Research paperCalcium oxide as an additive for both conservation and improvement of the combustion properties of energy grass: A preliminary study

- Adding CaO helps biomass (>50% moisture) conservation in storage.
- The additive increases pH and decreases mold degree.
- Additions of Ca change ash composition and transformation during combustion.
- Higher ash melting temperature and less melts quantity are resulted.

Degradation of biomass is one of the major reasons for high costs of feedstock collection, transport, and storage, which is largely associated with biomass moisture and microbial activities. Our concept is to add calcium oxide (CaO) to the biomass already when it is collected and in its natural (wet) condition. When a suitable quantity of CaO is added to moistened biomass, an alkali microenvironment will be formed with a pH exceeding 9, based on the reaction CaO + H2O ↔ Ca(OH)2. As a consequence, microbial activities are largely inhibited. The Ca(OH)2 will then successively react with CO2, following the reaction Ca(OH)2 + CO2 ↔ CaCO3 + H2O. The CaCO3 will reside in the feedstock throughout the entire production chain and end up as an additive/sorbent to improve combustion by decreasing slagging. Two experiments were conducted and proved the concept works for at least reed canary grass, but, as expected, the strength of the effect was dependent on the CaO dosage and initial biomass moisture.