We are in Domaine Neferis, one of Tunisia's most famous wineries. This 460 hectare vineyard is located in a green and prosperous area of the country where agriculture is the main industry. Making the perfect wine is an arduous process at the best of times. It demands a lot of sun, good soil, water and cold temperatures. But how do you install an environmentally friendly and sustainable cooling system in a country so warm?
Enter the MEDiterranean food and agro industry applications of Solar COoling technologies - or MEDISCO as it is known. This European Commission funded initiative has developed and tested a refrigeration system driven by solar energy for the food and agro industry in the Mediterranean region. The three and a half year project that began in October 2006 took advantage of the local conditions in Tunisia and elsewhere and provides real results which are both economically and socially sustainable.
The only effective way of ensuring a more environmentally friendly energy supply is by using renewable energy. By going renewable, we will also be able to diversify our energy sources and reduce the dependence on gas, coal and oil. "We all get heat from sun. We feel it on our bodies when it's warm," says Prof. Mario Motta, MEDISCO's Project Coordinator. 'We also derive electricity from solar energy but who ever heard of getting cold from sun? That's what MEDISCO is about. It turns heat into cold. In a way, it's magic." Yet, to really understand the magician's trick, one has to look closely at how MEDISCO actually works.
The process involves single axis tracking concentrating collectors that essentially orient panels towards the sunlight. These collectors are capable of producing heat at about 200°C which in turn drives an absorption-refrigeration machine. This machine cools a water-glycol mixture up to negative temperatures of about -10°C.
"By using heat instead of electricity, the wine is kept at the correct temperature required during its production process. This temperature varies depending on the wine typology and time required," says Prof. Motta.
MEDISCO is also proving its worth in tests at a dairy factory in Marrakech, Morocco. Hot weather there has often caused large quantities of fresh milk to go off meaning it cannot be sold to the public. Rural areas in the country where there are simply not enough energy resources available to run cooling equipment have also been affected by the high temperatures.
The countries involved in MEDISCO are Germany, Italy, France, Tunisia, Egypt, Morocco and Spain. And with an investment of €1.4 million, the European Union has high hopes for the project's future application.
"MEDISCO is totally relevant – we have proven that a new solar cooling concept works. The concept definitely has a future in hot and arid regions." says the Professor.
Indeed, experts echo the sentiment saying that the refrigeration system developed and tested by MEDISCO could really help the Mediterranean and indeed other areas with no conventional means of refrigeration due to a lack of water and non-existent or unreliable energy sources.