Worldwide sources of biomass

One of the problems with biomass is the question of whether there is sufficient bio­mass to replace fossil fuels and can it be transported to where it is used. It has been estimated that biomass contributes 39.7-45 EJ/year to the global energy supply (9-15%) from a total 425 EJ (Parikka, 2004; Faaij, 2006). There have been a number of estimates of the biomass available globally and the range of estimates is given in Table 4.5. These estimates vary considerably from 1135 to 93 EJ. A potential of 100 EJ would supply around 25% of the present global energy requirement. Smeets and Faaij (2007) estimate that there may be a surplus of biomass, after directly used woodfuel and roundwood have been utilized, of 71 EJ but this may be an underesti­mate. Considering ecological and technical considerations the biomass may be only 2.4 Gm3 (28 EJ). The potential global biomass energy contained in various biomass types is given in Table 4.6. The great variation noted by Hoogwijk et al. (2003) appears to be in the estimate of the biomass grown on surplus or marginal land. Marginal lands are those with little economic value but before these can be used the environmental impacts need to be determined. The marginal land may be a specific wildlife habitat such as a wetland or forest.

The potential biomass energy consisting of wood, energy crops and straw in the various regions is given in Table 4.7, where the total is given as 103.8 EJ. All regions except Asia use only a small proportion of the available energy.