Methodology and data System dynamics is used to

2. Methodology and data
System dynamics is used to study the causal patterns of systems. It was developed by Jay W. Forrester in 1961 who aimed to study how policies, decision making, structure, and time delay correlated with each other and how they affected the growth and stability of a given system (Dong et al., 2012). System dynamics is used to simulate the LY450139 consumption system in 2020. By building the “Economic–Energy–carbon emissions” model, the energy structure and level of CO2 emission in 2020 are estimated according to historical data. Also, the relevant GDP parameters are added to examine the impacts of different economic development speeds on CO2 emission reduction target. Then, relevant policy parameters are added to construct the “Economy–Policy–Energy–Carbon emissions” model, which would confirm the roles of policy factors in the target CO2 emission level.
2.1. Data
China's GDP, traditional and renewable energy consumption per year are shown in Table 1. Concerning the traditional energy consumption, coal always played a leading role over the past twelve years which accounts for more than 65% of the total energy consumption. In addition, alternative source of energy such as hydropower, nuclear and wind energy are used to generate electricity in China. They are encouraged to develop in a large scale to solve the energy and environmental problems in recent years. The hydropower's development is better and wind power has become a promising alternative source of energy with a sharp annual growth rate of 82%. Although solar energy was adopted in a limited scale due to high cost and technology problems in China, it is a promising source of renewable energy.1