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1. DEBRE MARKOS UNIVERSIY
COLLEGE OF NATURAL AND COMPUTATIONAL SCIENCE
DEPARTMENT OF BIOTECHNOLOGY
BIO ENERGY CROP PLANTS

2. Abstract
Bioenergy is a renewable source of energy that is produced from plants and animals.
Unlike bioenergy, fossil fuels, such as crude oil and coal, are not renewable. Because
they are created over thousands to millions of years, fossil fuels are limited. Some
forms of bioenergy have been around for a long time. Examples include burning
wood to create heat, using biodiesel and ethanol to fuel vehicles, and using methane
gas and wood to generate electricity. More recently, developed forms of bioenergy
use materials called “biomass,” such as sugar cane, grasses, straw, soybeans, and
corn. Biomass is any plant or animal matter that uses sunlight to store energy. Plants
do this through photosynthesis. Animal waste, which is comprised mainly of plant
material, is also biomass. Bioenergy crop plants that function as solar energy
collectors and thermo-chemical energy storage systems are the basis for biological
systems that are expected to contribute to renewable energy production, help stabilize
the rising levels of green house gases (GHG), and mitigate the risk of global climate
change (GCC). Wide genetic resource bases, especially of wild and semi-
domesticated perennial grasses and woody species of starch-, oil, and lingocellulose-
producing plants, are available to select, breed, genetically-modify, and develop
environmentally-friendly bioenergy crops. Plant species, They contribute to the
reduction of greenhouse gas emissions and thus the slowing of climate change and its
negative impacts. Bioenergy can be used to produce fuel for the transport sector or
through biomass combustion to produce heat and/or power. With rising energy costs
and uncertainty of fossil fuel reserves, it’s important to oversee cheaper, safer, and
more renewable forms of bio-energy. As a supplemental alternative energy to coal,
bio-energy crops could play an important role as environmentally safe .
Introduction
Bioenergy is defined as a renewable energy that is manufactured from biomass.
Organic materials such as trees,plants and waste materials come under the broad
area of biomass. Bioenergy has received a great interest during the recent
times because of rapid growth of fuel prices, fast fossil fuel depletion,environmental
degradation by fossil fuel and an alteration in global climate. A feedstock refers to a

3. material that serves as the basis for manufacturing another product. For the
production of bioenergy,biomass feedstocks serve as key inputs. Biomass feedstocks
can be made available from various sources such as agricultural or energy
crops,waste fuels, etc. These biomass feed stocks serve as the source of organic
matter (Yuan et al., 2008; Zych,2008; Chum et al., 2011)
Bioenergy development is intended, in part, to offset greenhouse gas (GHG)
emissions to the atmosphere, but analyses of the GHG balances of bioenergy crops
have concluded vastly different magnitudes of this benefit(Davis et al., 2009). Some
analyses indicate that theGHG emissions associated with bioenergy agriculture can
be significant, thus negating the intended mitigation(e.g., Crutzen et al., 2008;
Searchinger et al., 2008), and others find substantial emissions savings compared
with fossil fuel use (e.g., Farrell et al., 2006; Adler et al.,2007). These diverse
findings are the result of differing assumptions about the geography, system
boundaries,inventories, and land use associated with a given bioen-ergy cropping
system (Cherubini et al., 2009; Daviset al., 2009), but real differences among species
and management regimes are also clearly evident (Melilloet al., 2009; EPA, 2010;
Bird et al., 2011).
The large scale land-use changes associated with bioenergy production will
have consequences on many aspects of environmental and human health, including
food supply, water shed cleanliness, soil quality, and ecological diversity (e.g
Service 2007, Dominguez-Faus et al 2009, Ditomasoet al 2010, Pedroli et al 2013).
In some cases, theenvironmental costs associated with bioenergy pro-duction and
consumption have been estimated tooutweigh the benefits of reduced fossil fuel
combus-tion completely (Hill et al 2009, Tessum et al 2014)
The use of bioenergy crops to reduce the negative effects and exploit possible
positive effects of GCC is set to increase in the developing as well as the developed
world.Theoretical biomass resources are poten-tially the world’s largest sustainable
bioenergy source comprising about 220 billion oven-dry tons or 4,500 EJ of annual

4. primary production (if marine phytoplankton resourceis included). Oprovided by
bioenergy crops (Smeets et al., 2007)
There is a great challenge and concern, that cultivationof energy crops might
reduce land availability for feed and food production(FAO 2008).
Objective
To identify bioenergy crop plants.
To review opportunities for bioremediation with energy crops.
To evaluate the likely magnitude of available land and waste application rates.
To quantify possible nutrient and metal losses, via leaching in soils and water.
To quantify nutrient and metal uptake by energy crops.
To evaluate the likely magnitude of atmospheric emissions of CH 4 , N 2 O and CO 2
from wastes applied to energy crops.
To evaluate the impact of waste application, and/or siting on contaminated soils,
on biodiversity associated with energy crops.
To identify research requirements.
Characteristics of bioenergy crops
In addition, the large diversity available in germ plasm of perennial SRC and
lignocellulosic grasses for eco-physiological traits such as leaf area (LA), leaf area
index (LAI), and specific leaf area(SLA), branching habit, and biomass partitioning
patterns has been shown to influence clonal biomass production potential(Tharakan
et al., 2001; Carroll and Somerville, 2009), will help develop improved bioenergy
crops. Bioenergy crops with vegetative storage organs (e.g., stems in the C 4
sugarcane and roots in the C 3 sugar beet) are able to accept
assimilates for storage over longer periods than grain crops. Vegetative storage
reduces feed-back restriction to yield accumulation during environmental stress; and
sucrose, as the storage product of PS, is the least transformed and therefore
subject to smallest losses by subsequent metabolism (Wanget.al 2008)

5. Bioenergy crops to combat climate change
basid on biomass production and their use energy crop they are classified
following categories:
Traditional bioenergy crops
Biomass has always been a major source of energy for mankind and presently
contributes 10-14% of the world’s energy supply. Traditional biofuels derived from
natural vegetation or from crop residues are not new, have not always been good for
health or for the environment and have competed with food production in developing
countries where 70-75% of the energy used is in the form of biomass and almost 90%
of it is used for food preparation (Kotchoniand Gachomo, 2008; Lobell et al., 2008).
however, they are not sustainable; their exploitation may contribute to land
degradation and desertification (Karpand Shield, 2008).
First generation bioenergy crops (FGECs)
It is generally well understood that FGECs are limited in their ability to achieve
targets for oil-product substitution, GCC mitigation, and economic growth (Chhetri
et al., 2008; Carroll and Some rville, 2009; Lorenz et al., 2009). For most crops the
annual change in above ground C is equal to zero if the whole biomass is taken away
for energy production. The cost and sustainability of FGECs, other than sugarcane
(Wang et al.,2008), have been criticized as expensive sources to meet environmental
goals, and to provide energy alternative. These limitations can be partly overcome by
the utilization of lignocellulosic materials from their residues (Eisenbies et al.,2009)
Second generation bioenergy crops (SGECs)
The SGECs are expected to be more efficient than FGECs and to provide fuel made
from cellulose and non-oxygenated,pure hydrocarbon fuels such as biomass-to-liquid
(BtL) fuel(Oliver et al., 2009).
The use of indigenous perennial grass species is particularly promising, both

6. because these are likely to be well adapted to local environment, and because they
are less likely to adversely affect biodiversity than are non-native species,which are
frequently invasive. On average, increasing species richness in perennial herbaceous
poly cultures increased productivity and weed suppression, but well-adapted specie
sproduced high biomass yield regardless of richness(Fransworth and Meyerson,
2003; Picasso et al., 2008).
Third generation bioenergy crops (TGECs
In combination with other strategies including (meta)genomics,biodiversity studies,
and system biology, metabolic engineer-ing is a promising approach to the
improvement of biofuelyields and the establishment of renewable, non-
pollutingenergy source from TGECs that can mitigate GCC (Bush,2007; Ehrlich and
Pringle, 2008; Rubin, 2008). There is a large reservoir of boreal plant species that
can be harnessedin CH 4 production. These plants are easy to cultivate, harvest
and store, are tolerant to weeds, pests, diseases, drought and frost, and have good
winter hardness and able to grow on poor soils with low nutrient inputs (Finckh,
2008).
Dedicated bioenergy crops
The development and deployment of dedicated energy crops have been proposed as a
strategy to produce energy without impacting food security or the environment
(Lobell et al.,2008; Jessup, 2009). The dedicated energy crops are mainly perennial
herbaceous and woody plant species. Genetic resources for the development of
dedicated energy crops with low requirements for biological, chemical or physical
pretreatment are more environmentally friendly and will contribute more to GCC
mitigation (Petersen, 2008;Taherzadeh and Karimi, 2008).
Sources of bioenergy crop plants
Algae as a bioenergy source
Microalgae are unicellular orsimple multicellular organisms and can beprokaryotic
or eukaryotic in nature.Microalgae have the capability to grownaturally in fresh or

7. salt waters. Due to thesimple cellular structure of microalgae, theycan efficiently
convert solar energy.Microalgae are considered among the oldestliving organisms
onour planet earth.Microalgae canserve as the energy sources for theproduction of
biodiesel with renewablenature and apart from that microalgalbiofuels can help in
overcoming thelimitations of first and second generation ofbiofuels (Htet et al.,
2013;Saifullah et al.,2014)
Sugarcane as a bioenergy source.
Sugarcane comes under one of the mosteffective crops in the collection of solar
energy and its conversion to chemicalenergy. The potential of sugarcane as
abiomass feedstock is widely acknowledged.When sugarcane is given for
processing,there is the production of large amounts ofsugarcane bagasse which is
nowadays usedfor steam and electricity generation byburning in boilers(Cushionet
al., 2009; Weijde et al., 2013)
Maize as a bioenergy source.
Maize is one of the largest crops that is cultivated worldwide and it has the property
of playing an important role in biofuel development. If maize is to be used for the
production of biofuels, then it needs to be cultivated for two purposes viz: for grain
production as well as for the production of stem-biomass and that too in higher
yields. Because of the availability of resources such as those of agronomic and
genomicre sources, maize can be cultivated as a dual crop with ease. Due to the
presence of all these qualities and availability of resources,maize can be considered
as a best model crop for biomass quality in the field of research (Weijde et al., 2013).
Wheat as a bioenergy source.
Wheat has the potential to become a major biofuel crop. Using fermentation as a
process to produce ethanol from wheat provides a fuel that can be used to
runvehicles. Wheat comes under the category of C3 species of plants i.e. plants
performing C3 photosynthesis. These species of plants have enough potential of
accumulating carbon dry mass which provides enough biomass for energy

8. conversion (McKendry, 2002)
Edible vegetable oils as a bioenergy source
Edible oils have a great potential to be used as a feedstock for the production of
biofuels. Palm oil, soybean oil and rapeseed oil represent the main edible oils which
are produced worldwide and together they constitute 75% of the total edible oil
production in recent times. In spite of the enormous potential that biodiesel
possesses, the limitations come on the way in case edible oils as feed stocks because
of their growing demands and their high cost (Calle et al., 2009).
Non-edible vegetable oils as abioenergy source
Non-edible oils have a great capability to be used as feed stocks for biofuel
production particularly biodiesel. Non-edible oils as feed stocks for biodiesel
production can help in reducing the cost of biodiesel production. Jatropha,
Pongamia,Palm, Mahua, etc. are the various sources that are present in nature in
excess amounts and can serve as a great feedstock. When compared to edible oils,
these plants are very economical and are readily available in developing countries.
In order to decrease the viscosity of vegetable oils and to make them use as fuels,
there are several methods available that can carry out this processnamely: micro-
emulsification, pyrolysis,transesterification, etc. For the commercialproduction of
biodiesel, the mostcommonly used method employed istransesterification because
within a shorterreaction time and the use of lowtemperature and high pressure it
gives ahigh yield (Shikha and Rita, 2012; Liaquatet al., 2012).