  Pelletization of the loose rice straw is an attractive option to produce
renewable fuels. In this paper, we focus on the problem of how to improve this
pelletization process, especially to reduce energy consumption and improve
product quality. In detail, we first pretreat rice straw, and then investigate
the densification characteristics of the pretreated materials. Pretreatment
methods of the materials include hydrothermal treatment and adding a certain
proportion of economic additives, such as rapeseed meal and waste engine oil
respectively. In addition, the pretreated rice straw was pelletized by using a
biomass densification platform, meanwhile energy consumption and pellet quality
were tested. Experimental results indicate that the hydrothermal pretreatment
played an important role in reducing energy consumption and improving the
product quality, and waste engine oil has a better effect than the rapeseed
meal. We also observe that the obtained pellet quality reaches the standard of
middle-grade coal, and the proposed pretreatment method realizes the
comprehensive utilization of waste agricultural resources.
