Canada generates approximately 1.45 x 10(8) t of residual biomass per year, containing an estimated energy value of 2.28 x 10(9) GJ, which is equivalent to about 22% of Canada's current annual energy use. Anaerobic digestion of these biomass residues using conventional technologies could generate 1.14 x 10(10) m(3)/year of CH4 with a heating value of 4.56 x 10(8) GJ. Conversion of these residues using emerging technologies that favor the synthesis of H-2 and represses the synthesis of CH4 could generate 1.47 x 10(10) m(3)/year renewable H-2, with a heating value of 1.89 x 10(8) GJ. While CH4-production results in a larger amount of energy recovery, generating H-2 from waste biomass is a renewable alternative that could fuel the hydrogen economy. Additional research to further both the technical and commercial development of microbial bio-energy from biomass is warranted. (c) 2006 Elsevier Ltd. All rights reserved.