JOURNAL OF SCIECNCE TECHNOLOGY AND EDUCATION 8(3), SEPTEMBER, 2020
ISSN: 2277-0011; Journal homepage: www.atbuftejoste.com
Techno-economic Analysis of Hybrid Diesel Generator/PV/Battery
Power System for Telecommunication Application
Sanusi, Y. S., Dandajeh, H. A., Mustapha, H.
Department of Mechanical Engineering,
Ahmadu Bello University, Zaria, P.M.B 1045, Nigeria
ABSTRACT
In this study, the techno-economic analysis of a hybrid diesel
generator/PV/battery power system was carried out for
telecommunication substation in Nigeria. A case study of a
telecommunication substation located at Mabushi, Abuja was
considered. Homer Pro software was used to carry out the
technical, economic and environmental analysis of different
configurations of power systems: DG only system, DG/Battery
system, PV/Battery system and DG/PV/Battery system. The
systems were compared with the DG/PV/Battery power system
installed at Mabushi substation. Results show that the
currently installed DG/PV/Battery system is oversized when
compared with the optimized DG only system, DG/Battery
system and DG/PV/Battery system. The installed
DG/PV/Battery system has the least capacity factor of 6.42%
when compared to other systems. The optimized
DG/PV/Battery system has a capacity factor of 16.88 %. The
pure renewable system (PV/Battery system) has the highest
NPC and COE. This is due to PV/Battery system high capital cost
that contributed about 87.5% of total facility cost. The
optimized PV/Battery/DG presented in this study gave the least
NPC and COE of $51,291 and $0.453 respectively as compared
to NPC and COE of $63,600 and $0.592 obtained in the
currently installed power system. This implies that the
optimized PV/Battery/DG system presented in this study is the
most viable of all the systems considered and is therefore
recommended
for
installation
at
the
studied
telecommunication substation. The sensitivity analysis of the
diesel price on the COE in the recommended system shows that
for 100 % price increase in diesel fuel, the COE increases by
about 30%. This is due to the fact that the integration of the
PV/battery to the DG cushions the direct effect of the increased
fuel price on the COE.
INTRODUCTION
Telecommunication restructuring
framework led to the introduction of GSM to
Nigeria in 2001(Nkordeh, Bob-Manuel, &
Olowononi, n.d.). Recent statistics has
ARTICLE INFO
Article History
Received: February, 2020
Received in revised form: April, 2020
Accepted: May, 2020
Published online: August, 2020
KEYWORDS
Techno-economic Analysis, Hybrid Diesel
Generator, Power System
shown that the subscriber identity module
(SIM) penetration in Nigeria is 82% and the
number of lines connections is 151.8 million
(“SMA Intell. Data,” 2017). The growing
number of subscribers has necessitated the
Corresponding author: Sanusi, Y. S.
yinkasan@yahoo.com
Department of Mechanical Engineering, Ahmadu Bello
University, Zaria. © 2019 Faculty of Technology Education, ATBU Bauchi. All rights reserved
77
JOURNAL OF SCIECNCE TECHNOLOGY AND EDUCATION 8(3), SEPTEMBER, 2020
ISSN: 2277-0011; Journal homepage: www.atbuftejoste.com
need to build more telecommunication
infrastructure. Base stations (BSs) are among
the key energy consumption elements of
telecommunication infrastructure (M. H.
Alsharif, Nordin, & Ismail, 2015)(Ahmed et
al., n.d.).
A telecommunication transceiver
operating with power outage can be a major
source of communication failure. Therefore
a continuous safe and cost-effective energy
system is necessary to operate a
telecommunication substations so as to
curtail service disruption. There is a major
challenge of insufficient power generation in
Nigeria. Running industrial or business
ventures entirely on electricity from the grid
is not sustainable. Olatomiwa et al.
(Olatomiwa, Mekhilef, Olatomiwa, Mekhilef,
& Huda, 2014) reported that an
approximately 12,560 mobile sites are not
connected to the grid in Nigeria, while an
estimated 11,692 sites are linked to the
national grid. About 9% of the grid
connected sites have an average of 6-hour
grid outages per day, while, 10% have 6–12
hours grid outages per day and the
remaining 81% have over 12 hours grid
outages per day. Diesel generator are
mostly used to power off-grid base stations
and grid connected station during off-grid
hours. . In off-grid systems, the primary
component of plant-level energy costs is the
expenditure on diesel fuel for generators,
which accounts for almost 80% of the total
energy costs(Feng, Jiang, Lim, Tutorials, &
2012, n.d.)(Mancuso, Vincenzo, 2011).
Alternatively, the required energy
can be sourced from abundant solar energy
using solar photovoltaic (PV) system or PV
systems integrated to conventional
electricity generating system (diesel
generator) in a solar hybrid system. The
hybrid system can lead to a reduction in
electricity cost with a constant electricity
supply. Several works (Agarwal, Nitin, 2013;
Ahadi, Amir, Sang-Kyun Kang, 2016;
Cristóbal-Monreal, Iván R., 2016; Dufo-
López, Rodolfo, Iván R. Cristóbal-Monreal,
2016; Kusakana, 2015; Maatallah, Taher,
Nahed Ghodhbane, 2016) have been carried
out in the area of solar hybrid systems. Dufo
et al,(Dufo-López, Rodolfo, Iván R. CristóbalMonreal, 2016) discussed the various ways
of optimizing a PV-wind-diesel hybrid
system. Ahadi et al,(Ahadi, Amir, Sang-Kyun
Kang, 2016) has done an extensive
investigation on several hybrid renewable
energy system combinations of solar, wind
and diesel generators to supply energy to
remote communities. Maatallah et al,
(Maatallah, Taher, Nahed Ghodhbane, 2016)
performed a techno economic feasibility
study of solar PV/wind/Diesel with storage
batteries. They reported that the most
economical system has an NPC and LCOE of
$57,320 and 0.26 $/kW, respectively. Goel
and Ali(Goel, Sonali, 2014) used the HOMER
software to obtain the optimum net present
cost (NPC and energy cost/kWh for telecom
towers. Alsharif (M. Alsharif, 2017),
compared solar-powered base stations with
conventional energy sources, and obtained
OPEX savings that ranges between 32% and
66%. He concluded that the solar-powered
base stations would be a feasible long-term
solution for the telecommunication industry.
Summary of the findings of several
researchers (Oviroh, Peter Ozaveshe, TienChien Jen, Nosa Idusuyi, 2017; Shaahid, S.
M., 2009; Vishnupriyan, J., 2018) showed
that: (1) A 40-90% reduction in fuel
consumption by the diesel generator (DG)
with the solar hybrid system (2) a reduction
in the operation and maintenance cost of up
50 % (3) Carbon footprint savings of 30-75%
are also achieved as a result of the reduction
in the burning of fossil fuel. (4) Reduction of
diesel generator (DG) set run hour by about
50%. Most substations in Nigeria are run on
contract basis. In order to ensure power
availability on site most of the power
equipment are over-sized leading to
increased cost of electricity. Consequently,
this study was carried out to design and
Corresponding author: Sanusi, Y. S.
yinkasan@yahoo.com
Department of Mechanical Engineering, Ahmadu Bello
University, Zaria. © 2019 Faculty of Technology Education, ATBU Bauchi. All rights reserved
78
JOURNAL OF SCIECNCE TECHNOLOGY AND EDUCATION 8(3), SEPTEMBER, 2020
ISSN: 2277-0011; Journal homepage: www.atbuftejoste.com
Mabushi, Abuja, Nigeria (9°5.0'N, 7°26.9'E).
The substation is dedicated to serve the
vehicle inspection office headquarters and
adjoining subscribers. The substation was
installed to enhance the transmission of
telecommunication data. It has 3 RF radios,
a microwave and 2 DC lights that comprises
of the site load. Figure 1 shows the view of
Mabushi telecommunication substation,
located at (9°5.0'N, 7°26.9'E). The ambient
temperature varies between 18oC to 30oC.
optimized different hybrid energy systems
for a telecommunication substation in
Mabushi, located in the capital of Nigeria
(Abuja) using HOMER software. The
proposed system was compared with the
presently installed system at Mabushi
substation.
SITE DESCRIPTION
The telecommunication substation
in this study is located at kabir rabiu road,
a)
The overall view of the site
b) 3.5kW PV solar panel
c) 17kW DC Generator
Fig.1: Mabushi telecommunication substation, Abuja Nigeria
not required. The total rating of equipment
Site Load
on site is 988Watts that comprises of:
The Site loads are all DC loads,
therefore the use of an AC to DC converter is
Corresponding author: Sanusi, Y. S.
yinkasan@yahoo.com
Department of Mechanical Engineering, Ahmadu Bello
University, Zaria. © 2019 Faculty of Technology Education, ATBU Bauchi. All rights reserved
79
JOURNAL OF SCIECNCE TECHNOLOGY AND EDUCATION 8(3), SEPTEMBER, 2020
ISSN: 2277-0011; Journal homepage: www.atbuftejoste.com
optimizations under a range of input
assumptions to gauge the effects of different
changes in the model inputs. In the present
study, HOMER Software was used to
simulate hybrid energy system for off-grid
with different schedules and compared with
a system that run with diesel generator only
system. HOMER incorporates the entire cost
of the system to calculate the economic
viability of the systems. The metrics for
comparing the viability of the system are the
cost of electricity (COE) and the net present
cost (NPC).
Two DC security lamps: These
lamps
are
necessary
for
illuminating of the site scene
especially in the nights.
Three RF antennas: the radio
frequency antennas are the
receivers of the radio waves or
signals transmitted from a long
distance of hundreds of meters or
several kilometers away.
One micro wave transmitter: A
Microwave is a communications
system that uses a beam of radio
waves in the microwave frequency
range to transmit audio, video and
other
information
between
locations, from a few feet or meters
to several miles or kilometers apart.
TECHNICAL AND ECONOMIC ANALYSIS OF
THE SYSTEMS
Technical Analysis of the Systems
Base Case
The base case is the currently
installed power system at the Mabuchi
telecommunication substation. The system
comprises of 17kWDC Diesel generator (DG),
a 3.5kWh Photovoltaic (PV) solar panel and
24 batteries of 1KWh each, the schematic
illustration of the system is shown on figure
2a. The system has no AC/DC converter
because the generator has a DC output. The
electrical load on the system is represented
by the electrical incandescent lamp; this is
the generic symbol HOMER uses to indicate
loads on any system. The station combines a
photovoltaic (PV) array, battery and the
generator. The architecture is designed in
such a way that the DC generator and the
solar panels directly feed the required
energy to the DC load of the base station.
There is also provisions for both the diesel
DC generator and the Photovoltaic solar
panels to charge the batteries concurrently.
Excess energy stored in the battery bank are
used during night or when the PV cannot
supply the required energy to the load.
Homer Pro software
Hybrid Optimization Model for
Electric Renewable (HOMER) is a simulation
software. HOMER can model both the gridconnected and off-grid micro-power
systems comprising any combination of
photovoltaic (PV) modules, wind turbines,
small hydro, biomass power, generators,
micro-turbines, fuel cells, batteries, and
hydrogen storage etc. HOMER performs
three major computations: simulation,
optimization,
and
sensitivity
analysis(“HOMER Pro User Manual.,” 2016).
In the simulation process, HOMER models
the performance of a given system
configuration each hour of the year so as to
determine its technical feasibility and lifecycle cost. In the optimization process,
HOMER simulates many different system
configurations in search of the one that
satisfies the technical constraints at the
lowest life-cycle cost. In the sensitivity
analysis process, HOMER performs multiple
Corresponding author: Sanusi, Y. S.
yinkasan@yahoo.com
Department of Mechanical Engineering, Ahmadu Bello
University, Zaria. © 2019 Faculty of Technology Education, ATBU Bauchi. All rights reserved
80
JOURNAL OF SCIECNCE TECHNOLOGY AND EDUCATION 8(3), SEPTEMBER, 2020
ISSN: 2277-0011; Journal homepage: www.atbuftejoste.com
a)
Installed
PV/DG/Battery
system
b) DG only system
c)
DG/Battery system
DG: Diesel generator
PV: Photovoltaic
d) PV/Battery
e) PV/DG/Battery
system
system
Fig.2: Various configurations of renewable energy hybrid power supply.
DIESEL GENERATOR (DG) CASE STUDY
In this case, a diesel generator (DG)
is allowed to run the sites over the life span
of the facility. The schematic representation
of the generator alone running the site is
shown in Figure 2b.
Diesel generator (DG) and battery case
study
In this case study, the site is
powered by the combination of a diesel
generator and battery system (DG/Battery).
In this system a DG is made to run the site
and recharge the batteries until they their
full capacity (100%). The DG is then off
thereby allowing the batteries to power the
site until the batteries capacity drops to 50%.
The DG is then force-start to repeat the
cycle. Figure 2c is a schematic diagram that
gives the physical representation of the
system.
Photovoltaic (PV) array and battery case
study
The fourth case study is a pure
renewable energy system, where the PV and
the Battery (PV/Battery) system are used to
run the site continuously. The PV power the
site and charges the batteries during the
solar hour. The energy stored in the battery
is used to power the site during non-solar
hour. The schematic representation of this
system is shown in figure 2d.
Corresponding author: Sanusi, Y. S.
yinkasan@yahoo.com
Department of Mechanical Engineering, Ahmadu Bello
University, Zaria. © 2019 Faculty of Technology Education, ATBU Bauchi. All rights reserved
81
JOURNAL OF SCIECNCE TECHNOLOGY AND EDUCATION 8(3), SEPTEMBER, 2020
ISSN: 2277-0011; Journal homepage: www.atbuftejoste.com
Diesel Generator (Dg), Photovoltaic (Pv)
Array And Battery Case Study
The final case is the fifth case
whereby the system employs the use of all
the three components of the power system
available on site; the PV, the Generator and
the Batteries. The schematic representation
of this system can be seen as shown in figure
2e.
Where 𝑇 is the ambient temperature,
Tc,NOCT is the nominal operating cell
temperature [oC] and Ta,NOCT is the ambient
temperature at which the NOCT is defined
[20oC], 𝐺 and GT,NOCT are the instatenous
solar radiation and solar radiation at which
the NOCT is defined [0.8 kW/m2]
respectively. η is the PV array electrical
efficiency, while PV transmittance –
absorptance is expressed as 𝜏𝛼 and assumed
as 0.9 in HOMER software.
TECHNICAL
ANALYSIS
OF
SYSTEM
COMPONENTS
PV model
The output of the PV is modeled in
HOMER using the following equations
(Akhtari, Mohammad Reza, 2019; Baneshi,
Mehdi, 2016):
=𝑌 𝑓
1+𝛼 𝑇 −𝑇 ,
,
(1)
𝑌 is the PV rated capacity (kW) under
standard test conditions, 𝑓 is the PV
dearating factor [%]. 𝐺 is the instatenous
solar radiation incident on the PV array,
while, 𝐺 ,
is the incident solar radiation at
standard test conditions. 𝛼 is the
temperature coefficient of power [%/°C]. 𝑇
And 𝑇 ,
are the PV cell temperature and
PV cell temperature under standard test
conditions [25 °C] respectively.
The PV cell temperature (Akhtari,
Mohammad Reza, 2019) is computed from
Eq. (2):
,
𝑇 = 𝑇 +𝐺
6
,
,
1−
(2)
Daily Radiation
Clearnes Index
0.8
Monthly average solar
irradiance (KWh/m2/day)
5.5
5
0.6
4.5
0.4
4
0.2
3.5
3
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Clearness Index
𝑃
Solar Resources
The solar radiation data for the
telecommunication site (Abuja) was
obtained from NASA surface meteorology
and solar data base. The data was based on
the global horizontal radiation, monthly
averaged over 22 year period (July 1983 June 2005) and presented in Figure 3. The
monthly distribution of the clearness index
was also given in figure 3. The months of
May to August have relatively lower monthly
average solar radiation and clearness index.
This months are mostly characterized with
high rainfall activity when compared to
other months of the year. The month of
December has the lowest solar radiation due
to effect of winter. The annual daily average
global solar radiation and clearness index of
the telecommunication site was estimated
as 5.579 kWh/m2/day and 0.566
respectively.
0
Figure 3: Monthly average solar irradiance and clearness index for Abuja
Corresponding author: Sanusi, Y. S.
yinkasan@yahoo.com
Department of Mechanical Engineering, Ahmadu Bello
University, Zaria. © 2019 Faculty of Technology Education, ATBU Bauchi. All rights reserved
82
JOURNAL OF SCIECNCE TECHNOLOGY AND EDUCATION 8(3), SEPTEMBER, 2020
ISSN: 2277-0011; Journal homepage: www.atbuftejoste.com
Diesel Generator Model
The generator electrical efficiency
is the ratio of the generator’s electrical
energy output and the chemical energy of
the fuel (“HOMER Pro User Manual.,” 2016).
η
=
.
̇
computed as (Sanusi, Yinka S., Esmail MA
Mokheimer, 2017):
𝐶𝑅𝐹(𝑖, 𝑁) =
(4)
𝑚̇
=
Where 𝐹
is the fuel curve intercept
coefficient in L/hr/kW, 𝐹 is the fuel curve
slope in L/hr/kW, 𝑌 is the rated capacity
of the generator in kW, and 𝑃
is the
electrical output of the generator in kW.
,
=
∆
∆
∆
The maximum battery discharge power is
computed as:
𝑃 ,
, =
𝑃
η
,
,
∆
=η
∆
=η
,
∆
,
.𝑃
= η
∆
∆
,
,
(7)
/
,
(
)
)
(12)
RESULTS AND DISCUSSION
In this study, the techno-economic
analysis of power facility installed at
Mabushi telecommunication substation and
those of DG only system, DG/Battery system,
PV/Battery system and DG/PV/Battery
system were simulated and optimized using
HOMER software. The sensitivity analysis of
the optimized system was thereafter carried
out. Results of the optimized system for
different power configuration is shown in
Table1. The currently installed system has a
DG of 17 kW and is allowed to run for 3 hrs.
per day. Analysis shows that the required DG
to power the site is 4.1 kW. This DG can also
be used as a stand by energy supply during
non- solar hour and when the battery is fully
discharged. When the site is powered solely
by DG (4.1 kW), the service life of the
generator drop from 12.5 years in the
installed system to about 1.91 years. This
implies that, if two generators are used on a
12-hours basis, a total number of 14 (4.1kWDG) generators will be required over a 25
(6)
∆
∆
(
Where; N is the project lifetime in years, 𝑖 is
the annual interest rate.
The net present cost (or life-cycle cost) of a
component is the present value of all the
costs of installing and operating that
component over the project lifetime, minus
the present value of all the revenues that it
earns over the project lifetime.
Battery Model
HOMER uses the Kinetic Battery
Model (Azimoh, Chukwuma Leonard, Patrik
Klintenberg, Fredrik Wallin, Björn Karlsson,
2016) to determine the amount of energy
that can be absorbed by or withdrawn from
the storage bank at each time step.
The maximum battery charge power is
computed as:
𝑃 ,
=η
(5)
, .𝑃
,
,
,
(10)
The total annualized cost is computed from
𝐶 , = 𝐶 . 𝐶𝑅𝐹
(11)
Where 𝐶
the net is present cost (NPC) of
a system and 𝐶𝑅𝐹 is the capital recovery
factor.
The capital recovery factor can be
given by eq.12 as (Sanusi, Yinka S.,
Esmail MA Mokheimer, 2017):
(3)
Where Pgen is the electrical output in kW,
𝑚̇
is the mass flow rate of the fuel in
kg/hr and LHVfuel is the lower heating value
of the fuel in MJ/kg.
The amount of fuel the generator consumes
(𝑚̇
) is given as:
𝑃
$
𝐶𝑂𝐸 =
(8)
(9)
ECONOMIC
ANALYSIS
OF
SYSTEM
COMPONENTS
Cost of Electricity
The cost of electricity (COE) of
different power systems considered is
Corresponding author: Sanusi, Y. S.
yinkasan@yahoo.com
Department of Mechanical Engineering, Ahmadu Bello
University, Zaria. © 2019 Faculty of Technology Education, ATBU Bauchi. All rights reserved
83
JOURNAL OF SCIECNCE TECHNOLOGY AND EDUCATION 8(3), SEPTEMBER, 2020
ISSN: 2277-0011; Journal homepage: www.atbuftejoste.com
DG/PV/Battery system. In a pure renewable
system (PV/Battery system), the size of the
PV panel and battery required is significantly
higher than those of the currently installed
DG/PV/Battery system and optimized
DG/PV/Battery system. It can further be
seen from table 1 that the currently installed
DG/PV/Battery system is oversized when
compared to the optimized DG/PV/Battery
system. This will lead to higher capital and
operational cost.
years period. When the battery is installed
with DG (i.e. DG/Battery system), the hour of
operation of the generator will decreased by
about 37% (when compared to DG only
system) leading to the reduction of the
number of 4.1 kW generator from 14 to 9
DGs. This will also lead to reduction the
amount fuel used and generator
maintenance cost. Five generators (4.1 kW
each) will be required in the optimized
DG/PV/Battery system, as compared to two
DG (17 kW each) required in the installed
Table 1: System configuration of the installed facility and optimized systems
Installed
Optimized configurations
facility
DG/PV/Battery
DG
DG/Battery PV/Battery DG/PV/Battery
Diesel Generator
4.1
4.1
4.1
17 kW
Capacity
2521
4941
7857
Hours
of 1196
704
961
364
1082
operation/yr
5.95
3.04
1.91
Number
of 12.5
starts/yr
Operational life
PV panel
3.5 kW
14.3
3.19
Battery
Total Number
24
8
80
12
String Size
4
4
4
4
Strings in parallel
6
2
20
3
Bus voltage
48
48
48
48
The electricity production from
different power systems considered in this
work is summarized in table 2. The least
excess electricity is produced in DG/Battery
system while the PV/Battery system
produced the highest excess electricity of
13,622 kWh. This implies that electricity
power wastages is minimal in DG/Battery
system since excess electricity produced is
not used by the telecommunication system.
The installed DG/PV/Battery system has the
least capacity factor of 6.42%. This implies
that the installed system is highly underutilized when compared to other systems
considered. The optimized DG/PV/Battery
system that has similar configuration to the
installed system has capacity factor of 16.88
%. This is due to lower capacity of the power
components such as the DG, PV and battery
systems in the optimized system as
compared to those in installed system. For
instance, the number of battery suggested
by the optimized configuration is half of the
installed number on site. The reduced
battery system capacity and DG capacity
increases the utilization factor of the
optimized DG/PV/Battery system.
Corresponding author: Sanusi, Y. S.
yinkasan@yahoo.com
Department of Mechanical Engineering, Ahmadu Bello
University, Zaria. © 2019 Faculty of Technology Education, ATBU Bauchi. All rights reserved
84
JOURNAL OF SCIECNCE TECHNOLOGY AND EDUCATION 8(3), SEPTEMBER, 2020
ISSN: 2277-0011; Journal homepage: www.atbuftejoste.com
Table 2: Electricity production of the installed facility and optimized systems
Installed
Optimized configurations
facility
DG/PV/Battery
DG
DG/Battery PV/Battery DG/PV/Battery
Electricity
10386 9189
Production
10409
23540
10785
Total
electricity 976
1,626 18.4
13622
551
Produced
6.42
28.9
25.6
18.8
16.88
Excess electricity
Capacity factor (%)
the recommended system is lower than the
presently installed system by about 24%.
Analysis of the presently installed
DG/PV/Battery system and recommended
system (i.e. optimized DG/PV/Battery
system) shows that the two systems have
similar capital expenditure (CAPEX). The
installed system has higher number of
batteries and PV panel capacity while it has
lower number of replaceable diesel
generators compared to the recommended
system over the 25 years period considered
in this work. The higher capacity of the
presently installed system (Battery, DG and
PV panel) when compared to the
recommended system, is responsible for its
higher operation and maintenance cost
(OMEX) and Fuel cost. These costs are the
major contributors to the higher NPC and
cost of electricity in the installed system.
The cost breakdown of the installed
facility and optimized systems are given in
table 3. The PV/Battery system has the
highest NPC and COE. The capital cost is the
dominant cost of the PV/Battery system
contributing about 87.5% of total facility
cost. This implies that the installed
DG/PV/Battery system is more viable than
pure renewable energy source (i.e.
PV/Battery). The installed system is also
more cost effective than DG only system.
Unlike in PV/Battery system in which capital
cost is the dominant cost of the NPC. The
fuel cost contributed about 60% of the NPC
in the DG only system. The optimized
PV/Battery/DG gave the least NPC and COE.
This implies that this system is the most
viable of all the system considered in the
present
study
and
is
therefore
recommended for installation at the studied
telecommunication substation. The COE of
Table 3: Cost of the installed facility and optimized systems
Installed
Optimized configurations
facility
DG/PV/Battery
DG
DG/Battery PV/Battery DG/PV/Battery
Cost ($)
51291
68795 60815
97344
63600
Net present cost
27078
85156
27503
15082 19921
CAPEX
5972
12188
10505
OMEX
12493 8891
18241
0.00
25592
Fuel cost
41220 32003
0.453
0.86
0.596
COE
0.607 0.537
Corresponding author: Sanusi, Y. S.
yinkasan@yahoo.com
Department of Mechanical Engineering, Ahmadu Bello
University, Zaria. © 2019 Faculty of Technology Education, ATBU Bauchi. All rights reserved
85
JOURNAL OF SCIECNCE TECHNOLOGY AND EDUCATION 8(3), SEPTEMBER, 2020
ISSN: 2277-0011; Journal homepage: www.atbuftejoste.com
Figure 4 shows the cumulative cost
of the optimized systems. The jump
observed in the PV/Battery system is due to
the replacement cost of one of the major
components (batteries) of the system. It can
be seen from the figure that the optimized
DG/PV/Battery system with higher initial
cost when compared to the DG only and
DG/Battery systems has the lowest
cumulative cost at the end of the 25 years
period. This is due to the fact that DG only
and DG/Battery systems has diesel fuel as
their energy sources compared to optimized
DG/PV/Battery system that has solar and
diesel fuel as its energy sources. The break
even cost of optimized DG/PV/Battery
system over the DG only and DG/Battery
systems is observed at the end of the third
year and seventh year respectively. This
means that though the initial cost of
optimized DG/PV/Battery system is seven (7)
times more than that of the DG only system,
the fuel cost incurred in running the DG only
system would have been more than the
cumulative cost for the optimized
DG/PV/Battery system at the end of the
third year of the site operation. Thus, the
optimized DG/PV/Battery system became
more profitable than DG only and
DG/Battery systems at the end of the third
year and seventh year respectively.
Cummulative cost ($) X 1000
160
G
140
DPB
GB
PB
120
100
80
60
40
20
0
0
5
10
15
20
Number of year
Figure 4: Cumulative cost of different optimized
25
power configurations. As shown in Table 4,
all the emission parameters are highest
when running the site purely on DG. The
least value are obtained in the
recommended configuration (Optimized
DG/PV/Battery system). It is important to
note that no emission parameters are
reported in PV/Battery configuration since
no fossil fuel was used.
Nigeria is signatory to Kyoto
protocol on carbon emission (Ayoola, 2011),
there is however no enforceable regulation
on carbon emission especially in the power
sector. Therefore, the carbon credit that
supposed to accrue to the usage of
renewable energy is not applicable in the
financial analysis in this work. It is however
important to note the emission for different
Corresponding author: Sanusi, Y. S.
yinkasan@yahoo.com
Department of Mechanical Engineering, Ahmadu Bello
University, Zaria. © 2019 Faculty of Technology Education, ATBU Bauchi. All rights reserved
86
JOURNAL OF SCIECNCE TECHNOLOGY AND EDUCATION 8(3), SEPTEMBER, 2020
ISSN: 2277-0011; Journal homepage: www.atbuftejoste.com
Table 4: Emissions of the installed facility and optimized systems
Installed
Optimized configurations
facility
DG/PV/Battery
DG
DG/Battery PV/Battery DG/PV/Battery
Emissions
4925
11128 8640
5825
Carbon dioxide
31
54.5
Carbon monoxide 39.5
70.1
1.35
1.6
2.38
Unburned
3.06
0.188
2.39
hydrocarbon
0.425 0.33
12.1
21.2
Particulate matter 14.3
27.3
29.2
44.9
51.2
Sulphur dioxide
65.9
Nitrogen oxide
RECOMMENDED DG/PV/BATTERY SYSTEM
The recommended configuration
(Optimized DG/PV/Battery system) has the
lowest COE and emissions. The technical
data of components in the recommended
(optimized PV/Battery/DG) system is
summarized in Table 5.
Table 5: Technical Data for the recommended DG/PV/Battery system.
PV
Panel type
Flat plate
Rated capacity
1 kw
Temperature coefficient
-0.5%/oC
Nominal operating cell temperature
47oC
Efficiency at standard test
13 %
Battery
Battery type
Lead acid
Nominal voltage
12 V
Nominal capacity
1 kWh
Maximum capacity
80A
Depth of discharge
40 %
Diesel generator
Capacity
4.1 kW
Fuel curve slope
0.1 L/kWh
Life time
15,000 h
Battery
27%
Diesel
Generator
61%
PV Panel
12%
Figure 5: Cost break down of optimized PV/DG/Battery system.
Corresponding author: Sanusi, Y. S.
yinkasan@yahoo.com
Department of Mechanical Engineering, Ahmadu Bello
University, Zaria. © 2019 Faculty of Technology Education, ATBU Bauchi. All rights reserved
87
JOURNAL OF SCIECNCE TECHNOLOGY AND EDUCATION 8(3), SEPTEMBER, 2020
ISSN: 2277-0011; Journal homepage: www.atbuftejoste.com
The net present cost and cost of
electricity production for the recommended
DG/PV/Battery system are obtained as
$51,291 and $0.453 respectively. The cost
breakdown of the system shows that the
cost of operating the Diesel generator (i.e. its
Capital cost, maintenance cost and fuel cost)
dominated the NPC of electricity generation
a)
as shown in Fig. 5. The cost of the fuel
(diesel) is the major part of the annualized
Diesel generator cost. This implies that any
change in the Diesel price will affect the COE
for the recommended system. In section 4.2,
the sensitivity analysis of the NPC and COE
were reported.
Diesel Generator
b) PV Panel
Figure 6: Hourly power output from primary energy sources (kW) over a period of 360 days
solar radiation due to non-favorable
weather conditions. During the non
favourable weather conditions, power is
produced by diesel generator as seen in zone
B in Fig. 3b. Zone A is dominated by nondiesel power generation. This zone also falls
into non-solar period. This implies that
electricity
is
supplied
to
the
telecommunication system by stored energy
in the battery.
The hourly power production from
the diesel generator and PV system in the
recommended system for a whole year is
shown in Fig. 6. The power production from
the PV Panel occurs during the day (sunrise
to sunset) due to the availability of solar
radiation during this period and depicted by
the colourful zone between the hour of 6
and 18. There are however some black strips
during the day time indicating there is lack of
Corresponding author: Sanusi, Y. S.
yinkasan@yahoo.com
Department of Mechanical Engineering, Ahmadu Bello
University, Zaria. © 2019 Faculty of Technology Education, ATBU Bauchi. All rights reserved
88
JOURNAL OF SCIECNCE TECHNOLOGY AND EDUCATION 8(3), SEPTEMBER, 2020
ISSN: 2277-0011; Journal homepage: www.atbuftejoste.com
Sensitivity Analysis
The price of diesel is subject to
review by the federal government of Nigeria.
The sensitivity analysis of the diesel price on
the NPC and COE was carried out and shown
in Figure 7. As expected, an increased diesel
fuel cost increases the NPC and COE. For 100
% price increase in diesel fuel the COE
however increases by about 30%. This is due
NPC
LCOE
0.5
0.7
0.9 Cost ($/Litre)
1.1
Diesel
1.3
1.5
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Levelized cost of
electricity ($/kWh)
Net present cost ($ X
1000)
70
60
50
40
30
20
10
0
to the fact that the integration of the
PV/battery to the DG cushions the direct
effect of the increased fuel price on the COE.
For 100% increase in the price of diesel fuel
in the recommended system (i.e. $1.5/Litre),
its COE is still lower than COE obtainable in
PV/Battery and DG only systems (at $
0.75/Litre).
Figure 7: Hourly power output from primary energy sources (kW) over a period of 360 days
CONCLUSIONS
Different hybrid system of diesel
generator/PV/battery power system were
designed, analyzed and compared with that
of a hybid diesel generator/PV/battery
power
system
installed
at
a
telecommunication substation located in
Mabushi, Abuja. Nigeria. The following
conclusions were drawn from the study.
1. The
installed
DG/PV/Battery
system
is
oversized
when
compared to the optimized DG only
system, DG/ Battery system and
DG/PV/Battery system. Analysis
shows that the required DG to
power the site is 4.1 kW as
compared to 17 kW installed at the
substation.
2. The
installed
DG/PV/Battery
system has the least capacity factor
of 6.42% as compared to the
optimized DG/PV/Battery system
(capacity factor of 16.88 %)
3.
4.
presented in this study. This implies
that the installed system is highly
under-utilized when compared to
other systems considered.
The optimized PV/Battery system
has the highest NPC and COE of
$97344 and $0.86 respectively. The
capital cost is the dominant cost of
the PV/Battery system contributing
about 87.5% to the NPC.
The optimized PV/Battery/DG gave
the least NPC and COE of $97344
and $0.86 respectively as compared
to the NPC and COE of $97344 and
$0.86 respectively for the presently
installed PV/Battery/DG power
system. This implies that the
optimized PV/Battery/DG system is
the most viable of all the systems
considered in the present study and
is therefore recommended for
installation
at
the
studied
telecommunication substation.
Corresponding author: Sanusi, Y. S.
yinkasan@yahoo.com
Department of Mechanical Engineering, Ahmadu Bello
University, Zaria. © 2019 Faculty of Technology Education, ATBU Bauchi. All rights reserved
89
5.
6.
JOURNAL OF SCIECNCE TECHNOLOGY AND EDUCATION 8(3), SEPTEMBER, 2020
ISSN: 2277-0011; Journal homepage: www.atbuftejoste.com
Alsharif, M. H., Nordin, R., & Ismail, M.
(2015). Energy optimisation of hybrid
off-grid system for remote
telecommunication base station
deployment in Malaysia. Eurasip
Journal on Wireless Communications
and Networking, 2015(1), 1–15.
https://doi.org/10.1186/s13638-0150284-7
Ayoola, T. J. (2011). Gas flaring and its
implication for environmental
accounting in Nigeria. Journal of
Sustainable Development, 4(5), 244.
Azimoh, Chukwuma Leonard, Patrik
Klintenberg, Fredrik Wallin, Björn
Karlsson, and C. M. (2016). Electricity
for development: Mini-grid solution
for rural electrification in South
Africa. Energy Conversion and
Management, 110, 268–277.
Baneshi, Mehdi, and F. H. (2016). Technoeconomic feasibility of hybrid
diesel/PV/wind/battery electricity
generation systems for nonresidential large electricity consumers
under southern Iran climate
conditions. Energy Conversion and
Management, 127, 233–234.
Cristóbal-Monreal, Iván R., R. D.-L. (2016).
Optimisation of photovoltaic–diesel–
battery stand-alone systems
minimising system weight. Energy
Conversion and Management, 119,
279–288.
Dufo-López, Rodolfo, Iván R. CristóbalMonreal, and J. M. Y. (2016).
Optimisation of PV-wind-dieselbattery stand-alone systems to
minimise cost and maximise human
development index and job creation.
Renewable Energy, 94, 280–293.
Feng, D., Jiang, C., Lim, G., Tutorials, L. C.-…
S. &, & 2012, undefined. (n.d.). A
survey of energy-efficient wireless
communications. Ieeexplore.Ieee.Org.
Retrieved from
https://ieeexplore.ieee.org/abstract/
The sensitivity analysis of the diesel
price on the COE in the
recommended system shows that
for 100 % price increase in diesel
fuel, the COE increases by about
30%. This is due to the fact that the
integration of the PV/battery to the
DG cushions the direct effect of the
increased fuel price on the COE.
The recommended configuration
(Optimized DG/PV/Battery system)
also has the lowest emissions
beside the pure renewable system
(optimized PV/Battery system).
REFERENCE
Agarwal, Nitin, and A. K. (2013).
Optimization of grid independent
hybrid PV–diesel–battery system for
power generation in remote villages
of Uttar Pradesh, India. Energy for
Sustainable Development, 17(3), 10219.
Ahadi, Amir, Sang-Kyun Kang, and J.-H. L.
(2016). A novel approach for optimal
combinations of wind, PV, and energy
storage system in diesel-free isolated
communities. Applied Energy, 170,
101-115.
Ahmed, F., Naeem, M., Ejaz, W., Iqbal, M.,
Anpalagan, A., & Kim, H. S. (n.d.).
Renewable Energy Assisted Traffic
Aware Cellular Base Station Energy
Cooperation.
https://doi.org/10.3390/en11010099
Akhtari, Mohammad Reza, and M. B.
(2019). Techno-economic assessment
and optimization of a hybrid
renewable co-supply of electricity,
heat and hydrogen system to enhance
performance by recovering excess
electricity for a large energy
consumer. Energy Conversion and
Management, 188, 131–141.
Alsharif, M. (2017). A solar energy solution
for sustainable third generation
mobile networks. Energies, 10(4), 429.
Corresponding author: Sanusi, Y. S.
yinkasan@yahoo.com
Department of Mechanical Engineering, Ahmadu Bello
University, Zaria. © 2019 Faculty of Technology Education, ATBU Bauchi. All rights reserved
90
JOURNAL OF SCIECNCE TECHNOLOGY AND EDUCATION 8(3), SEPTEMBER, 2020
ISSN: 2277-0011; Journal homepage: www.atbuftejoste.com
Oviroh, Peter Ozaveshe, Tien-Chien Jen,
Nosa Idusuyi, and O. G. (2017).
Comparative Energy Cost Analysis of
Hybrid System and Diesel Generator
in Powering Selected Base Transceiver
Stations in Nigeria. ASME 2017
International Mechanical Engineering
Congress and Exposition. American
Society of Mechanical Engineers
Digital Collection.
Sanusi, Yinka S., Esmail MA Mokheimer,
and M. A. H. (2017). Thermoeconomic analysis of integrated
membrane-SMR ITM-oxy-combustion
hydrogen and power production
plant. Applied Energy, 204, 626-640.
Shaahid, S. M., and I. E.-A. (2009). "Technoeconomic evaluation of off-grid hybrid
photovoltaic–diesel–battery power
systems for rural electrification in
Saudi Arabia—a way forward for
sustainable development. Renewable
and Sustainable Energy Reviews,
13(3), 625–633.
SMA Intelligence Data. (2017). Retrieved
from SMA Intelligence Data website:
https://www.gsmaintelligence.com/m
arkets/2481/dashboard/
Vishnupriyan, J., and P. S. M. (2018).
Prospects of hybrid photovoltaic–
diesel standalone system for six
different climate locations in Indian
state of Tamil Nadu. Journal of
Cleaner Production, 185, 309–321.
document/6157574/
Goel, Sonali, and S. M. A. (2014). Cost
analysis of solar/wind/diesel hybrid
energy systems for Telecom tower by
using HOMER. International Journal of
Renewable Energy Research, 4(2),
305–311.
HOMER Pro User Manual. (2016). Retrieved
July 16, 2019, from
https://www.homerenergy.com/pdf/
%0AHOMERHelpManual.pdf
Kusakana, K. (2015). Operation cost
minimization of photovoltaic–diesel–
battery hybrid systems. Energy, 85,
645–653.
Maatallah, Taher, Nahed Ghodhbane, and
S. B. N. (2016). Assessment viability
for hybrid energy system
(PV/wind/diesel) with storage in the
northernmost city in Africa, Bizerte,
Tunisia. Renewable and Sustainable
Energy Reviews, 59, 1639–1652.
Mancuso, Vincenzo, S. A. (2011). Reducing
costs and pollution in cellular
networks. IEEE Communications
Magazine, 49(8), 63–71.
Nkordeh, N., Bob-Manuel, I., & Olowononi,
F. (n.d.). The Nigerian
Telecommunication Industry: Analysis
of the First Fifteen Years of the
Growths and Challenges in the GSM
Market (2001-2016).
Olatomiwa, L., Mekhilef, S., Olatomiwa, L. J.,
Mekhilef, S., & Huda, A. S. N. (2014).
Optimal Sizing of Hybrid Energy
System for a Remote Telecom Tower:
ACase Study in Nigeria MPPT Method
for Partially Shaded PV System View
project Selective harmonic elimination
in inverters using bio-inspired
intelligent algorithms View project
Optimal Sizing of Hybrid Energy
System for a Remote Telecom Tower:
A Case Study in Nigeria.
https://doi.org/10.1109/CENCON.201
4.6967509
Corresponding author: Sanusi, Y. S.
yinkasan@yahoo.com
Department of Mechanical Engineering, Ahmadu Bello
University, Zaria. © 2019 Faculty of Technology Education, ATBU Bauchi. All rights reserved
91