The importance of crushers in the mining industry declined with the introduction and resultant dominance of AG and SAG based circuits, but the recent move to consider more energy efficient circuits has caused the industry to re-consider the role of crushers. Different types of comminution equipment have different efficiency in the way the energy is applied in the size reduction process. Because of the general trend towards more sustainable production processes and emission of carbon dioxide, energy use has become more important. To fully understand how crushers can contribute to optimising the energy application in comminution circuits, detailed models of process performance are required. Such models need to take into account the mechanical design factors and how the crusher performance changes in response to feed conditions, the control strategy utilised and the wear of the crusher liners. It is also critical to analyse the total circuit, not just the individual crushers. To fully understand the performance of the entire circuit, dynamic simulation should be applied. Without the holistic understanding of the total circuit and the incorporation of transient effects, the full circuit performance cannot be adequately determined and the true energy picture will not be quantified. Based on detailed mechanistic modelling of crushers by the authors and the application of dynamic simulation, the opportunities to optimise the use of crushers for energy efficiency are examined.