Lab-scale co-firing of virgin and torrefied bamboo species Guadua angustifolia Kunth as a fuel substitute in coal fired power plants

Abstract

Bamboo is a potential sustainable biomass source for renewable heat and power production as it presents common fuel characteristics with other biomass feedstocks regarding heating value and chemical composition. This paper presents an evaluation of the combustion behaviour of the bamboo species Guadua angustifolia Kunth, virgin as well as torrefied, in blends with coal or pure, comparing with other biomass feedstocks such as wood and herbaceous biomass. The bamboo pre-treatment and the combustion experiments were carried out at dedicated installations at ECN, including a laboratory scale batch torrefaction reactor and a combustion simulation test facility. The results on combustion and co-firing reveal that in terms of fouling, the untreated bamboo shows behaviour closer to herbaceous biomass rather than to wood, with specific fouling factors of wood, bamboo and herbaceous biomass of 0.91·10−3, 2.9·10−3, 3.1·10−3 K·m2·W−1·g−1 respectively. Dry torrefaction improves its physical properties by increasing the density and grindability without improving significantly its fouling behaviour while the fouling behaviour of wet torrefied bamboo is similar to woody biomass; the specific fouling factors of dry torrefied and wet torrefied bamboo are 2.4·10−3 and 0.89·10−3 K·m2·W−1·g−1 respectively. The fouling behaviour of biomass and coal blends lies between the fuels of the blend. Alternative bamboo species were evaluated using the alkali index Ai based on their fuel composition. It appears that the fouling behaviour of alternative species is better than for G. angustifolia, therefore these should be further analysed.