G.E. Cell Tower System
Edesign 100
Section 9
Team 4:
Adam Willms - arw5176@psu.edu
Kevin Minton – kpm5164@psu.edu
Zequn Huang – zuh109@psu.edu
Yaoqing Yang – yyy5651@psu.edu
Submitted to Jeonghwan Jin
Date: 12/08/2010
Helix Turbine
Cell Tower
Solar Panel
Base Station
1.0 - Abstract
The purpose of our project is to design a telecom cell phone base station system that uses sustainable
energy sources as well as a diesel generator and sodium metal halide battery to optimize green power
used. We did a lot of external research to find an area, which has an unreliable energy grid, and also
illustrate environmental benefits of replacing the typical current solutions. We also figure out the whole
system which is feasible to implement with minimal resources and reusable across developing regions.
Table of Contents
2.0 – Introduction
3.0 - Mission Statement
4.0 - Customer Needs Analysis
5.0 - External Research
5.1 – Library/online
5.2 – Product Dissection
6.0 – Target Specification
7.0 - Concept Generation
8.0 – Concept Selection
9.0 – Final Specification
10.0 – Embodiment Design and Final Design Description
11.0 – Conclusions
12.0 – References
2.0 – Introduction
To create the most profitable green-energy cell tower, there were four main parts that our group
had to research and use the design process on:
o
o
o
o
Choosing a country (5.11)
Choosing a location in the country (5.12)
Choosing a turbine (5.13)
Choosing a Tower (7.0)
3.0 – Mission Statement
Team 4 believes that all persons regardless of age/gender/race/class should be able to have the
same opportunities to access and use cellular powered phones. We also believe in the conservation
of our planet and the use of green-energy to promote less pollution. Our role in this project is to
create a cell tower that will provide power for all people that is powered by the means of green
energy to cause minimal damage to the environment.
4.0 – Customer Needs Analysis
No.
1
Renewable Energy Source
2
3
Cost Effective
Durable
4
Ease of Manufacture
Customer Needs
A reliable energy source that is
reusable
A product which is profitable
A product which is easily
maintained
A product that is easy to
manufacture and distribute
Imp.
30%
35%
20%
25%
5.1 - External Research
5.11 – Choosing Country
Our country choice was Mauritius, an Island country just off of the southeast coast of Africa and about
five hundred miles off the coast of Madagascar in the Indian Ocean. Mauritius is a Republic nation that
has been independent since 1968. The total are of the country is about 2040 square kilometers, where
its 1,227,078 inhabitants reside. The only official language of Mauritius is English, but the Mauritian
people also speak French and Mauritian Creole, where the ancestries of the people are Indian, African,
Chinese, French and English, but no indigenous people on the island. The country has a steady
government that has elections on a five year basis, and is part of the Indian Ocean Commission, the
South African Development Community, and the Commonwealth of Nations. The country is an island
that was created by volcanoes, so the country’s highest points are roughly located in the middle of the
country. It’s highest peak is the Petite Riviere Moiré which is about 2717 feet in height. The overall
climate in Mauritius is tropical, modified by southeast trade winds. However, cyclones and anticyclones
affect the country from May-September and November-April. The environment itself is quite tropical
with beaches all along its coastline, but it also has many forests in its mountainous areas. The country
has a Ministry of Environment that is responsible for the cleanliness of the island. However, currently its
estuaries are being polluted due to garbage which is dumped into inland ravines by refuse companies
contracted by the Ministry of Environment.
Since Mauritius’ independence, it has developed from a low-income, agriculturally based
economy to a middle-income, diversified economy with growing industrial, financial and tourist sectors.
The country has a $12,356 per capita PPP and has the 6th highest GDP in Africa ($16.05 billion). The
country is also only one of three countries in Africa with a “high” Human Development Index rating.
From an economic standpoint, Mauritius’s unemployment rate is under 8%. Also, corporate tax
has been reduced to 15% to encourage non-resident companies to trade or invest through a permanent
establishment. Transportation is difficult in the country, being that the only means of transportation is
taxi cabs and public buses. Because of this, there are many transportation issues and the need for
energy is great, particularly in Port Louis, where over 80% of the country’s able workers work, and the
strong majority of people need to commute their each workday.
Mauritius Wind Speed:
The wind speed in Mauritius is measured in Beauforts, so the estimations of the wind speed
itself is fairly rounded. However, the speeds in Beauforts are measured from a scale of 0-10 (0 being no
wind and 10 being an extreme wind). The average Beaufort wind measurement per month in Mauritius
is as follows from January-December: 3-2-3-4-4-5-4-5-4-4-4-3. The conversion factor to miles per hour is
as follows on average was about 15mph. The conversion factor to meters per second from this
information is about 7 m/s per month.
5.12 – Choosing a Location in the Country
The Island is broken into 9 Districts:
1.) Black River – population: 60,587. It is the 3rd largest district in size, but the smallest in population. It
has unique constant wind effects that are prevalent from May-September and the highest peak on the
Island is located in this district.
2.) Flacq – population: 126,839. It is the largest district in size and has a well known market area.
3.) Grand Port – population: 106,665. Its northern region is mountainous, but its southern region is flat.
4.) Moka – population: 88,479. Called the central plateau of the island, its altitude is the highest district
on the island and contains the 2nd and 3rd largest peaks on the island.
5.) Pamplemousses – population: 122,352. This district is the most densely populated district on the
island.
6.) Plaines Wilhelms – population: 358,182. The district’s town of Curepipe lays on higher elevation than
any other town in the country.
7.) Port Louis – population: 127,855. This district is its own town, and is also the capital of the district.
Over 80% of the country’s people work here.
8.) Riviere du Remport – population: 98,854. Land levels and fairly flat and temperatures are fairly
tropical.
9.) Savanne – population: 66,356. Land levels are fairly flat and temperatures are fairly tropical.
The ideal location for our cell tower is a place that is of high elevation, around an area that is
fairly urbanized that has many people in it, but at the same time is not in the way of anything and does
not cause traffic of any sort. Our best location for the cell tower is the district Moka, particularly the
Moka-Port Louis mountain range. The reason for this location is because the tower will be at a relatively
high elevation, and wind speed, when the elevation of the wind turbine is doubled, increases up to 10%.
In addition, when near and urban area, when the size of the wind turbine is doubled, wind speed
increases about 36%. Placing the cell tower in this area will increase the wind speed at much as it
possibly can because Moka is already this highest elevated district in the country, the district is located
between the two most populated districts in the country, and has two of the three largest peaks in the
country. In addition, because so many people work in Port Louis, the need for energy there is great. So it
would be beneficial to place the cell tower in Moka. It is close enough to Port Louis to give them the
energy that they need, but at the same time the cell tower is far enough away that it will not disturb the
environment and will not cause any traffic or disturbance.
5.13 – Choosing a Turbine
When deciding on what type of alternative energy to use, there were many factors that needed to be
taken into account. Since our country we picked was Mauritius, we first looked at the landscape,
populations, population density, wind speeds, solar radiation and cell phone usage to determine where
to place the tower. After that was determined, our group had to choose what wind turbine would
produce the best results. There are two basic types of wind turbines, HAWT (horizontal axis wind
turbine) and VAWT (vertical axis turbine). HAWT turbines are what most people picture in their head
when they think of a wind turbine. Their rotor axis runs horizontally allowing for the gear box to be
located anywhere on a mounted pole. They contain a yaw mechanism that allows the blades to rotate
until they oppose the wind perpendicularly, maximizing the efficiency of wind obtained/natural wind
flow. The VAWT on the other hand is much more recent in design and therefore not as popular. Its rotor
shaft runs vertically allowing the gearbox to be located on the ground. This is an advantage in
maintenance of the machine since one wouldn’t have to climb hundreds of feet to repair a problem, but
a disadvantage in that the turbine can’t take advantage of the larger wind velocities at higher altitudes.
VAWT turbines typically have a more aesthetically pleasing look, and are much cheaper since they do
not require the extra cost of a yaw mechanism. Our group created a more detailed list of pros and cons
located below
HAWT Turbine
Main rotor shaft in horizontal direction
Advantages:
 Can be mounted higher
 Better efficiency
Disadvantages:
 Harder to maintain
 Higher wind-startup speed needed
 Need a yaw mechanism
Main rotor shaft in vertical direction
Advantages:
 No yaw mechanism needed
 Lower wind startup speeds
 Easier to maintain
Disadvantages:
 Decreased efficiency due to drag
 Don’t take advantage of wind speed at higher
altitudes
5.2 – Product Dissection/GE Battery
GE Durathon battery:
Advantages:
1. Suitable for extremely temperature. Performance unaffected by external temperatures (-40C to
+65C)
2. Minimum maintenance. No maintenance needed Remote Monitoring
3. Long life. Cycle life > 2500* cycles Fast recharge Float life > 15 years Indefinite shelf life
4. Green. >99 % recyclable No toxic or hazardous materials
5. High reliability. Integrated BMS optimizes performance of the battery.
6. High energy density. Energy density (150-220Wh/L)
GE packaged the high performance battery into specific modules and that modules are engineered into
energy storage solutions complete with integrated battery management and monitoring.
Case 1:
Green energy is sufficient and even more than what we need for the whole system, the energy goes to
charge controller, which will provide the energy to the BTS loads and cell tower(the inverter is
converting DC to AC power). The controller will put excess energy into the battery.
Case 2:
Green energy is not enough to support the system, and the battery will discharge to provide the
difference energy. If battery is empty, the generator will work to satisfy the loads.
Case 3:
No green energy, the generator will work instead. The generator will provide the exactly energy we
need for the BTS loads and the cell tower.
6.0 – Target Specification
We set our targets to try and make the cell tower almost 100% alternative energy powered, while
at the same time taking into consideration variable factors (no wind, no sun)to create a product
that minimizes cost and dump, as well as the amount of diesel fuel used.
7.0 - Concept Generation
Turbines – Refer back to 5.13
Tower Types:
Lattice Tower – Has the greatest flexibility and is often used in loading conditions. It typically has
three sides
Monopole Tower – A single tube tower that has one foundation and typically doesn’t exceed 200
feet.
Guyed Tower – A straight tower supported by guy wires to the ground which anchor the tower. It is
the cheapest tower to construct but requires the greatest amount of land.
Stealth Tower – Typically required by zoning, it is the most expensive tower.
8.0 – Concept Selection
Turbine:
concepts
cost
Durability
Land used
Safety
Ease of
manufacture
quality
Sum’+’
Sum’0’
Sum’-’
Net score
Continue
Lattice
tower
(reference)
0
0
0
0
0
Monopole Guyed
tower
tower
Stealth
tower
0
+
0
+
+
+
+
0
0
+
+
0
0
6
0
0
N
0
2
3
1
1
N
+
4
1
1
3
Y
0
2
2
2
0
N
After much research, our group decided to use a VAWT wind turbine called a helix turbine. This current
design is being tested in Nigeria and producing amazing results. It demonstrates all the positives of the
typical VAWT with less of the disadvantages. Because of its sleek “DNA appearance” it is not only a
marvel to look at, but it also solves the VAWT’s biggest flaw. Other VAWT’s have a lower efficiency than
HAWT’s because they produce a drag force. The helix allows for wind from any direction to be taken in,
but because of its new design, the normal drag force created is greatly reduced. The helix functions in
weather ranging from 32 – 131 degrees Fahrenheit, is ip67 rated weather resistant, and in recent tests
has been known to pay itself off in as little as 6 months.
Tower:
For our tower, we chose to use a lattice tower. It has the best flexibility/durability which is very useful
for our climate, since the tower will need to withstand monsoons and other extreme conditions.
9.0 – Final Specifications
PV Array Size
Turbine diameter
Battery Capacity
(effective)
Controller
efficiency
Turbine
0.97 Efficiency
from
0.20 to
0.5626 0.65
16 ft
Battery charging
efficiency
Generator
0.97 effiency
0.200.25 0.30
25 kwh
Battery
discharging
efficiency
0.92
4 kw
This chart is our final specification. We decide to use both solar and wind energy. And we decide to use
the PV array solar panel size 4. And we are going to use 16ft diameter wind turbine. Also, we will use
25kwh battery capacity. We use these numbers because these numbers could give us the lowest cost.
Turbine output
PV output
7,810 kwh
8,028 kwh
Generator output
Generator fuel
Generator hours
Dump energy
1,246
131
1,123
4,836
kwh
gal
hr
kwh
Also, when the green energy is not enough, we will use generator fuel instead. From our calculation, we
need to use 131 gal per year to make the cell tower work all the time.
From our research, we decided to take 12% as the interest rate. Then let’s calculate the total cost of the
project.
1. Initial cost:
Cell tower, generator and hut: $150000
Solar panel: $20000
GE Battery: $4688
Wind turbine: $25000
Total initial cost is $199688
2. Year cost:
Fuel: $655
Maintenance cost: $500 per year for the first ten years,
$1000 per year for 10 to 20 years,
$2000 per year for 20 to 30 years.
PV= $11051.2
3. Salvage value: $20000 after 30 years
PV=$667.5
Then the total cost for this 30 years project is :
$199688+$11051.2-$667.5=$210071.7
Then we are going to calculate the revenue for our project. First of all, we need to know how many
customers there will be to use our cell tower. We want to use the formula, P=population density*the
area which the cell tower covers*the percentage of people who are going to use our cell tower. From
the research, the population density is 341.53/km^2, the cell tower covered area is 49.9km^2, and 80%
percent people want to be our customers. So we get the customer numbers 13634. Assume we charge
them 0.0099$ per minute, and one customer wants to use 1000 minutes on average per year.
The revenue per year:
13634*0.0099*1000=$134976.6
Present value=
[1-1.12^ (-30)]/0.12*134976.6=$1087261
So the net profit is 1087261-210071.7=$877189.6
Do not forget, this is just for one cell tower! If it works well, we will build hundreds, even thousands of
cell towers. And we are going to earn millions, even billions of dollars!
10.0 – Embodiment Final Design Description
Our final design will encompass the most efficient
parts from every category of the cell tower that we
found from our research. The tower we will be using
is a lattice tower due to its durability. The turbine we
will be using is a Helix turbine mounted on the side of
the tower. On top of our hut, solar panels will be
placed to also bring in energy.
11.0 – Conclusion
From this cell tower project, we deeply realize that how important the design part of a project. Because
of the designing, we may get millions of dollars for a company. This project focuses on the green energy
use for cell towers, and which kind of green energy we are going to choose. Finally, we decide to use
solar and wind energy. Also, we use a lot of advantage technology in our project, such as helix wind
turbine, which increases the efficiency to a high level and save a lot of money. After calculating the cost
and revenue, we found that our project is a great success.
12.0 - References
GE durathon battery: http://geenergystorage.com/telecom.html
GE Solar panels:http://www.solarhome.org/solarpanelbrand_ge.html
Database: http://swera.unep.net
Turbine Information: http://www.helixwind.com/en/