Prospects for Gulf Region with closed greenhouse

In countries such as Saudi Arabia and the United Arab Emirates, water is scarce as rainfall is minimal. Growers in the Gulf Region rely on groundwater for evaporative cooling and irrigation. This source of water is running out and growers are deciding to end production. The governments of the Kingdom of Saudi Arabia and the United Arab Emirates want to create new possibilities for horticulture in the region by developing more sustainable and water-efficient technique

Towards a low emission greenhouse horticulture

For the pilot crop tomato, business concepts of low emission greenhouses for the midterm (10 year) have been designed. The study is carried out in cooperation with innovators in the horticultural sector, suppliers and extension services. The business concepts are evaluated for different indicators in the field of planet and compared to the current situation. The focus is on the reduction of energy consumption and CO2 emission for the cultivation with and without supplementary lighting. The energy concepts differ in the way the heat and power are produced or supplied on business level. The results show that the energy concepts without supplementary lighting have a lower environmental impact and have a better energy efficiency than the energy concepts with lighting. The energy concepts without supplementary lighting show that simultaneous production of heat and power on business level and the delivery of electricity to the public grid is most favorable looking at the energy use and CO2 emission on a national level. Second best is the conditioned greenhouse. In this energy concept solar energy is collected in summertime, stored and re-used in wintertime. Conditioned greenhouses also have good perspectives in reducing the use and emission of pesticides

Dehumidification of greenhouses

Dehumidification is an essential part of greenhouse climate control. High humidity is a cause of diseases which ultimately reduce the quantity and quality of production. The humidity surrounding the crop differs since the air temperature in the greenhouse is not homogenous. Humidity control increases energy consumption during heating periods. The various methods of dehumidification were evaluated from an economical, practical, and energetic point of view. It was concluded that the ventilation with outside air with heat recovery is the most economical, practical, and energy-saving method. Ventilation driven by buoyancy and wind cannot be controlled accurately though and gives rise to a heterogenic greenhouse climate. Therefore, the dehumidifying ventilation has to be mechanically controlled and the incoming air has to be distributed evenly over the greenhouse. Using this system the humidity can be controlled accurately in an energy-friendly way and the climate is more homogenous. For more sustainable greenhouses with lower heat demand realisable in the future this method will be indispensable. <br/

Meerlagenteelt in de praktijk : energie-efficienter broeien

Naast mogelijke voordelen als een betere kasbenutting, waardoor een lagere kostprijs, en productieuitbreiding zonder kasuitbreiding, biedt het broeien in meerdere lagen (in de kas en/of in de cel) grote mogelijkheden om het energieverbruik in de broeierij terug te dringen

Simulating the effect of forces pit ventilation on ammonia emission from naturally ventilated cow houses with CFD

Atmospheric NH3, mainly originates from agricultural sources, can cause serious environmental problems related to eutrophication and soil acidification. Emissions from dairy houses are 15% of total agricultural NH3 emissions. Due to open buildings, existing abatement options are limited. Pit air separation was identified as a potentially efficacious option. In this study a model simulation of a commercial dairy cow building with slatted floor is presented. The model was solved for 12 cases, differing wind speed, direction and both air and manure temperature. For each case three solutions were obtained, which correspond a) to a building where a forced pit ventilation system is applied at capacity of 250 and 500 m-3 h-1 cow-1 and b) to a building without forced pit ventilation system. The results show that due to forced pit ventilation system, at 250 and 500 m-3 h-1 cow-1, the ventilation rate was increased 3.1% and 6.2% respectively. The contribution of the pit ventilation system to the total ammonia released from the pit during winter, ranged from 31-35%, 16-19% and 11-8%, for wind speed of 1.0, 4.0 and 8.0 m s-1 respectively. Correspondingly, during summer, the contribution of the system ranged from 44-48%, 20-21% and 12-9%. Although obvious benefits arise from a forced pit ventilation system, the main mass flow of ammonia from the pit still emitted through the building ventilation openings, especially at high wind speeds

Is a sustainable protected horticulture in arid regions economically feasible?

Technology is being presented as a way to save water. This technology comes at a price though. An economical analysis is made based on the operational costs and the investment costs. The application of water saving technology has to be economically feasible for the grower otherwise they will never implement it. Technologies used in this paper are the application of soilless culture and the closed greenhouse. The economical evaluation showed that the application of soilless culture is more profitable then the production in the soil in a pad and fan greenhouse. The investment costs of soilless culture are relatively low and the production increase is high. The closed greenhouse becomes most profitable when the price of tomato is higher than 0.75 Euro/kg

Towards a more sustainable, water efficient protected cultivation in arid regions

The first step towards a more sustainable, water efficient greenhouse is made through the application of soilless culture. Numerous studies have shown that separating the root zone from the ground increases water efficiency up to 5 times since the process of irrigation is well controlled. Monitoring of the irrigation water and the drain water is an important aspect when applying this method. The ultimate system in terms of water saving is a closed greenhouse. No air exchange between the greenhouse air and the ambient is needed so no water is lost. Using a dynamic simulation model which acts as a virtual greenhouse, the operation of the Pad & Fan system and the closed greenhouse is evaluated under climate conditions in Riyadh. Water consumption is reduced by 95% and biomass production is increased by 75% due to the increased carbon dioxide level and the optimal climate. Almost 4 GJ of cooling is needed annually with a maximum cooling capacity of 650 W for the closed greenhouse

Koeling en ontvochtiging in de Floriadekas

Het initiatief van het provinciebestuur van Noord Holland om voor de Floriade in Hoofddorp in 2002 een “Kas voor de Toekomst” te ontwerpen, leidde ertoe dat er een projectgroep aan het werk is gegaan met ondermeer onderzoekers vanuit de instellingen IMAG, ECN, ECOFYS, TNO Bouw en het toenmalige Proefstation voor Bloemisterij en Glasgroente onder voorzitterschap van Ir. W.F.S. Duffhues om een programma van eisen te realiseren