**4. Conclusion and future perspectives**

Weed biomass is a promising feedstock for economic bioethanol production. The abundance of weed biomass worldwide is an assurance of its sustainability as a feedstock. Current research on the conversion of weed biomass to bioethanol is focused on pretreatment techniques. Different pretreatment techniques have been explored to convert weed biomass into bioethanol. Maximum bioethanol yields have been reported after fermentation of hydrolyzates from pretreated weed biomass. However, current technologies are still inadequate for bioethanol production from weed biomass to compete with starch and sugar based bioethanol in terms of production yield and cost. Production of cellulosic bioethanol from weedy plants is only at the laboratory scale. Further research to establish cost effective and efficient conversion processes including pretreatment technique(s) for a wide range of weed biomass is needed. Predictive models will also aid in the selection, design, optimization, and process control pretreatment technologies that match biomass feedstock with appropriate method and process configuration. On the other hand, active research is going on to ensure commercial production of bioethanol from weed biomass. This includes improvements in pretreatment technologies, specific activities of enzymes as well as isolation of new fermentation microorganism from natural environment. With strong support from various governments, bioethanol production from weed biomass will play a major role in meeting energy demand globally.
