“…Also, the tiered hybrid model presents a broad range of application, such as renewable energy (Lu and Zhang, 2010;Zhai and Williams, 2010), particularly for biomass conversion systems, e.g. household biogas digesters (Zhang et al, 2013a), biomass gasification (Wang et al, 2012) and pelletization , buildings (Chang et al, 2012;Chang et al, 2013;Han et al, 2013), industrial parks (Dong et al, 2013) and new energy explorations, such as shale gas production in China (Chang et al, 2014a).…”