RENEWABLE ENERGY

Energy is an important currency for human society. The world population growth and rapid economic pro­gresses are expected to result in considerable increase in the demand for energy. In the reference scenario, the International Energy Agency has projected an increase in energy need by 55%, between 2005 and 2030, at an average annual rate of 1.8% (IEA, 2007). Driven by such increasing demand, and the dwindling fuel production, the cost of petroleum fuel has gone up sky high in recent times, which can jeopardize the eco­nomic progresses of a nation. Despite the fuel crisis, increasing concentrations of CO2 and other heat­trapping greenhouse gases (GHGs) in the atmosphere, primarily due to the combustion of fossil fuels, is clearly the prime reason for rapid warming of the
planet (Shay, 1993). The use of renewable energy is largely motivated from the standpoint of global energy crisis and environmental issues. Renewable energy is a form of energy that is produced from natural sources like sunlight, wind, hydropower, geothermal and biomass, which can be naturally replenished. Currently, renewable energy supplies only ~18% of the world’s energy consumption (Kumar et al., 2010). Most of these renewable energy sources (hydropower, wind, solar and geothermal) target the electricity market, while the majority of world energy consumption (about two-thirds) is derived from liquid fuels (Campbell, 2008; Hankamer et al., 2007). This has stimulated recent interest to explore alternative sources for petroleum — based fuels and much of the attention has been focused on biomass-derived liquid fuels or biofuels (Haag, 2007; Schneider, 2006).

Bioenergy Research: Advances and Applications http://dx. doi. org/10.1016/B978-0-444-59561-4.00011-5