This article addresses particle size reduction technologies currently available and their potential application in bioenergy production from waste biomass. It is believed the reduction of the particle size of biomass wastes to nano-scale will have a significant impact on the quality, quantity, and price of biofuels. Currently, these technologies have not been developed for commercial application due to lack of efficiency. They can only function on small scale operations with high energy consumption. Advancing particle size reduction technologies to produce nano-scale particles at a commercial level is an emerging need.