Photovoltaic and Hydrogen Plant Integrated with a Gas Heat Pump for Greenhouse Heating: A Mathematical Study

Abstract

Nowadays, the traditional energy sources used for greenhouse heating are fossil fuels such as LPG, diesel and natural gas. The global energy demand will continue to grow and alternative technologies need to be developed in order to improve the sustainability of crop production in protected environments. Innovative solutions are represented by renewable energy plants such as photovoltaic, wind and geothermal integrated systems, however, these technologies need to be connected to the power grid in order to store the energy produced. On agricultural land, power grids are not widespread and stand-alone renewable energy systems should be investigated especially for greenhouse applications. The aim of this research is to analyze, by means of a mathematical model, the energy efficiency of a photovoltaic (8.2 kW), hydrogen (2.5 kW) and ground source gas heat pump (2.2 kW) integrated in a stand-alone system used for heating an experimental greenhouse tunnel (48 m 2 ) during the winter season. A yearlong energy performance analysis was conducted for three different types of greenhouse cover materials, a single layer polyethylene film, an air inflated-double layer polyethylene film, and a double acrylic or polycarbonate. The results of one year showed that the integrated system had a total energy efficiency of 14.6%. Starting from the electric energy supplied by the photovoltaic array, the total efficiency of the hydrogen and ground source gas heat pump system was 112% if the coefficient of the performance of the heat pump is equal to 5. The heating system increased the greenhouse air temperatures by 3-9 • C with respect to the external air temperatures, depending on the greenhouse cover material used.

Performance comparison between fuel cell coupled with geothermal source heat pump and geothermal source gas engine heat pump system for greenhouse heating: a mathematical study

“…Unfortunately, in winter, the cloudy day influenced the performance of the hydrogen system and the average clearness index can be considered equal to 0.2 [21]. In summer, when the cooling demand is very high, the cycle of the GSHP and the GSGEHP can be inverted, otherwise, natural or dynamic ventilation, operated by the fans, could be enough [26].…”

“…Regarding system 2, the equivalent thermal power supplies by the ICE (Q gas ) is given by [21]: Q gas = δ H2 q H2,gas LHV H2 ,…”

Comparison of selected physical parameters of rapeseed cultivars

“…The rapeseed cultivars were obtained from the 2014 to 2015 growing season at the individual farms located in the villages of Lublin voivodship. The seeds were cleaned in an air screen cleaner, where all foreign matter such as dust, dirt, stones and chaff seed were removed, renewable energy can be used to supply energy during this phase [13].…”

Evaluation of Compressor Heat Pump for Root Zone Heating as an Alternative Heating Source for Leafy Vegetable Cultivation

“…However, concerning HPs, their use in agriculture still mainly only refers to fruit drying [17,18]. Concerning greenhouse heating, studies have focused on HPs only in the case of geothermal source HPs, on integrated systems [11,16,[19][20][21][22] or they have investigated their financial and environmental viability using simulation tools [10]. There are many reasons why HPs have not garnered great interest in protected agriculture applications, mostly due to the traditional design in building experiences.…”