What does “cascade use” mean?

Cascading is a way to maximise the resource efficiency of biomass through double use of the raw materials, specifically material use in the first step and energy use in the second step. This means, agricultural areas that currently serve to grow energy crops for bioenergy could at first be used to grow raw materials for bioplastics. Products made from these bio-materials could then, at the end of their life cycle, be treated for energy recovery.