Modelling sustainability of primary forest residues-based bioenergy system

Lack of access to modern energy, such as electricity, liquid fuels and gas, limits socio-economic development in developing countries, particularly in rural communities. Primary forest residues are potential bioresources for producing modern forms of energy beyond traditional biomass, which can be supplied to economic activities in the rural communities. However, variations in production of primary forest residues over time exacerbate sustainability challenges for developing sustainable bioenergy systems based on the residues supply chains integrated with timber production. A model is presented showing dynamics of primary forest residues, as bioenergy feedstocks, stemming from forest plantations management, harvesting systems, and stakeholder influence and interest along the bioenergy production value chain. Using a case study of the Viphya forest plantations established for timber production in Malawi, management and harvesting systems, sawmilling technologies, residues production and post harvesting management were assessed and key sustainability challenges along the residues supply chain have been identified. The decreasing stocks of mature stand over time results from over-exploitation for timber production, delayed replanting, high death rate of replanted trees and underinvestment in plantations management. An integrated framework for forest management and bioenergy production can promote sustainable harvesting of mature stand for timber and primary forest residues production through synchronization of harvesting and replanting of timber and establishment of thresholds for harvesting timber to generate residues at a rate that can match with the scale and rate of the bioenergy conversion. The framework can promote stability, availability and reliability of timber and primary forest residues supply for bioenergy production.