Developing a framework to evaluate the life cycle energy and greenhouse gas emissions of space heating systems using zeolite 13× as an adsorbent material

The wide use of fossil-based space heating systems results in significant greenhouse gas (GHG) emissions. Using solar energy for space heating can help reduce GHG emissions. However, solar energy generation is intermittent and the energy needs to be stored for continuous supply. The zeolite 13× adsorbent heat storage system for space heating is a promising alternative. There is very limited research on the life cycle GHG footprint of this type of adsorbent storage system. In this study, we developed a framework that integrates engineering design with life cycle assessment to evaluate the energy and emission performances of a zeolite 13×-based heating system charged by a solar air collector. A simulation model was developed for this adsorbent storage system. The life cycle GHG emissions of the residential heating system are estimated to be 0.1160 kg CO2 eq per kWh of the heat delivered over a 20-year lifetime. The operational phase contributes 74 % of the overall emissions because of the energy required by the humidifiers. The material production stage accounts for 25 %, mainly attributed to the upstream emissions in the manufacturing of photovoltaic thermal (PVT) air solar systems. The net energy ratio (NER), which is the ratio of energy output to fossil energy input, is 2.9. The continuous days without sunlight, the adsorbent vessel length-to-diameter ratio (L/D), and the pellet diameter of the zeolite 13× storage appear to be the parameters most sensitive to both emissions and NER. The uncertainty analysis shows emissions and NERs of the space heating system in the range of 97.2–152.3 g CO2 eq/kWh and 2.4–3.0, respectively. Compared with other alternative heating systems in the market, the adsorbent system has a much better GHG performance. The research highlights the importance of selecting a suitable space heating system given the high influence of operational energy on the life cycle emissions and the range of electricity generation emissions in different provinces. •A simulation model for a zeolite 13×-based space heating system with a solar collector was developed.•The net energy ratio and life cycle (LC) greenhouse gas (GHG) emissions of the space heating system were developed.•The LC GHG emissions of the heating system are 0.1276 kg CO2 eq per kWh.•The NER of the heating system is 3.2.•The performance of the space heating system depends significantly on the grid energy mix.