POSSIBILITY OF CLIMATE CONTROL OF A GREENHOUSE WITH CONCENTRATING SOLAR POWER SYSTEM - A CONCEPT DESIGN
There are several greenhouses built with solar panels integrated into the roof. In summer 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 access to the cultivation space. As a result, the crops will 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 or Thermo Acoustic Stirling Machine (TASM) 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 better internal climate control of greenhouses and buildings. This lower heat load makes it easier to keep the greenhouse cool with the absorber cooler or TASM. In this study the details of energy flows and thermal conversion with an absorption cooler or TASM were determined. Calculations showed a 47% heat load reduction (from 337 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, was required to cool the greenhouse further with an absorption cooler or TASM. The possibility of light regulation is an important advantage the Fresnel lenses have. The light amount can vary between 15-77% of the incoming radiation. The excess of the energy generated can be used for extra illumination (light and energy regulation) and/or energy supply and/or a desalination system.
Sonneveld , P. (2014). POSSIBILITY OF CLIMATE CONTROL OF A GREENHOUSE WITH CONCENTRATING SOLAR POWER SYSTEM - A CONCEPT DESIGN. Acta Hortic. 1054, 55-61
greenhouse, Fresnel, concentrators, climate, CSP System, cooling