Page 64 - Biofuels Refining and Performance

Photosynthetic Plants as Renewable Energy Sources 47

Carbon reintroduced
Sun in atmosphere

Atmospheric CO 2

Refineries
Trees
Trees

Sequestered carbon petroleum, natural gas

Figure 2.1 Simplified carbon cycle.

Multiple economic benefits can be derived—for example, sugar can be
used as such for fermentation to alcohol—depending on the market.
Biomass combustion, unlike fossil fuels, does not contribute to
increased CO levels in the atmosphere [2].
2
Increased employment opportunities resulting from the above.

While the advantages of using biomass-based energies are apparent, it
is important to note that biomass cannot by itself provide complete replace-
ment of fossil fuels. Hence, it is one of the solutions toward achieving energy
efficiency. Further factors, such as competition for biomass between energy
production and human nutritional needs, as well as the possible environ-
mental effects, must be kept in mind. There are several factors that should
be considered in using plants for the generation of energy; efficiency of
solar energy absorption and conversion, quality of biomass produced, plant
growth, growth under marginal conditions, soil characteristics, and cost-
effectiveness of production of energy and conversion. We will focus on the
utilization of terrestrial plants for production of renewable energies.

2.3 Photosynthetic Process
There are essentially two types of reactions in photosynthesis: a series of
light-dependent reactions that are temperature independent (or light
reaction) and a series of temperature-dependent reactions that are light