We propose a directed technical change model with two sectors, clean and dirty, to analyze the impact of the degree of substitutability between sectors and the degree of scale effects on the environmental quality. The technological knowledge is biased towards the clean sector; i.e., the environmental quality is improved whenever the elasticity of substitution between inputs in both sectors increases and, along with that, the economy: (i) is rich in renewable capital, (ii) has higher relative supply of clean labor under scale effects, and (iii) enjoys higher relative R&D productivity in the clean sector. The improvement in the environmental quality benefits the welfare. Moreover, the growth rate is higher in the presence of scale effects.

我们提出了一个有清洁和肮脏两个部门的有针对性的技术变革模型，以分析部门之间的可替代性程度以及规模影响程度对环境质量的影响。技术知识偏向清洁部门；也就是说，只要两个部门的投入之间的替代弹性增加，并且与此同时，经济，环境质量就会得到改善：（i）拥有丰富的可再生资本，（ii）在规模效应下，清洁劳动的相对供给更高， （iii）在清洁部门的相对研发生产率较高。环境质量的改善有益于福利。此外，在存在规模效应的情况下，增长率更高。