Densification of corncobs using algae as a binder

Abstract

Corn residues are abundantly available, but utilizing this potential biomass energy source is limited by their low density and non-uniform physical characteristics. Densification may be used to solve this problem. Many studies have used high temperature and pressure to compress biomass materials into pellets, as well as expensive additives to produce high-quality pellets. In this study, we investigated whether moderate temperature and pressure with a binding agent from an inexpensive and environmentally friendly source offers an alternative solution. We used locally available algae (Spirogyra sp. and Chara sp.) as a binding agent for densification of corncobs and studied the effects of pressure (100-200 MPa) and algae-to-biomass ratio (10-40% w/w), at a fixed die temperature of 30°C, on pellet characteristics. We found that algae can be successfully used as binder for densification of biomass. Using the algae at 20% w/w or less with an applied pressure of 150-200 MPa improved the relaxed density of the pellets by 250-285%, higher than the bulk density of the original corncobs before compaction, with energy density of 12-14 GJ/m3.