Efficient Use of Cesspool and Biogas for Sustainable Energy Generation: Recent Development and Perspectives

© 2019, AEXTJ. All Rights Reserved 109
Available Online at www.aextj.com
Agricultural Extension Journal 2019; 3(2):109-115
ISSN 2521 – 0408
RESEARCH ARTICLE
Efficient Use of Cesspool and Biogas for Sustainable Energy Generation: Recent
Development and Perspectives
Abdeen Omer
Department of Agriculture, Energy Research Institute, University of Nottingham, Nottingham, United Kingdom
Received: 25-03-2019; Revised: 20-04-2019; Accepted: 15-05-2019
ABSTRACT
Biogas from biomass appears to have potential as an alternative energy source, which is potentially rich
in biomass resources. This is an overview of some salient points and perspectives of biogas technology.
The current literature is reviewed regarding the ecological, social, cultural, and economic impacts of
biogas technology. This article gives an overview of present and future use of biomass as an industrial
feedstock for the production of fuels, chemicals, and other materials. However, to be truly competitive
in an open market situation, higher value products are required. Results suggest that biogas technology
must be encouraged, promoted, invested, implemented, and demonstrated, but especially in remote rural
areas.
Key words: Biogas application, Biomass resources, Environment, Sustainable development
INTRODUCTION
Energy is an essential factor in development since
it stimulates, and supports economic growth,
and development. Fossil fuels, especially oil
and natural gas, are finite in extent and should
be regarded as depleting assets, and efforts are
oriented to search for new sources of energy. The
clamor all over the world for the need to conserve
energy, and the environment has intensified as
traditional energy resources continue to dwindle
while the environment becomes increasingly
degraded.Thebasicformofbiomasscomesmainly
from firewood, charcoal, and crop residues. Out of
the total fuelwood and charcoal supplies, 92% was
consumed in the household sector with most of the
firewood consumption in rural areas.
The term biomass is generally applied to plant
materials grown for non-food use, including that
grown as a source of fuel. However, the economics
of production are such that purpose-grown crops
are not competitive with fossil-fuel alternatives
under many circumstances in industrial countries,
Address for correspondence:
Abdeen Omer
E-mail: abdeenomer2@yahoo.co.uk
unlesssubsidiesand/ortaxconcessionsareapplied.
For this reason, much of the plant materials used
as a source of energy at present is in the form of
crop and forest residues, animal manure, and the
organic fraction of municipal solid waste and
agro-industrial processing by-products, such as
bagasse, oil-palm residues, sawdust, and wood off-
cuts. The economics of the use of such materials is
improved since they are collected in one place and
often have associated disposal costs.[1]
Combustion remains the method of choice for
heat and power generation (using steam turbines)
for dryer raw materials, while biogas production
through anaerobic digestion or in landfills is
widely used for the valorization of wet residues
and liquid effluents for heat and power generation
(using gas engines or gas turbines). In addition,
some liquid fuel is produced from purpose-grown
crops (ethanol from sugarcane, sugar beet, maize,
sorghum, and wheat or vegetable oil esters from
rapeseed, sunflower oil, and oil palm). The use of
wastes and residues has established these basic
conversion technologies, although research,
development, and demonstration continue to try
and improve the efficiency of thermal processing
through gasification and pyrolysis, linked to
combined cycle generation. At the same time,

Omer: Efficient use of cesspool and biogas for sustainable energy generation
AEXTJ/Apr-Jun-2019/Vol 3/Issue 2 110
considerable effort is being made to increase the
range of plant-derived non-food materials. To
achieve these several approaches are being taken.
The first is to provide lower cost raw materials for
the production of bulk chemicals and ingredients
that can be used in detergents, plastics, inks, paints,
and other surface coatings. To a large extent, these
are based on vegetable oils or starch hydrolysates
used in fermentation to produced lactic acid (for
polylactides) or polyhydroxybutyrate, as well as
modified starches, cellulose, and hemicellulose.
The advantages are biodegradability, compatibility
with biological systems (hence, less allergic
reactioninuse)andsparingoffossilcarbondioxide
emissions (linked to climate chance). Associating
an economic value to these environmental benefits,
linked to consumer preferences has contributed
to increased production in this area. The second
expanding activity is the use of plant fibers, not
only for non-tree paper but also as a substitute for
petroleum-based plastic packing and components
such as car parts. These may be derived from
non-woven fibers, or be based on bio-composite
materials (lingo-cellulose chips in a suitable
plastic matrix). At the other end of the scale, new
methods of gluing, strengthening, preserving, and
shaping wood have increased the building of large
structures with predicted long-lifetimes. These
include a wide range of natural products such as
flavors, fragrances, hydrocolloids, and biological
control agents. In spite of decades of research
and development, engineering (recombinant
DNA technology) is being widely investigated to
achieve this, as well as to introduce new routes to
unusual fatty acids and other organic compounds.
In addition, such techniques are being used to
construct plants that produce novel proteins and
metabolites that may be used as vaccines or for
other therapeutic use. Processing of the crops
for all these non-food uses will again generate
residues and by-products that can serve as a source
of energy, for internal use in processing, or export
to other users, suggesting the future possibility
of large multi-product biomass-based industrial
complexes.
TECHNICAL DESCRIPTION
Bacteria form biogas during anaerobic
fermentation of organic matters. The degradation
is a very complex process and requires certain
environmental conditions as well as different
bacteria populations. The complete anaerobic
fermentation process is briefly described below, as
shown in Table 1. Biogas is a relatively high-value
fuel that is formed during anaerobic degradation of
organic matter. The process has been known, and
put to work in a number of different applications
during the past 30 years, for rural needs such as
in:[2]
Food security, water supply, health cares,
education, and communications.
During the past decades, thousands of biogas units
were built all over the world, producing methane
CH4
for cooking, water pumping, and electricity
generation. In order not to repeat successes in
depth on local conditions and also conscientious
planning urged.[4]
The goals should be achieved
through:
• Review and exchange of information on
computer models and manuals useful for the
economic evaluation of biogas from biomass
energy
• Exchange of information on methodologies
for economic analysis and results from case
studies
• Investigation of the constraints on the
implementation of the commercial supply of
biogas energy
• Investigation of the relationship between
supplies and demand for the feedstock from
different industries
• Documentation of the methods and principles
for evaluation of indirect consequences such
as effects on growth, silvicultural treatment,
and employment.
Biogas technology can not only provide fuel but
is also important for comprehensive utilization
of biomass forestry, animal husbandry, fishery,
agricultural economy, protecting the environment,
realizing agricultural recycling, as well as
improving the sanitary conditions, in rural areas.
The introduction of biogas technology on wide
scale has implications for macro planning such
as the allocation of government investment and
effects on the balance of payments. Factors that
determine the rate of acceptance of biogas plants,
such as credit facilities and technical backup
services, are likely to have to be planned as part
of general macro-policy, as do the allocation of
research and development funds.[5]
Biogas is a generic term for gases generated from
the decomposition of organic material. As the
material breaks down, methane (CH4
) is produced,
as shown in Figure 3. Sources that generate biogas

are numerous and varied. These include landfill
sites, wastewater treatment plants, and anaerobic
digesters. Landfills and wastewater treatment
plants emit biogas from decaying waste. To date,
the waste industry has focused on controlling these
emissions to our environment and in some cases,
tapping this potential source of fuel to power gas
turbines, thus generating electricity. The primary
components of landfill gas are methane (CH4
),
carbon dioxide (CO2
), and nitrogen (N2
). The
average concentration of methane is ~45%, CO2
is
~36%, and nitrogen is ~18%. Other components
in the gas are oxygen (O2
), water vapor, and trace
amounts of a wide range of non-methane organic
compounds.
For hot water and heating, renewables
contributions come from biomass power and heat,
geothermal direct heat, ground source heat pumps,
and rooftop solar hot water, and space heating
systems. Solar assisted cooling makes a very
small but growing contribution. When it comes to
the installation of large amounts of PV, the cities
have several important factors in common. These
factors include:
• A strong local political commitment to the
environment and sustainability
• The presence of municipal departments
or offices dedicated to the environment,
sustainability or renewable energy
• Information provision about the possibilities
of renewables
• Obligations that some or all buildings include
renewable energy.
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are preferred. Please embed symbol fonts, as well,
for math, etc.
BIOGAS UTILIZATION
The importance and role of biogases in energy
production are growing. Nowadays, a lot of
countries in Europe promote the utilization
of renewable energies by guaranteed refund
prices or emission trading systems. A general
schematic of an agricultural biogas plant, with
the anaerobic digester is at the “heart” of it. Pre-
treatment steps (e.g., chopping, grinding, mixing,
or hygienization) depend on the origination of the
raw materials.
In the past two decades, the world has become
increasingly aware of the depletion of fossil fuel
reserves and the indications of climatic changes
based on carbon dioxide emissions. Therefore,
extending the use of renewable resources,
efficient energy production and the reduction of
energy consumption are the main goals to reach
a sustainable energy supply. Renewable energy
sources include water and wind power, solar and
geothermalenergy,aswellasenergyfrombiomass.
The technical achievability and the actual usage of
these energy sources are different around Europe,
but biomass is seen to have great potential in many
of them. An efficient method for the conversion of
biomass to energy is the production of biogas by
microbial degradation of organic matter under the
absence of oxygen (anaerobic digestion). It is now
possible to produce biogas at rural installation,
upgrade it to bio-methane, feed it into the gas grid,
use it in a heat demand-controlled combined heat
and power (CHP) and to receive revenues.
Biogas is a mixture containing predominantly
methane (50–65% by volume) and carbon
dioxide, and in a natural setting it is formed in
swamps and anaerobic sediments, etc., due to its
high methane concentration, biogas is a valuable
fuel. Wet (40–95%) organic materials with
low lignin and cellulose content are generally
suitable for anaerobic digestion. A key concern
is that treatment of sludge tends to concentrate
heavy metals, poorly biodegradable trace organic
compounds, and potentially pathogenic organisms
(viruses, bacteria, and the like) present in
wastewaters. These materials can pose a serious
threat to the environment. When deposited in soils,
heavy metals are passed through the food chain,
first entering crops, and then animals that feed on
the crops and eventually human beings, to whom
they appear to be highly toxic. In addition, they
Table 1: Anaerobic degradation of organic matters[3]
Level Substance Molecule Bacteria
Initial Manure, vegetable, wastes Cellulose, proteins Cellulolytic, proteolytic
Intermediate Acids, gases, oxidized, inorganic salts CH3
COOH, CHOOH, SO4
, CO2
, H2
, NO3
Acidogenic, hydrogenic, sulfate‑reducing
Final Biogas reduced inorganic compounds CH4
, CO2
, H2
S, NH3
, NH4
Methane formers

also leach from soils, getting into groundwater and
further spreading contamination in an uncontrolled
manner. European and American markets aiming
to transform various organic wastes (animal farm
wastes, industrial, and municipal wastes) into two
main by-products:
• A solution of humic substances (a liquid
oxidate)
• A solid residue.
ECOLOGICAL ADVANTAGES
An easier situation can be found when looking at
the ecological effects of different biogas utilization
pathways.The key assumptions for the comparison
of different biogas utilization processes are:
• Biogas utilization in heat demand controlled
gas engine supplied out of the natural gas grid
with 500 kWe – electrical efficiency of 37.5%,
thermal efficiency of 42.5%, and a methane
loss of 0.01
• Biogasutilizationinalocalgasengine,installed
at the biogas plant with 500 kWe – electrical
efficiency of 37.5%, thermal efficiency of
42.5%, and a methane loss of 0.5
• Biogas production based on maize silage
using a biogas plant with covered storage
tank – methane losses were 1% of the biogas
produced
• Biogas upgrading with a power consumption
0.3 kWe/m3
biogas – methane losses of 0.5.
Figure 1 presents the results of the greenhouse
gas (GHG) savings from the different biogas
utilization options, in comparison to the fossil
fuel-based standard energy production processes.
Biogas can be converted to energy in several
ways. The predominant utilization is CHP
generation in a gas engine installed at the place
of biogas production. There are mainly two
reasons for this. First, biogas production is an
almost continuous process; it is rather difficult
or, in the short-term, even impossible, to control
the operation of anaerobic digesters according to
any given demand profile. Second, the promotion
of renewable energies is focused on electricity
production. Due to that, biogas plant operators
receive the predominant fraction of revenues
from the guaranteed feed-in tariffs for electricity.
Summarizing the results of the eco-balances, it
becomes obvious that – not only using fossil fuels
but also using renewable fuels like biogas – CHP
cogeneration is the optimal way for fighting
climate change. From a technical point of view, it
can be concluded that biogas production, i.e., the
conversion of renewable resources and biowaste to
energy, can be seen as state-of-the-art technology.
Bacteria form biogas during anaerobic
fermentation of organic matters. The degradation
is a very complex process and requires certain
environmental conditions as well as different
bacteria population. The organic matter was
biodegradable to produce biogas and the variation
show a normal methanogens bacteria activity and
good working biological process, as shown in
Figures 2 and 3.
Gasification is based on the formation of fuel gas
(mostly CO and H2
) by partially oxidizing raw solid
fuel at high temperatures in the presence of steam or
air. The technology can use wood chips, groundnut
shells, sugar cane bagasse, and other similar fuels
to generate capacities from 3 kw to 100 kw. Three
types of gasifier designs have been developed
to make use of the diversity of fuel inputs and to
meet the requirements of the product gas output
(degree of cleanliness, composition, heating value,
etc.). The requirements of gas for various purposes,
and a comparison between biogas; and various
Figure 1: Greenhouse gas emissions savings for different
biogas utilization pathways in comparison to fossil energy
production

the impact of global warming. This global concern
is manifest in the 1997 Kyoto protocol, which
imposes an imperative on developed nations to
identify feasible options by the next conference
of the parties to the convention meeting later
in 2001. Possible actions range from basic
increases in energy efficiency and conservation to
sophisticated methods of carbon sequestration to
capture the most common GHGs emission (CO2
).
On the other hand, renewable energies have
always been identified as a prime source of clean
energies that emit little or no net GHGs into the
atmosphere. Forest ecosystems cause effects on
the balance of carbon mainly by the assimilation
of CO2
by the aboveground biomass of the forest
vegetation. The annual emissions of GHGs from
fossil fuel combustion and land use change
are approximately 33 × 105
and 38 × 105
tones,
respectively. Vegetation and in particular forests
can be managed to sequester carbon. Management
options have been identified to conserve and
sequester up to 90 Pg C in the forest sector in the
next century, through global afforestation.[9,10]
This
option may become a necessity (as recommended
at the framework convention on climate change
meeting held in Kyoto), but a preventative
approach could be taken, reducing total GHGs
emissions by substituting biomass for fossil fuels
in electricity production.
Simply sequestering carbon in new forests is
problematic because trees cease sequestering
once they reach maturity, and as available land is
used up the cost of further afforestation will grow.
Indeed the cost of reducing the build-up of GHGs
in the atmosphere is already lower for fossil fuel
substitution than for sequestration, since fast-
growing energy crops are more efficient at carbon
removal, and because revenue is generated by the
scale of electricity. Some biomass fuel cycles can
Figure 2: Organic matters before and after treatment in
digester
Figure 3: pH sludge before and after treatment in the
digester
commercial fuels in terms of calorific value and
thermal efficiency are presented in Table 2.
ENVIRONMENTAL ISSUES
There is an unmistakable link between energy and
sustainable human development. Energy is not
an end in itself, but an essential tool to facilitate
social and economic activities. Thus, the lack of
available energy services correlates closely with
many challenges of sustainable development, such
as poverty alleviation, the advancement of women,
protection of the environment, and jobs creation.
Emphasis on institution-building and enhanced
policy dialogue is necessary to create the social,
economic, and politically enabling conditions for
a transition to a more sustainable future. On the
other hand, biomass energy technologies are a
promising option, with a potentially large impact
for Sudan as with other developing countries,
where the current levels of energy services are low.
Biomass accounts for about one-third of all energy
in developing countries as a whole, and nearly
96% in some of the least developed countries.[6-8]
Climate change is a growing concern around the
world, and stakeholders are aggressively seeking
energy sources and technologies that can mitigate
Table 2: Comparison of various fuels[5]
Fuel Calorific
value (kcal)
Burning
mode
Thermal
efficiency (%)
Electricity, kwh 880 Hot plate 70
Coal gas, kg 4004 Standard
burner
60
Biogas, m3
5373 '' 60
Kerosene, L 9122 Pressure
stove
50
Charcoal, kg 6930 Open stove 28
Soft coke, kg 6292 '' 28
Firewood, kg 3821 '' 17
Cow dung, kg 2092 '' 11

also provide the additional benefits of enhanced
carbon storage. The relative merits of sequestration
versus fossil fuel substitution are still debated. The
flow of carbon during the life cycle of the biomass
should determine whether it is better left standing,
used as fuel or used as long-lived timber products.
Where there are existing forests in good condition,
there is general agreement that they should not
be cut for fuel and replanted. This principle also
concurs with the guidelines for nature protection,
i.e., energy crops should never displace land uses
of high ecological value. Where afforestation is
undertaken, however, fossil fuel substitution, both
usingwoodfuelandusingtimberasarenewableraw
material, should be more sustainable and less costly
approach than sequestration could also be used to
displace the harvest of more ecologically valuable
forests. For efficient use of bioenergy resources, it
is essential to take account of the intrinsic energy
potential. Despite the availability of basic statistics,
many differences have been observed between the
previous assessments of bioenergy potential.[11-16]
These were probably due to different assumptions
or incomplete estimations of the availability,
accessibility, and use of by-products. The biomass
sources have been used through:
• Anaerobic digestion of municipal wastes and
sewage
• Direct combustion of forestry and wood
processing residues
• Direct combustion in the case of main dry crop
residues
• Anaerobic digestion of moist residues of
agricultural crops and animal wastes.
Wood is a very important raw material used by
number of industries. Its excessive utilization as
fuel results in soil erosion, degradation of the land,
reduced agricultural productivity, and potentially
serious ecological damage. Hence, minimization
of fuelwood demand and a national level and the
increment an increase in the efficiency of fuelwood
use seems to be essential. The utilization of more
efficient stoves and improvement of insulation
using locally available materials in buildings are
also effective measures to increase efficiency.
Biogas or commercial fuels may be thought of as
possible substitutes for fuelwood. In rural areas
of Sudan, liquefied petroleum gases (LPGs) are
a strong candidate to replace firewood. Indeed,
increased, LPG utilization over the past decade has
been one of the main reasons that have led to the
deceleration of the diffusion of biogas technology
into rural areas.
CONCLUSIONS
1. Biogas technology can not only provide
fuel but is also important for comprehensive
utilization of biomass forestry, animal
husbandry, fishery, evaluating the agricultural
economy,protectingtheenvironment,realizing
agricultural recycling, as well as improving
the sanitary conditions, in rural areas
2. The biomass energy, one of the important
options, which might gradually replace the
oil in facing the increased demand for oil and
maybe an advanced period in this century.Any
county can depend on the biomass energy to
satisfy part of local consumption
3. Development of biogas technology is a vital
component of the alternative rural energy
program, whose potential is yet to be exploited.
A concerted effect is required by all if this is
to be realized. The technology will find ready
use in domestic, farming, and small-scale
industrial applications
4. Support biomass research and exchange
experiences with countries that are advanced
in this field. In the meantime, the biomass
energy can help to save exhausting oil wealth
5. The diminishing agricultural land may hamper
biogas energy development, but appropriate
technological and resource management
techniques will offset the effects.
The following are recommended:
1. The introduction of biogas technology on a wide
scale has implications for macro planning such
as the allocation of government investment and
effects on the balance of payments. Factors that
determinetherateofacceptanceofbiogasplants,
such as credit facilities and technical backup
services, are likely to have to be planned as part
of general macro-policy, as do the allocation of
research and development funds
2. In some rural communities, cultural beliefs
regarding handling animal dung are prevalent
and will influence the acceptability of biogas
technology
3. Coordination of production and use of biogas,
fertilizer and pollution control can optimize
the promotion and development of agricultural
and animal husbandry in rural areas.

ACKNOWLEDGMENT
A special thanks to my spouse Kawthar Abdelhai
Ali for her support and her unwavering faith
in me. Her intelligence, humor, spontaneity,
curiosity, and wisdom added to this article and
also I acknowledge the energy research institute
to support this work.
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