In the last years more than 1000 bio-gas plants were built up in the Po Valley (Northern Italy) to treat by fermentation the waste products of cows and pigs farming and agriculture biomass.
The high volume plastic-houses with two wide roof vents built up by Idromeccanica Lucchini for the Parolara project in North Italy.
Most of them have 1 MW electric capacity, but very few till now have done a profitable use of their waste heat. The “Parolara greenhouse project” near Mantova, 10.000 pigs and 300 ha of open field crops, mainly rice and corn, was born by the strong willing of the property to find a profitable use of their 1MW bio-gas plant and to find an “environmental friendly” solution.
Soilless cultivation on hanging gutters by using a closed system to sterilize by UV and to recycle the nutrient solutions.
They decided to re-use their waste heat in a 2 ha hi-tech greenhouse, so they had chosen as general contractor Idromeccanica Lucchini, an Italian leader in the construction of hi-tech plastic-houses. Later it was chosen to grow tomato specialties by using a soilless closed system, so Lucchini joined its forces with Riococo, a specialist in coco-based substrates.
"Riococo's worldwide experience was very helpful to this project for the choice of the right bags volume and coco mix", said greenhouse crop consultant Paolo Battistel of Ceres Srl. "The use of a super-washed clean product made immediately clear within only 3 weeks after planting the Riococo quality is quite higher than any other coco product used till now in Italy."
Truss tomatoes are grown on Riococo 16 liters bags, filled with a special dust-free mix of coco fibers and chips. Rooting exceeded expectations.
Summer is very hot in the Po Valley, with peaks of 24-27°C in the night and 37-40°C in the day, like this year. Battistel explained that because of this reason it was chosen to built up a plastic-house with high volume (6 m at gutter level), 2 wide roof vents, protected by insect nets and white painted steel to get some cooling effect in the summer and allow more light inside in the wintertime.
The plastic-houses are covered by double inflated foils with 30% diffuse light. A low-pressure fog system and recirculation fans help to keep the climate 3-4°C colder than outside in the day, with peaks of -7°C.
"To get more cooling capacity, the greenhouse is covered by using a new type of double inflated foils with 30% diffuse light; then a low pressure fog system and recirculation fans were installed. This enables the greenhouse to always be 3-4°C colder than outside in the day, with peaks of -7°C, 1-2°C colder in the night. Roof whitening is not necessary."
Bio-gas plant waste heat
The greenhouses use the waste heat of a 1 MW CHP plant. It burns bio-gas produced by fermentation of pigs farming and agriculture biomass.
The waste heat of the bio-gas plant is stored in a buffer tank, then heat distribution is provided by a rail and grow pipe system. In deep winter the heat of the bio-gas plant is integrated by a traditional gas boiler, where fuel gases are used to produce also CO2. Parolara property and Lucchini are now looking for co-operation to develop a system to clean and recover also the CO2 produced by the fermentation process.
For the crop protection only physical and biological methods are used. The goal is to get tomatoes with zero chemical residual.
Substrates on gutters
To realize the substrate cultivation on hanging gutters, Riococo has provided new 16 liters bags filled with a special dust-free coco fibers and chips mix. Battistel: "The rooting of the tomato crops exceeded expectations and also the recycling and sterilization by UV lamps of the nutrient solution is made easier and safer. The high quality of the substrate and the design of a specific fertigation program made the steering of the irrigation strategy very accurate."
Because the very good feedback of local retail, in the future Parolara farm will grow only Coeur de Boeuf tomatoes and specialties.
The consultant stressed out that another important goal of the project was to cultivate high quality tomatoes with zero chemical residues. "For this reason we have chosen to apply only physical and bio-control to the crops. As first crops it was chosen to grow Coeur de Boeuf (CdB) and on-the-vine tomatoes (TOV). After the good feedback of local retail, the future of Parolara farm will be to grow mainly CdB tomatoes and other specialties.
For the training of the farm technicians, wide experience on open field crops, but zero experience on hi-tech greenhouses and tomato crops, it was chosen the 30 years long expertise of a International consultancy company. Farm staff was trained in a six-months intensive course, made partly of theoretical lessons, but mainly of “learning by doing” experience inside real greenhouses in Italy, Holland, Russia and Morocco. The crop advisors took care also of the practical training of the workers team, young people coming mainly from African countries.
International consultancy company Ceres arranged in only 6 months the theoretical and practical training of technicians and workers inside real greenhouses in Italy, Holland, Russia and Morocco.
A last goal of the project team is now to convince other owners of similar bio-gas CHP plants to evaluate the real possibility to make money with their waste heat by growing vegetables.
For more information:
Consultation and technical experise:
Turnkey greenhouse projects: