ABSTRACT
The point of considering plant scale is to get some understanding of just how big an anaerobic digestion (AD) plant is; also to consider how big, or small, it has to be or can be. In most EU countries plant scale categories follow a similar pattern, fairly broad bands that consider maximum electrical output alone. The chapter considers how to determine what scale is going to be right for any potential situation, the issues that will affect the decision, and the implications of that choice. The decision can often be dictated by one of two things: the feedstock available and the ambition of the owner. To address the issue of scale in a more controlled, more graduated way, some modular systems are now being developed. These are systems that can grow as the needs of the owner grow. They tend to be specialist systems in that they are designed to deal with a specific feedstock.
