Designing an Autonomous Renewable Energy System for Balfour General Hospital

Group members
1.
Instructor
Autonomous Energy System
Date

INTRODUCTION.
With increasing demand of green energy, various technologies has evolved to address the deficit.
Green sources of energy can be integrated in a hybrid system to provide useful energy and reduce
over-reliance on the organic form of energy such as fossil fuels. The Orkney Island in the Scotland is
a populated subcontinent landmass surrounded with water of the Atlantic Ocean and North Sea. Most
regions of the Island is marginalized with less population connected to the grid. Economically,
traversing oceanic water with transmission lines with endeavor of supplying energy to less dense
populated island is very expensive on the scale of expenses and returns. With evolving technology in
the field of green renewable energy, stand-alone micro-grids have proven to be reliable in
rejuvenating such remotely accessible area with electrical energy. For instance, Orkney Island has
become globally popular for embracing technology in renewable sources of energy. Most of the
renewable energy harnessed in this island come from wind, tidal energy and solar insolation
integrated systems [1]
This report entails designing of the autonomous renewable energy for the Balfour general hospital.
The location of the hospital is suitable for installation of a stand-alone solar PV energy integrated with
wind and back up diesel generator. Feasibility study of the hospital and the surrounding vicinity was
carried out to determining designing factors of the hybrid system. Load analysis of the hospital was
also carried out with my weight on heavy hospital electrical equipment.
FEASIBILITY STUDY.
The study sort to find factors that could enhance quality and quality of power harnessed from the
location of installation. The hybrid system to be designed includes wind power, solar PV system
power, battery storage bank and back-up diesel generator. The process was split into three major
categories as mentioned below.
I. Wind power
II. Solar Energy
III. Diesel generator.
For the design considerations, the main primary electricity units are wind and solar energy. The main
function of the generator in the network is to offer back-up when there is peak load demand or and
when the primary sources incur faults and require repair and maintenance.
Analyzing availability of power on the site

Availability of natural sources of energy in the sight was studied. The GIS location of Balfour
general hospital is located at latitude 58o26’N and longitude 305’39”W as shown in the map below.
Fig 1: The GIS location of Balfour Hospital in Westray Orkney Island, Scotland.
Climatic conditions were retrieved from the meteorological data. Sun hours recorded from the year
2009 to 2018 as retrieved from the database is shown below [2].
Fig 2: Hours of sunshine in Westray Orkney Island for a decade [2].
The pattern shows a trend of intermittent behavior of daily sunshine hours, a correlation which is vital
when determining the capacity of solar PV system. Average temperature profile of the Westray
Orkney as retrieved from meteorological data is shown below [2].

Fig 3: Average temperature and precipitation of Westray Orkney Island [2].
The following data was extracted from the above bar and line graphs.
Table 1: Extracted Values of Temperature and Sun days in Westray Orkney Island.
Month Minimum
temperature
in 0C
Maximum
temperature
0C
Hot
day
0C
Sun
days
(2018)
Total
sun
hours
per
year
January
February
March
April
May
June
July
August
1
1
2
4
6
8
10
10
6
7
8
10
13
15
17
17
10
11
14
17
20
22
23
23
6
8
4
9
18
16
9
6
96.6
113
99
216
246.3
301
240
212

September
October
November
December
9
6
4
2
15
12
8
6
21
17
13
10
3
1
3
3
171
85.5
107
81
Average 7.16
The average maximum temperatures received on the island occurs in summer and low temperatures
are experienced during winter season. The location receives high temperatures in the middle of the
year and low temperatures at the beginning and end of the year. Therefore, most of solar energy in
this location can be harnessed during the summer period and back-up systems such as diesel generator
or wind power can be used to compensate for the power deficit during winter season.
The bar graphs below shows monthly sunny days, cloudy days and precipitation days.
Fig 4: Average monthly values of cloud sun and precipitation days [2].
Amount of cloudy cover directly influences the amount and intensity of sun rays reaching the earth’s
surface. The heavier the amount of cloud cover, the less efficiency solar system becomes.
Hospital equipment and daily load demand
Equipment in the Balfour hospital were classified into four main categories namely;

I. Medical electrical equipment
II. Structural equipment
III. Computer and telecom equipment.
Medical electrical equipment further classified into heavy and light electrical equipment depending on
the wattage rating. Structural equipment has system that operates Heat Ventilation Air Conditioner
(HVAC) and lighting system. Balfour General hospital accommodate a capacity of 68 inpatients. It
has 20 medical beds, 42 beds for surgical operations and 6 beds located in the midwifery unit. It is a
24-hour operational hospital.
The hospital has numerous devices that runs on the electric power. However, this report analyzed
major hospital equipment that consumes high wattage as shown below.
Table 2: Hospital Electrical Pilot Loads and Operation hours.
Item
Number
Equipment Quantity Electrical
specification
Wattag
e
Operation
hours
Total kWh
1 X-ray 1 250V A 5kW 5.6 28
2 Operating theatre
light
1 120V 2kW 10 20
3 Gastro scope 1 250V 10kW 3 30
4 Electrocardiograph 1 250V 6kW 4 24
5 Electro-surgical
unit
1 120V 3kW 9 27
6 Defibrillator 1 120V 5kW 6 30
7 ICU (patient
monitor)
4 250V 6kW 3 18
8 Oxygen
Concentrator
1 120V 0.5kW 20 10
9 Analyzer
Hematology
1 120V 3kW 5 15
10 Incubator
laboratory
1 250V 4kW 10 40
11 Refrigerator 1 120V 5kW 7 35
12 CT-Scanner 1 250V 4kW 7 28
13 Cardiotocograph 1 250V 3kW 11 33
14 Nebulizer 1 250V 1kW 10 10