NBER Publications by David Hemous

Can directed technical change be used to combat climate change? We construct new firm-level panel data on auto industry innovation distinguishing between "dirty" (internal combustion engine) and "clean" (e.g. electric and hybrid) patents across 80 countries over several decades. We show that firms tend to innovate relatively more in clean technologies when they face higher tax-inclusive fuel prices. Furthermore, there is path dependence in the type of innovation both from aggregate spillovers and from the firm's own innovation history. Using our model we simulate the increases in carbon taxes needed to allow clean to overtake dirty technologies.

This paper introduces endogenous and directed technical change in a growth model with environmental constraints and limited resources. A unique final good is produced by combining inputs from two sectors. One of these sectors uses "dirty" machines and thus creates environmental degradation. Research can be directed to improving the technology of machines in either sector. We characterize dynamic tax policies that achieve sustainable growth or maximize intertemporal welfare, as a function of the degree of substitutability between clean and dirty inputs, environmental and resource stocks, and cross-country technological spillovers. We show that: (i) in the case where the inputs are sufficiently substitutable, sustainable long-run growth can be achieved with temporary taxation of dirty innova...

This paper evaluates whether the cyclical pattern of fiscal policy can affect growth. We first build a simple endogenous growth model where entrepreneurs can invest either in short-run projects or in long-term growth enhancing projects. Long-term projects involve a liquidity risk which credit constrained firms try to overcome by borrowing on the basis of their short-run profits. By increasing firms' market size in recessions, a countercyclical fiscal policy will boost investment in productivity-enhancing long-term projects, and the more so in sectors that rely more on external financing or which display lower asset tangibility. Second, the paper tests this prediction using Rajan and Zingales (1998)'s diff-and-diff methodology on a panel data sample of manufacturing industries across 17 OEC...