Energy Efficiency in Greenhouses and Comparison of Energy Sources Used for Heating

Sustainability in greenhouse farming, one of the areas where the most energy is needed in the agricultural sector, can be achieved by increasing energy efficiency. Due to increasing energy costs in Türkiye and worldwide, increasing energy efficiency in greenhouses is seen as possible using renewable energy sources that do not produce waste instead of fossil energy sources. This study determined the heat-energy demand in the provinces of Türkiye with continental (Kırşehir and Kütahya) and Mediterranean (Antalya and Mersin) climates. For this purpose, the heat-energy requirement was calculated for greenhouse types with three different insulation properties (S-1: roof and side walls polyethylene, S-2: roof polyethylene, side walls polycarbonate, and S-3: roof polyethylene, side walls polycarbonate, and thermal curtain). Then, the amount and cost of fossil (coal, fuel oil, and natural gas) and renewable energy sources (geothermal and biogas) to be used in obtaining this energy, the heating cost for unit tomato yield, and the amount of carbon dioxide (CO2) released into the atmosphere were compared. According to the results obtained, the highest heat-energy requirement was 356.5 kWh m−2 year−1 in the S-1 greenhouse in the Kütahya province, and the lowest was 46.3 kWh m−2 year−1 in the S-3 greenhouse in the Mersin province. Depending on energy conservation, 6% of energy savings can be achieved in S-2 and 29% in S-3 compared to S-1. The highest heating cost for producing one kilogram of tomatoes was 0.70 USD kg−1 in fuel oil and Kütahya province (S-1). The lowest was calculated as 0.06 USD kg−1 in geothermally heated greenhouses in Kırşehir and Kütahya provinces (S-3). The highest CO2 to be released into the atmosphere with fuels was equal to 253.1 kg m−2 year−1 in coal fuel in Kütahya province (S-1). The lowest was calculated as 1.1 kg m−2 year−1 in geothermally heated greenhouses in Kırşehir and Kütahya provinces (S-3). The results of this research can be used to develop feasibility studies for greenhouse companies, greenhouse sector policies, policymakers, environmental protection, and taking precautions against the climate crisis.