This paper presents the feasibility analysis and study of integrated renewable energy (IRE) using solar photovoltaic (PV) and wind turbine (WT) system in a hypothetical study of rural health clinic in Borno State, Nigeria. Electrical power consumption and metrology data (such as solar radiation and wind speed) were used for designing and analyzing the integrated renewable energy system. The health clinic facility energy consumption is 19 kWh/day with a 3.4 kW peak demand load. The metrological data was collected from National Aeronautics and Space Administration (NASA) website and used to analyze the performance of electrical generation system using HOMER program. The simulation and optimization results show that the optimal integrated renewable energy system configuration consists of 5 kW PV array, BWC Excel-R 7.5 kW DC wind turbine, 24 unit Surrette 6CS25P battery cycle charging, and a 19 kW AC/DC converter and that the PV power can generate electricity at 9,138 kWh/year while the wind turbine system can generate electricity at 7,490 kWh/year, giving the total electrical generation of the system as 16,628 kWh/year. This would be suitable for deployment of 100% clean energy for uninterruptable power performance in the health clinic. The economics analysis result found that the integrated renewable system has total NPC of 137,139 US Dollar. The results of this research show that, with a low energy health facility, it is possible to meet the entire annual energy demand of a health clinic solely through a stand-alone integrated renewable PV/wind energy supply.
The global environmental concerns over the use of fossil fuels for electric power generation have increased the interest in the utilization of renewable energy resources. In particular, rapid advances in wind turbine generator and photovoltaic technologies have brought opportunities for the utilization of wind and solar resources for electric power generation worldwide [
Moreover, the economic aspects of these technologies are now sufficiently promising to also justify their use in small-scale stand-alone applications for residential/ranch, communication, and health clinic use; several design scenarios have been proposed for the design of solar/wind power systems for stand-alone applications [
Integrated renewable (solar/wind) energy systems use two renewable energy sources, allow improving the system efficiency and power reliability, and reduce the energy storage requirements for stand-alone applications. The integrated renewable (solar/wind) systems is becoming popular in remote area power generation applications due to advancements in renewable energy technologies.
This study is on the feasibility analysis of a health facility load data and the renewable resources and evaluates the performance of the designed stand-alone PV/wind generation systems.
A standard health clinic in rural Nigeria requiring 19 kWh per day to run is considered and was used in the establishment of a hypothetical study for the electrical load data described by [
Power consumption rating.
Power consumption | Power |
Qty | Load |
---|---|---|---|
Vaccine refrigerator/freezer | 60 | 1 | 60 |
Small refrigerator (nonmedical use) | 300 | 1 | 300 |
Centrifuge | 575 | 1 | 575 |
Hematology mixer | 28 | 1 | 28 |
Microscope | 15 | 1 | 15 |
Security light | 10 | 4 | 40 |
Lighting | 10 | 2 | 20 |
Sterilizer oven (laboratory autoclave) | 1,564 | 1 | 1,564 |
Incubator | 400 | 1 | 400 |
Water bath | 1,000 | 1 | 1,000 |
Communication via VHF radio | 1 | ||
Stand-by | 2 | 2 | |
Transmitting | 30 | 30 | |
Desktop computer | 200 | 2 | 400 |
Printer | 65 | 1 | 65 |
The electrical load (daily load demands) data for a health facility.
Time | Daily load demands | Total/hr | |||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | ||
0.00–0.59 | 60 | 40 | 400 | 2 |
|
||||||||||
1.00–1.59 | 60 | 40 | 400 | 2 |
|
||||||||||
2.00–2.59 | 60 | 40 | 400 | 2 |
|
||||||||||
3.00–3.59 | 60 | 40 | 400 | 2 |
|
||||||||||
4.00–4.59 | 60 | 40 | 400 | 2 |
|
||||||||||
5.00–5.59 | 60 | 40 | 400 | 2 |
|
||||||||||
6.00–6.59 | 60 | 400 | 2 |
|
|||||||||||
7.00–7.59 | 60 | 400 | 2 |
|
|||||||||||
8.00–8.59 | 60 | 400 | 2 |
|
|||||||||||
9.00–9.59 | 60 | 15 | 20 | 400 | 2 | 30 | 400 | 65 |
|
||||||
10.00–10.59 | 60 | 300 | 28 | 15 | 20 | 400 | 2 | 30 | 400 |
|
|||||
11.00–11.59 | 60 | 300 | 28 | 15 | 20 | 400 | 2 | 30 | 400 |
|
|||||
12.00–12.59 | 60 | 300 | 575 | 15 | 20 | 1564 | 400 | 2 | 30 | 400 |
|
||||
13.00–13.59 | 60 | 300 | 575 | 15 | 20 | 400 | 2 | 400 | 65 |
|
|||||
14.00–14.59 | 60 | 300 | 20 | 400 | 1000 | 2 | 65 |
|
|||||||
15.00–15.59 | 60 | 20 | 400 | 2 |
|
||||||||||
16.00–16.59 | 60 | 400 | 2 |
|
|||||||||||
17.00–17.59 | 60 | 400 | 2 |
|
|||||||||||
18.00–18.59 | 60 | 40 | 400 | 2 |
|
||||||||||
19.00–19.59 | 60 | 40 | 400 | 2 |
|
||||||||||
20.00–20.59 | 60 | 40 | 400 | 2 |
|
||||||||||
21.00–21.59 | 60 | 40 | 400 | 2 |
|
||||||||||
22.00–22.59 | 60 | 40 | 400 | 2 |
|
||||||||||
23.00–23.59 | 60 | 40 | 400 | 2 |
|
||||||||||
Total |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
1: Vaccine refrigerator/freezer, 2: Small refrigerator (nonmedical use), 3: Centrifuge, 4: Hematology mixer, 5: Microscope, 6: Security light, 7: Lighting, 8: Sterilizer oven (laboratory autoclave), 9: Incubator, 10: Water bath, 11: Communication via VHF radio stand-by, 12: Communication via VHF radio transmitting, 13: Desktop computer, 14: Printer.
Daily load profile of the health clinic (load variation).
As from 06.00 hrs to 08.59 hrs, load is at the least (462 W). The load increased a little at 09.00 hrs (992 W) and at 10.00 hrs reached a certain level (1255 W) and remains there till 11:59 hr and at 12:00 hr increased again and reached the highest load (3366 W). It comes down at 13.00 hrs (1837 W) and remains there till 14.59 hrs, decreases little at 15.00 hrs (482 W), and remains there till 17.59 hrs where it starts to increase again. As from 10:00 hr to 15:59 hr, most of the energy generated by solar at these times is stored in the battery for use at night with wind energy.
At night between 18.00 hrs and 05.59 hrs, the load is minimal (502 W). Since wind blows much at night than in day, wind energy and the stored energy in the battery can compensate at these hours of time till day time when solar takes up.
Climatic conditions determine the availability and magnitude of solar and wind energy at a particular location. For different districts and locations, climatic conditions, including solar radiation, wind speed, and air temperature, are always changing. At the potential location, an analysis of the characteristics of solar radiation and wind conditions were made for better utilization of the solar and wind energy resources.
The data for monthly average solar radiation and wind speed for a given year (2013) were obtained from National Aeronautics and Space Administration (NASA) [
(a) HOMER output graphic for solar (clearness index and daily radiation) profile. (b) HOMER output graphic for wind speed profile.
In the months of September, October, January, February, and March, the solar radiation increases with differences from month to month as (0.43), (0.32), (0.26), (0.69), and (0.40), respectively, whereas, in the months of April, May, June, July, August, November, and December, the solar radiation decreases with differences from month to month as (0.08), (0.26), (0.39), (0.54), (0.29), (0.05), and (0.49), respectively.
In the months of January and February, the wind speed remains the same without differences from the months. In the months of March, April, October, November, and December, the wind speed increases with differences from month to month as (0.4), (0.1), (0.3), (0.6), and (0.5), respectively. In the months of May, June, July, August, and September, the wind speed decreases with differences from month to month as (0.4), (0.7), (0.2), (0.2), and (0.2), respectively. In the months of July, August, and September the wind speed has constant decrease of (0.2) differences from month to month.
The difference in months falls in the range of 0.1–0.7, and these differences are due to earth’s rotation.
The block diagram for a typical stand-alone PV/wind generating system is shown in Figure
Configuration of the integrated renewable (PV/wind) energy system with the energy storage and dump load.
The HOMER software was used to design an optimal integrated renewable power system. The description of HOMER can be found in Ani [
The network architecture for the HOMER simulator (proposed PV/wind power system).
The proposed PV module is rated at 5 kW. The initial cost of the modules is $10,000, and its operation and maintenance cost is $57, with the total NPC (for the PV module only) of $10,057, as can be seen in Figure
Net present cost of components of the integrated renewable PV/wind energy system.
The BWC Excel-R wind turbine has a capacity of 7.5 kW. Its initial cost is $27,000, and its operation and maintenance cost is $3,441, with the total NPC (for the wind turbine only) of $30,441. The turbine is estimated to last the project.
The Surrette 6CS25P battery is rated at 6 V and has a capacity 1,156 Ah. Twenty-four batteries initially cost $27,480 and the replacement cost and the operation and maintenance cost add a further $11,927 and $55,056, respectively, and a salvage cost of $-2,494 having the total NPC (for the batteries only) of $91,968.
The converter is rated 19 kW. Its initial cost is $3,800, and its operation and maintenance cost is $872, with the total NPC (for the converter only) of $4,672. The converter is estimated to last the project.
The integrated renewable energy component system has total capital of $68,280; the replacement cost and the operation and maintenance cost add a further $11,927 and $59,426, respectively, and a salvage cost of $-2,494, giving the total NPC (for the coupled (complete) system) of $137,139, as shown in the appendix (Figure
The average solar radiation in this location is relatively high. This gives a relatively good possibility and opportunity to engage the photovoltaic (PV) technique and technology as a component of an integrated renewable PV/wind energy system in order to produce clean energy for powering health clinic loads. Although wind speed is relatively moderate with an average of 3.8 m/s throughout the year, it compensates for solar during the months of poor radiation.
It can be noticed that more solar irradiance can be expected from the month of February to June while less solar irradiance is to be expected from December to January. On the other hand, more wind speed can be expected from the month of December to May while less wind speed is to be expected from August to October.
Solar PV compliment wind power during the months (August, September, and October) of poor wind speed, while wind compensates for solar power during the months (December and January) when solar radiation is less as shown in Figure
Electrical production of integrated renewable PV/wind energy system.
The integrated renewable energy system (PV/Wind) produces 9,138 kWh/yr (55%) from solar PV array and 7,490 kWh/yr (45%) from wind turbine making a total of 16,628 kWh/yr (100%) as shown in Table
Simulation results of the electricity production (kWh/yr), battery and inverter losses, and excess energy of the energy system configuration (PV/wind).
System operation | PV/wind system | |
---|---|---|
Consumption | kWh/yr | % |
DC primary load | 7,082 | 100 |
The total load to be supplied |
|
|
|
||
Production | kWh/yr | % |
PV array | 9,138 | 55 |
Wind turbine | 7,490 | 45 |
Total energy generated |
|
|
|
||
Losses | kWh/yr | |
Battery | 460 | |
Inverter | 1,250 | |
Total losses |
|
|
Excess energy going to dump load | 7,836 | |
Total energy supplied to the load | 7,082 |
Excess electricity always occurs when the battery state of charge (SOC) is at 93% upwards and discharges less (at the rate of 1.5 kW to 2.5 kW) and this is between Novembers and Mays. Between Junes and Octobers when the integrated renewable (solar radiation and wind speed) is low, the battery SOC is at 92% downward and discharges much (at the rate of 3 kW to 10 kW) and there will be no excess electricity from this point downward (due to poor solar radiation and less wind speed) as shown in Figures
Excess electricity versus battery state of charge.
Integrated renewable energy (PV/Wind) versus battery state of charge.
The network architecture for the HOMER simulator, proposed PV/wind power system and its optimization results.
Cost summary of the integrated renewable energy system.
This paper describes the feasibility study of load data and the renewable resources and evaluates the performance of the designed stand-alone PV/wind generation systems. Hourly average wind speed and solar radiation data from the site for the generating unit and the anticipated load data are used to predict the general performance of the generating system. These power systems are very well suited to supply the specific load demand of the rural health clinic that presents a peak in the day time (afternoon) when the solar radiation is maximum and minimal load at night time when the wind blows much (since wind blows much at night than in day). Such performance evaluations are useful in estimating the component sizes needed for generation systems to supply power to loads reliably. It is also helpful in performing a detailed economic analysis (cost benefit study) for the generating unit. Of particular interest is the introduction of dump load model. The excess wind and solar-generated power, when available, are used to heat water in an electric water heater, and the remaining power is sold to the community. This heated water can be used for any purposes in the health clinic such as drinking water. Finally, in the integrated renewable PV/wind energy system, there is no fuel consumption, which means no emission of CO2, CO, UHC, PM, SO2, and
See Figures
Electricity production summary of the integrated renewable energy system.
PV output summary.
Wind turbine (BWC Excel-R) output summary.
Battery bank state of charge summary.
Converter output summary.
Emission output summary.
The authors declare that there is no conflict of interests regarding the publication of this paper.