An exploration of shared heat storage systems in the greenhouse horticulture industry

This paper presents a study of a shared heat storage (SHS) system that's integrated with the horticulture industry. In the present day, many greenhouses in Northwestern Europe are equipped with combined heat and power plants (CHPs) and gas boilers to complete three main needs, i.e., heat, power for lighting and carbon dioxide as a fertilizer. The redundant electric power can eventually be sold on the electricity market. However, these three main needs do not allow much flexibility to profit, for example, from opportunities on the energy spot market. Recently, large SHS devices have become commercially available. The present study was conducted to examine their impact on acclimatization costs and carbon dioxide emissions. A real-world case study, comprising data from nine greenhouses and 21 CHPs, was used. The novelty of this research is that it quantifies the impact of SHS on operational costs in the horticulture industry. Accordingly, the simulation was based on an optimal control problem that was cast as a linear programming problem. In brief, the heating costs can be reduced by 0.5 €/m²/y to 6.12 €/m²/y if an SHS system is installed. Moreover, a sensitivity analysis was performed, and (i) the cost reduction with respect to insulation was examined. This seems not to be a critical parameter. Under current circumstances, the storage device is mainly used for relatively short periods (up to 50 days); therefore, (ii) the size of storage was optimized. The optimal size of the storage was around 550 m³/hectare or 50 000 m³ for this case study; (iii) carbon capture techniques were found to have a modest impact on the operational costs (−3 c€/m²/y), while (iv) the most critical parameter was the gas price. The main finding is that SHS systems are already efficient under current market conditions.