The impact of learning-by-doing on the timing and costs of CO2 abatement

A particular ceiling on atmospheric CO2 concentrations can be maintained through a variety of emission pathways. Over the past decade, there has been considerable debate over the characteristics of a least-cost pathway. Some have suggested that a gradual departure from the emissions baseline will be the most cost-effective because it reduces the pressure for premature retirement of the existing capital stock, and it provides valuable time to develop low-cost, low-carbon-emitting substitutes. Others counter that a major flaw in analyses that support this line of reasoning is that they ignore learning-by-doing (LBD). In this paper, we examine the impact of LBD on the timing and costs of emissions abatement. With regard to timing, we find that including learning-by-doing does not significantly alter the conclusions of previous studies that treated technology cost as exogenous. The analysis supports the earlier conclusion that for a wide range of stabilization ceilings, a gradual transition away from the "no policy" emissions baseline is preferable to one that requires substantial near-term reductions. We find that the major impact of including learning-by-doing is on the costs of emission abatement. Depending upon the sensitivity of costs to cumulative experience, LBD can substantially reduce the overall costs of emissions abatement. (C) 2004 Published by Elsevier B.V.