E-CO2: recovery and reuse of CO2 from wine fermentations

Fermentation is a natural process that enables the transformation of must in wine, through the conversion of sugars in ethyl-alcohol and carbon-dioxide (CO2). Stoichiometrically, with 45 million hectoliters of wine with an average alcohol content of 12% v/v, annually produced in Italy, it is possible to estimate the huge production of 45,000 tons. Every year the production of wine leads to the release of a large amount of carbon dioxide in the atmosphere and this contributes to the amount of greenhouse gases. The CO2 reabsorbed by photosynthesis is only a small part of the total amount produced; therefore it is necessary to reduce this issue. In order to succeed in this challenge, a project called E-CO2 was kicked off in June 2011: it aims at the considerable reduction of emissions in the step of fermentation. The CO2 is collected, purified and compressed, restoring the important value of the resource (which is free because it results from process waste and left into the atmosphere) and the project assesses the CO2 re-use in various ways in the wine industry as well as in other sectors that usually consume large quantities. The carbon dioxide has an extremely important market, in continuous expansion, and it is used for operations such as carbonation of beverages, creation of modified/protected atmosphere for foods or in wine industry operations. A further possible application in agriculture and the nutraceutical field is its use for feeding photosynthetic organisms such as unicellular algae. In winemaking, CO2 is very useful for the control of oxidation and extraction of aromatic compounds. Wineries are direct users of technical gases and they may create an important synergy with gas producers, creating a 'a CO2 bank' for self-use throughout the year. This could reduce the CO2 production from combustion and chemical reactions, which are the present ways of production. However the generous resource as the one from winery fermentations has never been seriously evaluated so far due to the periodicity; a so large-scale production in a short time range would require the construction of huge facilities with heavy economic impact, with risk of depreciation. In E-CO2 project, the application of technologies for collection and storage technologies, already widespread and entreched in other sectors (as breweries), was evaluated and it has been observed that the wine sector represents a real innovation. Chemical analyses which were carried out showed that the purity of the CO2 from alcoholic fermentation is extremely close to that required for international marketing as a gas with a “food grade” quality and a mild purification would be sufficient. Additionally, among the compounds that “contaminate” the wine CO2 , it is possible to find also fermentation aromas, which, if properly condensed, may serve as an additional resource to be evaluated as a food ingredient. The project has received the strong attention of several actors in Verona’s wine scene as well as of retailers of technical gases.