Effects of electric power supply for artificial illumination of greenhouse crops at volatile current supply

Abstract

In Germany, the increasing generation of electricity based on renewable energy is accompanied by a high volatility in the current availability. This requires not only flexible capacities for current production, but also for current use and results in a high variability of the electricity tariff. Greenhouses could be such flexible users of volatile current supply. They can use it for heating the greenhouse and illuminating the crops. The present study considers the use of volatile current supply for the artificial illumination of greenhouse crops. In a model study, the effect of illuminating a tomato crop on photosynthesis and the potential yield at different times of the day and of the year is evaluated. In addition, the lamps release heat into the greenhouse and thus decrease the heat energy consumption. The photosynthesis model was evaluated for the application of artificial light using measurements in a greenhouse on complete crops. Simulated scenarios show the effects of variable artificial lighting. Obviously, the effect is higher at night and during winter time compared to summer. However, even during bright summer days, a photosynthesis driven model generates a slight increase in yield. The aspect of deriving the crop yield directly from the crop photosynthesis is discussed.