This paper examines the choice between subsidizing investment or output to promote socially desirable production. We exploit a natural experiment in which wind farm developers could choose an investment or output subsidy to estimate the impact of these instruments on productivity. Using regression discontinuity and matching estimators, we find that wind farms claiming the investment subsidy produced 10 to 11 percent less power than wind farms claiming the output subsidy, and that this effect reflects subsidy incentives rather than selection. The introduction of investment subsidies caused the Federal government to spend 12 percent more per unit of output from wind farms.
Aldy, Joseph, Todd Gerarden, and Richard Sweeney. "Investment versus Output Subsidies: Implications of Alternative Incentives for Wind Energy." HKS Faculty Research Working Paper Series RWP18-012, March 2018.