Biomass energy resource enhancement: the move to modern secondary energy forms

Income growth and industrialization in developing countries is driving their economies towards the use of secondary energy forms that deliver high efficiency energy and environmentally more benignant-uses for biomass. Typical of these secondary energy forms are electricity, distributed gas systems and liquid fuels. This trend suggests that the hitherto separate pathways taken by biomass energy technology development in developing and industrialized countries will eventually share common elements. While in the United States and the European Union the majority of the bioenergy applications are in medium- and large-scale industrial uses of self-generated biomass residues, the characteristic use in developing countries is in rural cook-stoves. Increasing urbanization and investment in transportation infrastructure may allow increasing the operational scale in developing countries. One factor driving this trend is diminishing individual and household biomass resource demands as rural incomes increase and households ascend the energy ladder towards clean and efficient fuels and appliances. Scale increases and end-user separation from the biomass resource require that the biomass be converted at high efficiency into secondary energy forms that serve as energy carriers. In middle-income developing country economies such as Brazil, secondary energy transmission is increasingly in the form of gas and electricity in addition to liquid transportation fuels. Unfortunately, the biomass resource is finite, and in the face of competing food and fibre uses and land constraints, it is difficult to substantially increase the amount of biomass available. As a result, development must emphasize conversion efficiency and the applications of bioenergy. Moreover, as a consequence of economic growth, biomass resources are increasingly to be found in the secondary and tertiary waste streams of cities and industrial operations. If not used for energy production, this potential resource needs to be disposed of in some other manner owing to its negative environmental impacts. The development cycle for biomass thus moves in a stepwise fashion. The first step is the gathering of wood and agricultural residues by families for cooking, heating and lighting. Next, investments are made in anaerobic digesters, which simultaneously address energy, environmental and hygiene needs, and in efficient wood- and straw-fired stoves, which improve the indoor air environment and reduce the depletion of forests for fuelwood. The final stage is the village-scale operation of digesters and gasifiers that provide distributed gas to households and enterprises not necessarily associated with agricultural or forestry activities. At this stage, industries that process biomass into pulp, paper, lumber and sugar (from sugar cane) can move from being merely self-sufficient in process heat needs to becoming significant exporters of electrical energy into the regional and national grids. The key to all these advances is the availability of highly efficient, environmentally sound and economically viable conversion technologies. (author)