Improving clean energy greenhouse heating with solar thermal energy storage and phase change materials

Greenhouses consume a great deal of energy to heat their building envelopes. The strategic integration of solar energy and thermal energy storage (TES) can help to boost energy performance and reduce the carbon emission in the sector. In this paper, the benefits of adding phase change materials (PCM) to the water tank of a solar heating system have been evaluated using the Transient System Simulation (TRNSYS) program. Initially, the hourly heating load of a reference greenhouse was evaluated using TRNSYS software. The results were validated with natural gas consumption data. The validated simulation was then used to investigate the impact of PCM on the performance of a large-scale solar energy system. Four system configurations were evaluated; no PCM materials in the tank, then 20%, 40%, and 60% of the water tank volume occupied by PCM. Energy performance improvements of 10% to 14% were observed by increasing the proportion of PCM amounts over the baseline conventional system. Finally, an economic study was conducted to investigate the cost feasibility of different PCM concentrations. It was shown that PCM price, cost of natural gas, and carbon tax are the principal influence factors on the payback period.