Does vegetation in the greenhouse reduce power production?
At first glance the evaporation of water due to vegetation in the greenhouse seems to reduce heat generation through latent heat losses. However, since the heat transfer from plants to air is about five times greater than from a plain surface to air, the plant cover stays correspondingly cooler and loses much less infrared radiation to the glass and to the sky (loss proportional to T^4, T in Kelvin). This over-compensates the latent heat losses so that vegetation improves heat generation and power production. This has been proved, also experimentally, by the Institute of Thermodynamics and Mechanics (ITM) at Stellenbosch University. With the newly developed infrared reflection layers at the bottom side of the collector glass IR losses and the above compensation will be much smaller. Therefore re-condensation is applied, saving all evaporation energy.
