Energy transition under irreversibility: a two-sector approach

In this paper, we analyze the optimal energy transition of a two-sector economy (energy and final goods) with exhaustible oil reserves, a renewable source of energy and a pollution threat. The latter corresponds to a pollution threshold above which a part of the capital is lost (following flooding for instance). Part of the energy is used as energy services by a representative consumer through a CRRA utility function and the other part is used as input in a Leontief production function to produce final goods. Moreover, we assume that both energy sources are complementary. We use the optimality conditions as in Boucekkine et al. (2013) to show that the optimal energy transition path may correspond to a corner regime in which the economy starts using both resources, then crosses the pollution threshold and therefore loses a part of its capital. At the end, the economy never adopts only renewable energy. This result is in line with the asymptotic energy transition arguments stating that the transition to "clean" energy may happen only in the long run. We extend the present model to allow for additional investment in energy saving technologies. Our main results show that this additional investment favours the energy transition in the sense that it increases the time within which the economy may experience the catastrophe and the welfare of the society. For policy implications, economic instruments such as taxes on "dirty" energy, subsidies on "clean" energy or incentives for energy saving technologies need to be implemented in order to promote the energy transition. But those economic instruments should be carefully designed in line with the asymptotic energy transition result.