In 1995, according to the International Energy Agency, IEA, world biomass energy consumption was 930 million tonnes of oil equivalent, Mtoe, which represents 14% of final energy consumption. Until the end of the 19th century, biomass was the main source of energy in the world and, if since then its share in final consumption has decreased, it still represents today more than coal and a figure equivalent to the natural gas.
The recent increase in the use of biomass for energy purposes is mainly due to population growth in developing countries and increased consumption in industrialized countries. Other causes are: a stable per capita rate; a gradual move away from more primitive forms of energy use, such as the use of dung and straw for cooking, increasing energy efficiency through, for example, more efficient stoves; and a renewed interest in traditional and modern uses of biomass due to population growth, technological advances and environmental concerns.
The relative importance of biomass energy varies considerably between rich and poor countries. In the industrialized countries, in the former Eastern bloc and in the Middle East, it provides only 2 to 3% of total energy, while in Africa, Asia and Latin America it represents a third of energy consumption.
90% of biomass energy consumption takes place in developing countries. In some of the world’s poorest countries, biomass represents between 80 and 90% of energy consumption. For 2 billion people, biomass is the main source of energy for domestic use. It also meets the energy needs of many traditional and agricultural industries such as bread making, textiles, tobacco and tea drying, fish smoking and brick making.
The remaining 10% of biomass consumption in the industrialized world represents 3% of the world’s energy in this region, mainly firewood for domestic use and the production of electricity and heat in industry. In the United States, it represents 4%; in Austria, Sweden and Finland, 12, 18 and 23% respectively. In Western Europe, it covers 3% of energy consumption, and the European Union wants to reach 8.5% by 2010.
In developing countries, poor populations’ dependence on biomass forces women and children to spend several hours a day collecting firewood. Biomass cooking is very polluting, as suspended particles, carbon monoxide, methane and organic compounds are emitted. Prolonged exposure causes respiratory diseases, lung cancer and blindness, and may endanger pregnancies. These risks can be reduced by improving ventilation, introducing more efficient stoves, using cleaner fuels, raising awareness of the health risks of biomass burning and centralizing treatment facilities.
Interest in biomass energy enhancement is evident in developing countries’ efforts to increase conversion to liquid and gaseous fuels and through cogeneration of heat and power. Examples include the use of ethanol from sugarcane residues in Brazil, the use of solid residues and manure in biogas digesters in India and China, and cogeneration with sugarcane bagasse. in Brazil, India, Thailand and Mauritius.
Recent concerns have focused on the potential ecological impact of energy crops and forest plantations, such as loss of biodiversity, loss of soil nutrients, erosion and water pollution. This is why regulations have been developed to reduce the impact of biomass in many Western countries.
However, it is recognized that the environmental impact caused by biomass is less than that produced by fossil fuels, and that energy crops can be managed to be much less harmful than intensive agriculture. Currently, the traditional view of biomass as an unconventional form of energy, a precursor to fossil fuels, is changing.
The future of biomass in the global energy supply is uncertain; while some predict that their percentage will be between 14 and 22% in 2060, the Intergovernmental Panel on Climate Change predicts 25 to 46% for 2100.
Although its global use is likely to increase, biomass energy faces two ecological problems: high water consumption and low photosynthesis efficiency. This limits biomass production to regions with sufficient rainfall and competes with other land uses such as food production, carbon sequestration and habitat protection.
In Spain, an increase in biomass consumption of 6 million toe is expected over the period 1999-2010. Of these, more than 5 million will be used for electricity generation and just under a million for thermal applications. Electricity produced by biomass comes from autogenerators.
The Institute for Energy Diversification and Conservation, IDEA, assesses potential resources at 16.1 million toe, broken down as follows:
- Energy crops: estimated at 5.7 million toe for 10% of available surfaces and according to minimum grouping criteria. Its potential is divided into 4 million toe of major rainfed energy crops and 1.7 million toe of irrigated poplar whose economic viability is more uncertain.
- Residual biomass: evaluated at 10.4 million toe, divided into 1.4 million toe of forest residues under favorable economic operating conditions, 1 million toe of ligneous agricultural residues, such as olive stalk or corn .
The power objective to be installed in the new urban solid waste recovery plants is 168 MW. For biogas, the target set by the Renewable Energies Promotion Plan is estimated at an additional 78 MW. In addition, the plan contemplates an important area of new development. It is expected that in 2010, Spanish vehicles will consume 500 ktoe of bioethanol.