  This paper studies a model for the optimal control (by a centralized economic
agent which we call the planner) of pollution diffusion over time and space.
The controls are the investments in production and depollution and the goal is
to maximize an intertemporal utility function. The main novelty is the fact
that the spatial component has a network structure. Moreover, in such a
time-space setting we also analyze the trade-off between the use of green or
non-green technologies: this also seems to be a novelty in such a setting.
Extending methods of previous papers, we can solve explicitly the problem in
the case of linear costs of pollution.
