Growth dynamics of energy technologies: using historical patterns to validate low carbon scenarios

Historical growth dynamics of energy technologies reveal a consistent relationship between the extent to which a technology’s installed capacity grows and the time duration of that growth. This extent – duration relationship is remarkably consistent across both supply-side and demand-side technologies, and both old and new energy technologies. Consequently, it can be used as a means of validating future scenarios of energy technology growth under carbon constraints. This validation methodology is tested on the extents and durations of growth for a range of low carbon technologies in scenarios generated by the MESSAGE energy system model which has been widely used by the IPCC. The key finding is that low carbon technology growth in the scenarios appears generally conservative relative to what has been evidenced historically. This is counterintuitive given the extremely rapid growth rates of certain low carbon technologies under tight carbon constraints. Reasons for the apparent scenario conservatism are explored. Parametric conservatism in the underlying energy system model seems the most likely explanation.