The forest and savanna are already denuded of trees, hence this study focused on grasses, weeds and leaves as a possible source of sustainable, highly renewable replacement for wood as an energy source. A study of the availability and productivity of the material across Nigeria showed that it varies from 381 g/m(2) a in Gombe, 732 g/m(2) a in Ekpoma, 610 g/m(2) a in Auchi to 1421 g/m(2) a in the Benue-Plateau forest of Jos area. The turnover rate was, however, positive across the country ranging from 0.097 to 0.130 while the annual incremental yield varied from 26 g to 402 g. (C) 2008 Published by Elsevier Ltd.