Innovation-Led Transitions in Energy Supply
扩展了定向技术变革模型，发现创新与生产要素（能源资源）之间的互补性可推动能源供应从煤炭向天然气再到可再生能源的转型，即使没有政策干预。最优碳排放税呈J形，其福利价值是研究补贴或可再生能源强制令的两倍。
Generalizing models of directed technical change, I show that complementarities between innovations and factors of production (here, energy resources) can drive transitions away from a dominant sector. In a calibrated numerical implementation, the economy gradually transitions energy supply from coal to gas and then to renewable energy, even in the absence of policy. The welfare-maximizing tax on carbon emissions is J-shaped, immediately redirects most research to renewables, and rapidly transitions energy supply directly to renewables. The emission tax is twice as valuable as either the welfare-maximizing research subsidy or the welfare-maximizing mandate to use renewable resources.