Promoting Global Energy System Transformation Toward Carbon Neutrality: A Four-Stage Pathway of System Integration

The global energy landscape has undergone profound changes since the industrial revolution, characterized by three major shifts in primary energy sources [1]. These include the transition from biomass to coal between 1850 and 1950, followed by the shift from coal to oil from 1950 to 2000 and the more recent move toward a diversified energy structure at the beginning of the 21st century. Each shift was driven by visible crises—deforestation, air pollution, and oil supply disruptions—and the competitiveness of new technologies [2,3]. Currently, achieving carbon neutrality by 2050–2070 has become a global policy target, with 151 countries committed to national carbon neutrality goals by May 2024 [4]. In this context, energy system transformation (EST), also referred to as energy transition, has become a central concept representing the urgent need for radical structural changes in energy systems within a relatively short timeframe. Specifically, primary energy sources and carriers must predominantly derive from renewable energy and electricity, with an accelerated shift away from fossil fuels [5]. However, EST toward carbon neutrality presents a significantly more complex challenge. Aacademic discussions on EST have become increasingly popular in recent years. An early example is that Steve Rayner concluded energy system must be recognized to be as much a social system as it is a technical one after discussions of climate science and policy in his paper published in 2010 [6].