Does Subsidizing Renewable Energy Technologies Today Really Accelerate Their Realization of Cost Reductions in the Future?

Proponents of public subsidies to renewable energy technologies often claim that subsidizing renewables today accelerates their realization of cost reductions in the future on account of learning-by-doing. A number of previous studies claim to find evidence that certain renewable energy technologies are characterized by statistically and economically significant learning effects; however, these studies assume away potentially important channels of cost reductions besides learning. John's paper uses data for the U.S. wind energy industry to show the implications of the assumptions implicit in previous studies of learning in renewable energy technologies.