Enviro-Economic Assessment of Energy Conservation Methods in Commercial Greenhouses in Iran

Abstract

Population growth, rapid cultural development and urbanization have led to increased food demand. However, in Iran, due to limited water resources, only about 50% of the total arable area can be used for horticultural purposes. Therefore, yield improvement is very dependent on high-efficiency horticultural technologies such as commercial greenhouses. Although better yields can be obtained in commercial greenhouses than in field-scale cultivation, the energy demand is considerably higher. Moreover, the investment and energy costs are correspondingly larger in commercial greenhouses compared with any other horticultural sector. Hence energy conservation in commercial greenhouses has been emphasized in recent years in order to sustain more cost-efficient crop production. A study on energy use in the commercial greenhouse sector can thus help to identify the challenges and options for improving profitability. In this paper, the authors assess the commercial greenhouse industry in Iran, including the number of existing and planned greenhouses, plus the range in yield and energy use in the sector compared with other agricultural sectors. The results are based on a ‘typical’ commercial greenhouse for the region. The results show that the solar blind system can reduce heating and cooling demand by 60% and 90% respectively. The solar blind system can supply 70 kWh/m2 of electricity annually, which can be used for supplementary lighting or cooling systems. The maximum electrical power that can be supplied by a solar blind system is estimated to be about 113 kW per m2 of photovoltaic module. The implications for the horticultural greenhouse industry are discussed.