Evolutionary features of global embodied energy flow between sectors: A complex network approach

With international trade, energy embodied in goods flows between sectors at a global scale and forms a complex network. Using the world input-output tables from 1995 to 2009, this study aims to apply complex network theory to study the evolutionary features of global embodied energy flow between sectors. The results show that 80% of flows are between different countries, while 80% of embodied energy is consumed in the national production process. Over time, embodied energy consumption increases, and sectors tend to import more energy from sectors in other countries. The network is sensitive; change in some sector or flow can quickly spread and impact the whole system. Only 0.02% of key flows possess large amounts of embodied energy and account for 80% of embodied energy. Sectors with large-scale impact, strong impact, strong intermediary ability, and strong central ability play key roles in the network. Furthermore, the network presents an obvious clustering feature. More than 60% of sectors cluster into the top 3 largest communities, and sectors in EU countries cluster into the biggest community and attract more sectors to join. Therefore, the key flows, key sectors and key communities should receive more attention when making energy-related policies.