Thanks to financing from the European Agriculture Fund for Rural Development directed to the Veneto Region of Italy and its own Program for Rural Development 2007-2013, several producers have been able to come up with innovations by working in direct contact with the world of university and research. The Consorzio di Tutela del Soave, taking advantage of this possibility, kicked off a project called E-CO2 in June 2011. The project has been directly focused on obtaining value from CO2, considered a waste by-product generated during the wine production process, studying the possibilities of adding value in order to create a new resource.
“Our territory ˗ explains Aldo Lorenzoni, Director of the Consorzio del Soave ˗ promptly took advantage of the opportunity to realize a dream that oenologists have been harbouring forever, to promote and sustain a research project with highly visible results, focused on the developing eco-sustainability of the wine-making process”.
To realize such an ambitious project it was necessary to co-operate with a wine producer large enough, within the two year time span of the project, to make available a significant amount of space and technology. This was the reason for the involvement of Collis Veneto Wine Group, one of the leading Italian producers, capable, thanks to 3000 associated growers, of turning 140,000 tonnes of grapes into 110,000,000 litres of wine in 4 production plants. “The Colognola ai Colli facility seemed immediately to be the best solution ˗ explains Giancarlo Lechthaler, Director of Collis Veneto ˗ due to the 49,000 tonnes of grapes processed every year. We accepted the challenge and the results and attention that we have received in competitions and projects, but also from the press, has been a good payback for the work we did“.
Carbon dioxide in the winery
In the field of oenology, the uses of carbon dioxide are numerous, and first and foremost, go towards producing the frigories required to maintain the must at low temperatures. But CO2 also has a blanketing and control effect on the development of micro-organisms (yeasts, etc.) and is used in refrigeration and the protection of harvested grapes and in the continuous cooling of the pressed grapes. These operations require CO2 to be utilized in liquid form directly after mechanical harvesting as well as to lower the temperature of the pressed grapes to around 5°C, to obtain an immediate and homogeneous state of coldness, to reduce stress and to protect against excessive oxidation.
Another important point is the use of CO2 as a technical and antioxidation gas during all the operations ranging from fermentation to bottling and where it is important to replace the amount of oxygen between the wine and the closure in order to avoid oxidation.
Carbon dioxide can be used also in cryoextraction, a process through which the partial freezing of grapes before pressing results in higher quality white wines. Enzymatic processes that can lead to degeneration of the aromatic components are inhibited, preserving the aromas and thereby producing a better bouquet that can be maintained in the finished product.
With CO2 it is also possible to freeze only the less-ripened grapes (with a lower sugar content) in order that the must that is released in the pressing comes only from the ripest grapes.
Finally, carbonic maceration exploits CO2 to induce intercellular fermentation of the whole grape, which is the basis for the production of Nouveau wines.
In the scope of the E-CO2 project, the study of special uses of the gas was of great importance.
CO2 plays a role as an important carbonic substrate for any photosynthesizing organism. Verona-based Algain Energy, producer of bio-algae for the extraction of important components such as antioxidants and other food elements, evaluated, along with university partners on the project, the production of part of the alga Haematococcus pluvialis of the component Astaxantina, a strong pigmented antioxidant for uses ranging from livestock feed to human consumption Other algae are capable of producing proteins (like spirulina), precious fatty acids (like Omega3) and other molecules, and have been opening new market opportunities in human nutrition over the past few years.
On another front, some large multinational energy companies are conducting research on algae for the extraction of combustibles like oil (bio-diesel) or bio-ethanol, as well as other components capable of reabsorbing substances that are harmful to the environment, like heavy metals, or that can be used in the purification of waste water or the capture of carbon dioxide.
In particular, the results of the E-CO2 project can be considered quite interesting since, on one hand the CO2 emitted can be immediately reabsorbed without entering the atmosphere, and on the other hand it is possible to capture it in useful carbonic medium with high antioxidant qualities, that can, in the future, ideally substitute compounds currently used for these purposes, such as sulphur dioxide.
The research project unfortunately only laid the foundation for this type of use. In the future, further in-depth studies (already in progress) will allow for obtaining a compound so pure as to not compromise the end product from a visual or sensorial level and, finally, to close the from vine to wine sustainability cycle.
CO2 recovery from oenological sources
E-CO2 was the first project that concretely achieved, by publishing all the data, the recovery of CO2. The system used for the recovery of carbon dioxide is small, produced by industry leader Tecnoproject Industriale, an Italian company, and is in testing at several large facilities that will in the future require systems of much higher capacity. The CO2 flows into the system without being pushed, according to the natural flow of the hectolitres of fermenting must. Once it arrives at the entrance to the machine, the CO2 is gathered in a dosage flask that, when reaching a determined level, activates a compressor that insufflates the carbon dioxide. The first step of purification takes place at the level of several active carbon filters that carry out the first cleaning of the majority of the aromatic compounds and other molecules that arise naturally from the fermentation. A higher level of compression allows for further purification of the gas thanks to a cold stripping that separates the CO2 from nitrogen, oxygen, and argon and arrives at a 99.99% level of cleanliness with a 5% concentration of dissolved oxygen. At the next step, storage, the carbon dioxide enters a tank at 18 bar that allows it then to be used on site or to be transported by truck to other destinations.
The quality of carbon dioxide
In the first phase, the project was able to evaluate the quality of the carbon dioxide at the entrance and exit of the purification and compression system. From the analysis, it was possible to ascertain that the quality coming out of the fermenters was already very high, which would allow, if use is limited strictly to the winemaking process, to reutilize the compressed CO2 as dry ice or in liquid form during the processing of the must. At the exit of the system the expected result was verified: compressed CO2 produced from oenological sources is food grade. The test recovery system therefore functioned correctly, in that the two test samples contained only small quantities of excess ethanol that will have to be eliminated in order to effectively achieve the 99% purity required by the ISBT (International Society of Beverage Technologists). “We are able to carry out small modifications to the system ˗ states Stefano Faccioli of Air Liquide ˗ that allow us to eliminate excess traces of ethanol in order to meet the required quality levels. We have achieved an excellent result. The wine system can really become a source of clean and high quality CO2 production”.
(article by Nazareno Vicenzi – E-CO2 Project Manager – Consorzio Tutela Vini Soave)