Bioenergy is the dominant source of energy for most of the world’s population who are living in extreme poverty and use this energy mainly for cooking. They have limited access to other forms of energy such as electricity or liquid fuels. These traditional uses of biomass for energy use, in particular the residues of agriculture and forestry, are linked to negative impacts on health through indoor air pollution from unvented cooking stoves.
A different kind of bioenergy is now taking prominence based on cash crops and plantations and using technologically advanced processing of biomass into biofuels. Bioenergy is seen as part of the solution to climate change, as a renewable source of energy, as well as providing income and employment opportunities for rural populations.Bioenergy has emerged as a key factor in both development and environment.
At the same time, it has become apparent that the sustainable use of bioenergy requires balancing many factors, including the possible competition between food security and energy security, the competing uses of water resources, effects on rural development, agricultural markets and food prices, as well as the impacts on the environment, biodiversity and others. This has to be done at the local, the national and the international levels, based on proper information and understanding. Knowledge management, mobilization and implementation at country level are central pillars of such an approach.
FAO's International Bioenergy Platform as well as its support to the Global Bioenergy Partnership for which it hosts the secretariat and the involvement in the Bioenergy Wiki are some of the mechanism put in place to ensure that that key partners, stakeholders and interest groups work to ensure that food security, energy security, rural development and mitigation of climate change are not mutually exclusive targets. These issues are further elaborated in the section Key issues
The two graphs below show how, at present, bioenergy is mainly used in developing countries, the traditional use of bioenergy. A situation that is likely to change rapidly with the increased popularity of biofuels
Share of bioenergy in total primary energy supply in |
different world regions in 2004 (Source: IEA 2006)
Share of bioenergy in total energy supply |
(Source: FAO, 2000; Hall et al., 2000)
Biogas is the gas produced from biomass by anaerobic digestion, a biochemical process where organic matter is converted into methane (CH4). Three types of bacteria (fermentative, acetogenic and methanogenic) participate in the pathways from which carbon dioxide to methane are produced, usually at temperatures between 35 and 55°C in periods varying from 10 to 20 days. Handling and disposal (usually as organic fertilizer) of the slurry is part of the process, as is the storage and distribution of the produced gas.
Bioethanol is derived from the fermentation of mainly sugar and starch crops and, in the future, from cellulosic materials. Depending on agro-ecological and socio-economic context, sugar beet, sugar cane, sweet sorghum are currently the most common sugar crops, with maize, potatoes and cereals the most common starch crops. The breakeven point for Brazilian bioethanol is estimated to be around 35 US$/barrel of oil
Biodiesel is produced through transesterification of plant oil (which can also be used directly depending on engine configurations). The derived ethyl or methyl esters can used as a pure biodiesel or be blended with conventional diesel. Biodiesel can be made from all plant oils, and is so far derived principally from canola (rapeseed), palm or soybean oils, animal fats, waste vegetable oils, or micro-algae oils.
Second-generation biofuels The use of “next-generation” cellulosic biomass feedstock has the potential to dramatically expand the resource base for producing biofuels in the future. So far, however, the costs of producing liquid fuels from cellulosic biomass are not competitive with petroleum-derived fuels, even with the recent rise in petroleum costs. Various government and industry-sponsored efforts are under way to lower the costs of making liquid fuel from cellulosic biomass by improving the conversion technologies.
The economic competitiveness of biofuels and the development of the conversion pathways, will depend on the future price of petroleum. Since these conversion technologies are close to being viable, their deployment is important so that operators can streamline new facilities. Government incentives such as loan guarantees and guaranteed markets for new cellulosic biofuel production facilities can play an important role in the early stages of the second generation of biofuels.