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Content archived on 2022-12-27

SOLAR HEATED FISH BREEDING FARM WITH A WASTE WATER HEATED GREENHOUSE

Objective

The objectives of the project are:
- To gain experience with energy saving techniques and the use of solar energy in fish breeding farms and greenhouses.
- To investigate the prospects of a climatic wall construction for the reduction of heat losses and the temperature control of greenhouses.
- To optimize system components and capacities, flow rates and control strategy as well as to predict results from scaling up by the use of simulation models.
- To determine the economic viability of the proposed schemes.
The Fish Breeding Farm.
During the realisation and operating period, the principle of the fish plant process has been changed from fresh water system to a nearly full recirculation system. Due to that, the energy demand decreased drastically.
In one of the three fish breeding basins about 400 eels of 0.4 - 1.2 gr weight each (Anguilla-Anguilla) were placed. Because of the different rate of growth of the individual eels, they were separated in different sizes and therefore the two other basins of the system were used.
The Greenhouse Climate
In general, Patras has a very hot summer and a relatively cold winter. For the warm summer days, the temperatures of the greenhouse have been kept at relatively tolerable levels for the growth of the plants and without active ventilation. This is important in comparison with a conventional greenhouse where the temperature increases to a high level. In the winter, the temperature inside is very close to the ideal one for the plants. In spring andautumn days, the results are satisfactory. In the greenhouse, cultivations of tomatoes (3x) and cucumbers (1x) were grown during about 3 years. No specific problems were encountered even in extreme outdoor weather conditions, as the temperature varies smoothly and the greenhouse temperatures were kept between the needed levels for optimal growth. This makes all year round production possible and is contrary to normal greenhouses in Greece, where indoor temperatures occur above 48 deg.C and below 2 deg. C.
The Solar Energy Installation
One year after start up, when solar collectors were under stagmation and operating conditions, some header tubes of the collector field were broken due to u.v.-aging of the plastic. There has been no direct request to repair this nstallation. Due to that, no measuring results of the solar system are available.
The results of the experiments of this demonstration project correspond with the expectations of the participants : the use of solar energy for greenhouses and fish breeding can be very attractive. The need for auxiliary energy for heating or cooling is drastically reduced under an appropriate design.
A fish-breeding farm (with 3 basins of 4 m2 each) and a small greenhouse with 150 m2 floor space for growing tomatoes are built. The breeding capacity is 6 tons of eel per year. Solar heat accumulated at the greenhouse (acrylic double walls with water circulation) and in the solar panels (25 m2) is used in the eel breeding farm ; waste heat from the fish basins can be used to condition the greenhouse. When the double walls of the greenhouse are filled with water the light transmittance of the greenhouse improves. Day-night variations are balanced in a heat storage tank with a capacity of 5 m3 water. The fish breeding farm has been separated from the greenhouse and the solar energy installation by means of two heat exchangers, which can be cleaned easily. No auxiliary heat from conventional energy sources is used. Only electricity for circulation pumping and controls is required.
Different thermostats and a 3-way valves control the process.
Due to the low water temperature the solar collectors (25 m2) have been chosen uninsulated and unglazed. Heating of the fish basins only occurs by heat from the insulated storage tank. The greenhouse has window shutters for natural ventilation on warm days. The climate cover has a surface area of about 260 m2.

Call for proposal

Data not available

Coordinator

VAN HEUGTEN/UNIVERSITY OF PATRAS
EU contribution
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Address
HE - PATRAS

Greece

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Total cost
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