ENERGY AUDIT ON OBAFEMI AWOLOWO UNIVERSITY

Transcription

1 Proceedings of the OAU Faculty of Technology Conference 2015 ENERGY AUDIT ON OBAFEMI AWOLOWO UNIVERSITY M. B. Toyinbo*, F. K. Ariyo, T. Olowu and M. O. Omoigui Department of Electronic and Electrical Engineering Obafemi Awolowo University, Ile-Ife, Nigeria. * of Corresponding Author: ABSTRACT This paper presents an energy audit carried out on Obafemi Awolowo University community with the halls of residence and Academics areas as the case study. To analyze, verify and monitor the use of electrical energy, and introduce Energy Conservation Measures (E.C.M.) aimed at ensuring optimum utilization of energy in the university community.two sets of data were collected and analyzed; they were the power control room data at the peak period (Rating on each of the six feeders used by the university community per hour), each generator data (rating) and solar inverter requirement. The data from the power control room at the peak period is to be compared to an estimated solar power generation requirement putting the following factors into consideration; cost effectiveness, useful life, cost of maintenance and availability. The data analyses were carried out using MATLAB and HOMER (Hybrid Optimization of Multiple Electric Renewables) software. The results of the analysis show the necessity of implementing energy conservation and management method because the economic analysis of each energy source is not viable. Keywords: Renewable Energy, Audit, HOMER Simulation, Economic Analysis, Conservation, Management. INTRODUCTION Although energy cannot be created or destroyed, it can be wasted if adequate measures are not taken to ensure conservation. Energy audit is a process of checking the way energy is used and identify areas where wastage can be minimize if not totally eradicated. Energy audit consists of several tasks which can be carried out depending on the type of audit and the function of audited facility. It started with review of historical data of energy consumption which can be compiled from the electricity bills. This data is important in order to understand the patterns of energy used and their trend (Das, 2006). Energy audit attempts to balance the total input of energy with its use.energy Auditing is the process for accessing energy usage by individual energy-consuming device on a residential or commercial scale. It is a detailed examination of a facility s energy usage and costs with a view to making appropriate recommendations on energy conservation which ultimately reduce energy cost by implementing equipment and operational changes (Glover, et al., 2008). Energy audit identifies how and where electrical energy is purchased and utilized; the various loads in the facility; areas where energy is used at variance with economical standard. Summarily, energy audit focuses on where, when, why and how energy is used in a facility, the community of Obafemi Awolowo University, Ile Ife. Energy audit attempts to strike a balance between energy cost and consumer comfort thereby preventing a trade-off of residents comfort at the table of financial gain.the Energy demand of a nation depends on the population, level of industrialization and period of the day (peak or off-peak). It is estimated that, to ensure adequate power supply, Nigeria requires about 40,000 MW as against less than 5000MW currently generated. The objective of this work is to analyze the different energy source on campus and ascertain the economic viability of each, thereby providing an energy conservation method. EXPERIMENTAL PROCEDURE The Energy Audit of a building is usually conducted in three phases, the first phase is preparing for the audit visit, during which data from energy meters are collected and analyzed to determine the energy consumption and how it varies with time. It also involves gathering preliminary information on facilities to be audited. The second phase involves facility inspection, during which valuable information on how to reduce energy waste as well as improving occupants comfort in a building. This involves identification of areas of ineffective operation of energyconsuming equipment. The third stage is the adoption of energy conservation measures. This is based on the implementation of the recommendation of the audit report. HOMER simulates the operation of a system by making energy balance calculations in each time step of the year. For each time step, HOMER compares the electric and thermal demand in that time step to the energy that the system can supply in that time step, and calculates the flows of energy to and from each component of the system. For systems that include batteries or fuel-powered generators, HOMER also help decides which of the energy source is economically viable. THEORETICAL DEVELOPMENT The maximum power on each feeder per day is calculated using the formula below (1) 446

2 ( ) (2) Where, is the phase apparent power, is the phase voltage, Is the phase Current, Is the line voltage. For the purpose of this particular energy audit that would be carried out, the values for, would be the maximum value recorded for a particular day so as to know the maximum power that can be used Blue Yellow Red Fig 1. Line Representation of Power (kva) consumption on each Feeder EXPERIMENTAL PROCEDURE FOR THIS STUDY Three sets of data were collected and analysed, they were the power control room (Obafemi Awolowo University) data at the peak period, generator data (rating) and solar inverter requirement using HOMER (Hybrid Optimization of Multiple Electric Renewables) software. HOMER performs these energy balance calculations for each system configuration that you want to consider. It then determines whether a configuration is feasible, i.e., whether it can meet the electric demand under the conditions that you specify, and estimates the cost of installing and operating the system over the lifetime of the project. The system cost calculations account for costs such as capital, replacement, operation and maintenance, fuel, and interest. RESULTS AND DISCUSSION Data Analysis for halls of Residence The energy consumed at the halls of residence is determined using the formula stated below: Given the average maximum current per hour on feeder 3B supplying the halls of residence, the estimated energy demand at the halls of residence is Estimated power demand (Total Power) (3) Therefore total power1.022 MVA. Load Profile The load profile Simulation is carried out with HOMER software Solar Radiation Profile Figure below shows the solar resources profile over one year. The solar resource data for Osun, Nigeria was obtained from NASA surface Meteorology and solar energy website. The approximate location of the site is about 4 40' east of the Prime Meridian or longitude 0 and 7 30' north of the equator. Fig 2.Halls of Residence Load profile simulation 447

3 Fig 3.Halls of Residence Baseline data profile chart. Fig 4. Halls of Residence Solar radiation profile Economic Analysis All calculations are done with exchange rate of $1 to N190. The tariff of the utility company in Nigeria, The Power Holding Company of Nigeria (PHCN) known as Ibadan Electricity Distribution Company places the Universities under special class A2 with demand is N18.52 per kwh ($0.109) with a maximum demand fixed charge of N33, Constraints are conditions which a system must satisfy for it to be feasible. HOMER discards systems that do 448 not satisfy the specific constraints so that they do not appear in the optimization or sensitivity result. Maximum capacity shortage is set at 5% (HOMER, 2010). A survey of the whole university community electricity consumption pattern showed that the average consumption per month is Daily tariff ( 18.52) (4) monthly tariff Daily tariff 30 (5)

4 Fig 5. Halls of Residence Generator Fuel flow simulation Fig 6. Halls of Residence Generator Efficiency simulation. Considering the halls of residence; monthly tariffdaily KWh( ) 0.7 Where 0.7 is the campus supply factor (supply from national grid) The maximum energy consumed at the halls of residence is determined as follows: Given the maximum current per hour on feeder 3B supplying the halls of residence, 449 the estimated energy demand at the halls of residence is MVA which equals KVA monthly tariff hrs ( ) 0.7 N 9,795, per month. The average yearly tariff of the halls of residence will be around N60 million

5 Generator as alternative supply Assuming a running period of 8 hours per day; The operating cost Running cost + Maintenance cost Total fuel required per hour 120litres of diesel. 1litre of diesel N 120 Total fuel required for 8 hour litres Running cost (960litres N 120) N Monthly Running cost (N 115,200 30) N 3,456,000 Maintenance cost (10% Capital cost) N 3,500,000 Yearly. The yearly operating cost is therefore estimated to be around N 45 million which is greater the capital cost. Solar powered Inverter system as an alternative supply This study is being conducted with the aim of developing a standard procedure for the design of large-scale institutional solar PV (Photovoltaic) systems using the roofs of buildings and car parks. The standard procedure developed will be validated in the design of a 1MW solar PV system for Obafemi Awolowo University, Ife. The performance of the 1MW grid-connected solar PV system will also be simulated over the guaranteed life of the system using solar PV planning and HOMER software. The study is necessary because Nigeria has experienced a number of power crises over the last two decades, mainly due to the heavy reliance on the other conventional means of power generation which is has some peculiar problems and also might not be environmentally friendly. The project began by a simple prefeasibility study to obtain an idea of the amount of energy that will be generated by the system, estimate the total space (area) required for the installation of the system and access the economics of the whole project as follows solar capacity required ( ) ( 1.2) (6) ( 1.2 ) MW Solar module specification and cost Sharp ND-240QC, output power240w, open circuit voltage37.6, maximum output voltage29.3v, maximum output current8.19a, maximum system voltage600v, cost$252. Number of modules required Inverter requirement Grid tie trestech 100KVA three phase solar inverter, output power100kw, input voltage620vdc, output voltage415vac, cost $12000 Units required 1000 kw 100 kw Battery requirement MSDF approve 12V/200AH solar battery, cost$120 Inverter input voltage requirement620v, Unit of battery in series to a 100KVA inverter Total batteries in series Inverter input current A 620 Total numbers of batteries required 52 Solar charge controller Number of solar modules connected with controller in series Number of solar modules connected with controller in parallel 50 6, 8.19 Number of solar modules per charge controller 5 630, Total number of charge controller needed Cost analysis Solar modules $ 3.94 M Inverter 10 $12000$120,000 Battery 5200 $ 120$624,000 Charge controller 521 $ 120$62, CONCLUSION Evidently from this project research it can be observed that the different energy supply addressed give a rapid increase in cost in response to the increase in the demand complexity. To therefore reduce the cost the load must be reduced drastically by implementing the recommendations stated. Based on the energy audit conducted, there are several improvements and implementations which should be taken into account in order to achieve adequate Energy savings. REFERENCES Das, D., Electrical Power Systems, New Age International (P) Ltd., Publishers, New Delhi, India, Glover, J.D., Sarma, M.S., and Overbye, T.J., Power System Analysis and Design, 4th ed. Thomson Learning, Toronto, Grainger, J.J. and Stevenson (JR.), W.D. Power System Analysis, 1st ed. McGraw-Hill, Inc., Singapore, HOMER software, Introduction to HOMER, National Instrument Corporation, Saadat, H., Power System Analysis, 1st ed. McGraw-Hill Companies, Inc., New York, 1999.