Ahindra Nag and P. Manchikanti

2.1 Introduction

Renewable energy is an energy resource naturally regenerated over a short time scale derived from the sun (such as thermal, photochemical, and photoelectric) or from other natural environment effects (geothermal and tidal energy). It is forecasted that approximately half of the total resources in the world will be exhausted by 2025. This survey has also revealed that global warming and climate change are serious issues that need immediate action. The use of fossil fuels (coal, oil, gas, etc.) con­tributes significantly to global warming and climate change [1]. Worldwide there is strong support for renewable energy, as proven by a number of surveys [1, 2]. In 2003, a European Commission survey across the 15 European Union (EU) countries showed that 69% of the citizens supported more renewable energy-related research, compared to 13% for gas, 10% for nuclear fission, 6% for oil, and 5% for coal. Understandably, due to the inherent recycling nature as well as environmental benefits involved, renewable sources of energy are the solution for energy man­agement. There is an increased investment globally in such technologies for not only enhancing the preservation of biological resources but also for increasing energy efficiency and pollution control [1].

Biomass is one such renewable source of energy. Out of the 1.1 X 1020 kW heat generated every second by the sun, only 47% (~7 X 1017 kWh) reaches the earth’s surface. Solar energy is utilized by conversion to dif­ferent energy forms such as biomass, wind, or hydropower. Green plants are only able to effectively use visible light of wavelength falling between [7]

400 and 700 nm. This photosynthetically active radiation constitutes about 43% of the total incident solar radiation to produce biomass. Biomass energy generally involves the utilization of energy contents of such items as agricultural residues (pulp derived from sugarcane, corn fiber, rice straw and hulls, and paper trash) and energy crops. So, bio­mass is a comprehensive term that includes essential forms of matter derived from photosynthesis or ultimately available as animal waste [2]. The production of energy from plants is not a new idea; wood burning has been in common use since ancient times. About one-seventh of the energy used around the world is derived from firewood. Biomass sup­plies 14% of the world’s primary energy consumption and is considered to be one of the important renewable resources of the future. With the increase in population and the demand for resources, demand for bio­mass is expected to increase rapidly. On average, 38% of the primary energy resources in developing countries is biomass. In the United States alone, biomass sources provide about 3% of all the energy con­sumed. In terms of energy efficiency measures and stabilization of energy consumption between 2010 and 2020, the European Renewable Energy Council (EREC) survey estimates that among the various types of renewable energy resources, biomass-derived energy will be a sig­nificant portion of energy used [1]. The survey also reveales that biomass and biofuels are the top two in terms of employment that they gener­ate. Burning new biomass does not contribute to new CO2 into the atmosphere as replanting harvested biomass ensures that CO2 is absorbed and returned for a cycle of new growth [2].