A new type of closed-loop greenhouse cooling and heating system that permits C02 enrichment of a variety of principal crop and native species over long periods of time without loss of C02 during ventilation will be constructed, installed in an encisting greenhouse, and tested for its ability to achieve energy balance during a range of selected cooling/heating load conditions produced in the growth chamber during long-term C02 enrichment using lettuce as a test crop. This approach to optimal growing conditions is based on the wThermal Bankw heat storage system: phase change materials (PCM) in flexible film laminate containers that remove excess heat from the circulating atmosphere during periods of high insolation or supplementary lighting, cooling it to desired growing temperatures, and later, when heat is required to maintain desired growing temperature, returns heat to the circulating air. Data on the energy balance achieved in the test chamber during Phase I will guide us in determining the requirements for a complete greenhouse version to be fabricated and tested in Phase II and used to study additional crops for their response to continuous C02 enrichment, optimized photoperiods and other controlled variables.Applications:This project will provide an energy efficient, closed loop greenhouse cooling and heating system that permits continuous exposure of crops to C02 enrichment and other airborne materials such as growth control agents or air pollutants under totally controlled growing conditions. In addition to its scientific value, the system has major commercial potential as an energy-efficient approach to growing plants under optimal controlled conditions to produce economically attractive yields and premium quality plants.
