Environmental Engineering Reference
In-Depth Information
3.4.6 Poplar .......................................................................................................................... 41
3.4.7 Eucalyptus .................................................................................................................. 41
3.5 Biodiesel ................................................................................................................................. 42
3.5.1 Biodiesel Production Methods .................................................................................... 42
3.5.1.1 Catalytic Transesterfication ......................................................................... 43
3.5.1.2 Noncatalytic Transesterfication ................................................................... 43
3.5.2 Major Biodiesel Crops ................................................................................................44
3.5.2.1 Soybean ........................................................................................................44
3.5.2.2 Jatropha ........................................................................................................44
3.5.2.3 Canola .......................................................................................................... 45
3.5.2.4 Camelina ...................................................................................................... 46
3.5.2.5 Castor ........................................................................................................... 46
3.5.2.6 Oil Palm ....................................................................................................... 46
3.6 Conclusions ............................................................................................................................. 47
References ........................................................................................................................................ 47
3.1 IntroductIon
Fossil fuels (coal, petroleum, and natural gas) are neither sustainable nor ecofriendly because the
source is finite and their use cause considerable pollution. (Naik et al. 2010). There has been a dra-
matic increase in the price of oil in 2008, and more drastic price increases nicknamed “peak oil” in the
coming years are predicted (Goldemberg 2007; Potters et al. 2010). Dwindling oil reserves, less than
adequate investments into oil exploration and production, and rising demand for oil are major reasons
for the anticipated oil price increase (Lloyd's 2011). Most greenhouse gas emissions are the result of
electricity production and heating (27%) using fossil fuels. Other causes of greenhouse gas emissions
include land use/change and forestry (18%), agriculture (13%), other energy sectors (13%), transportation
(12%), manufacturing and construction (11%), and industrial process (3%) (World Resource Institute
2011). The concerns about dwindling fossil fuel reserves and oil price increases, and the relationship
between fossil fuels and global climate change have generated great interest in bioenergy/biofuels.
Unlike fossil fuels, biofuels are renewable because they can be grown repeatedly. Also, biofuels
are carbon neutral and essentially reduce the carbon emissions (Naik et al. 2010). Using biofuels to
produce bioenergy is one part of the solution to curb global climate change and allow the United
States to become energy independent.
Bioenergy is broadly defined as renewable energy derived from biological materials that are
used to produce heat, generate electricity, and provide energy for transportation (Yuan et al.
2008). Generally, biofuels are broadly categorized into four categories—first-generation, second-
generation, third-generation, and fourth-generation biofuels—depending on the type of feedstock
being used. First-generation biofuels are based primarily on corn and soybean and other edible food
crops that compete for agricultural croplands, natural fresh water resources, and fertilizers. These
fuels are used primarily as small blends, and the energy input and output ratios do not meet the
large-scale commercial use. Second-generation biofuels are derived from cellulosic biomass (e.g.,
miscanthus, switchgrass, sweet sorghum). Biofuels derived from nonedible plant resources are also
considered to be second-generation biofuels. Algae are the source of third-generation biofuels, but
fourth-generation biofuels are chemically created with the help of petroleum-like hydroprocessing
and revolutionary processes such as Joule's “solar-to-fuel” method (Zarrilli 2007; Yuan et al. 2008).
Biodiesel is derived from animal fat and vegetable oil (Jena et al. 2010).
Biomass is a general term used to describe materials of biological origin, including all living
matter derived from plants and animals. Energy from biomass is gained from several sources, such
as wood, grasses, and animal materials (Babu 2008). Traditionally, biomass is similar to fossil fuels
in that it is burned to heat water or produce steam and generate electricity. There are four categories
