Samenvatting

There are several greenhouses built with solar panels integrated into the roof. In summer time this will operate very well, although broad shadow stripes can result in growth and yield differences. In winter the amount of sunlight is further limited by the solar panels and will result in further reduction of light accession to the cultivation space. As a result, the crops suffer from growth problems. These drawbacks are eliminated by the application of Concentrating Power Systems (CSP) with Fresnel lenses. A Fresnel lens works like a normal lens but is much thinner. When the sun shines, the lens receives both direct and indirect sunlight. The lens will concentrate all direct sunlight, which can be collected as thermal energy in the focal point. This absorbed radiation can be converted with an absorption cooler into cold water for cooling. This cold water can cool the greenhouse without the need of water use. The indirect solar radiation, the diffuse light will not focus and is therefore available as a fairly constant light source in the building or in the greenhouse. The capture of all direct radiation at high intensities will diminish the incoming heat load, which is useful for a better internal climate control of greenhouses and buildings. This lower heat load makes it easier to keep the greenhouse cool with the absorber. In this study the details of energy flows and thermal conversion with absorption cooler is determined. Calculation shows a 47% heat load reduction (from 337 W/m2 to 157 W/m2) with the Fresnel lenses in the covering of the greenhouse. In the case of the collector in focus, only 48% of the captured direct radiation, available as thermal energy, is required to cool the greenhouse further with an absorption cooler. Cooling a greenhouse can result in up to 90% reduction in water consumption of the cultivation. The possibility of light regulation is another important advantage the Fresnel lenses have. The light amount can vary between 15 – 77% of the incoming radiation. The access of the generated energy can be used for extra illumination (light and energy regulation) and/or energy supply and/or a desalination system.