Energy resources will play an important role in the world's future. Rural bioenergy is still the predominant form of energy used by people in the less developed countries, and bioenergy from biomass accounts for about 15% of the world's primary energy consumption and about 38% of the primary energy consumption in developing countries. Furthermore, bioenergy often accounts for more than 90% of the total rural energy supplies in some developing countries. Earth life in rural areas of the world has changed dramatically over time. Industrial development in developing countries, coming at a time of low cost plentiful oil supplies, has resulted in greater reliance on the source of rural bioenergy than is true in the developed countries. In developed countries, there is a growing trend towards employing modern technologies and efficient bioenergy conversion using a range of biofuels, which are becoming cost wise competitive with fossil fuels. Currently, much attention has been a major focus on renewable alternatives in the developing countries. Renewable energy can be particularly appropriate for developing countries. In rural areas, particularly in remote locations, transmission and distribution of energy generated from fossil fuels can be difficult and expensive. Producing renewable energy locally can offer a viable alternative. Renewable energy can facilitate economic and social development in communities but only if the projects are intelligently designed and carefully planned with local input and cooperation. Particularly in poor rural areas, the costs of renewable energy projects will absorb a significant part of participants' small incomes. Bio-fuels are important because they replace petroleum fuels. Biomass and biofuels can be used as a substitute for fossil fuels to generate heat, power and/or chemicals. Generally speaking, biofuels are generally considered as offering many benefits, including sustainability, reduction of greenhouse gas emissions, regional development, social structure and agriculture and security of supply. (C) 2007 Elsevier Ltd. All rights reserved.