Towards Autonomous Solar Driven Agricultural Greenhouses in Qatar - Integration with Solar Cooling

Abstract

Qatar is a peninsula located in the Middle East and classified as a hot subtropical desert based on its geographical location and climate. The weather is hot and humid in the summer, but mild in the winter. Aridity is the general characteristic of the country, while natural vegetation such as trees and shrubs can be found in some regions. The hot climate and high humidity in summer as well as aridity in Qatar impose major challenges for expansion in the agricultural sector. The government of Qatar has been and will continue to support local food production through the Qatar National Food Security Program (QNFSP) and other initiatives to develop the agricultural sector to the maximum realizable extent. The focus of this research work is on design, modeling and optimization of small to large-scale agricultural greenhouses for improving their energy and water use efficiency and equipping them with solar PV systems. The solar PV is integrated with the structure of greenhouse, as a roof mounted system, without compromising the supply of daylight and required solar energy for plants growth. The ultimate goal is to develop a Passive Solar Greenhouse (PSGH) design that reduces the cooling load drastically and integrate it with solar cooling to cover 100% of the cooling load. The aim of the optimized PSGH design is to maintain favorable crops growing conditions inside a greenhouse such as temperature, humidity, daylight, ventilation and minimize the cooling load and energy consumption. Five different sizes of pitched roof greenhouses with the optimized PSGH design (28mx8m, 28mx20m, 28mx50m, 28m×100m and 28mx150m) were modeled and compared with the conventional greenhouse design in terms of their dynamic cooling loads and overall energy consumption. The analysis showed that the cooling load of the PSGH design has been reduced by approximately 74%, while over 77% reduction in annual energy consumption has been achieved, compared to a conventional greenhouse design.