Assessing Energy Utilisation

TITLE ENERGY UTILIZATION AND SOLAR ENERGY OPTION FOR MAKERERE UNIVERSITY HALLS

GROUP MEMBERS:

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Applied Energy Technology Project Course, Final Report

ABSTRACT Makerere University is faced with several energy challenges ranging from deficiency, high costs, unreliability and poor quality of energy services. The steadily rising energy costs amidst reducing remittance to the university from government have created urgency to reduce expenditure on energy. Therefore, there is need to seek for measures to reduce the energy consumption through energy efficiency interventions and to explore the potentiality of solar energy utilisation. This study was carried out to assess the energy utilisation in Makerere university halls and to design a supplementary solar energy system; it was limited to Mitchell hall. The engineering stock approach was used to obtain the estimated energy consumption of each hall section; this provided the input to the solar thermal and PV designs.

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The annual electricity consumption for Mitchell hall was found to be 125605.4kWh. Introduction of energy efficiency interventions has brought an electricity consumption reduction of 4.7% since 2007 but electricity tariffs have doubled since 2005. •

• •

The research shows that substituting 40% of the annual electric energy consumption with solar energy leads to a saving of …………kWh per year. Energy efficiency measures are not studied anywhere not the theory but implementation is nowhere?????????? Adopting energy saving stoves can save the hall about …. and the environment. The payback period of the supplement system at what rates

Key words: energy efficiency, energy management, solar energy, domestic energy consumption.

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ACRONYMS CFCs

Chlorofluorocarbons

kW

Kilowatt

kWh

kilowatt hour

LPG

Liquefied Petroleum Gas

MEMD

Ministry of Energy and Mineral Development

NEMA

National Environmental Management Authority

PV

Photo Voltaic

REP

Resource Efficiency Program

SWH

Solar Water Heater

UShs

Uganda Shillings

W

Watts

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TABLE OF CONTENTS ABSTRACT................................................................................................................................i ACRONYMS ...........................................................................................................................iii TABLE OF CONTENTS..........................................................................................................iv CHAPTER ONE: INTRODUCTION........................................................................................5 1.1 Background .....................................................................................................................5 1.2 Problem Statement and Justification................................................................................5 1.3 Main Objectives...............................................................................................................6 1.3.1 Specific Objectives....................................................................................................6 1.4 Scope................................................................................................................................6 CHAPTER TWO: METHODOLOGY......................................................................................7 2.0 Introduction......................................................................................................................7 2.1 Problem Identification......................................................................................................7 2.2 Study Visits.......................................................................................................................7 2.3 Literature Review.............................................................................................................7 2.4 Data Collection.................................................................................................................7 2.4.1 Students’ Rooms........................................................................................................8 2.4.2 Businesses.................................................................................................................8 2.4.3 Kitchen Section.........................................................................................................8 2.4.4 Outdoor, Corridor and Toilet Facilities.....................................................................8 2.4.5 Electric Bills..............................................................................................................8 2.5 Estimating Energy Consumption......................................................................................9 2.6 Design of Solar Water Heating System............................................................................9 2.6.2 Sizing the Heat Accumulator for Block B...............................................................10 2.6.4 Calculation of Time for Heating the Water.............................................................13 2.6.5 Sizing the Heat Exchanger for Block B..................................................................14 2.6.6 Circulation Pump and Pipe System.........................................................................14 2.7 Design of Solar PV System for Block B........................................................................16 2.7.1 Electric Energy Demand.........................................................................................16 2.7.2 Module Selection.....................................................................................................16 2.7.3 Battery Sizing..........................................................................................................16 2.8 Economic analysis..........................................................................................................19 2.9 Results Report ...............................................................................................................19 2.10 Constraints ...................................................................................................................19 CHAPTER THREE: RESULTS...............................................................................................20 3.1 Energy Supply and Consumption...................................................................................20 3.1.1 Biomass energy.......................................................................................................20 3.1.2 Liquefied Petroleum Gas (LPG).............................................................................21 3.1.3 Electricity consumption...........................................................................................22 3.2 Proposed Supplementary Solar System .........................................................................25 CHAPTER FOUR: DATA ANALYSIS....................................................................................29 CHAPTER FIVE: CONCLUSIONS AND RECOMMENDATIONS.....................................31 REFERENCES.........................................................................................................................31 APPENDIX..............................................................................................................................33

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CHAPTER ONE: INTRODUCTION 1.1 Background Makerere University is Uganda's premier institution of higher learning and is ranked among the largest in East and Central Africa. It has a student population of 33,488 registered students (31,826 Undergraduates and 1,626 Postgraduates) as of July 2007. The main campus is located about 5km to the north of the city centre on Makerere hill; one of the seven hills on which Kampala, the capital city of Uganda is built. The campus has an area of 300 acres (two square kilometres) http://www.ugandatourism.org/Makerere%20University.php). The University is one of the “big” consumers of energy in Uganda and is therefore, faced with several energy challenges; the energy use is increasing steadily and so are the energy bills. The university electric needs include from lighting, space conditioning, maintaining laboratories and machinery, entertainment, and water heating among others. Also the because of lack of enough electricity to satisfy demand the utility company does periodic load shedding, to cope with load shedding, some faculties and administrative offices in the university have back up diesel thermal generators. However, the fuels cost are also ever increasing. The government in association with electricity utility company are consistently increasing the cost of electric energy to encourage energy efficiency so as to be able to increase the rate of electrification of rural areas and places with the urban poor. Currently, the university administration is seeking for measures to reduce the expenditure on energy as the cost of energy is rising yet the university budget is getting constrained due to reduction in revenues received from the government. The central government decided to gradually reduce funding of public universities’ activities and/or services to be able to fund basic education as a way of to decreasing illiteracy. 1.2 Problem Statement and Justification There is a rising concern over energy consumption in Makerere University students’ hall of residence; this is mainly because of heavy monthly energy bills the university receives. In an effort to save the situation, in 2007, the university administrators proposed a plan to limit on the number of appliances used by students in halls of residence, this move was however futile due to resistance from the students and the students’ leadership. There is a need to look at the energy utilization of the University halls to find out the extent to which energy efficiency interventions can save electricity bills and to investigate the cost of introducing solar energy as a supplementary energy supply. This is in line with the government’s plans of reducing power deficits through energy efficiency and exploitation of renewable energy sources. It is hoped, that this project will offer valuable options to stakeholders in higher institutions of learning to consider efficient use of energy use in students’ residences. 5

The design of a solar thermal and PV system was chosen due to the high potential for solar energy which can be harnessed. 1.3 Main Objectives •

To assess the energy utilization in Makerere University Halls and to design a supplementary solar energy system.

1.3.1 Specific Objectives • • • •

To determine the annual electricity consumption in Mitchell Hall To determine the annual energy consumption capita for cooking To assess the energy efficient options that can be introduced To design a supplementary solar energy system

1.4 Scope The study was limited to Mitchell hall one of the ten halls of residence at Makerere University, it was thought that all the halls have similar energy usage patterns and therefore one would representative of the others.

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CHAPTER TWO: METHODOLOGY 2.0 Introduction This chapter presents the methods and materials that were adopted in order to achieve the objectives of the study. It also details on how and why the different data collection methods were applied and how the data collected was utilized. 2.1 Problem Identification The problem was identified from the idea of the course lecture on how to contribute to the one’s campus energy system, after a background study the group brain stormed on the several topics and the most appropriate one was chosen through discussion. It was agreed on that the problem be broken down into tasks and everyone was given several tasks to accomplish, some tasks were assigned to more than one person. 2.2 Study Visits Several study visits were made to obtain information regarding the extent of the problem and to collect data that would aid in the solving of the problem. All the ten halls of residence were visited and walk through energy audits were done on two halls, Mitchell hall and Africa Hall. The administrative offices were visited to obtain authority to carry out the study and for the accounts department was visited to obtain information on the energy costs the university halls incur. Other places visited included the Umeme Head Offices (Uganda’s electricity utility company), the Ministry Of Energy And Mineral Development and businesses sell electrical appliances. 2.3 Literature Review Literature search was made regarding energy management in institutions in Uganda and elsewhere. This was done to find out what has been done by earlier studies and to discover gaps that need to be addressed. Several materials were consulted these included text books, journals, lecture notes and the internet. The Internet was served as an important source of information especially on accessing several journals on energy. 2.4 Data Collection Data collection was carried out through study visits. Mitchell hall was focused on during the study to represent all the other halls of residence as it was thought that all the halls have the same pattern of energy utilisation.

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Data collection techniques applied depending on the section visited included observations, interviews, and administering questionnaires to students, business owners and Hall officials. 2.4.1 Students’ Rooms All the six blocks of the halls were visited and samples of 3 out of 4 rooms on each block were taken for the study. The students occupying these rooms were asked about the appliances they have and their power ratings were checked and recorded. 2.4.2 Businesses All the business owners were contacted and the same procedure as that of the students’ rooms was carried out, the businesses include secretarial bureaus, hair salons, laundry services and canteens. 2.4.3 Kitchen Section This is the major sole consumer of energy in the hall. A separate questionnaire was prepared and several kitchen officials were interviewed about the energy situation in the kitchen. The kitchen energy consumption records were also reviewed and summarised. 2.4.4 Outdoor, Corridor and Toilet Facilities In these areas, walk through audits were carried out and the residents who occupy places near each appliance were asked on how long these appliances are on in a day. 2.4.5 Electric Bills The electricity consumption data was collected from the UMEME Head Offices in Kampala. The records for the different halls of residence were reviewed and summarised.

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2.5 Estimating Energy Consumption The engineering stock approach was used to estimate the energy consumption for the different section of the hall. Using this approach, the consumption is estimated based on an aggregation of “predicted” consumption of the electricity by equipment and the multiple energy consumptions which are then linearly added (Baringanire, P. 2007). 2.6 Design of Solar Water Heating System The procedure for the design of the solar water system is given below and the assumptions taken are considered. The The mean radiation intensity on in Makerere is 5.6kWh/m2/day, and an average of 8 sunshine hours per day throughout the year. The presented is the Design of Solar water heating System for Block B, this was the same procedure followed for all the other blocks. 2.6.1 The Solar Collector Currently, there are 8 electric water heaters on Block B, each with a power rating of 3000W and is in use for about 4 hours daily. Energy consumed by the water heaters is about 35,040kWh/yr and can be substituted by a solar collector system of equivalent annual energy output. The solar collector is therefore selected by considering this energy demand. Solar Collector Model Selected Model AE-40 Manufacturer Alternate Energy Technologies, LLC Glazing type Glass Absorber material Copper tubes and fins Gross area 3.7 m2 Rating 420 W (Source: Florida Solar Energy Centre (FSEC), University of Central Florida) The solar collector model selected has the absorber material made of copper tubes fins. A double glass cover was chosen because it increases the collection efficiency at high temperatures by preventing heat loss by convection and conduction to the environment. It is mostly applicable for temperatures above 700C because it slightly more expensive than single glazing. Also the efficiency of the solar collector system at low temperatures is reduced because of the added absorption and reflection of the cover. 2.6.1.1 Determining the Number of Modules Required Module rating = 420 W Total energy generated per day = Module rating (W) x Sunshine hours/day = 420 x 8 = 3.360 kWh/day/module Total energy generated per year = 3.360 kWh/day/module x 365 days/year = 1226.4 kWh/year/module 9

But the Energy demand is 35,040kWh/year, therefore, the Number of modules required is = 35,040kWh/year = 28.6 modules 1226.4 kWh/year/module Therefore 29 modules will be considered The modules will be connected in parallel because: • With parallel connection there is a high potential of achieving enhanced efficiency in tandem solar cells. • Also, the system can remain in operation when one module fails; this is due to different current contribution for each module and the voltage is unaltered. 2.6.1.2 Collector Orientation This angle is mainly dependent on the location, i.e. the latitude angle; this is the angle at which the collector would be oriented so as to maximize solar energy absorption. Makerere University is located along Latitude 0° 19' 60N, therefore, the collector should face south at an angle of 0° 20'. Slight changes in the orientation may be considered during installation. 2.6.1.3 Estimating the Collector Efficiency The following parameters were assumed to estimate the solar collector efficiency: • Absorbance ‘a’ = 0.9 • Transmittance ‘t’ = 0.9 • Overall heat loss coefficient ‘Uloss’ = 8 W/m2K • Temperature Difference between working fluid and surrounding = 40K Since the Radiation intensity = 5.6kWh/m2/day, then Insolation ‘I’ can be determined. I= 5600 Wh/m2/day = 700 W/m2 8 h/day to determine the efficiency of the collector we use η=

(T pm − Ta ) Puse = at −U loss IA I

η= 35.3% the solar collector efficiency will be 35.3% 2.6.2 Sizing the Heat Accumulator for Block B 2.6.2.1 Need for energy storage Energy storage is employed in solar thermal energy systems to shift excess energy produced during times of high solar availability to times of low solar availability; like at night when there is no sunlight and/or during periods of low irradiation such as cloudy days. Therefore, it is always a necessity to store energy using heat accumulators in solar thermal energy systems. Attributes used to determine a good energy storage system: • The storage system should have competitive energy costs 10

• • • • •

The system should be safe to work with, and have minimal hazards It should be flexible and be used from any location around the world It should have limited or no negative environmental impacts like pollution The system should also be feasible, basing on the current technology The system should store the energy in a form that is readily available and easily convertible to usable forms when required.

2.6.2.2 Sizing the Hot Water Storage Tank Assumptions used in sizing the accumulator: • There are 112 people on block B assuming they with per capita consumption of 50 litres/day of hot water. • A scaling factor of 1.1 was assumed to cater for any additional hot water demand. • Water temperature in the tank was assumed to be 700C and a minimum allowable temperature of 300C. • 50 litres of tank size per square meter of collector area was considered and this was based on a solar fraction of 50%. • A cylindrical tank with height of 2m was considered. Total hot water demand = 1.1 * (112 * 50 litres/day) = 6160 litres/day Required collector area = 6160 litres/day 50 litres/m2 = 123 m2 2

Using V = πr h Where V = Daily hot water demand = 6.16 m3 r = Radius of tank h = Height of tank = 2 m r = 0.99m ≈ 1m Therefore, inside Diameter of the tank = 2 m

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2.6.2.3 Estimation Heat Insulation Required The accumulator will be made of stainless steel and insulated with fibre glass on the outside because fibreglass has the following advantages: • It is resistant to water absorption • has low thermal conductivity • has a high ratio of surface area to weight • and is non combustible and this limits threats of fire if installed properly Assumptions used: • Thermal conductivity (k) = 0.05 W/m/K (from tables) • Thickness of insulation ∆x = 120 mm • Almost the whole outside cylindrical surface area of tank to be insulated so as to minimize losses (neglecting area taken up by pipe inlets and outlets) • Temperature inside the tank (Ti) to be = 700C and daily ambient temperature (Ta) to be 250C Using Fourier’s law of conduction Q = -k A ∆T/∆x [W] ∆T = Ti – Ta= 70 – 25 = 450C ∆x = 0.12 m K = 0.05 W/m/K A = 2πr2 + 2πrh (surface area of the cylindrical tank) h = 2 m, r = 1 m and hence A = 18.8496 m2 Therefore, Q = 353.43 W Heat loss for the design is 354W and since it is less than 10% of the demand, it can be tolerated.

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2.6.4 Calculation of Time for Heating the Water Assumptions used • Water flow rate of 1 litre per m2 solar collector per minute •

Initial water temperature being 300C and final water temperature being 700C; rise in water temperature, ∆T = 70 - 30 = 40K

Collector area Total flow rate Density of water Mass flow rate

= 123 m2. = 123 litres/minute = 2.05*10-3 m3/s = 1000kg/m3 = 2.05 kg/s

Using Puse = m cp ∆T Where m = mass flow rate of water = 2.05 kg/s cp = specific heat capacity of water = 4.18 kJ/kgK Puse = 342.76 kW The following formula was used in estimating the time required to heat the water from 300C to 700C: +

Ts = Ts +

∆t ( mc p ) s [ Puse − Ls − (UA) s ( Ts − Ta ) ]

Where

T T

+ s

= Final water temperature = 70˚C

= Initial water temperature = 30˚C Δt = time for heating the water from 300C to 700C, seconds m = mass of water in the tank = 1000kg/m3*6.16m3 = 6160kg Cp = specific heat capacity of water = 4.18 kJ/kgK Puse = 342.76 kW Ls = load of the tank (W), assumed to be zero U = heat loss coefficient assumed to be 8 W/m2K A = surface area of the tank = 18.8496 m2 Ta = ambient temperature = 25˚C s

Therefore ∆t 3011.50s = 50.19 minutes

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2.6.5 Sizing the Heat Exchanger for Block B Heat Exchanger Area Using Q = U A ∆Tln , Where Q = Useful heat = 342.76 kW A = Heat exchanger area (m2) ∆Tln = Logarithmic mean temperature difference assumed to be 50C U = Overall heat transfer coefficient. U for liquids inside and outside the tubes is in the range 150-1200W/m2K. U was assumed to be 1000 W/m2K. Therefore, the heat exchanger area A = 68.552 m2 A counter flow heat exchanger was chosen since it ensures a better heat exchange between the two liquids. 2.6.6 Circulation Pump and Pipe System Assumptions used • Smooth Copper pipes with inside diameter di =35.9 mm and outside diameter do = 42.4 mm from the available standard sizes on market, overall pipe length to be 100 m • 8 valves and 16 bends of 90º were considered • Considering screwed pipe fittings and gate valves to be used then loss coefficients are 0.19 and 1.2 for the valve and bend respectively (from table) • Density of water = 1000kg/m3 • Kinematic Viscosity of water ϑ = 5.9*10-7 m2/s • Volumetric flow rate of the pump V = 1 m3/h d ⋅ν Using Re = i and ν = V A ϑ Where A = Cross sectional area of the pipe, A = πd i 4 Therefore, velocity v = 0.28 m/s and Re = 17037.2881 Since Re > 2300, the flow is turbulent. 2

= 0.001m2

Using Blasius’s equation for smooth pipes and turbulent flow; f = 0.3164 ⋅ Re −0.25 = 0.0277

 ρc 2  +  Σξ * ρc 2  Using ∆Ploss =  λ * L D * 2   2   Where: λ = friction factor = f L = Overall length of piping system (m) D = Inner diameter of pipe (m) ρ = density of water (kg/m3) c = velocity of water in the pipe = v ξ = loss coefficient as a result of a bend and a valve Therefore, ∆Ploss = 3836.8480 N/m2 Pump power, P = ∆Ploss x V 14

= 1.0658 W

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2.7 Design of Solar PV System for Block B 2.7.1 Electric Energy Demand Solar PV system was designed to power the following equipment in the table below. Table Electricity consuming components in Block B of Mitchell Hall Component Quantity Power Demand Length of use Energy use per (W) (h/day) day (kWh/day) Flat iron 49 1000 0.4 19.6 Computer 15 100 7 10.5 Subwoofers 7 2500 5 87.5 Radio 46 40 7 12.88 Bulb 42 60 6 15.12 Energy saver bulb 10 20 6 1.2 Coloured TV 25 150 5 18.75 Fluorescent tubes 21 40 12 10.08 DVD player 18 25 4 1.8 Fan 26 60 3 4.68 Laptop 7 100 4 2.8 Fridge 11 150 6 9.9 Speakers 3 2200 4 26.4 phone charger 87 12 0.2 0.2088 Photocopier 1 4500 10 45 10957 266.4188 2.7.2 Module Selection •

The energy requirement per day = 266418.8Wh/day

•

It was assumed that 20% of the energy is lost through the battery and inverter

•

Total energy requirement per day (losses inclusive) is 120% of the demand. = 319702.56 Wh/day

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Total solar power needed, there is 8 hours of sunshine a day = 319702.56 /8 = 39962.82 W

The selected module is manufactured by Brightwatts, power rating of 200W. Total number of modules needed = 39962.82 /200 = 199.8141 Therefore, 200 modules will be needed. 2.7.3 Battery Sizing Assumptions: • 12 V inverter input voltage 16

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5 days of storage for the battery

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50% discharge limit

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Coolest temperature for the battery to be 250C (room temperature)

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Multiplier effect of 1.00

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Battery of 400 Ah storage capacity and 12 V

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Lead-Acid batteries (Trojan deep cycle batteries) considered

Total energy requirement per day (20% loss inclusive) = 319702.56 Wh/day Total amp hours per day = 319702.56 /12 = 26641.88 Ah/day Considering 5 days of storage = 26641.88 *5 = 133209.4 Ah Considering the discharge limit of 50% = 133209.4 /0.5 = 266418.8 Ah Therefore, the total battery storage capacity needed is 266418.8 Ah Number of batteries = 266418.8 /400 = 666 Batteries required will be 666 and should be connected in parallel. INVERTER SIZING Total power when all the components are in use = 10957W Total power with 20% loss inclusive = 1.2 x10957 = 13148.4 W. Therefore the inverter rating can be considered to be 13149 W Investment cost The costs were based on world market survey for the month of April (www.solarbuzz.com). The cost of batteries was specific for a certain voltage and Amp hour (Ah) rating. An average cost per Ah was estimated for 12 V Trojan deep cycle batteries of different Ah rating. The other costs apart from the modules, batteries and inverter are small and were assumed to be 5%. Component Solar Module Battery (12 V) Inverter Sub total Others (5%) Grand total

Quantity 200 666 1

Total capacity 200x200 W 666x400 Ah 13149 W

Unit cost 4.81 US$/W 2 US$/Ah 0.72 US$/W

Total cost ($) 192,400 532,800 9,467.28 734,667.28 36,733.364 771,400.644

Therefore the total initial investment is US$ 771,400.644 Annual energy requirement is 266.4188 x 365 = 97242.862kWh/year. Assuming the operation and maintenance costs are minimal and the life time for system to be 20 years, the cost per kWh will be = US$ 771,400.644 = 0.3966 US$/kWh 20 x 97242.862 kWh/yr Comparing with the current domestic tariff for grid power (0.22US$/kWh), this unit cost for solar PV electricity is high.

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Circuit diagram for the system

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2.8 Economic analysis An economic analysis was carried out in order to determine the feasibility of the new system. Also the Investment costs and operating were estimated in order to estimate the payback period of the system if the proposed system is to be installed. 2.9 Results Report A report of the project was prepared detailing the proceeding of events and findings. A presentation of findings was made before a panel of faculties. 2.10 Constraints The data collected from the Hall was raw data and required being processed. The challenges encountered are that the hall does not have a culture of record keeping; very little is recorded. Although everything was done to avoid suspicions, a few respondents were unwilling to disclose the total number of running hours for their electrical appliances, and it required a lot of time and explanation before they could release any information. This was especially common with the small business owners at the hall of residence. In addition, there was a time constraint.

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CHAPTER THREE: RESULTS 3.1 Energy Supply and Consumption The main energy consuming activities in include: lighting, domestic hot water supply, catering, laundry, students’ electric appliances such as radios, computers, refrigerators, kettles, percolators, television. There are 3 major sources of energy electricity, biomass and liquefied petroleum gas (LPG). The main source of energy is electricity. It is used for a range of applications including especially lighting all the sections in general. In students’ rooms it is used for entertainment, water heating, ironing clothes and air conditioning. In the kitchen it is used for refrigeration, preparing food and heating water. In bathrooms electricity is used for water heating however, most of the bathrooms water heaters are no longer functional. Some students prepare hot water for bathing from their rooms using small heaters. Biomass and LPG are used for cooking purposes and are only utilised in the Kitchen section. In case of electricity load shedding, these sources of energy are used solely for the kitchen energy applications since none of the 10 halls of residence have diesel generators to provide electricity during load shedding. 3.1.1 Biomass energy Biomass is used in form firewood for cooking, this is however poorly utilised as it is converted to energy using the traditional three stone stoves which have low energy efficiencies of about 15% (JEEP, 2008). The pictures 2.1 below show logs of firewood ready to be used on the three stone stoves shown in picture 2.2 below. JEEP, 2008. Analysis of the Stove Efficiency

Figure2.1: Biomass used for cooking at Mitchell Hall

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Figure 2.2: The cooking stoves at Mitchell Hall; traditional three stone stoves (foreground) and a defunct modern stove (left centre) Besides the losses incurred when using the three stone stove, due to inefficient wood combustion a lot of smoke is emitted leading pollution of the surrounding, this put the life of the people cooking in danger as they are likely to get respiratory diseases. Therefore there is a need to replace these stoves with more efficient one. The hall uses one Lorry of firewood per week this amounts to approximately 6 tonnes of wood. Each lorry of fire wood costs about 350,000U - 400,000 UShs transport costs inclusive. 3.1.2 Liquefied Petroleum Gas (LPG) This fuel is used for cooking purposes only (i.e. for preparing maize flour, meat, fish, greens, and beans) and is the most expensive fuel per energy provided; it is supplied by Shell Uganda Limited which provided the storage container of 850 litres (figure 2.3). The hall is supplied with an average of 700liters of gas every 21 to 25 days (normal use: 21 days; economical use i.e. substituting LPG with other sources of energy like biomass: 25 days).

Figure 2.3: LPG storage tank at Mitchell Hall

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3.1.3 Electricity consumption Grid electricity is used for lighting, domestic water heating and running electrical equipment possessed by students, small business owners, catering department and offices. Table 3.3 shows the Monthly electricity consumption for Mitchell Hall for years from 2006 to 2009 in kWh; this information was summarised from the electric bills obtains from Umeme offices. Table 3.1 Showing Monthly Electric Consumption for Mitchell Hall Energy (kWh) Month 2006 2007 2008 2009 8085.65436 January 7963.715346 4498.769157 3 8348.073403 5538.04513 February 8363.919759 11504.19694 5 4358.671705 8488.15551 March 5363.994584 8457.317101 7 9862.767739 9627.16183 April 6878.342126 13313.37643 6 11169.76775 May 7396.726881 14051.41961 9832.355115 10638.2025 June 8365.864895 14558.1829 1 8361.37216 July 4165.098245 11844.42703 6 8583.27181 August 3239.791575 3456.71324 5 Septembe 7676.26093 r 6994.515647 8429.299749 3 10629.2746 October 8270.014544 11781.6152 2 November 9935.661133 12534.03922 11459.68381 December 7692.593079 11483.39057 11317.44322 8434.82 Average 7052.50 10492.67 9186.33 Estimating Electricity Consumption on Each Block The table below shows electricity consumption on different blocks of Mitchell hall.. Table3.1 shows electricity usage for block B. Block C has a total of 45 rooms with a total of 99 students. Students’ Population Block No. of rooms B 52 C 45 D 52 F 62

No. of students 112 99 106 120

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Table 3.1: Electricity use for blocks B, C, D and F Block B C Equipment R(W) No. H No. H Flat iron 1000 49 0.4 46 0.4 Computer 100 15 7 7 7 Subwoofers 2500 7 5 6 8 Radio 40 46 7 29 6 Percolator 2200 50 1 37 1 Bulb 60 42 6 42 6 Energy saver bulb 20 10 6 3 6 Coloured TV 150 25 5 16 5 Fluorescent tubes 40 21 12 17 12 Water Heaters 3000 8 4 6 4 DVD player 25 18 4 9 4 Fan 60 26 3 38 4 Laptop 100 7 4 2 4 Fridge 150 11 6 12 18 Speakers 2200 3 4 5 4 Phone charger 12 87 0.2 73 0.5 Photocopier 4500 1 10 3 10 Salon machine 65 2 7 Blender 120 6 1 Kettle 2200 1 0.2 2 0.3 Printer 4 6 3 0.1

D

F

No. 26 20 12 24 28 27 5 20 15

H 0.2 8.5 6 4.5 0.5 6.0 6.0 6.0 12

No. 31 30 8 21 27 30 6 23 31

H 0.2 8 5 4.3 0.5 5.5 6 6.3 12

14 10 3 3 7 60 1 1 3 2 2

6.2 1.5 6.0 12 5.5 0.5 8.0 7 1 0.3 3

17 13 2 8 12 68 5 1 2 4 14

5.3 1.5 5 12 6 0.5 10 7 1 0.3 5

R (W) - power rating in Watts H: - Hours per Day No.: - Number of appliances Estimating Electricity Consumption in the Kitchen Section a) Electric Heaters The electric heaters is are used for boiling water for drinking or for preparing water for cooking purposes using other energy sources. The boiler has a capacity of 120 litres; it is used to prepare water four times a day on average, this approximates to 480 litres a day. This is equivalent to 480/1000 cubic metres. Density of water 1000m3/kg, assuming it is initially at 20oC and is the boiler is switched off when it is at 100oC. Specific heat capacity of water is 4.2kJ/oC. Energy consumed = Mcp∆T = 0.48*1000 X 4.2 (100-20) =161280 kJ = 161280/3600 kWh = 44.8kWh The boiler consumes an average of 44.8kWh of electricity per day. b) Lighting

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The catering section consists of 12 fluorescent tubes of 40Watts which are on for 12 hours a day. Energy consumed = 12 X 40 X 12 = 5.76kWh c) Cold Room For storage, a cold room is used for food storage at a temperature as low as 3oc. d) Dining Hall has 8 fluorescent tubes 40Watts that are on for 24 hours in a day. e) Quadrangle security lights; this has six security lights that are on for 12 hours at day.

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3.2 Proposed Supplementary Solar System

Design of Solar Collector system for Block C 6 water heaters of power rating of 3000W each in use for about 4hours daily. Energy produced by the water heaters is 26,280kWh/yr and can be substituted by a solar collector system of equivalent annual energy output. Solar Collector Model Selected Model: AE-40 Manufacturer: Alternate Energy Technologies, LLC Glazing type: Glass Absorber material: Copper tubes and fins Gross area: 3.7 m2 Rating: 420 W (Source: Florida Solar Energy Centre (FSEC), a research institute of the University of Central Florida) Estimated number of modules: 22 modules, connected in parallel. Collector tilt: 0o 20’ Cover glass: A double glazing cover was chosen. It is also used in applications involving temperatures above 700C. Absorber: The absorber material will be made of copper tubes fins. Efficiency of the system 35.3% SIZING OF THE ACCUMULATOR Assumptions used in sizing: • The solar heating plant was designed for Block C of 99 people with per capita consumption of 50 litres/day of hot water. • A scaling factor of 1.1 was assumed to cater for any additional hot water demand. • 50 litres of tank size per square meter of collector area was considered and this was based on a solar fraction of 50%. Total hot water demand = 5445 litres/day Required collector area = 108.9 m2 Daily hot water demand = 5.445 m3 25

Cylindrical tank,

Height = 2 m, inside diameter

=2m

HEAT INSULATION The accumulator will be made of stainless steel and insulated with fiber glass on the outside. • Thickness of insulation ∆x = 150 mm • Heat loss considered for the design is 283W, it is less than 10% of the demand, it can be tolerated. HEAT EXCHANGER AREA Therefore, the heat exchanger area A = 60.6936 m2 A counter flow heat exchanger CIRCULATION PUMP AND PIPE SYSTEM Assumptions used • Smooth Copper pipes, length to be 100 m, Inside pipe diameter d i of 35.9 mm was chosen (outside diameter = 42.4 mm) • 8 valves and 16 bends of 90º were considered • Considering screwed pipe fittings and gate valves to be used then loss coefficients are 0.19 and 1.2 for the valve and bend respectively (from table) Pump power P = 1.0658 W Solar PV System for Block C Solar PV system excludes 37 percolators of 2200W and 6 water heaters of 3000W which can be catered for under solar thermal system. Electricity consuming components in Block B of Mitchell Hall Module selection Assumptions used: • 8 sunshine hours per day •

20% of the energy is lost through the battery and inverter

The energy requirement of the components per day= 291088Wh/day Total energy requirement per day (20% loss inclusive)= 349305.6Wh/day Total array power needed = 349305.6/8 = 43663.2 W The chosen module is manufactured by Brightwatts, and has a rating of 200W. The total number of modules needed = 43663.2/200 = 218.316 Therefore, 219 modules will be needed. BATTERY SIZING Assumptions used: • 12 V inverter input voltage •

5 days of storage for the battery

•

50% discharge limit 26

•

Coolest temperature for the battery to be 250C (room temperature)

•

Multiplier effect of 1.00

•

Battery of 400 Ah storage capacity and 12 V

•

Lead-Acid batteries (Trojan deep cycle batteries) considered

Total energy requirement per day (20% loss inclusive) = 349305.6Wh/day Total amp hours per day = 349305.6/12 = 29108.8 Ah/day Considering 5 days of storage = 29108.8 *5 = 145544 Ah Considering the discharge limit of 50% = 145544/0.5 = 291088Ah Therefore, the total battery storage capacity needed is 291088Ah Number of batteries = 291088/400 = 727.72 Batteries required will be 728 and they will be connected in parallel. INVERTER SIZING Total power when all the components are in use = 8,667W Total power with 20% loss inclusive = 1.2*8,667= 10400.4 W. Therefore the inverter rating can be considered to be 10,401 W Investment cost The costs were based on world market survey for the month of April (www.solarbuzz.com). The cost of batteries was specific for a certain voltage and Amp hour (Ah) rating. An average cost per Ah was estimated for 12 V Trojan deep cycle batteries of different Ah rating. The other costs apart from the modules, batteries and inverter are small and were assumed to be 5%. Component Solar Module Battery (12 V) Inverter Sub total Others (5%) Grand total

Quantity 219 728 1

Total capacity 219*200 W 728*400 Ah 10401 W

Unit cost 4.81 US$/W 2 US$/Ah 0.72 US$/W

Total cost ($) 210,678 582,400 7,488.72 800,566.72 40,028.336 840,595.056

Therefore the total initial investment is US$ 840,595.056 Annual energy requirement is 291.088*365 = 106,247.12kWh/year. Assuming the operation and maintenance costs are minimal and the life time for system to be 20 years, the cost per kWh will be = 840,595.056 = 0.3956 US$/kWh 20 x 106,247.12 Comparing with the current domestic tariff for grid power (0.22US$/kWh), this unit cost for solar PV electricity is high. Circuit diagram for the system

27

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CHAPTER FOUR: DATA ANALYSIS In the halls of residence, the students own old electrical equipment that have low energy efficiencies. This contributes to the increase in the electric consumption. According to the available data that was collected at UMEME, electric energy consumption increased by about 10.9% in 2006 from that of 2005 while 48.8% in 2007 from that of 2006. In 2008, the electric consumption reduced by 12.4% from that of 2007 while the electric consumption for 2009 has been projected to reduce by about 4.5% from that of 2008. This is partly attributed to the government’s intervention to promote energy saving bulbs; some students have embarked on using the energy saving bulbs for lighting thus saving energy. Average monthly electricity consumption (Kwh) for year from 2006 to 2009

Energy Consumption Block B 140 120 100 80 Total kwh/day 60 40 20 0

1 Electrical Appliance

Flat iron Computer Subwoofers Radio Percolator Bulb Energy saver bulb Coloured TV Fluorescent tubes Water Heaters DVD player Fan Laptop Fridge Phone charger Photocopier

29

Figure4.1: Energy Consumption by Appliance on Block B

30

CHAPTER FIVE: CONCLUSIONS AND RECOMMENDATIONS it is important that the hall of residence is provided with improved energy saving stoves so as to improve on the energy conversion efficiency and to reduce the associated environmental impacts. This is partly attributed to the government’s intervention to promote energy saving bulbs; some students have embarked on using the energy saving bulbs for lighting thus saving energy. The largest and longest term energy impact on any campus will come from a comprehensive strategy that examines all campus energy use, the associated costs (both financial and environmental), and comes up with strategies that reduce energy use across the board. Such strategies should look at all sectors of energy use and be both innovative and comprehensive. The University needs to appoint a full time Energy Manager. The energy manager would be responsible for managing the electricity, gas, biomass and water use. The manager would monitor how much energy and water is being used in each of the Halls, and analyses the data to identify areas where further improvements can be made. Makerere University can set an example for other Institutions and the nation by implementing renewable energy projects like solar, energy efficiency and environmental sustainability projects on campus to demonstrate their feasibility and cost effectiveness. Makerere University is a centre of intellectual power, capable of leading experiments on new technologies, and using these projects as teaching tools and research opportunities to better the education of the next generation of voters, consumers, politicians, and business leaders; people who will be making energy decisions for years to come. Academia has traditionally been at the forefront of cultural and technological change, and campuses once again can be the catalyst that drives this country into sustainable energy independence. While achieving energy independence may at first seem daunting, the research aims to make it a reality by highlighting the incredible number of ways to begin. As David Orr says, “No institutions in modern society are better equipped to catalyze the necessary transition to a sustainable world than universities. They have access to the leaders of tomorrow and the leaders of today. They have buying and investment power. Consequently what they do matters to the wider public. REFERENCES 1. David Orr.” The Last Refuge: Patriotism, Politics, and the Environment in an Age of Terror.” 2. Department of Energy. Office of Energy Efficiency and Green Power. “Energy Solutions for your Building: University Buildings.” www.eere.energy.gov/buildings/info/university/index.html

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3. Department of Energy. Office of Energy Efficiency and Green Power. “Energy Solutions for your Building: University Buildings.” www.eere.energy.gov/buildings/info/university/index.html 4. Department of Energy. Office of Energy Efficiency and Green Power. “Solar Technologies Program: Residential and Commercial Water Heating.” www.eere.energy.gov/solar/sh_use_water.html 5. University of Colorado Environmental Center. “Energy Conservation: Renewable Energy at CU.” 2005. www.ecenter.colorado.edu/energy/cu/renewables.html 6. Department of Energy. Office of Energy Efficiency and Green Power. “Energy Solutions for your Building: University Buildings.” www.eere.energy.gov/buildings/info/university/index.html 7. Ugandan Ministry of Energy and Mineral Development, save energy and save money brochure 8. http://www.ugandatourism.org/Makerere%20University.php 9. Diane Brown. “U-M Earns Award for Energy Efficiency”. The University Record Online. 2004. www.umich.edu/~urecord/0304/Mar08_04/01.shtml 10. Harvard Green Campus Initiative & FAS Resource Efficiency Program. “Harvard Green Cup 2005.” www.greencampus.harvard.edu/greencup/ 11. Baringanire, P. (2007), Electricity Consumption Estimation for Rural Households in Uganda, M. Eng. Unpublished Thesis, Makerere University, Kampala.

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APPENDIX A) Mitchell Hall 1/2(MUK) Electricity Consumption Data PERIOD Dec Nov Oct Sept Aug Jul Jun May Apr Mar Feb Jan TOTAL

2009

9485.632 10377.51 7588.691 8179.064

2008 10421.4 11205.69 9457.494 8556.082 5421.538 3877.652 8615.92 8741.825 8717.126 7025.852 2312.232 4852.086 89772.2

kWh 2007 8934.145 9465.472 12430.66 12786.06 10599.03 11923.96 12139.86 11606.76 13058.89 9134.565 8963.156 370.264 121980.1

2006 4996.933 7597.19 6324.75 6428.683 6940.337 7069.516 5511.055 5735.523 5029.615 4133.444 748.7263 2910.052 63993.13

2005 4413.039 5285.278 4683.204 4412.661 3755.857 4882.03 7167.561 5408.297 4206.557 1750.659 46429.3

B) Mitchell Hall 2/2(MUK) Electricity Consumption Data 2008 2008 2007 2007 2006 Ushs kWh Ushs kWh Ushs Dec 9739959.72 20259.79 9147474 19000.51 5653517 Nov 10429684.4 21699.61 9297476 19323.6 7360518 Oct 9293083 19314.34 10927393 22756.77 6467906 Sep 7803142 16225.91 10665568 22228.22 6772567 Aug 6473932 13406.37 8089908 16871.9 6980338 Jul 4496825 9298.522 10690845 22256.41 7247472 Jun 8869051 18419.25 10877069 22645.27 5721188 May 8730276 18137.38 10510857 21877.58 5615146 Apr 8453090 17566.76 11416471 23779.72 4937814 Mar 7252731 15051.97 7701307 16032.48 4127779 Feb 3081996 6346.217 8961969 18619.88 1961942 Jan5683993 11766.42 1808053 3673.211 3399665 6624585 TOTAL 90307763.12 188109.5 110094390 229682.5 2 PERIOD

2006 kWh 11707.75 15289.35 13418.89 14048.2 14489.52 15042.36 11861.07 11649.22 10237.04 8546.757 4000.071 7015.887 137923.1

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PERIOD Dec-05 Nov-05 Oct-05 Sep-05 Aug-05 Jul-05 Jun-05 May-05 Apr-05 Mar-05 Feb Jan total

2005 Ushs 4328379 4111314 3990294 3771461 3231571 4470556 5531242 4589902 3609577 1856627

2005 2009 2009 kWh Ushs kWh 8966.936 8544.673 8279.228 7821.809 6693.587 9272.212 11516.2 9532.124 14002132.88 29888 7483.263 14019127.82 29032.66 3811.162 12731398.66 26409.48 6386908 13287.21 9823900.66 20370.53 39490923 82425.98 56963468.02 118326.5

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PERIOD AMOUNT(Ushs) kWh 7-May09 9413078.54 20236 Apr-09 9508727.92 20441.62 Mar-09 7799207.4 16766.54 Feb-09 2773622.33 5962.663 Jan-09 5931411.65 12751.2 TOTAL 35426047.84 76158.03 Dec-08 4787009.08 10290.99 Nov-08 5105824.95 10976.37 Oct-08 4795990 10310.3 Sep-08 3732351 8023.714 1-Aug 3885551 8353.06 Jul-08 2638589 5672.372 Jun-08 4769961 10254.34 May-08 4571642 9828.001 Apr-08 4306137 9257.225 Mar-08 3905627 8396.219 Feb-08 1964089 4222.349 Jan-08 3364921 7233.822 TOTAL 47827692.03 102818.8 Dec-07 4897887 10529.35 Nov-07 4796610 10311.63 Oct-07 5024212 10800.92 Sep-07 4594309 9876.73 Aug-07 3052954 6563.164 Jul-07 5027293 10807.55 Jun-07 5111412 10988.38 May-07 4997319 10743.11 Apr-07 5216181 11213.61 Mar-07 3356936 7216.656 Feb-07 4698662 10101.07 Jan-07 1608555 3458.031 TOTAL 52382330 112610.2 Dec-06 3265943 7021.042 Nov-06 3743213 8047.065 Oct-06 3452372 7421.822 Sep-06 3707880 7971.107 Aug-06 3673676 7897.576 Jul-06 3879718 8340.52 Jun-06 3090472 6643.819 May-06 2878273 6187.639 Apr-06 2534784 5449.215 Mar-06 2148572 4618.946 Feb-06 1583459 3404.08 Jan-06 1999033 4297.471 TOTAL 35957395 77300.3 35

Dec-05 Nov-05 Oct-05 Sep-05 Aug-05 Jul-05 Jun-05 May-05 Apr-05 Mar-05 TOTAL

2216944 1587374 1751091 1660205 1430935 2137323 2117120 2007783 1595793 1004303 17508871

4765.93 3412.497 3764.451 3569.067 3076.188 4594.763 4551.331 4316.281 3430.596 2159.025 37640.13

C) Total Electricity Consumption Data for Mitchell

36

Dec-05 4328379 9206.83 9 Nov-05 4111314 8721.01 3 Oct-05 3990294 8474.09 Sep-05 3771461 8009.59 9 Aug-05 3231571 6863.40 4 Jul-05 4470556 9502.17 2 Jun-05 5531242 11732.14 May-05 4589902 9747.16 4 Apr-05 3609577 7666.118 Mar-05 1856627 3951.68 9 TOTAL 3949092 3 83874.2 37

QUESTIONAIRRE STUDENTS’ ROOMS 1. How many do you sleep in this room? 2. What electrical gadgets do you posses and for how long do you run them? Electrical Equipment

Power rating (KW)

No. of running hrs during day

No. of running hrs during night

Bulb Fan Radio TV Water heater Percolator Kettle Fridge Computer Flat iron Blender Speakers Printer Rice cooker Phones 3. Do you have access to warm water? 4. If yes, how long do you utilize the warm water during….. a) Morning b) Afternoon c) Evening CORRIDORS Electrical No. Equipment

Power rating (KW)

No. of running No. of running hrs during day hrs during night

Flourescent tubes Water Heaters

38

SECRETARIAL BUREAUS Electrical No. Equipment

Power rating (KW)

No. of running No. of running hrs during day hrs during night

KITCHEN 1. How many students do you feed during a) break fast b) lunch c) Evening tea d) Supper 2. What type of fuel do you use for cooking different meals? Tick where appropriate. Type of fuel Biomass LPG Electricity

Breakfast

Lunch

Evening tea

Supper

3. Why do you utilize fuel in such a manner as indicated above?

39

4. What is the fuel consumption for each type? Type of fuel Biomass (tons) LPG (litres/m3) Electricity (Kw)

Breakfast

Lunch

Evening tea

Supper

6. What are the delivery costs for each of the following fuels? Type of fuel Cost (UShs) Biomass LPG 7. What are the rental costs of LPG storage tank per month? 8. What electrical equipments do you posses? Tick where appropriate Electrical No. of Power No. of running No. of running Equipment equipments rating hrs during hrs during night (KW) day Bulbs a) Fluorescent tubes b) Energy savers c) 100Watts d) 75Watts e) Others specify Fan Radio TV Water heater Percolator Kettle Fridge Computer Flat iron Blender Speakers Printer Boilers Cookers 9. How many workers are employed in the catering section? 5. How many hours do you run on each type of fuel?

40

Type of fuel Biomass(Hrs) LPG(Hrs) Electricity (Hrs)

Breakfast

Lunch

Evening tea

Supper

41