OPTIMIZATION AND A COMPARISON BETWEEN RENEWABLE AND NON-
RENEWABLE ENERGY SYSTEMS FOR A TELECOMMUNICATION SITE
Mohamed El Badawe¹, Tariq Iqbal and George K. Mann
Faculty of Engineering and Applied Science, Memorial University of Newfoundland
¹Corresponding author: m.elbadawe@mun.ca
ABSTRACT
The renewable energy based hybrid energy system is the
better solution to deal with environment pollution. It can
also be used to provide power to stand alone applications,
such as telecommunication sites, that are located in remote
and rural areas. The aim of this paper is to optimize and
compare a non-renewable energy system with a renewable
energy system for a particular telecommunication site in
Mulligan, Labrador, Canada. The current system works by
using diesel generator and batteries and the proposed system
is a combination of wind and solar with the existing diesel
generator and batteries. Hybrid Optimization Model for
Electric Renewable (HOMER) software is used to obtain the
most feasible configuration of a hybrid renewable energy
system. The results show the hybrid renewable energy
system is more cost effective and better for the environment
over the diesel generator because it reduces the running time
of diesel generator and also reduce the emissions. It is
expected that the proposed system and other similar
configurations will help the Bell Aliant to provide
uninterrupted power for their sites in remote areas of
Labrador.
Index Terms— renewable energy systems; non-
renewable energy system; feasibility study; hybrid power
systems; photovoltaic; wind turbine; diesel generator.
1. INTRODUCTION
The oil crises started in the beginning of 1970s, since that
date the world has been experiencing the higher prices of the
conventional fuel as well as negative impacts on the
environment. In the last few years some oil countries
reported that the fossil fuel started in depletion which is
going to lead to a higher prices of oil. Moreover, the
industrialized countries reported that the world already has
seen many environmental issues such as toxic gases that
produced from the fossil fuel after burned which will cause
air pollution then global warming. Toxic gases such as
sulfur oxides (SOX), nitrogen oxides (SOX), and the most
dangerous one is carbon dioxide (CO2) because it is the
main gas for greenhouse effect and it is not easy to control.
On the other hand, the energy consumption around the
world has been increasing while the fossil fuel has been
decreasing. All the above reasons have led engineers and
environments to find a sustainable and friendly environment
solution and focus on renewable energy [1],[3],[6],[7].
Renewable energy is electricity supplied from
renewable energy sources, and the renewable hybrid energy
system is a system that contains two or more renewable
energy sources. Renewable energy sources such as wind,
solar, geothermal, tides, hydropower, and various forms of
biomass. Wind and solar are the most interest areas in
renewable energy these days. Renewable energy is very
important to overcome the negative impacts on the
environment and oil prices. Most importantly, renewable
energy is very important to generate a power for remote
communities and remote service places such as
telecommunication repeaters [4], [5].
These alternative sources usually are integrated
with diesel generator to provide a suitable reliability of the
system to power loads. The most popular alternative sources
are wind and Photovoltaic (PV), but they are seasonal
sources which can’t provide a continuous power to loads.
Also, these power source produce fluctuating power.
Therefore, diesel generator and batteries are using as a
backup for long-term and short-term power storage
respectively in most of remote areas applications [2],[4],[8].
The aim of this paper is to optimize and compare a
non-renewable energy system (existing system) with a
renewable energy system (proposed system) for a particular
telecommunication site in Mulligan, Labrador, Canada. A
non-renewable energy system currently is working by using
diesel generator and batteries. Taking this system step
further by adding renewable energy sources wind and
photovoltaic to provide an uninterruptible power to remote
telecommunication facilities, will lead to a reduction of
diesel generator run times. This paper also shows the pre-
feasibility of the proposed hybrid renewable energy system
and the results show the cost effectiveness of the proposed
system.
2. ELECTRICAL LOAD
Data Synthesizer is used to generate the load data, and then
use it in HOMER. The approximately power consumption at
Mulligan site is 79.5kWh/day with 3.9kW peak and the
system runs on 48V DC bus. Telecommunication companies
are working very hard to provide an uninterruptable power
to their sites and provided a service with high quality
throughout the year. Therefore, the hourly load is almost a
constant, as the power consumption remains same. Bell
Aliant telecommunication site load profile is shown in
figure 1 which is produced by HOMER.
Figure 1. Load profile for Mulligan site
3 . RENEWABLE ENERGY RESOURCES
The most important factor in developing the hybrid energy
system is the location where is the system will be used.
Choosing such a place depends on the availability of the
renewable energy resources. Some resources are available in
specific places for most of the time such as hydro, and some
resources are available seasonally such as wind and
photovoltaic. Canada has imense renewable energy
recourse but at this particular place (Mulligan
telecommunication site) wind and solar energy are
abundantly available. Collecting weather data is one of the
main task for this pre-feasibility study for a renewable
energy system.
3.1. Solar Energy Resource
The latitude and longitude of Mulligan village are 53°.86'N
and 59°.92'W respectively with time zone GMT3:30
Newfoundland. The hourly solar radiation data is collected
for year from NASA website. The average solar irradiation
is only 2.85kWh/m²-d and sensitivity analysis is done with
three different values. Clearness index and the average daily
radiation for a year are shown in table I while figure 2
shows the solar radiation in a year produced by HOMER.
Figure 2. Monthly solar radiation
TABLE I. CLEARNESS INDEX AND AVERAGE DAILY
IRRADIATION FOR A YEAR
Month
Clearness Index
Daily Radiation
(kWh/m²-d)
January
0.496
0.950
February
0.525
1.760
March
0.509
2.890
April
0.502
4.200
May
0.474
4.980
June
0.421
4.830
July
0.412
4.530
August
0.442
4.040
September
0.418
2.750
October
0.412
1.660
November
0.458
1.020
December
0.427
0.650
3.1. Wind Energy Resource
The second renewable source implemented in the system is
wind. Wind data for this site is still under collection. So,
scaling up the wind speed data from windatlas.ca is used to
get the approximate wind speed at Mulligan’s
telecommunication site. Figure 3 shows the average hourly
wind speed for a year. The average wind speed is estimated
6.261m/s and for sensitivity analysis three values of wind
speed are chosen. The monthly average wind speed is shown
in table II.
TABLE II. MONTHLY AVERAGE WIND SPEED FOR A YEAR
Month
Wind Speed (m/s)
January
6.910
February
6.500
March
6.665
April
6.256
May
5.847
June
5.970
July
5.520
August
5.561
September
6.011
October
6.338
November
6.788
December
6.788
Figure 3. The average hourly wind speed for a year
4. SYSTEM OPTIMIZATION
The non-renewable energy system (existing system) and the
renewable energy system (proposed system) are simulated
in Homer software.
4.1. Non-Renewable Energy System
The existing system architecture is shown in figure 4 which
consists of a diesel generator and batteries to power the
load. A Perkins 404C-22G diesel generator with 25kW at
1800rpm is using there and the engine is rebuild every
15,000 hours. The initial capital cost is $16308, replacement
cost is $13590, and operational and maintenance cost is
$0.1/hr. Two strings of VRLA GNB XL3000 batteries are
using at Mulligan each battery is 2V and has a capacity
3000Ah with 48V total bus voltage. These batteries are
replaced every 10 years. The initial capital cost, replacement
coast, and maintenance and operation coast of all batteries
are $86000, $60000, and $100 respectively. A converter is
included in order to maintain the flow of energy between the
AC and the DC bus. The size of the convertor that is used in
this system is 7kW. The initial capital cost and replacement
cost are $2500 and $1500 respectively and maintenance and
operation coast is $100.
Figure 4. Existing power system at Mulligan
4.2. Renewable Energy System
The proposed hybrid renewable energy system is shown in
figure 5 which consists of the existing power system, wind
turbine, and photovoltaic. The proposed system is going to
reduce diesel fuel consumption and associated operation and
maintenance cost. In this system the wind turbines and PV
will be the primary power source and diesel generator will
be using as a backup for long term storage system and
batteries for short term storage system.
Figure 5. Proposed hybrid power system for Mulligan
4.2.1. Solar Panels
STP280-24/Vd solar modules are used in this system and
each module panel provides 280W with 24V. Therefore, two
PV modules are connected in series to meet the bus voltage
which is 48V. A total of 5.6kW PV rated capacity is used in
this system. Modules are connected in 10 strings each string
has two modules with twenty modules in total. The initial
cost of each two panels connected in series is $1745,
replacement cost is $1342, and operational and maintenance
cost is $52.
4.2.2. Wind Turbine
Two BWC-Excel-R/48 are used in this system. Each one has
rated capacity 7.5kW and provides 48V DC. The initial
capital cost $23081, replacement cost is $17000, and annual
operation and maintenance cost is $462 for each one. The
technical parameters of wind turbine are obtained from
Bergey Windpower. The hub and anemometer are located at
30m height.
5. RESULTS AND DISSCUSSION
Both systems are simulated in HOMER software, and the
optimal results were obtained for each case. Figure 6 shows
the optimization result for the non-renewable energy system.
As shown in the figure the total Net Present Cost (NPC) is
$823,072. Diesel generator burns 12,672L of fuel per year
and annual generator run time is 1,536 hours. In twenty
years the diesel generator will burn 25,3440L of fuel. For
this site the diesel fuel can be transported only by a
helicopter. Therefore the total cost of diesel fuel at $5 per
liter, would be very high. The probability of fuel prices
increase is also high. The total cost is calculated with
constant price of fuel, which is $5 per liter. The total fuel
cost during these 20 years will be $1,267,200 and the total
cost for the whole system will be $2,090,272. Figure 7
shows the monthly average electric production of the system
which is totally produced by diesel generator.
Figure 6. Optimized result for the non-renewable energy system
Figure 7. Monthly average electric production for non-renewable energy
system
The renewable energy based system was also simulated in
HOMER software with four sensitivity variables. These
variables are wind speed, solar irradiation, load, and diesel
price and each of these variables has three different values.
Therefore, 81 sensitivity cases have been tested for the
system. Figure 8 shows the optimized results for the
proposed system. The total Net Present Cost (NPC) is
$1,011,514. The system will consume only 335 liters of
diesel fuel per year and annual generator run time is
expected to be 145 hours. The lifetime of this system is 25
years, but 20 years life is used to make the comparison
between two systems. In twenty years the diesel generator
will burn 6,700L of fuel and it will cost $33,500. The total
cost of the system will be around $1,045,014. Figure 9
shows the monthly average electric production of the
system. Photovoltaic production is 14% with 6,403kWh/yr.
Diesel generator production is 2% with 1,052kWh/yr.
Finally, wind turbine is expected to supply the rest of the
load which is 84% with 38,325kWh/yr.
The difference cost between two systems is
$1,045,258 which is a very significant number for a small
system. Diesel generator run times are reduced and diesel
generator in the proposed system will produce only 2% of
the total power production. Moreover, the reduction of
yearly diesel fuel consumption from 12,672L to 335L has a
large impact on the environment and it will reduce the
helicopter trips to the site. Also, the diesel generator will
require less maintenance and operation cost and longer
period of service before a replacement.
Figure 8. Optimized result for the renewable energy system
Figure 9. Monthly average electric production for renewable energy system
5. CONCLUSION
This paper compares two different systems for providing
uninterruptible power for a telecommunication tower on a
remote site. This comparison based on the pre-feasibility for
each system is done using HOMER software. The first
system is non-renewable energy system and the second is
renewable energy system. The renewable energy based
proposed system is a combination of wind and photovoltaic
which is environment friendly system and it will save extra
cost associated with transporting diesel and maintenance.
Analysis indicates that a renewable energy system based
will cost $1,011,514 less in its expected life. Therefore, a
renewable energy based hybrid system is recommended for
Mulligan Labrador site.
6. ACKNOWLEDGMENT
The authors would like to thank Ministry of Education and
Scientific Research of the Great Socialist People’s Libyan
for giving the corresponding author a scholarship to do his
master degree at Memorial University of Newfoundland and
Mr. Stephen Smith of Bell Aliant for providing the site load
data, location, and configuration information.
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