The Solar Greenhouse: state of the art in energy saving and sustainable energy supply

The objective of the solar greenhouse project was the development of a Dutch greenhouse system for high value crop production without the use of fossil fuels. The project was completed and the results are reported here. The main approach was to first design a greenhouse system requiring much less energy, next to balance the availability of natural energy with the system¿s energy demand, and finally to design control algorithms for dynamic system control. This paper discusses the first two design steps. Increasing the insulation value of the greenhouse cover was the first step towards a reduction in energy demand. The challenge was in maintaining a high light transmission at the same time. A first generation of suitable materials was developed. The realizable energy saving is almost 40 %. The next reduction in fossil fuel requirement was accomplished by capturing solar energy from the greenhouse during the summer months, storing it in an underground aquifer at modest temperatures, and finally using the stored energy during the winter months by using heat pumps. Then the total realizable energy saving is more then 60%. For sustainable energy supply per ha greenhouse at this low energy demand 32 ha biomass is needed, or 600 kW nominal wind power or 1.2 ha PV assuming storage via the public grid

Les besoins en eau de la tomate sous serre à film polyéthylène en Tunisie

Water consumption of a tomato crop under polyethylene greenhouse in Tunisia. Comparison of the water consumption of tomato hybrids with determinate and indeterminate growth and cultivated in lysimeters permitted to conclude that varieties with determinate growth have a smaller water consumption than the indeterminate ones. Comparison ofthe water consumption of a tomato crop cultivated on a lysimeter with the water consumption of a tomato crop cultivated in a lateral isolated greenhouse, preventing lateral infiltration and with water stock control by neutron probe indicates a surestimation of the water consumption by the lysimeter method with about 15 %. Daily measuring of the water consumption of a Kikuya-grass cultivated on a lysimeter under PE greenhouse permitted to obtain the potential evapotranspiration in function of the global radiation under greenhouse, while comparison of the water consumption of the Kikuya-grass with the tomato crop allowed us to obtain the cultural parameters of this evapotranspiration in function of the stage of growth of a tomato crop

Agronomical and biological results of solar energy heating by the combination of the sunstock system with an outside captor on a muskmelon crop grown in polyethylene greenhouses

Six cultivars of muskmelon (Early Dew, "68-02", "Early Chaca", "Jivaro", "Super Sprint" and "Cantor") transplanted at two differents dates were cultivated under two PE greenhouses heated by solar energy recovery and compared to a control greenhouse. The greenhouses were covered with a double shield of normal PE of 100 microns. The first greenhouse was considered as the control. The second one was equipped with a sunstock solar energy collector distribution system, consisting in a covering of 37 % of the ground surface by flat black PVC tubes, used during the day as a solar energy captor for heating the water of a basin and during the night as a radiant mulch for heating the greenhouse by emission of radiation warmth. The third greenhouse was equipped also with the same sunstock System, but connected with a supplementary outdoor collector by means of flat PE tubes corresponding to about 28 % covering of the greenhouse, and resulting in a more important energy stock, available for heating during the night. Minimum air temperature was raised by about 1, 5 and 2, 5°C respectively in the second and the third greenhouse, while the minimum soil temperature was raised with about 1 and 2°C respectively. Evolution of the maximum temperatures was more irregular and was depending also from the incident energy. Plant growth under the solar heated greenhouse was more accelerated, and resulted in an earlier fruitset, an earlier production and a higher total yield

De Zonnekas : gewasproduktie zonder fossiele energie

The Solar Greenhouse project aimed at the development of a greenhouse system for high value crop production with sustainable energy supply. The project meets the EET goal to substantially increase contribution of sustainable energy in energy supply. Moreover CO2 emission is reduced considerably. The research contained three themes: Decrease of the energy demand of the greenhouse system. Matching the time patterns of sustainable energy supply and greenhouse energy demand and Optimal control of the designed greenhouse syste

The solar greenhouse: state of the art in energy saving and sustainable energy supply

The objective of the solar greenhouse project was the development of a Dutch greenhouse system for high value crop production without the use of fossil fuels. The project was completed and the results are reported here. The main approach was to first design a greenhouse system requiring much less energy, next to balance the availability of natural energy with the system's energy demand, and finally to design control algorithms for dynamic system control. This paper discusses the first two design steps. Increasing the insulation value of the greenhouse cover was the first step towards a reduction in energy demand. The challenge was in maintaining a high light transmission at the same time. A first generation of suitable materials was developed. The realizable energy saving is almost 40 %. The next reduction in fossil fuel requirement was accomplished by capturing solar energy from the greenhouse during the summer months, storing it in an underground aquifer at modest temperatures, and finally using the stored energy during the winter months by using heat pumps. Then the total realizable energy saving is more then 60%. For sustainable energy supply per ha greenhouse at this low energy demand 32 ha biomass is needed, or 600 kW nominal wind power or 1.2 ha PV assuming storage via the public grid

De Zonnekas : gewasproduktie zonder fossiele energie

The Solar Greenhouse project aimed at the development of a greenhouse system for high value crop production with sustainable energy supply. The project meets the EET goal to substantially increase contribution of sustainable energy in energy supply. Moreover CO2 emission is reduced considerably. The research contained three themes: Decrease of the energy demand of the greenhouse system. Matching the time patterns of sustainable energy supply and greenhouse energy demand and Optimal control of the designed greenhouse syste