ESTIMATION OF ENERGY OF EUCALYPTUS PLANTATIONS FOR FUELWOOD SUPPLY TO TEA FACTORIES IN NANDI COUNTY (KENYA)

Abstract

Trees and woodlots in plantation establishments are prominent features for wood biomass. In Kenya fuelwood remains the major supplier of energy, making its contribution to total energy supply crucial. However, there is paucity of information and lack of research initiatives on the how fuelwood help in meeting household and industrial energy demands in Kenya. This study determined the biomass energy supply to Nandi Tea Factories from plantations of eucalyptus situated at Eastern Produce Kenya (EPK). Specifically, the study determined: the standing volume of eucalypts plantations of different ages at EPK, variation in proximate and calorific values as a function of age, and developed tree biomass and volume models above ground biomass equation. Four trees were randomly selected from each age group for destructive sampling to enable biomass and proximate value determination. The mean height ranged from 8 to 40 m, dbh from 7 to 25 cm while the standing volume ranged from 15.86 to 736.88 m3 ha -1 . The results revealed significant differences among age (P = 0.0001), calorific value (P = 0.0001), volatile matter (P = 0.0001), ash content (P = 0.0001), fixed carbon (P = 0.0001), desorption (P = 0.0001) and absorption (P = 0.0001). The mean ash content ranged from 0.49 to 0.97%, volatile content was 70.1 to 70.67%, desorption ranged between 0.03 to 0.09%, absorption content ranged from 0.02 to 0.09%, fixed carbon was 10.64 to 10.09% and calorific value w ranged from 18.53 to 19.57 Mj/kg. Ash varied negatively with age The mean ash content, desorption and absorption of E. grandis plantation decreased with increasing age of the trees while the volatile content, fixed carbon and calorific values increased with increasing age of the trees. Tree volume was best described by the function Tree biomass increased with volume of the forest plantation as fitted using regression. The tree biomass and volume were positively correlated with a regression coefficient (R2 ) of 0.9736. There was a sigmoid relationship between the standing volume and tree age. The recommended harvesting age should be 10 years as determined by the energy content of the trees and further research is needed to know the contribution of the soil organic components and plantation management practices in Eucalyptus plantations as they impact on the amount of biomass and hence the energy content.