ISHS Acta Horticulturae 443: International Conference on Greenhouse Technologies
CO2 OPTIMIZATION IN THE GLASSHOUSE TOMATO |
| Authors: | D.P. Aikman, J.R. Lynn, Z.S. Chalabi, B.J. Bailey |
| Keywords: | Model, energy balance, dummy price |
| DOI: | 10.17660/ActaHortic.1997.443.17 |
| Abstract:
An estimate of the anticipated cash worth per unit of assimilated CO2 is used to convert the output from a model for canopy photosynthesis, as a function of the current light level and of the potential glasshouse carbon dioxide concentration, to an estimate of the future cash benefit. An energy balance model can be used to predict the rate of ventilation air exchange, and hence the loss of CO2 for any internal concentration. For a source of pure CO2 at a known fixed cost, an optimization routine can be used in real time to determine the CO2 set-point that will maximize the difference between the benefit and cost. If fuel burners, linked to heat storage, are used to generate the CO2, then the CO2 could be regarded as free, provided the heat can be used or stored for later use. A dummy price can be used as a basis for optimizing the distribution of the CO2 that will be generated. The dummy price should be adjusted so that the sum of the computed demands for CO2 over the rest of the day will match the total available. This procedure ensures that the CO2 is used with equal marginal benefit throughout the day and so, given a relation of diminishing returns, used to maximal effect. As an initial estimate of this dummy price, the real price of the fuel may be used. If the demand that this creates exceeds the amount needed for heating, then fuel should be burned to meet the CO2 demand alone, and the heat should be stored while possible. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
