Page 63 - Biofuels Refining and Performance

46 Chapter Two

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, bio-
mass 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 sup-
plies 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 bio-
mass 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 con-
sumed. 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 sig-
nificant portion of energy used [1]. The survey also reveales that biomass
and biofuels are the top two in terms of employment that they gener-
ate. Burning new biomass does not contribute to new CO into the
2
atmosphere as replanting harvested biomass ensures that CO is
2
absorbed and returned for a cycle of new growth [2].

2.2 Mechanism and Efficiency
of Photosynthesis in Plants
In photosynthesis, CO from the atmosphere and water from the earth
2
combine to produce carbohydrates, which are the components of bio-
mass and solar energy that drive this process. When biomass is effi-
ciently utilized, the oxygen from the atmosphere combines with the
carbon in plants to produce CO and water (see Fig. 2.1). Typically, pho-
2
tosynthesis converts less than 1% of the available sunlight to be stored
as chemical energy.
The advantages of using plants for renewable energies (fuels and
chemicals) are listed follows:

Advances in agriculture and forestry technologies have resulted in
increased utilization of land resources for cultivation of energy crops.
By increasing harvesting of solar energy, there is effective usage of
biomass-based resources.