The main drawback of greenhouse heating systems based on solar energy is the unavailability at nighttime and the variation of its value from hour to hour and month to another during daylight-time. However, use the combination of two-source of renewable energy (solar energy and biomass heat energy) successfully provides appropriate amount of heat energy for heating greenhouse at nighttime. The commercial greenhouses have the highest demand of heat energy for heating the indoor air as compared with other agricultural industry sectors. The investigation presented in this article is aimed at evaluating the technical and design feasibility of using biomass heat energy to assist the solar energy heating system at the eastern area of coastal delta, Egypt (Latitude and longitude are 31.045°N and 31.37°E, respectively, and altitude 6.0 m above the sea level). The hybrid heating system (solar and biomass heating systems) is mainly consists of two different heating systems, a complete solar heating system (6 collectors, storage tank and heat exchanger) and biomass burner (water and air coils, and air heat exchanger). The obtained results reveal that, over 180 days heating season (from November 2015 to March 2016) the solar heating system collected 12712 kWh (45.763 GJ) of which 12316 kWh (44.338 GJ) of solar heat energy was stored in the storage tank. It provided 30.32% of the total heat energy required for heating the greenhouse. The biomass heating system provided 19795 kWh (71.262 GJ) of heat energy which provided 58.55% of the total heat energy required for heating the greenhouse (225.389 kWh). Ultimately, the heat energy provided by the hybrid heating system (88.87%) has been used successfully to heat up the indoor air of the commercial greenhouse sweet coloured pepper. It also provided high water use efficiency of 29.860 kg/m3. High water use efficiency (29.860 kg/m3) and high annual irrigation water productivity (447.9 LE/m3) were achieved during this study.
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