Sustainable Design for Appledore Island

Sustainable Design
for Appledore Island
Final Alpha Team Project
Cyara New
Reid Balkind
Abhi Gupta
Valerie Katz
Yungton Yang

2

Introduction
Appledore Island is located about six miles off the coast of Maine and New
Hampshire; the island is completely self-sufficient and is home to the Shoals Marine
Laboratory. Being self-sufficient, it produces its own power and freshwater and it
manages all of its wastewater.
To generate power, Shoals Marine Laboratory uses one of its three diesel
generators, arrays of solar panels, and a 7.5 kW Bergey Wind Turbine to provide
power in winter months when wind is more prevalent and the sun less intense. In
an effort to make the island more sustainable, the Alpha Team aims to move
Appledore Island away from diesel generators and towards cleaner sources of
energy.
Freshwater supply comes from a well that is twenty feet deep with a six-foot
diameter. The water from this well is treated by filtration and chlorination. If the
water level in this well gets too low, however, there will be mixing between this
fresh well and a saltwater watershed, making it unsuitable for consumption. To
prevent this during dry summers when the well is insufficient and cannot meet the
freshwater demand, a reverse osmosis unit desalinates salt water, a process that is
energy intensive. The Alpha Team aims to facilitate this process by producing the
requisite additional energy in a sustainable way, or determine a new process to
implement altogether.
Finally, the island treats wastewater through four septic systems, three leach
fields, four composting toilets, and a FRICKle filter that treats gray water. The
FRICKle filter contains foam media on which bacteria grow. These bacteria respire

3
anaerobically and purify the water. All systems are therefore quite sustainable, but
there is room for additional considerations as there are still inefficiencies with the
FRICKle Filter.
The mission of Shoals Laboratory is to “provide education and research
programs that advance the 1) understanding of marine and coastal ecosystems and
2) development of sustainable solutions to environmental challenges” (The Mission
of the Shoals Marine Laboratory). The Alpha Team’s goal is to facilitate Shoals
Laboratory’s second goal and help to continue the islands efforts of becoming
increasingly sustainable. This will be accomplished through the implementation of
sustainable designs to improve the islands energy systems by shifting away from
diesel, a freshwater supply independent of the existing well, and a better
wastewater treatment system.

Energy
While Appledore Island has made strides in its energy production via the
implementation of solar panel and a wind turbine, it still uses some diesel for fuel.
Several solar arrays are in place on top of dorms two and three, and a 7.5 kW wind
turbine was brought onto the island in 2007. Diesel fuel is still being used however
to supplement the energy provide via these sustainable methods. Based on the
average generator capacity utilization graph (Appendix A) it was determined that
the island uses diesel generators to obtain 652.5 kWh/day. At this rate the
Appledore’s greenhouse gas footprint is 163 kg CO2 / day. (Appendix A)

4

Technologies Considered
To provide the island with more sustainable sources of energy to meet the
demand of 652.5 kWh/day currently being met by diesel fuel engines, several
“green” energy systems were considered. Solar panels with storage were considered
to harness solar energy, a wind turbine with hydrogen storage, fuel cells, and
batteries were considered to harness wind energy. Hydroelectric, geothermal, and
biomass systems were also considered.

Energy Source vs Annualized Cost
$14,000.00
$12,000.00
$10,000.00
$8,000.00
$6,000.00
$4,000.00
$2,000.00
$0.00
Solar with
Storage

Wind with
Storage

Geothermal

Hydropower

Biomass (BFB)

Figure 1. Comparing Energy Type to Annualized Costs
In comparing the several energy systems available, the three cheapest
options were hydropower, solar with storage, and biomass. A detailed calculation of
the annualized costs can be found in Appendix B.
Wind power was also ruled out because the island has a wind turbine, and it
is primarily used in the winter, when the wind is the strongest. As the Alpha Team
seeks to replace diesel generator usage, most of which is during the summer on

5
Appledore, it is not reasonable to install another wind turbine. The annualized cost
of wind power was determined to be $13,030.17.
For a geothermal power plant, the Alpha Team recommends a flash steam
power plant because at 235°C (Lecture Slides 2-25 Slide 5), the pressure of the
steam would be 100000 kPA (Appendix B – Geothermal), and at this pressure steam
becomes a liquid. Flash steam must be 175-235 degrees, so the well needed to
extract this high temperature superheated liquid would be 2.5-3.5 km deep, making
geothermal an impractical endeavor. The cost of geothermal power was determined
to be $13,138.14 per year.

Hydroelectric Energy
Hydroelectric was another option explored, with an abundance of water
surrounding the island providing the requisite environment for this system.. All
calculations are available in Appendix B – Hydroelectric. With the significantly low
annualized cost of $4,756.58 per year, hydroelectric was a very affordable choice for
Appledore. After calculation, however, is that it requires a massive area of 2,250,000
m2, or 617 acres. Considering the island spans only 95 acres, the proposal for such a
large basin is unreasonable. It would impede the marine activities that take place
around the island and seriously hinder research conducted by Shoals Laboratory.
Furthermore, the system would need to be located far enough from the island and
large enough (about 0.86 square miles) that it would not be worthwhile. The basin
would need to be 6 meters deep with a channel that is 30 m x 5 m, and would need
50 turbines each with a 0.108 m radius.

6

Solar Energy
The Alpha Team recommends solar energy with storage to as a possibility to
eliminate diesel use because solar power is already used on the island and
extending this infrastructure is very viable and simple. All calculations are available
in more detail in Appendix B - Solar. Also it is cost effective at $9,880.07 per year.
We recommend BP 3160 solar panels whose max power output is 160 W per panel,
this equates to 836.8 Wh produced per panel per day. Because Appledore only
averages 5.23 peak sun hours per day, additional energy must be stored (Lecture
Slides 2-9 Slide 19). Accounting for inefficiencies with the inverter and battery, solar
panels must collect 1028.26 kWh/day. This equates to 1229 panels that would cover
approximately 16668 ft2.
Because solar panels are most efficient when they are perpendicular to the
sun’s rays these panels should be placed at an angle. However, during the summer
months, the sun is higher in the sky, and thus the panels should have a tilt less than
45 degrees. It is recommended to place solar panels at the locations latitudinal
angle, + 15 degrees, and so for a summer bias we subtract 15 degrees and
recommend that these panels be placed at about a 28 degree angle (Lecture Slides
2-9 Slide 17). At this angle the panels would cover 14,722 square feet. The
advantages of solar energy remain the time of maximum energy usage; the summer
provides the maximum output. The other advantage remains that the infrastructure
already exists. The problem, however, is the large amount of space needed to
accommodate the panels. However, in comparison to other sources, area usage is
low, and cost is not severely high. Our recommendation is that these panels be

7
placed on top of buildings with appropriately slanted roofs before resorting to open
space on the north side of the island.

Biomass Energy
Biomass energy was the final option considered. Biomass energy very simply
utilizes different waste material for energy generation, with an efficiency of 90%
(What to Expect from Biomass Boiler Systems). There are many sources of fuel for
biomass systems, inclusive of wood pellets, wood chips, human and animal waste,
crop residue, and municipal solid waste (Types of Biomass Fuels). Furthermore,
there are two main types of biomass systems that the Alpha Team considered: the
combined cycle and the bubbling fluidized bed. In the first system, waste is burned
and the heat generated is used to boil water, which then turns into steam and turns
a turbine to produce electricity. The main fuel used is carbon based options, which
usually consists heavily of wood related waste and pellets. In the second system,
solid particles levitate above liquid moving at a low velocity, causing the particles to
act as a fluid. The bubble and fluid movement causes interactions with high heat
transfer, allowing for water to be boiled, which turns into steam and turns a turbine.
The main fuel used in this system is wood, plant remains, and solid waste. The Alpha
team recommends the utilization of the second system, simply because of the higher
number of feedstock options, and because the capital cost of a BFB is half as much as
a CC system ($4,114 vs $8,180) (Capital Cost for Electricity Plants). All calculations
are outlined in Appendix B – Biomass. Because Biomass systems are generally used
for large scale energy production, it seems unfeasible for Appledore Island to
implement this system. If there was a larger energy need, biomass would be a viable

8
option. Furthermore, biomass systems require a large amount of space for the
boilers and fuel storage (Advantages and Disadvantages of Biomass). Currently,
biomass energy would have an annualized cost of $11,846.90, but this is not
considering the cost of resources. Biomass fuel is very expensive, and even with the
use of waste from the island, fuel would need to be imported.

Energy Conclusion
With the technologies looked into: solar power, hydropower, and biomass
considered, solar was determined to be the best solution. Hydropower is the
cheapest option, but it is very space intensive. Biomass is economically viable for
large energy production needs, but for the small scale of Appledore is not feasible as
biomass may need to be imported. Solar power was determined to be the best
option. It is relatively cheap, and reliable as sun input is reliable in summer months.
Additionally solar arrays are already in place in Appledore, so extending this
existing system makes most sense.

9

Drinking Water Treatment
Celia Thaxter Island Garden
Each season Shoals Laboratory uses about 157,029 gallons of water sourced
from both a well on the northern region of the island, as well as a reverse osmosis
unit (2014 Sustainable Energy Report 46-47). In the summer of 2014 the size of the
watershed was estimated to be 53,840 ft^2, but this well must be supplanted by a
reverse osmosis unit because if the water in the well runs too low, the risk is run of
contamination with saltwater.
Water conservation efforts on the island are evident as residents are
restricted to only two “navy style” showers a week in which water only runs during
rising. These efforts however can be improved with the Celia Thaxter Island Garden.
This garden was first cultivated in the late 1800s when by Celia Thaxter whose
father established a hotel on the island. She had a love for gardening and art, and her
prose and poetry received considerable fame. The garden drew in many artists and
writers and for this reason holds great historical value and is worthy of being
preserved (About Celia Thaxter's Island Garden). The flowers in the garden need
freshwater, however when water is limited it is difficult to justify using fresh well
water to cultivate the blooms when it is needed elsewhere. Our proposal is a rain
water collection system estimated roughly to cost around $4,000. The island
conducts tours of the garden seven times a summer, each tour with 24 people, and
each person is charged 100, this brings in a total $16,800, and it is reasonable to
have some of this revenue directed towards a system to make the garden more
sustainable.

10

Technologies Considered
Because the well currently on the island is insufficient in dry years, other
freshwater sources are necessary. To meet the additional freshwater need options
considered included: digging another well, slow sand filter, rapid sand filter, and
solar distillation. Reverse Osmosis is currently in use on Appledore but uses a high
level of energy, making it necessary to consider other options. Solar distillation was
possibly the most environmentally friendly option as once it was built it would only
require upkeep to run and no further inputs. Comparatively, while the two types of
filtration would require upkeep and inputs to keep it running, they would still be
relatively minor complications for an operation this small. These two methods
would also take up very little space on the island and don’t depend on
uncontrollable variables such as the sun.

Filtration System vs Annualized Cost
$2,000.00
$1,600.00
$1,200.00
$800.00
$400.00
$0.00
Slow Sand Filtration

Rapid Sand Filtration

Solar Distillation

Figure 2. Filtration System vs Annualized Cost
The rapid sand filter cost includes the cost of system installation, sand,
backwashing, chlorine, and the contact tank. The slow sand filter cost includes the

11
cost of the system installation, sand, chlorine, and contact tank. The solar distillation
cost only includes the cost of system install, per nature of the technology. All
calculations are outlined in Appendix C.
With slow sand and rapid sand filtration systems already partially or
completely in place on Appledore, the Alpha Team believes it is in the best interest
of the island to continue working with sand filters. However, because solar
distillation is so cheap, the Alpha team performed an analysis on all 3 systems.

Solar Distillation
Solar distillation utilizes solar energy in order to evaporate and purify salt
water. Because this process utilizes salt water versus fresh water which the other
two require it would put much less of a strain on the island. The fresh water source
has steadily grown smaller which poses a potential problem. This method uses solar
heat to evaporate salt water. A black heat-absorbent surface is placed at the bottom
of the container to help capture heat inside the container more quickly. The
evaporated water then condenses on the cool plastic of the top part of the container.
During the condensation part of the process much of the heat energy is reabsorbed.
This evaporated water is now pure of salt and bacteria and will drip down the side
to a collection basin where it can now be used to drink safely. This process isn’t very
time efficient and does require a comparatively large area to hold all of the housings.
The upside to this process though is that it doesn’t require any further treatment to
the water and the solar distillation housings only require the water to work. It is
also environmentally friendly in this regard. The annualized cost of the system is

12
$617.51, which is outlined in Appendix C – Solar Distillation. However, the size
required is 2592.5 m2, a very large section of space.

Rapid Sand Filtration
Rapid sand filtration utilizes porous media filtration in order to clean the
water of colloidal and suspended solid. It requires fresh water to run as it won’t
clean the salt out of sea water. The water is run through a tank containing sand and
uses gravity to pull it through. The sand will remove any suspended solids in the
water. As the sand gets more clogged up the water will experience head loss or a
loss of pressure. In order to clean the sand it must be backwashed. Backwashing is
when water is forced the opposite way through the filter. The water will cause the
sand to expand and release all of the collected waste from the water. This process
does require energy to run. After the water is filtered through the sand it still may
have bacteria present, such as cryptosporidium or giardia lambia. Thus, it requires
disinfection which is accomplished with the use of chlorination. The water is sent to
a contact tank where it is exposed to chlorine that should kill varying levels of
bacteria depending on the amount of time spent in there. After leaving the contact
tank the water will be safe enough to drink. This process is very time efficient but
does have its fair share of downsides. First of all, it requires fresh water to run.
Second of all, it requires energy and chlorine to run which contribute to annual
costs. Another problem is that it does require the use of chemicals to clean the water
which is an area of concern for many people. The Alpha Team calculates a rapid
sand filter would need to be 0.043 m2. It would also require 78.792 kg of sand
initially and then 3.747 kg of chlorine per year with a contact tank with an area of at

13
least 275 gal, and 3.5 kw/day to backwash. With these factors in mind the
annualized cost of a rapid sand filter would come out to $1,730.99. All calculations
are outlined in Appendix C – Rapid Sand Filtration.

Slow Sand Filtration
Slow sand filtration is a process very similar to rapid sand filtration. Rather
than utilizing backwashing the sand, though, the top layer of sand must be replaced
every few months. This process has all the same pros and cons of rapid sand
filtration except for discrepancies in the price to run it and the fact that slow sand
filtration does require it’s consumers to be careful of water usage, as it does take
time for water to cleanse under this system. The slow sand filter would need to be
2.17 m2 and would require 7000 kg of sand with the top 2 inches of it being replaced
yearly. It would also require the same amount of chlorine and a contact tank as the
rapid sand filter. This means that the slow sand filter comes out to be $859.26
annually. All calculations are outlined in Appendix C – Slow Sand Filtration.

Drinking Water Conclusion
In conclusion, the Alpha Team recommends the use of a slow sand filter. It is
a cheap option for water purification and requires little space to operate. Although
the use of chlorine is a downfall of this process, the benefits are greater than the
losses, and ultimately beats out the other technologies. Rapid Sand filtration is very
expensive in regards to the other choices, while solar distillation is cheap and does
not use chlorination, but requires a large amount of space that would be difficult to
find on Appledore.

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Wastewater Treatment
Technologies Considered
The island’s wastewater systems at the time being are relatively sustainable,
however the FRICKle filter has been having issues due to its design, so the Alpha
Team proposes wastewater treatment options for effluent from primary settling.
Two general methods were considered: combined blackwater and greywater
treatment and separate blackwater and greywater treatment. In combined
treatment systems, septic tanks are proposed for primary treatment, where solids in
the wastewater will settle and be anaerobically digested, with remaining liquid
waste being passed to a secondary treatment system. These secondary treatment
systems include constructed wetlands, leach fields, rotating biological filters, and
trickle filters. This provides 4 options in combined treatment, with the septic tank
paired with each secondary option. For separated systems, a composting toilet
would be used to separate and collect blackwater, with the remaining greywater
being treated in a secondary system, either constructed wetlands or leach fields.
This provides 2 separated treatment options, with the composting toilets paired
with the two secondary options. The Alpha Team compared the annualized costs of
the 6 options presented, and proceeded to conduct a more thorough review of the
top 2 options. All calculations are outlined in Appendix D.

15

GW and Combined Systems Annualized Costs
8000.00
6000.00
4000.00
2000.00
0.00
Septic + CW

Septic +
Leach

Septic +
RBC

Septic +
Trickling

Compost + Compost +
CW
Leach

Figure 3. Wastewater Treatment Options vs Annualized Costs
The Alpha Team decided to consider two technologies for a combined system. We
would use either a septic tank with a constructed wetlands or a septic tank with a
leach field as they were by far the cheapest options.

Septic Tank
Septic Tanks are necessary for primary treatment of wastewater. In the
septic tank, solids settle and are anaerobically digested. The purpose of the septic
tank is to collect the solids and remove large pieces of material such that the
secondary treatment option can consume the remaining waste and cleanse it such
that consumption or environmental discharge is acceptable. The Alpha team
calculates that the annualized cost of this system is $1,193.30, compared to the
other primary treatment option of composting toilets which cost $6,708.59, nearly 3
times as much as septic tanks. Comparing size, the septic tank was 2400 gal, while
22 composting toilets would be needed, or about 2200 liters (581 gal). All

16
calculations are outlined in Appendix D, under the septic tank and composting toilet
sections.

Constructed Wetlands
The constructed wetlands receive wastewater from a pipe connected to the
septic tank. Wastewater can either flow above the existing soil, or it can flow
through the soil, such as gravel, clay, or sand. The flow of the wastewater is
relatively even, flowing across the width of the wetland. The Constructed Wetland
contains microorganisms known as periphyton that break down the pollutant in
wastewater, and much of the waste and excess concentration of nutrients are
consumed by the many plants that exist in the wetland. The purpose of the
constructed wetland is to mimic natural wetlands, and thus it is necessary to place
plants into the system. As saltwater is used from the ocean, it is necessary to use
saltwater plants such as saltmeadow hay, salt grass, sea lavender, and salt marsh
aster. The cost of just the wetlands is $435.36, while the cost of the combined septic
tank and constructed wetlands system is $1628.66. The size of the wetland is
3208.33 ft3. All calculations are listed under Appendix D – Combined System
Constructed Wetland.

Leach Field
Leach fields are a secondary treatment option for wastewater, cleaning the
water after it has gone through a primary treatment option. The system generally
contains a large number of perforated pipes that leach wastewater from them into
the soil such that the microorganisms can cleanse it, but animals in the ecosystem
won’t be able to reach it. The leach fields contain bacteria in the soil that remove

17
dissolved organic material in the effluent. The annualized cost of the system is
$623.71, with a size of 4800 ft2. All calculations are listed under Appendix D –
Combined System Leach Field.

Conclusion
After comparison of the constructed wetlands and leach field, the Alpha team
chose the constructed wetlands as the secondary treatment option for wastewater,
allowing for the entire system to be composed of a septic tank and a constructed
wetland. There were many considerations that led to this decision. As the
calculations show, the constructed wetlands is cheaper than the leach field by a cost
of $1628.66 to $1817.01, which is another good reason to use the constructed
wetlands over the leach field. The constructed wetlands also provides Appledore’s
inhabitants with an aesthetically pleasing piece of land and wildlife a habitat to live
in. Taking all of these considerations into account, it is clear why the septic tank and
constructed wetlands combination is better than the septic tank and leach field
system.

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System Placement

Solar Panel Field

Constructed
Wetlands

Slow Sand
Filtration

The placement of systems is dependent on existing infrastructure and the
natural characteristics of the island. The Alpha team recommends placing a Solar
Panel Field in an area that is large and open, such as the north side of Appledore
Island. These could hypothetically go anywhere there is room and direct sunlight.
Ideally, the Slow Sand Filtration would be placed in an area where the soil is mostly
sand as it requires a lot of sand to function. Further, close placement to housing and

19
dormitories will provide fast access to drinking water for the population on the
island. Constructed Wetlands were placed very close to water in a marshy area,
necessary for water flow into the system. Placement also considered the location of
the restrooms, as it is necessary to treat the water in a timely manner without
allowing the harsh smell of the wastewater to reach the people of Appledore.

Conclusion
The most sustainable design for Appledore Island includes Solar Power for
Energy, Slow Sand Filter with Chlorination for Drinking Water, and Constructed
Wetlands with a Septic Tank for Wastewater. The Alpha Team finds solar power the
best option for energy because of its inexpensiveness and space efficiency.
Appledore currently uses solar power, making it viable to extend the infrastructure
onto more buildings or further onto the island. The next step is to increase the
production and application of the solar energy so Appledore no longer needs to use
Diesel Fuels. The Slow Sand Filter was chosen because it was the less expensive
compared to rapid sand. However, it does require a high usage of sand but it does
not backwash the water, which is important as energy demand does not increase.
Appledore must watch its water consumption as the slow sand filter cleans slowly,
and there will be less water available in comparison to other systems. As for
wastewater, Constructed Wetlands are the lease least expensive overall and
extendable. Because of their characteristics, it will provide a good habitat for
wildlife and blend in with the environment. The Constructed Wetlands are also
much smaller than the Leach fields, making it the best option for wastewater. The

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Alpha Team finds these to be the most sustainable options for Appledore moving
forward.

WORKS CITED
About Celia Thaxter's Island Garden.. (n.d). Retrieved May 5, 2015, from
http://www.sml.cornell.edu/sml_publiced_aboutthegarden.html
“Advantages and Disadvantages of Biomass”. Eco Home Essentials, 2015. Web. 11
May 2015.
Bach, Alan, Michelle Bowen, Paroma Chakravarty, and Sean Snow. 2014 Sustainable
Engineering Report. Shoals Marine Laboratory, 2015.
Capital Cost for Electricity Plants. U.S. Energy Information Administration, April 12,
2013. Web. 11 May 2015.
Jones, Ben. “What to Expect from Biomass Boiler Systems.” The Green Home:
Construction and Lifestyle. Web. 11 May 2015.
The Mission of the Shoals Marine Laboratory. (n.d). Retrieved May 5, 2015, from
http://www.sml.cornell.edu/sml_welcome_mission.html
“Types of Biomass Fuels.” Types of Biomass Fuels. Hurst Boiler and Welding
Company, Inc., 2015. Web. 11 May 2015.

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Appendix A
Appledore Island information

60

88%

50

74%

40

59%

30

44%

20

29%

10

15%

0

0%

10:15 AM

4:15 PM

10:15 PM

4:15 AM

Capacity Utilized

Power Used (kW)

Average Generator Capacity Utilization over a Day

10:15 AM

The above graph (Lecture Notes 1-30 Slide 20) outlines the average generator
capacity utilization on Appledore over the course of 1 day. For a baseline, it is
assumed that the power used is 30 kW, and therefore the overall energy used per
day is 720 kWh. However, the Alpha Team aims to attain a more accurate measure
of energy used. Therefore, the graph was broken as follows:
30 kW * 12 hr + 26.25 kW * 3 hr + 21.25 kW * 6 hr = 652.5 kWh/day
Knowing the energy used per day, the amount of CO2 produced can be calculated.
652.5 𝑘𝑊ℎ
1

*

3.6∗106 𝐽
𝑘𝑊ℎ

∗

69.22 𝑔 𝐶𝑂2
106 𝐽

= 163 kg CO2 /day

The rate at which energy is used can also be determined.

22
652.5 𝑘𝑊ℎ
24 ℎ𝑟

= 27.1875 kW

Because Appledore only functions for 3 months of the year, costs, energy usage, and
other factors relying on time must keep this in consideration.
365 𝑑𝑎𝑦𝑠
1

3 𝑚𝑜𝑛𝑡ℎ𝑠

∗ 12 𝑚𝑜𝑛𝑡ℎ𝑠 = 91.25 days  91 days

Appendix B
Energy Systems
Solar Energy
The annualized costs were calculated as follows. First, the uniformed costs:
Capital Cost = $4183/kW, Discount Rate = 0.05, Lifetime = 20 years
0.05

($4183*27.1875 kW)[1−(1+0.05)−20 ]= $9125.61
Then the annualized costs were calculated by adding uniform and O&M Costs:
$9125.61 + ($27.75/kW/yr * 27.1875 kW) = $9,880.07
It is assumed that BP 3160 Solar Panels are used, which have a max power output of
160W, voltage of 35V, current of 4.5 amps, and a size of 31” x 63”. (Lecture Slides 29 Slide 22). Appledore has 5.23 Peak Sun Hours (Lecture Slides 2-9 Slide 23), or the
effective sunlight received per day. Therefore, the energy per panel per day is:
160 W * 5.23 PSH = 836.8 Wh /day / panel
Assuming the efficiency of the inverter is 0.75, and the efficiency of the battery is
0.8, the amount of energy needed to be stored is:
EPSH + Enight =

5.23 ℎ𝑟
∗ 652.5 𝑘𝑊ℎ
24ℎ𝑟

0.8

The number of panels needed are:

+

(18.77 ℎ𝑟)
∗ 652.5 𝑘𝑤𝐻
24 ℎ𝑟

0.8∗0.75

= 1028.26 kWh

23
1028260 𝑊ℎ
1

1 𝑝𝑎𝑛𝑒𝑙

* 836.8 𝑊ℎ = 1229 panels

The area needed is:
(31 in * 63 in)*(1229 panels) = 2,399,836.5 in2 = 16,665.53 ft2
The preferred angle for the panels is:
42.96° - 15° = 27.96°  28°
Shifting the area used by the panels to:
63” *cos(27.96°) = 55.65” = Adjusted Side Length
31” * 55.65” = 1725 in2 = Adjusted Area per panel
1 𝑓𝑡

1725 in2 * 1229 panels *(12 𝑖𝑛)2 = 14,722.4 ft2
Hydroelectric Energy
The annualized costs were calculated as follows. First, the uniformed costs:
Capital Cost = $2936/kW, Discount Rate = 0.05, Lifetime = 50 years
0.05

($2936*27.1875 kW)[1−(1+0.05)−50 ]= $4372.42
Then the annualized costs were calculated by adding uniform and O&M Costs:
$4372.42 + ($14.13/kW/yr * 27.1875 kW) = $4,756.58
Size of the basin was assumed to be 1500m x 1500m x 6m.
V = 13,500,000 m3
A = 2,250,000 m2
The channel has a length of 30m and width of 5m, having an area of 150 m2. This
makes the velocity of fluid:
𝑄

vfluid = 𝐴 =

2250000
150 𝑚

𝑚3
ℎ𝑟

1ℎ𝑟

* 3600 𝑠 = 4.167 m/s

Assuming the Alpha Team uses 50 turbines, each turbine will have a radius of :

24
𝑐𝑦𝑐𝑙𝑒𝑠

Etotal = Ptotal*

𝑑𝑎𝑦

652500 Wh = Ptotal *

ℎ𝑟𝑠

*𝑐𝑦𝑐𝑙𝑒

4 𝑐𝑦𝑐𝑙𝑒𝑠
𝑑𝑎𝑦

6 ℎ𝑟

*𝑐𝑦𝑐𝑙𝑒

Ptotal = 27,187.5 W
Ptotal = nturbines * pturbines
27,187.5 W = 50 turbine * pturbines
pturbines = 543.75 W
1

pturbines = 2 * At pv3 *efficiency
1

𝑘𝑔

543.75 W = 2r2(1027𝑚3 )(4.167)3(0.4)
r = 0.108 m
Biomass Energy
The annualized costs were calculated as follows. First, the uniformed costs:
Capital Cost = $4114/kW, Discount Rate = 0.05, Lifetime = 20 years
0.05

($4114*27.1875 kW)[1−(1+0.05)−20 ]= $8975.08
Then the annualized costs were calculated by adding uniform and O&M Costs:
$8975.08 + ($105.63/kW/yr * 27.1875 kW) = $11,846.90
Wind Energy
The annualized costs were calculated as follows. First, the uniformed costs:
Capital Cost = $6230/kW, Discount Rate = 0.05, Lifetime = 30 years
0.05

($6230*27.1875 kW)[1−(1+0.05)−30 ]= $11,018.29
Then the annualized costs were calculated by adding uniform and O&M Costs:
$11,018.29 + ($74.00/kW/yr * 27.1875 kW) = $13,030.17

25
Geothermal Energy
The annualized costs were calculated as follows. First, the uniformed costs:
Capital Cost = $6243/kW, Discount Rate = 0.05, Lifetime = 45 years
0.05

($6243*27.1875 kW)[1−(1+0.05)−45 ]= $9549.39
Then the annualized costs were calculated by adding uniform and O&M Costs:
$9549.39 + ($132/kW/yr * 27.1875 kW) = $13,138.14
Pressure of steam is calculated as stated:
1 Kb *

1000 𝑏
1 𝐾𝑏

∗

1∗106 𝑃𝑎
1𝑏

1 𝑘𝑃𝑎

* 1000 𝑃𝑎 = 100,000 kPa

Appendix C
Drinking Water Treatment Systems
Chlorination
The annualized cost for chlorine were calculated.
Present cost * Chlorine (kg) = Annualized Cost
$10/kg * 3.747 kg = $37.47
Sizing for the contact tank was completed as follows:
Residual Chlorine = 1.2 mg/L
Concentration of E.Coli = 0.034 – 0.05 mg min/L
Concentration of Girardia = 47 – 150 mg min/L
Concentration = 150 mg/L = ConcC2 * time = ConcC2 * V/Q
150 = 1.2 *

𝑉
2.2

𝑔𝑎𝑙
𝑚𝑖𝑛

V = 275 gal or 1041 L

26
Slow Sand Filtration
The annualized costs were calculated. First, the annualized costs for the system:
Capital Cost = $100/m2, Discount Rate = 0.05, Lifetime = 15 years
0.05

($100*2.17 kW)[1−(1+0.05)−15 ]= $20.91
Uniformized Cost + O&M Cost = Annualized Cost
$20.91 + $100.00 = $120.91
Then the annualized cost for the sand:
Capital Cost = $1/kg, Discount Rate = 0.05, Lifetime = 15 years
0.05

($1*7000 kg)[1−(1+0.05)−15 ]= $674.40
Uniformized Cost + O&M Cost = Annualized Cost
$674.40 + $0.00 = $674.40
Then the annualized cost for the contact tank:
Capital Cost = $1/gal, Discount Rate = 0.05, Lifetime = 15 years
0.05

($1*275 gal)[1−(1+0.05)−15 ]= $26.49
Uniformized Cost + O&M Cost = Annualized Cost
$26.49 + $0.00 = $26.49
The annualized costs were calculated by adding chlorine, system, contact tank, and
sand:
$37.47 + $120.91 + $674.40 + $26.49 = $859.26
The slow sand filter was sized as follows:
Assuming flow rate (Q) = 1.168 gal/min because demand = needed flow rate

27
Assuming V = 0.05 gpm/ft2 as average loading rate such peak loading rate does not
exceed 0.1 gpm/ft2
𝑄

A=𝑉=

𝑔𝑎𝑙
𝑚𝑖𝑛
𝑔𝑝𝑚
0.05 2
𝑓𝑡

1.168

= 23.36 ft2 = 2.17 m2

Amount of sand used:
Assuming depth of sand is 4 feet:
(23.36 ft2) * (4 ft) = 93.44 ft3
93.44 ft3 *

28,316.85 𝑐𝑚3
1 𝑓𝑡 3

= 2.65 * 106 cm3

Density of Sand = 2.65 g/cm3
Mass of Sand = 7000 kg
Rapid Sand Filtration
The annualized costs were calculated. First, the annualized costs for the system:
Capital Cost = $100/m2, Discount Rate = 0.05, Lifetime = 20 years
0.05

($100*0.043 m2)[1−(1+0.05)−20 ]= $0.35
Uniformized Cost + O&M Cost = Annualized Cost
$0.35 + $500.00 = $500.35
Then the annualized cost for the sand:
Capital Cost = $1/kg, Discount Rate = 0.05, Lifetime = 20 years
0.05

($1*78.792 kg)[1−(1+0.05)−20 ]= $6.32
Uniformized Cost + O&M Cost = Annualized Cost
$6.32 + $0.00 = $6.32
Then the annualized cost for backwashing:

28
Capital Cost = $4183/kW*70 GPD*0.05 kW/GPD = $14,640.5
Discount Rate = 0.05, Lifetime = 20 years
0.05

($14640.5)[1−(1+0.05)−20 ]= $1174.79
Uniformized Cost + O&M Cost = Annualized Cost
$1174.79 + $0.00 = $1174.79
Then the annualized cost for the contact tank:
Capital Cost = $1/gal, Discount Rate = 0.05, Lifetime = 20 years
0.05

($1*275 gal)[1−(1+0.05)−20 ]= $22.07
Uniformized Cost + O&M Cost = Annualized Cost
$22.07 + $0.00 = $22.07
The annualized costs were calculated by adding chlorine, system, contact tank, and
sand:
$37.47 + $500.35 + $6.32 + $1174.79 + $22.07= $1,740.99
The rapid sand filter was sized as follows:
𝑄

A=𝑉=

𝑔𝑎𝑙
𝑚𝑖𝑛
𝑔𝑝𝑚
0.05 2
𝑓𝑡

1.168

= 23.36 ft2 = 2.17 m2

Amount of sand used:
Assuming depth of sand is 27”, or 2.25 feet:
Vsand = 1.05 ft3 = 29,733 cm3
Density of Sand = 2.65 g/cm3
Mass of Sand = 78,792 g = 78.792 kg

Solar Distillation

29
The annualized costs were calculated. First, the annualized costs for the system:
Capital Cost = $0.35/m2, Discount Rate = 0.05, Lifetime = 10 years
0.05

($0.35*2592.5 m2)[1−(1+0.05)−10 ]= $117.51
Uniformized Cost + O&M Cost = Annualized Cost
$117.51 + $500.00 = $617.51
The size of the Solar Distillation system was determined as follows:
A=
Q=

1.168 𝑔𝑎𝑙
𝑚𝑖𝑛

∗

1440 𝑚𝑖𝑛
𝑑𝑎𝑦

∗

𝑄∗2.3
𝐸𝐺
3.7854 𝐿
𝑔𝑎𝑙

= 6366.74 L/day

E = 0.3
G=

A=

𝑘𝐽
𝑠
𝑚2
𝑑𝑎𝑦

5.23 ∗ℎ𝑟

∗

3600 𝑠
ℎ𝑟

𝐿
∗2.3
𝑑𝑎𝑦
𝑚2

6366.74

0.3∗18.828𝐽/

=

18828 𝑘𝐽
𝑚2
𝑑𝑎𝑦

= 2592.5 m2

𝑑𝑎𝑦

Appendix D
Wastewater Treatment Systems
Septic Tank
The annualized cost of the septic tank was determined as follows:
Capital Cost = $3.60/gal, Discount Rate = 0.05, Lifetime = 20 years
0.05

($3.60*2400 gal)[1−(1+0.05)−20 ]= $693.30
Uniformized Cost + O&M Cost = Annualized Cost
$693.30 + $500 = $1193.30
The size of the septic tank was determined as follows:

30
V=

𝐴𝑣𝑔 𝐹𝑙𝑜𝑤 𝑅𝑎𝑡𝑒
𝑑𝑎𝑦

*

𝑑𝑎𝑦
1

=

2400 𝑔𝑎𝑙𝑙𝑜𝑛𝑠
𝑑𝑎𝑦

∗

𝑑𝑎𝑦
1

= 2400 gallons

Composting Toilet
The annualized cost of the composting toilet was determined as follows:
Capital Cost = $3000/unit, Discount Rate = 0.05, Lifetime = 15 years
0.05

($3000*22 units)[1−(1+0.05)−15 ]= $6358.59
Uniformized Cost + O&M Cost = Annualized Cost
$6358.59 + $350 = $6708.59
The sizing of the toilets was completed as follows:
500 L/year urine * 0.25 years = 125 L/summer urine / person
50 L/year feces * 0.25 years = 12.5 L/ summer feces/person
160 people live on island at peak time
𝐿 𝑢𝑟𝑖𝑛𝑒

125 𝑝𝑒𝑟𝑠𝑜𝑛 * 160 persons = 20,000 L urine
𝐿 𝑓𝑒𝑐𝑒𝑠

12.5 𝑝𝑒𝑟𝑠𝑜𝑛 * 160 persons = 2,000 L feces
Each toilet holds 1,100 L of waste, with 22,000 L of waste
22,000 𝐿 𝑤𝑎𝑠𝑡𝑒

Thus number of toilets = 1000 𝐿 𝑤𝑎𝑠𝑡𝑒/𝑡𝑜𝑖𝑙𝑒𝑡 = 22 toilets
Combined System Constructed Wetland
The annualized cost of the combined constructed wetland was determined as
follows:
Capital Cost = $0.72/ft3, Discount Rate = 0.05, Lifetime = 20 years
0.05

($0.72*3208.33 ft3)[1−(1+0.05)−20 ]= $185.36
Uniformized Cost + O&M Cost = Annualized Cost

31
$185.36 + $250 = $435.36
The cost of the entire system is:
$435.36 + $1193.30 = $1628.66
Sizing for the wetlands were as follows:
Hydraulic Retention Time = 10 days
Flow rate from septic tank is 2400 gal
𝑉

𝑉

HRT = 𝑄 = 10 days = 2400 𝑔𝑎𝑙/𝑑𝑎𝑦
V = 24,000 gal *

0.13368 𝑓𝑡 3
𝑔𝑎𝑙

= 3208.33 𝑓𝑡 3

Separated System Constructed Wetland
The annualized cost of the separate constructed wetland was determined as follows:
Capital Cost = $0.72/ft3, Discount Rate = 0.05, Lifetime = 20 years
0.05

($0.72*2180 ft3)[1−(1+0.05)−20 ]= $125.95
Uniformized Cost + O&M Cost = Annualized Cost
$125.95 + $250 = $375.95
The cost of the entire system is:
$375.95 + $6708.59 = $7084.54
The sizing of the constructed wetland was completed as follows:
Assuming flow rate (Q) = 1677 gallons/day
Assuming Hydraulic Retention Time = 10 days
𝑉

𝑉

HRT = 𝑄 = 10 days = 1677 𝑔𝑎𝑙/𝑑𝑎𝑦
V = 16770 gal *

0.13368 𝑓𝑡 3
𝑔𝑎𝑙

= 2180 𝑓𝑡 3

32
Combined System Leach Field
The annualized cost of the combined leach field was determined as follows:
Capital Cost = $0.70/ft2, Discount Rate = 0.05, Lifetime = 15 years
0.05

($0.70*4800 ft2)[1−(1+0.05)−15 ]= $323.71
Uniformized Cost + O&M Cost = Annualized Cost
$323.71 + $300 = $623.71
The cost of the entire system is:
$623.71 + $1193.30 = $1817.01
The sizing of the leach field was completed as follows:
Appledore Percolation rate = 36.3 min/in
Treatment Area = 2.00 ft2/gal/day
2.00 𝑓𝑡 2
𝑔𝑎𝑙
𝑑𝑎𝑦

*

2400 𝑔𝑎𝑙
𝑑𝑎𝑦

= 4800 𝑓𝑡 2

Separate System Leach Field
The annualized cost of the separate leach field was determined as follows:
Capital Cost = $0.70/ft2, Discount Rate = 0.05, Lifetime = 15 years
0.05

($0.70*3554 ft2)[1−(1+0.05)−15 ]= $239.68
Uniformized Cost + O&M Cost = Annualized Cost
$239.68 + $300 = $539.68
The cost of the entire system is:
$539.68 + $6708.59 = $7248.27
Sizing of the leach field was completed as follows:
Appledore Percolation rate = 36.3 min/in

33
Treatment Area = 2.00 ft2/gal/day
Using Greywater Flow Rate of 1677 gal/day
2.00 𝑓𝑡 2
𝑔𝑎𝑙
𝑑𝑎𝑦

*

1677 𝑔𝑎𝑙
𝑑𝑎𝑦

= 3554 𝑓𝑡 2

Rotating Biological Filter
The annualized cost of the RBC media was determined as follows:
Capital Cost = $2.85/ft2, Discount Rate = 0.05, Lifetime = 20 years
0.05

($2.85*7360 ft2)[1−(1+0.05)−20 ]= $1683.17
Uniformized Cost + O&M Cost = Annualized Cost
$1683.17+ $1500 = $3183.17
The annualized cost of the RBC tank was determined as follows:
Capital Cost = $3.00/ft3, Discount Rate = 0.05, Lifetime = 20 years
0.05

($3.00*101.91 ft3)[1−(1+0.05)−20 ]= $24.53
Uniformized Cost + O&M Cost = Annualized Cost
$24.53+ $1500 = $1524.53
The cost of the entire system is the media, tank, and septic tank:
$3183.17 + $1524.53 + $1193.30 = $5901.00
Sizing of the media is as follows:
BOD Removed = BOD5 * 0.5
441
220.5
190.5

𝑚𝑔
𝐿

𝑔𝑎𝑙

𝑚𝑔
𝐿

𝑚𝑔
𝐿

* 0.5 = 220.5
– 30
𝐿

𝑚𝑔
𝐿

𝑚𝑔
𝐿

= 190.5

𝑚𝑔
𝐿
𝑙𝑏

𝑙𝑏

*2400 𝑑𝑎𝑦 *3.785 𝑑𝑎𝑦 * 2.2046* 10-6 𝑑𝑎𝑦 = 3.8 𝑑𝑎𝑦

34
𝑙𝑏

1

3.8 𝑑𝑎𝑦 * 0.6 𝑙𝑏 ∗

1000 𝑓𝑡 2
1

𝑓𝑡 2

= 7360 𝑑𝑎𝑦 media

Size of Tank was calculated as follows:
Assuming media of 3ft radius disk, area = 28.27 ft2
Area of a 12 ft radius disk = 113.097 ft2
28.27 𝑓𝑡 2
113.097𝑓𝑡 2

= 0.25 ratio

Therefore, to proportionally determine the surface area:
104,000 ft2 * 0.25 = 25,996.09 ft2
Proportion of total SA to media area:
25,996.09 𝑓𝑡 2
7360 𝑓𝑡 2

= 3.532

Shaft length can then be determined as :
25 𝑓𝑡
3.532

= 7.078 ft

Volume then is determined as:
7.078 ft * 6 ft wide * 2.4 ft deep = 101.92 ft3
Trickling Filter
The annualized cost of the combined leach field was determined as follows:
Capital Cost = $6500/m3, Discount Rate = 0.05, Lifetime = 20 years
0.05

($6500*1.817 m3)[1−(1+0.05)−20 ]= $947.71
Uniformized Cost + O&M Cost = Annualized Cost
$947.71+ $1500 = $2447.71
The cost of the entire system is:
$2447.71+ $1193.30 = $3641.00

35
The sizing for the trickling filter is as follows:
2400 gal/day = 9.085 m3/day
𝑄

𝑚3

Hydraulic Loading Rate = 𝐴 = 10 𝑚2 𝑑𝑎𝑦 =
A = 0.9085 m2
V = 0.9085 m2 * 2m = 1.817 m3

9.085
𝐴

𝑚3
𝑑𝑎𝑦