Progrès technique et limites à la croissance
       dans le cadre d'une économie circulaire
       
          Marc Germain et Philippe Toint

This article studies the interactions between technical progress and
bio-physical limits to growth in the context of an economy with material and
energy resources, whose productivities are limited above. The economy is
circular in the sense that the waste from activity is recycled as usable
material. The energy resource is renewed by an external energy flow. Technical
progress is bounded and can be of four types, depending on whether it affects
the use or extraction of each of the two resources.
 
A developing economy begins by growing before necessarily decreasing towards a
stationary state determined by the external energy flow. In other words,
monotonous growth towards the stationary state is excluded. This equilibrium
exists provided that the ratio between the total amount of matter and the
external energy flow is sufficiently high.

The economy undergoes a profound structural change during its development, in
the sense that a significantly larger share of capital must be devoted to the
extraction of energy at the expense of the extraction/processing of matter. In
the long run, only technical progress that improves efficiency in energy ue
has a positive impact on activity, with other forms of progress having only a
transitory effect. Technical progress is especially favourable if it
simultaneously improves the use and extraction of both resources.