Efficiency assessment of green technology innovation of renewable energy enterprises in China: a dynamic data envelopment analysis considering undesirable output

The rapid development of renewable energy enterprises has produced important benefits for contemporary efforts to address serious environmental pollution and depletion of fossil energy resources. However, the environmental pollution that exists in the production and operation of enterprises has been ignored, and so an objective evaluation of this issue is becoming urgent. This paper established an evaluation index system for green technology innovation efficiency and used dynamic data envelopment analysis (DEA) considering undesirable output to measure the green technology innovation efficiency of renewable energy enterprises, and the improvement potential of ineffective enterprises was put forward. The results show that: (1) the green technology innovation of renewable energy enterprises needs to be greatly improved. The average efficiency score of sample was 0.385 over four years, and only 16 enterprises were found to operate effectively; (2) when effective and inefficient DMUs were compared, the latter were found to have significant output shortfalls, especially in environmental tax, and were found to show an improvement potential of 55.71 percent; (3) the efficiency analysis of different types of renewable energy enterprises found that the green technology innovation efficiency score of nuclear energy enterprises was the highest, and rapidly rose; (4) the green technology innovation efficiency of renewable energy enterprises in the western region greatly exceeded the efficiency of the eastern and central regions. The efficiency evaluation results could not only provide a guidance for central and local governances to optimize the structure of renewable energy sector, but also potentially provide a reference for the operation and management of renewable energy enterprises in China.