International Journal of Mechanical Engineering and Technology (IJMET)
Volume 10, Issue 03, March 2019, pp.855-863. Article ID: IJMET_10_02_088
Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJMET&VType=10&IType=3
ISSN Print: 0976-6340 and ISSN Online: 0976-6359
© IAEME Publication Scopus Indexed
Sanni Timilehin F., Olajube Ayobami, Abdulkareem Ademola, Alabi Gideon
Electrical and Information Engineering department, College of Engineering,
Covenant University, Ota, Nigeria.
ABSTRACT
The challenge of climate change results primarily from the global use of fossil fuel. Renewable energy as alternative energy source allows the use of natural sources such as micro-hydro, wind; solar, and biomass that are sustainable to be explored.
The increase in the dependence on renewable energy calls for attention which can be solved by the use of energy management. Energy management will provide a consistent and controllable power supply. There is the need for the integration of energy management into the grid planning and design. In this work, Energy management using energy storage is thus considered as one design method for the system to maximize simplicity and increase reliability using HOMER, a conventional simulation tool.
Keywords : energy management, energy storage, homer, and solar energy.
Cite this Article : Sanni Timilehin F., Olajube Ayobami, Abdulkareem Ademola,
Alabi Gideon, Renewable Energy Towards a Sustainable Power Supply in the
Nigerian Power Industry: Covenant University as a Case Study, International Journal of Mechanical Engineering and Technology , 10(3), 2019, pp. 855-863 http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=10&IType=3
Energy is the bedrock for development. It determines and creates growth and increase in the technological, economical and health sectors of any nation [1,2]. In most developing countries, the citizens depend largely on the national grid for power supply. The grid becomes over-crowded based on the population especially in Nigeria which is one of the largely populated nation of Africa. However, there are still several remote areas that are not connected to the grid and those connected have low dependency on the grid due to irregularity of supply. This is because of the poor reliability of the nation‟s utility grid without neglecting the financial and environmental reasons. The vast of the remote dwellers depend on dieselgenerators which might not always be available and the urban dwellers who are able to afford
http://www.iaeme.com/IJMET/index.asp 855 editor@iaeme.com

Sanni Timilehin F., Olajube Ayobami, Abdulkareem Ademola, Alabi Gideon diesel contribute greatly to the high carbon dioxide emission. The carbon emission is increasing due to the unreliability of the national grid. This can be reduced by increase dependence on renewable energy via the integration of energy storage systems and energy management topologies. Amid the environmental problems of using gasoline and diesel generators, the cost of operation and maintenance is very high. However, the citizens of
Nigeria are will agree to change to the use of renewables but for the cost [3].
Nigeria is the number seven of the world's population review (approximately 196 million people in 2018) and 60% of the populace do not have access to the electricity. The lack of adequate energy supply is largely due to insufficient energy supply generation by the inefficient power plants. The most populous black nation in the world depends largely on the non-renewable energy sources for about 90% of its energy needs.
Most private organizations and industries run on-site diesel generators (dirty energy) as a reliable energy source. And this is mainly responsible for the high operating and maintenance costs which invariably raise the cost of production and sale of deliverables. Each of these problems minimize the reliability of the Nigerian power system. It has significantly impacted the manufacturing and communication industries negatively [4].
Renewable energy is generally considered an energy source that is inexhaustible, for example, wind, hydro, geothermal or solar power technologies . The central objective of energy management is to deliver energy in form of electricity with the minimum cost and slightest natural impact. Energy management is the planning of the use of energy for increased efficiency and reliability [5]. Energy management can also be defined as the use of strategies and control methods to achieve distribution of power supply. The major aims of energy management include maintaining optimum energy and reducing the impact of fossil fuel in the environment.
Covenant University, Ota, Nigeria, which is a case study in this research has a power plant capacity of 6 MW using a stand-alone gas turbine and 13 diesel generators up as backup which is achieved by spending huge amount of money [6]. This estimate does not include the cost of purchasing spare parts, oils and maintenance. Therefore, this research aims to reduce the running expenses to the current energy supply system using renewable energy storage technology. The system design and methodology used to achieve the objectives are provided.
HOMER is used to simulate the different system designs and the effects of both systems are analysed.
In developing countries, renewable energies aim to provide sustainable energy to the socially viable part of society, to tackle energy shortages, to promote rural infrastructural development and to provide clean energy. Renewable energy has become a dependable source of energy that has the capacity of meeting the energy needs of the generation to come. The growing popularity of the renewable energy sources is based on environmental concerns and the rapid rate of depletion of reserves of traditional energy resources as a result of heavy use.
Sustainable alternative energy solutions will eradicate environmental challenges and the energy crisis associated with fossil fuel [7]. Low access to electricity in a country results in increased poverty, poor economic performance, reduced employment opportunities.
Increase in population indicates an increase in energy demand in the country as depicted by the population increase and global industrial transformation of the twentieth century which led to an increase in energy demand [8]. Energy management is key to the efficient use of the energy produced. Some of the advantages are resource conservation, protect the climate and save money while having permanent access to energy. http://www.iaeme.com/IJMET/index.asp 856 editor@iaeme.com

Renewable Energy Towards a Sustainable Power Supply in the Nigerian Power Industry:
Covenant University as a Case Study
Figure 1 Percentage of energy consumption in Nigeria [9]
The use of renewable energy in Nigeria is minimal as can be seen in figure 1. A crucial reason for this study is to increase citizens of developing countries to buy into the advantages of renewable energy. This will take the form of policies, regulations, a legislative framework, license agreements for private operators, definitions of institutions and rules for the service and products of RE [10]. To improve investment potential and develop RE technologies in the country, incentives are needed through effective policy [11]. The high cost of installation is the main problem of renewable energy development in Nigeria. The solution is to stimulate the private sector to force the development of education and trainings. One way to do this is to put in place incentive policies, such as tariff definitions [12-14].
Nigeria can be described as a country that naturally has renewable and non-renewable energy resources. Renewable sources include biomass, wind power, solar energy and hydropower, with varying degrees of sustainable potential of 3.5-7.5 kW h/m
2
/day for solar radiation, 83 million tonnes/year for crop residues and 61 million tonnes/year for animal wastes to mention but a few [15].
The nation, Nigeria, has enough solar radiation to provide the energy used locally by rural residents who have a lower demand for electrical load. [16]. Solar energy is available in all parts of the world, and its potential as a renewable source is unlimited [17]. Many Nigerian scientists have conducted studies on the possible analysis of solar energy applications, many of which have indicated significant potential for use of resources.
Fig. 2 represents the photovoltaic potential of some regions of the country which includes
Port Harcourt, Uyere, Lagos, Abuja and Maiduguri.
With the results given, Maiduguri shows the highest solar photovoltaic potential followed by Sokoto. Other results include the Federal District in the north center, which has a capacity of 3000 watts / m 2 / day. In the southern axis where Port Harcourt has the least potential in
July but maintains a degree of value above the threshold. Other research has shown that during the period from June to August, the country is experiencing a significant decline in its potential due to cloudy environmental coverage caused rainy season. http://www.iaeme.com/IJMET/index.asp 857 editor@iaeme.com

Sanni Timilehin F., Olajube Ayobami, Abdulkareem Ademola, Alabi Gideon
Figure 2 Solar energy potential in Nigeria
For the basis of this research, Covenant University (CU) has been chosen as the case study because it can be referred to as a miniature city with a gas-powered supply station of 6MW rating and its major conventional load types. The main purpose of conserving this energy will foster less operating cost, reduced energy consumption, lesser lighting fixture replacement and less accrued heat generated by them, leading to an eco-friendly environment and making buildings environmentally sustainable.
The case study has had a major population growth of over 8529 students, 374 faculties and 502 non-academic staff. With the following population data as follows [18];

A residential capacity of 10 resident hostels with about 400 rooms per hostel

2 colleges, 6 schools and 22 departments.

University guest house, Library, Chapel, Lecture theatres.

Residential buildings (1-2-3-bedroom flats and duplex)
All these and more makes Covenant University not only a suitable case study but also can be regarded to as a mini-town.
With an energy audit carried out in Covenant University in the department of physical planning and development (PPD).
1000
800
600
400
200
0
Figure 3 Daily consumption of different buildings [18]. http://www.iaeme.com/IJMET/index.asp 858 editor@iaeme.com

Renewable Energy Towards a Sustainable Power Supply in the Nigerian Power Industry:
Covenant University as a Case Study
Electricity usage in a university campus differs in terms of load definitions and consumption patterns [19]. The factors include the building design, types of electrical appliances, types of lamps, and their power ratings. Figure 4 shows the electric power demand of Covenant University. Analysis of load demand and the use of smart metering is crucial to sustainable developments [20-22].
CST Building
21%
CDS Building
18%
Pet Engr.
9%
Chem Engr.
15%
Mech Engr.
15%
EIE Engr.
14%
Civil Engr.
8%
Figure 4 Percentage Consumption in various academic buildings
The system designed in this research is a hybrid system consisting of a photovoltaic system, conventional diesel system and battery storage. The converter is bidirectional, which maintains the power flow between AC and DC components, since the flow comes in two different directions DC and DC to AC. The flow from the solar system passes through the charging controller to charge the battery and at the same time to feed the electricity it transports through the inverter. The controller monitors charging and discharging the battery so that the battery is not damaged by overload or over-discharge.
Since this research is based on a detailed analysis of the energy flow which reveals the energy loss (charge controller, rectifier, battery and inverter) in the system and storage requirements. In addition, the developed model was used to determine the optimal measurement parameters for the PV system in which the results obtained were compared and tested with HOMER.
Figure 5 Modelled hybrid energy system http://www.iaeme.com/IJMET/index.asp 859 editor@iaeme.com

Sanni Timilehin F., Olajube Ayobami, Abdulkareem Ademola, Alabi Gideon
A microgrid model system consisting of Photovoltaics, diesel generator, and battery storage are included. The modelling methodology is described with the theoretical aspects below.
( ) (1)
(E
DEG
) = Hourly energy generated by diesel generator
(P
DEG
) = with a nominal power output;
( )
The rectifier model is given below;
(2)
( )
( ) ( )
(3)
(4)
At any time (t),
( ) = ( ) ( ) (5)
The model of the charge controller is given in equations 8 and 9, and the battery in equation 10.
( ) ( ) (8)
( ) ( ) ( ) (9)
During the charging process, when the total output of all the generators exceeds the load demand, the battery capacity of the bank available over time, t, can be described through;
( ) ( ) ( )
The depth of discharge (DOD) is,
(10)
( ) (11)
(12)
Homer software has an inbuilt function that calculates the data of the region you select. The coordinate selected was 6.6699
o
N, 3.1574
o
E which is the location of Covenant university.
The results downloaded were gotten from NASA datasets which was used in the research to determine the amount of solar irradiation available.
The calculated model is designed and used to build a hybrid system model (PV / diesel).
The data inputs for the program are the data dial for the hourly loading, latitude, longitude, and cost of the reference components. The program, which is designed according to the size of the system components (scalability parameters) and system performance throughout the year, is defined according to the energy provided by each energy system throughout the year. of the year. The program designed to study how to provide a hybrid system (PV / diesel) can be used.
10
5
0 http://www.iaeme.com/IJMET/index.asp 860 editor@iaeme.com

Renewable Energy Towards a Sustainable Power Supply in the Nigerian Power Industry:
Covenant University as a Case Study
Figure 6 Daily radiation available in covenant university
With the PV in the hybrid system, table 2 is the output of the PV generation method in the system.
Table 2 The table of PV in the hybrid system (kW)
January
February
March
April
May
June
TOTAL
Electricity generated
1538.295
1586.851
1498.562
1554.395
1488.347
1333.962
9131.135
Supplied to the load via inverter
987.628
971.97
1094.416
1045.61
1049.806
936.894
6086.324
Charging the battery directly
239.282
199.718
232.446
219.627
221.725
215.577
1328.375
With the diesel generator in the hybrid system, table 3 describes the output of the generation method.
Table 3 Electricity received by the inverter and supplied to the AC load (kW)
January
February
March
April
May
June
TOTAL
Electricity generated
1177.104
1016.936
1096.767
1074.702
1143.499
1188.892
6697.9
Supplied to the load directly
874.649
724.017
792.623
781.803
826.317
867.973
4867.382
Charging the battery via the rectifier
299.517
289.982
301.472
289.705
314.101
313.288
1808.065
This section explains the derived results from the HOMER software and includes the technical terms such as the battery charge, supply, excess, losses, and consumption in kW.
With regard to power supply and battery charging, the electric current supplies electrical power through the inverter, and charges the battery directly, while the oil generator directly feeds electricity to the AC load and charges the battery through the rectifier as shown in the table 4.
Table 4 Electricity generated and supplied and battery charge by the PV in hybrid system in (kw)
Months
JAN
FEB
MAR
APR
MAY
JUN
Electricity generated
2715.399
2527.428
2802.411
2629.097
2522.854
2544.529
Supplied to the load
1862.277
1695.987
1887.039
1827.413
1876.123
1804.867
Charging the battery
538.799
489.7
533.918
509.332
535.826
528.865
Losses
0.159
0.154
0.154
0.146
0.179
0.177
Excess electricity generated
314.164
341.587
381.3
292.206
219.718
188.945 http://www.iaeme.com/IJMET/index.asp 861 editor@iaeme.com

Sanni Timilehin F., Olajube Ayobami, Abdulkareem Ademola, Alabi Gideon
Total 15741.718 10953.706 3136.44 0.969 1737.92
The hybrid system can fully meet load demand for example in January, the electricity generated was 2715.399 kW as seen in Table 4, to meet an expected demand of 2148.238 kW and still charges the battery.
The design of a stand-alone hybrid power system using energy storage is the summary of work done. This is proposed to solve one of the priorities of the United Nations which is climate change [2]. It is noted that the combination of PV solar array, battery storage, and a diesel generator can fully minimize the dependence on diesel resource which in turn reduces the amount of carbon emission. It is also important to note that the use of the hybrid system might not significantly reduce the net present cost (NPC) but it has been able to cut down the dependence on diesel which reduces the greenhouse effect.
The authors wish to acknowledge Covenant University, Canaanland, Ota, Nigeria for sponsoring this research work.
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Covenant University as a Case Study
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