The solar refrigeration system in Tunisia

Trials underway in Tunisia and Morocco might pave the way to the use of the energy of the sun to refrigerate dairy and other foodstuff, providing a cheap option for places that lack reliable access to electricity.

Solar energy is already being used to power air conditioning in buildings in many places around the world. Scientists from the Fraunhofer Institute for Solar Energy Systems (ISE) in Freiburg, Germany, want to build on this existing technology to use the sun’s energy to provide cooling in the food and agro sector.

The researchers set up MEDISCO (MEDiterranean food and agro Industry applications of Solar COoling technologies) to test the viability of the technology in the Mediterranean region, which is famous for receiving good sunshine on most days of the year.

“Our method is ideal for countries which have many days of sunshine and in remote areas where there are no conventional means of refrigeration owing to a lack of water and non-existent or unreliable energy sources,” explained Tomas Núñez in a press release.

They have set up experimental solar cooling systems at a dairy in Marrakech, Morocco, and a winery in Tunis, Tunisia. The objective is to assess which systems would actually serve the needs of the food industries in the region.

The team is also working with partners in Egypt, Tunisia and Morocco to analyze what the needs of the market are. They sent out surveys to several companies in the three countries to identify which industries would benefit the most from the solar cooling systems.

The device works in a similar way to solar water heating systems. Several concentrating collectors reflect direct sunlight onto an absorber. The solar radiation then heats a water-glycol mixture up to nearly 95⁰ Celsius. The hot water is used to drive the absorption refrigeration machine. “We do not use electricity to provide the refrigeration, we use heat,” explained Núñez.

The system is able to reduce the temperature down to below 0⁰ Celsius, which is why the water-glycol mixture is used. A pure water coolant would freeze in the tubes. The solution is them pumped through a heat exchanger or a system of pipes to cool down the milk or wine.

The project is funded by the European Commission Sixth Framework Programme (FP6) and run by the Polytechnic University of Milan. The smaller panels are supplied and installed in cooperation with universities, energy agencies and companies from Egypt, France, Germany, Italy, Morocco, Spain and Tunisia.

The Mediterranean Renewable Energy Centre (MEDREC), based in Tunisia, will be responsible for the transfer of the experiences of the MEDISCO project at a regional level.