Projects / PROSOL Industry

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IMELS, in collaboration with the Tunisian Ministry for Industry and Energy, ANME, MEDREC, and UNEP launched the project PROSOL Industrial in order to promote the development of solar thermal systems in the industrial sector.

Moving the steps from the success cases of application of Solar Water Heating in residential and tertiary sector in Tunisia (“PROSOL Residential” and “PROSOL Tertiary”), but also with the awareness of the greater complexity of the integration of this technology to industrial processes, different actions have been carried out in the past years in order to delineate the main aspects of this particular application, including studies on heated water needs of Tunisian factories belonging to different manufacturing sectors and studies on the potential of solar thermal energy application to industrial processes. Moreover, in 2011, the Department of Energy of POLIMI has been charged of a technical assistance activity resulting in:

  • A regional training on solar thermal technology including practical sizing exercise of solar thermal system for industrial processes and software for the implementation of energy performance studies, held in Milan in July 2011, attended by three ANME technicians
  • 3 feasibility studies for integration of solar thermal technology into industrial process including collector type, nominal working condition, investment costs, carried out by POLIMI
  • 3 feasibility studies for integration of solar thermal technology into industrial process including collector type, nominal working condition, investment costs, carried out by technicians from PROSOL Unit (ANME) with the supervision of POLIMI

Feasibility studies embraced the integration of solar water heaters in various industrial applications, for producing hot water and/or steam at different temperature levels, in order to understand what processes could be suitable for integration of solar technology and find optimal operating conditions.

A major emphasis has been placed on cost-effectiveness of solar integration, also on the basis of current Tunisian policies of incentives for renewable energy sources and fossil fuels, and on possible developments, in a sustainable direction, of these policies.

Two detailed feasibility studies were carried out by the POLIMI, with the assistance of a local consulting firm:

  • Estimation of the Potential of Solar Thermal Applications in Industrial Sector in Tunisia
  • Regulatory and incentive framework for the promotion of solar thermal in Industrial Sector in Tunisia

For more details about the studies, please visit the sections “Studies & Development” in our website.  

PILOT PROJECT: Implementation of a solar thermal plant for industrial use in BENETTON Tunisia.

During 2011, a feasibility study campaign for integration of solar thermal systems into industrial processes was carried out in Tunisia, financed by UNEP.  According to the results, the IMELS decided to co-finance one plant from the selected end-users which was the textile producer BENETTON.

The project is at an advanced stage and the works onsite started on the 16th April 2014 and are expected to be achieved on June 2014


Description of the intervention:

The solar field will be installed on a metal frame fixed to reinforced concrete girders. The location of the pump will be constructed outside of the building, close by the department of washing; the tank will be placed next to the pump.


Purpose and scope:

The solar thermal system enables to produce hot water expansion of the hot water already used in the process department washing/ dying.

In the production unit, textile products are washed and treated to produce a large part of the Benetton ready to-go cotton clothing.

In particular, the system will consist of a solar field with a total surface of 1000 m2 and close by a reservoir of 30 m3.


Current Status:

The existing system uses a steam power plant, equipped with generators that output a total capacity of 4.6 MW thermal, and through heat exchangers and a water recovery system, is able to supply all production departments.


Below the current data:

Yearly fuel consumption 3.600.000 m3 gas
Yearly energy consumption 36 GWh Thermal energy
Fuel price 0,25 Dt/m3 Calculated on base of energy bill
Yearly energy cost 900.000 Dt/year Based on energy bills
Estimated yearly boiler efficiency 0,025 Dt/kWh Considers gas energy content of 9,8 kWh/m3 and fuel price
Yearly fuel consumption 3.600.000 m3 gas

The procedure consists in the realization of a unit for the supply of thermal energy from solar energy to supplement the current system of production of hot water, the solar system will not be able to integrate the system steam generation, the latter being a system of low temperature (80/85 ° C), but will play the role of intermediate with the part of the system for recovering the water from the washing department, so as to increase the energy recovery, thereby reducing the demand for the steam plant.


The main components for the realization of the unit of renewable energy production are:

  • Thermal solar collector with plane glass
  • Solar pump
  • Plate heat exchanger
  • Secondary pump
  • Reservoir


Main energetic results

Delivred solar heat 803.000 kHw/year Thermal energy delivered by the solar thermal loop to the storage tank
Saved fuel 82.000 m3 gas amount of a gas saved thanks to the solar system
Saved CO2 emissions 161 t/year according to average CO2 emissions of natural gas (reference : 200g/ kWh
Solar fraction 8.0 range : 6.2-11 % Ratio of total energy consumtion covered by the solar system
Average system efficiency 43 % Solar system's energy delivery divided by incident radiation on collector surface
Average temperature increase of pre-heated water 2.6 °C Average pre-heated water temperature to load : 42 °C
Average temperature increase of pre-heated water during the day 8 °C In average the solar plant will affect the system 8h per day


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