Polluting is Easy, Cleaning is Hard

Cleaning a heterogeneous flow environment is far from simple. We consider the flow capture problem, which has flows and sinks in a heterogeneous environment, and investigate positioning machines for CO$_2$ capture from the atmosphere. Our idealized 2-dimensional model reveals salient features of the problem. Maximum capture efficiency depends on the required capture rate: long term efficiency decreases as the number of capture units increases, whereas short term efficiency increases. If efficiency is important, the removal process should begin as early as feasible. Knowledge of transport controlling manifolds offers predictability for unit placement. Arrays of units carry a high risk of failure without accounting for environmental heterogeneity and chaos in their placement, design, and operation.