brother Alec and our wine team, we make the wines of Domaine Dujac, founded by my father-in-law, Jacques Seysses, in 1968. I juggle this responsibility with my role as winegrower for the Snow-covered vineyards in Napa, where I have spent the past 20 years bringing the philosophy of terroir back to the land bought by my grandparents in the Vaca mountains in 1955.

Last year the Napa Valley was on fire again. Then in April, Burgundy and all of France suffered a catastrophic freeze which was declared a natural agricultural disaster. As an oenologist and steward of the lands of these two beautiful historic wine regions, I have recognized that there is no greater problem for our world and our industry than that of climate change. The fine wine community has made impressive progress in taking decisive and direct action to adapt and reduce our impact.

Over the past four years, I have studied my industry in depth from the perspective of sustainability and greenhouse gas emissions. A small transparent piece of this puzzle particularly caught my attention and my imagination: the carbon dioxide emitted by the yeasts during fermentation.

While winemaking does not produce large volumes of CO2, it is a point of production with a clear opportunity for capture – and if the industry worked together, sequestering carbon during fermentation could turn wine into an emissions-producing industry. negative.

Why carbon capture is difficult and essential

Each winegrower is perfectly aware of the abundance of this natural gas during fermentation. As in all living cells that breathe, CO2 is the byproduct of yeast metabolizing sugar into alcohol. The grape sugar accumulated during a growing season in our vines is digested in a few days in our vats. The concentration of carbon dioxide released during fermentation is so high that the gas stings the eyes and burns the throat, and the cellar teams must ensure that it is evacuated. Every year, tragically, people die in wine production facilities during fermentation due to asphyxiation.

Meanwhile, the planet’s atmosphere has reached 420 parts per million CO2, a concentration never before seen in 2.6 million years– when trees grew at the South Pole. As the pendulum returns to this warmer equilibrium, governments are already studying direct air capture (DAC) technologies, such as the private start-up Carbon engineering, to mop up 200 years of burnt fossilized carbon. DAC will be essential in stabilizing the planet’s CO2 concentration so that the Earth remains hospitable to those of us who have evolved over the past 100,000 years. The objective: a concentration of 350 ppm of CO2 (which is higher than the pre-industrial 280 ppm).

“While winemaking does not produce large volumes of CO2, it is a point of production with a clear opportunity for capture – and if the industry worked together, sequestering carbon during fermentation could make wine an industry to be. negative emissions. “

Direct air capture is just the best: huge fans suck air into a refinery where the CO2 is removed, and then the air is returned to the atmosphere. The collected CO2 is transformed into other carbon-based materials, such as biofuel, or sent underground to remineralize. While DAC factories run on green energy, critics of the DAC point to the huge electrical expenses to run fans and concentrate atmospheric CO2 to 420 ppm as pure carbon dioxide.

During alcoholic fermentation, the free space of a tank is 990,000 ppm of CO2 without pollutants. During winemaking, every year the winery buildings are filled with pure, clean carbon dioxide, and we simply blow it out the windows. I think the ventilation of our cellars is a lost opportunity.

Like all prototypes, emerging carbon sequestration facilities are expensive. At Domaine Dujac, we were quoted 100,000 euros for an installation that converts CO2 into organic bicarbonate. This labor-intensive process involves the loading and unloading of 30 tons of white powder in steel columnsat the same time as the harvest and the vinification take place, the busiest months of our year. Then, unlike CO2 capture in the cement industry, for example, we only generate CO2 for one season, meaning that expensive machinery would go unused for the remaining 10 months of the year. Finally, in this emerging industry, there is currently no real market for the 30 tonnes of baking soda that we will be producing.

All this effort and expense would only capture eight tonnes of CO2 per year, a tiny amount. In perspective: A return flight Paris-San Francisco in economy class generates four tonnes of CO2 per person. I take this trip five times a year. Or compare it to the impact of a glass bottle of wine: Domaine Dujac’s 575 gram bottle is responsible for around 0.75 kilograms of CO2. The CO2 from fermenting wine in this 750 milliliter bottle is approximately 0.01 grams—grams!

We therefore understand why winegrowers have not yet taken the trouble to trap this natural gas. After studying the options currently available, I concluded that the answer to carbon capture lies in the collective. The whole of Burgundy could capture 20,000 tonnes of CO2, the entire Bordeaux wine-growing area could capture 80,000 tonnes per year, and the state of California an impressive 300,000 tonnes. Together, this would represent real and impactful CO2 reductions.

The future of carbon capture in wine would require pipelines under and around wine-growing areas to move compressed carbon dioxide to a central carbon recycling center where biofuel would be produced throughout the year. If scaled up, carbon capture during fermentation has the potential to transform our businesses into a CO2 negative industry.

Admittedly, nothing about this is straightforward or straightforward – my research has been an emotional roller coaster of many disappointments. The costs of DAC remain unclear, and it may seem meaningless when the world produces 50 gigatons of CO2 per year. (The Paris Agreement states that all countries achieve zero emissions by 2050 and that no nation on earth is on track to meet that target.)

Yet the capture of carbon during fermentation represents something fundamentally unique in our industry’s efforts: while the elimination of new glass would represent 65% reduction in our emissions, and the use of electric tractors too reduced emissions from agriculture, this is not enough to bring us to zero emissions. CO2 capture offers the possibility of negative emissions. If we get the carbon from our cellars to a DAC plant where they produce biofuel which is then used for air transport, we are moving somewhere. Once again, it comes down to the collective.

Today, with climate change and its partner, globalization, the sphere surrounding our land extends to the atmosphere of the Earth itself. It is our responsibility to expand our awareness of our own radius of impact.

At Domaine Dujac, we are building a new eco-responsible cellar which should be completed for the 2022 harvest. We have used renewable materials; wood, recycled cork and Burgundy straw. We are adding charging stations for cars and offering to partially subsidize the electric cars of our employees. We have two underground tanks collecting rainwater for cleaning and wine applications. Finally, we have invested in stainless steel pipes on our tanks to lead the captured CO2 to a carbon dioxide compressor outside the cellar. In 2022, we will be renting the above mentioned equipment for trial use before committing to the facility. In the meantime, I expect the carbon sequestration options to multiply.

Why climate change is the land

The terroir is much more than what the AOP vineyard designates plotted on a map, but the intersection of the site, the climate and the people.

The human element is vast at the edge of infinity, encompassing tradition, know-how, agricultural choices, commercial choices, and even the political and economic context in which a wine region finds itself. All these variables in the “people” category inevitably go back and have an impact on the first two elements, the vineyard and the climate.

Today, with climate change and its partner, globalization, the sphere surrounding our land extends to the atmosphere of the Earth itself. It is our responsibility to expand our awareness of our own radius of impact.

In the Old World, the most important measure of a wine region’s success is the maintenance of production over generations. The generational transition happens thanks to a whole set of people who work together in a transparent way over time. Their greatest legacy is not the bottles left behind but the way they have protected and passed on a cultural heritage. Thus, our terroirs have survived the war, the revolution, the overabundance of wine and wild speculation.

My research has led me to dozens of inspiring eco-success stories. The work of Good goods, Gotham Project, Monarch tractor, Napa Green, and the IWCA– to name a few – gives me so much hope. I was given a seat on Porto ProtocolGlobal Steering Committee to address the subject of carbon dioxide sequestration from wine fermentation. Visit the Porto Protocol website for hours of hands-on content on all topics related to sustainability and wine.

To pass the baton, this generation of wine professionals is reorganizing the production and distribution of wine to slow down climate change and achieve true sustainability. Carbon recycling by DAC is inevitable. Our alcoholic fermentations give our industry the opportunity to become a key player in the future of green fuel and climate stabilization.

Diana Snowden Seysses was born and raised in Napa Valley. She graduated from the Viticulture and Oenology program at UC Davis in 2001, and has worked in Californian and French wineries with Robert Mondavi Winery, Mumm Napa, Domaine Araujo, Château La Fleur de Boüard, Domaine Leflaive and Ramey Wine Cellars. In 2003, Diana became an oenologist at Domaine Dujac in Burgundy, and consultant at Domaine de Triennes in Provence. In 2005 she became a winemaker at Snowden Vineyards in Napa Valley and in 2016 she became a winemaker for Ashes & Diamonds, also in Napa. She is a recognized authority on climate change as it relates to wine and sits on the global steering committee of the Port Protocol.

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