Thallada Bhaskar*, Balagurumurthy Bhavya,

Rawel Singh, Desavath Viswanath Naik, Ajay Kumar,

Hari Bhagwan Goyal

Bio-Fuels division (BFD), Indian Institute of Petroleum (IIP),

Council of Scientific and Industrial Research (CSIR), Dehradun 248005, India
*Corresponding author: Thallada Bhaskar; E-mail: tbhaskar@iip. res. in; thalladab@yahoo. com

1 INTRODUCTION

The demand for energy sources to satiate human energy consumption continues to increase. Currently, the main energy source in the world is fossil fuels. Although it is not known how much fossil fuel is still available, it is generally accepted that it is being depleted and is nonrenewable. Prior to the use of fossil fuels, biomass was the primary source of energy for heat via combustion. With the introduction of fossil fuels in the forms of coal, petroleum, and natural gas, the world increasingly became dependent on these fossil fuel sources. Renewable energy is of growing importance in responding to concerns over the environment and the security of energy supplies. Given these circumstances, searching for other renewable forms of energy sources is reasonable. Other important consequences associated with fossil fuel uses include global warming. Also, fossil fuel resources are not distributed evenly around the globe, which makes many countries heavily dependent on imports.

Governments across the world are stimulating the utilization of renewable energies and resources such as solar, wind, hydroelectricity, and biomass. The three major forces that drive them are (i) secured access to energy; (ii) threat of climate change; (iii) develop/maintain agricultural activities (Lange, 2007). Agricultural economies could be supported by promot­ing the exploitation of local (bio) resources for food, energy, and material. Interestingly, each of these major drivers also represents one of the three dimensions of sustainability, namely, profitability (affordable energy), planet (climate change), and people (social stability).

Current use of fossil fuels is split, with about three-quarters for heat and power generation, about one-quarter for transportation fuel, and just a few percent for chemicals and materials (US Department of energy, 2006). The heat and power sector can be supplied with a variety of renewable sources, namely wind, solar, hydropower, and biomass. The transportation sector has a much more limited choice, however. At this time, biomass is the only resource that can provide renewable liquid fuels. Apart from the transportation sector, biomass is also a promising feedstock for the chemical industry due to the presence of a wide range of functionalities available with biomass, the natural polymer.

Biomass is unique in providing the only renewable source of fixed carbon, which is an essen­tial ingredient in meeting many of our fuel and consumer goods requirements. Wood and annual crops and agricultural and forestry residues are some of the main renewable energy resources available (Bridgewater, 2006). Biofuel production has been growing rapidly in recent years.

Biomass, a renewable energy source, via photosynthesis, has provided energy for life for the longest period of existence. Industrial processes that take in biomass can be integrated with the natural photosynthesis/respiration cycle of vegetation. If used in this manner, biomass is a renewable energy source and by its utilization, much less CO2 is added overall to the atmosphere compared with the fossil fuel counterpart processes. When combined with CO2 sequestration, biomass-based processes can actually lower the CO2 concentrated in the atmosphere (Van swaaij et al., 2004). Lignocellulosic biomass, which is not competing with the food chain, should be used for the production of fuels, chemicals, power, and heat. This competition can be avoided by first using the abundant residues from forests, agriculture, and subsequently energy crops. The potential of special energy crops is estimated to be in the range of 50-250 EJ/annum (Berndes et al., 2003).

Biomass combines solar energy and carbon dioxide into chemical energy in the form of carbohydrates via photosynthesis. The use of biomass as a fuel is a carbon neutral process since the carbon dioxide captured during photosynthesis is released during its combustion. Biomass includes agricultural and forestry residues, wood, byproducts from processing of biological materials, and organic parts of municipal and sludge wastes. Photosynthesis by plants captures around 4000 EJ/year in the form of energy in biomass and food (Kumar et al., 2009a).

The most important factor is that all fossil fuels are taken out from under the earth’s surface, and its continuous excavation creates many geothermal disturbances. Biomass is grown and consumed only over the earth’s surface and hence does not create such problems.

The events of the last few years have brought into sharp focus the need to develop sustainable green technologies for many of our most basic manufacturing and energy needs. Since the beginning of the new millennium, we have witnessed an ever-increasing merger of technical, economic, and societal demands for sustainable technologies. As such, this seeks to develop a new "carbohydrate-lignin economy" that will initially supplement today’s petroleum economy and, as these nonrenewable resources are consumed, will become the primary resource for fuels, chemicals, and materials (Yunqiao et al., 2008).