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Renewable Energy for the Expanded Joe Mullins
Water Treatment Plant in Melbourne, Florida
Katie Welsh, Alana Stevens, Alexis Mendez,
Brice Peters, Mateo Arimany, Cameron Roberts, Shadrach Elechi, Rebecca Kitto, Siri Swangjai,
William Lee, Paige Wachtler, Takashi Kida, Samantha Perry, Katie Burke, Casselle Russell,
and Juan Pablo Aljure
Florida Institute of Technology Department of Marine and Environmental Science
ABSTRACT The Joe Mullins Reverse Osmosis (R.O.) Plant currently
supplies a customer base of 135,000 consumers in Melbourne,
Florida with water. It is projected that the consumer base will rise
to 208,000 by 2025 (2000/2007 Census Bureau). The current
R.O. plant has the capacity to supply the 15.7 million gallons per
day that is consumed by the customer base in 2009, but needs to
be expanded in order to ensure that the predicted 24.1 million
gallons per day in 2025 can be met. The expansion will also
allow for additional water from Lake Washington to be utilized by
the northern counties that are more populated due to tourism. The
renewable energy would provide one third of the required energy
with a reasonable water cost per 1000 gallons.
INTRODUCTION
The Joe Mullins Reverse Osmosis (R.O.) Plant currently
supplies the Melbourne, Florida customer base 6.5 MGD of water
with 3 artisan wells (2 MGD each) and has a 1.5 MGD brine
discharge maximum. It is proposed that the plant be expanded to
supply 16 MGD with 10 artisan wells with a 4.0 MGD brine
discharge maximum. The St. John’s River Water Management
District proposes that the expansion would allow northern
counties in Florida to consume additional water, and lower
Melbourne’s consumptive use to 8 MGD or less. To improve the
current R.O. plant to reach the energy capacity needed to produce
the proposed 16 MGD, renewable energy sources in the form of
PV modules and batteries will be used to pump the wells and
brine discharge, operate the plant, and include an energy backup
system. Two different options will be explored in a manner where
33% of the power will come from the PV modules and/or
batteries, and the remaining power will be acquire from Florida
Power and Light Company (FPL). The required permits from the
Florida Department of Environmental Protection, St. Johns River
Water Management District and other relevant authorities will
also be explored along with the environmental impacts of the
renewable energy design and discharge of the brine. A proposed
budget including the possibility of funding and a comparison to
current water usage prices and operation of similar plants will also
be included to determine the overall feasibility of the expansion of
the R.O. plant in a term of twenty years.
TECHNICAL SPECIFICATIONS
The technical specifications are designed to produce
33% of the required energy, and will explore the use of two
different options. The remaining energy that is not provided by
renewable sources will be acquired through FPL.
Option 1 presents a design that will use only PV
modules to produce all of the required energy to operate the plant,
pump the wells, and discharge the brine, and option 2 uses a
combination of PV modules and batteries to increase the overall
function of the PV modules by increasing the hours available from
the sun from 5.67 hours to 8.5 hours (See tables1 and 2 below).
Both options use the same basic design of a square area that
allows 21 ft² per panel with 4.9 ft. between rows to ensure that the
panels do not shadow one another and lessen the total energy
production. Both options also require that the PV panels face
south and are tilted at 28º to receive maximum sun hours year
round (See basic technical design figures 1 and 2).
In comparison, both options will be able to produce the needed energy to operate the plant, and are also feasible in an economical stand point; however, option 2, which uses batteries, will require less acres of land for the set up, and also creates a profit for the R.O. plant rather than a deficit. Table 1: Energy and area required for consumption without batteries.
Figure 1: Technical design of the space needed for each PV module, and the area needed to reduce shadow overlap.
Figure 2: Technical design of the angles and design needed to obtain the optimum amount of sun hours from the PV panels. Table 2: Energy and area required for consumption with batteries.
Circuit Design (no batteries)
Option 1
Unit energy required 11 KWh/KGal
Maximum daily water processed 16,000 Kgal
Maximum daily energy required 176,000 KWh Energy needed by the plant from the PV array (33%) 58,667 KWh Energy supplied by PV Array before inverter with 97% eff. 60,481 KWh
Sun hours with no batteries available 5.67 hours
Power supplied from PV array 10,667 KW
280 W Panels needed 38,096 Area needed for PV array @ 21 ft2/panel + separations 22 acres
Circuit Design (with batteries) Option 2
Maximum daily water processed 16,000 Kgal
Maximum daily energy required 176,000 KWh Energy needed by the plant from the PV array (33%) 58,667 KWh Energy required by batteries before inverter with 97% eff. 60,481 KWh Hours availability in total from sun-hours and batteries 8.5 hours min
Power required after photocontroller 7,115 KW Power needed by PV array before 97% eff. Photocontroller 7,333 KW
280 W Panels needed 26,191 26,191 Area needed for PV array @ 21 ft2/panel + separations 16 acres
BUDGET AND FUNDING
Budgeting and funding for each option is outlined in a
plan that would include financing the entire project for a term of
twenty years in order to make the overall cost more economical
and affordable for the city of Melbourne.
The total cost for option 1, which does not include the
batteries, is $358.8 million (See figure 3 for itemized cost
breakdown). The total average of water that is predicted to be
produce in twenty years is 93,440 million gallons, which would
suggest that the total cost to consume water would be $3.84 per
K/gal (See figure 4). In comparison to the current cost of $3.67
per K/gal, the cost would be greater if produced by the PV panels
on in option 1 and would leave the city with a $0.17 per K/gal or
$794,240.00 deficit that would need to be offset with grants or an
alternate type of funding (See figure 5).
The total cost for option 2, which includes batteries in
the design, is $332.7 million (See figure 6 for itemized cost
breakdown). The total average of water that is be predicted to be
consumed in twenty years is 93.440 million gallons, which would
suggest that the total cost to consume water would be $3.56 per
K/gal (See figure 7). In comparison with the current cost of $3.67
per K/gal, the cost is less and would not require any grants or
alternate funding to complete the project, and will allow the R.O.
plant to profit instead of face a deficit (See figure 8).
Figure 3: Itemized cost over twenty years without batteries.
Figure 4: Itemized cost per K/gal of water produced without batteries.
Figure 5: Comparison cost of current water consumption prices with predicted prices of the expanded R.O. plant without batteries.
Figure 6: Itemized cost over twenty years with batteries.
Figure 7: Itemized cost per K/gal of water produced with batteries.
Figure 8: Comparison cost of current water consumption prices with predicted prices of the expanded R.O. plant with batteries.
ENVIRONMENTAL IMPACT
Another key concern regarding the expansion of the Joe
Mullins Reverse Osmosis Water Treatment Plant is the impacts it
would have on the environment regarding both solar array
construction on the land, and the disposal of an additional 2.5
million gallons of brine due to the expansion. When considering a
model of solar panel for a renewable energy to fuel the plant two
mainstream prototypes are recommended: the cost-effective
cadmium panels, and the more reliable Poly-Crystalline solar
panels.
One major benefit of the cadmium-based PV array is the
sheer amount of electricity produced by the set-up. There are
about 20,000 MT of Cd used each year, half of which, is used for
Ni/Cd batteries. If used for PV panels, 20,000 MT/yr could
supply 1010 m2 of new PV annually. At 10% sunlight-to-
electricity efficiency, 1,000 GWp of new PV capacity per year
would be produced and approximately 1.6 million GWh of energy
a year. The U.S. utility grid produces around 3 million GWh a
year so it would only take two years of using the world’s Cd to
replace the entire U.S. grid.
Although the cadmium based arrays are cheaper, the
hazardous material used to manufacture them minimizes their
potential use considerably. The cadmium that is used in
producing the arrays is a byproduct of copper, lead, and zinc
mining which can be extremely harmful for both humans and the
ecosystem. Cadmium also poses a threat of contaminating Lake
Washington, the source of water for the treatment plant. It is also
a toxic material that can lead to kidney and breathing problems
according to the U.S. Labor Department Doctors recommend
seeking treatment if blood levels of a human reach levels of
cadmium over 5 µg/l in the blood. Amounts used in these arrays
include:
Amount of Cadmium in CdTe Layers of Various Thickness
Microns 5 2 1 0.5 0.2
g/m² 14 g 5.5 g 2.75 g 1.4 g 0.55 g
This table illustrates the possibility of a PV repairman c
accumulating cadmium poisoning from long-term exposure with
the substance in the arrays.
Another common substance found in cadmium based
solar panels is arsenic. Arsenic can easily contaminate
groundwater used for drinking. It could also provide an
occupational hazard to personnel hired to examine the PV
modules. The physical and environmental impacts that occur
from cadmium panel use outweigh the cost-effective benefits.
Poly-Crystalline solar arrays, although pricier, are much
more reliable and environment friendly. The silicon material they
are made of provides greater strength and require less repair.
Although, the PVs are safe while in use, the extraction of
materials used to manufacture them may cause environmental
disturbances and occupational hazards due to the mining of silica
particles. If inhaled, these particles have the potential to cause
lung disease. In addition, the production of the silicone panels
require the use of fluorine, chlorine, nitrates, sulfur dioxide,
nitrogen oxide, carbon dioxide, and more silica particles that
could be dangerous for employees.
While in use, the Poly-Crystalline solar panels have the
least impact on the environment including water, land, and sea,
but natural disasters such as summer hurricanes and fires, which
are common to Brevard County, must be taken into consideration.
Ingress of water into the panel is not a problem because these PV
models are sealed to prevent the corrosion of metal contacts which
could cause a system failure. In most cases, because, they can be
successfully sealed, the panels have a 20 year warranty.. This
highly effective sealing also prevents the module from leaching
material to the environment. These systems are so stable, that it is
almost impossible to break them into many smaller pieces. In
fact, CdTe and other semiconductors are some of the most stable
and impervious materials found. This stability also reduces the
risk of fire damage. Unless, trace elements are found on the
outside of the model due to accidental spills during the
manufacturing process, fires are not an issue.
A second, and just as important environmental concern
is the disposal of the additional brine waste water. After
expansion, brine quantities will increase from 1.5 million gallons
a day to 4.0 million gallons a day. Three possible solutions that
will be explored for discarding the waste are deep-well injection,
off-shore dumping into the Atlantic Ocean, and creating an
evaporation pond.
Because of ecosystem destruction, it is not likely that
the Melbourne Water Management company will allow for an
increase in brine disposal into the Eau Gallie River. The possible
impacts for discharging addition brine include a possible
degradation in water quality, a change in the designated use
regarding the Eau Gallie River, and a negative alteration in the
habitat of fish, crustaceans, sea grasses, and sediments.
Before deep-well injection can occur certain
requirements are necessary before permits will be issued. First,
the site for the future injection must be thoroughly examined to
determine whether it is geologically suitable. It must also be
inspected to ensure that the brine waste does not migrate into a
source of underground drinking water. A plan must be set for
closing the well and financial assurance must be observed. Lastly,
the site must be ensured that the pressure caused by the injection
process itself does not cause fractures in the injection zone or the
migration of fluids for the next 10,000 years.
There are some hazards pertaining to the process of
deep-well injection that must be addressed. The land that
surrounds the Joe Mullins Reverse Osmosis Water Treatment
Plant is on Florida Karst Topography. This means that the
geography is limestone based with many cracks and fissures that
may lead to a sinkhole formation. There is also the possibility of
a leak from the seepage of the brine from its confining layer
through the cracks and fissures into the superficial aquifer. In
such a situation, the brine would increase the salinity and add
other contaminants into the water and sediment.
Some environmental and man-made solutions have
facilitated the process. For example, geographically, the land is
separated into many poorly permeable layers that prevent the
brine and drinking waters to mix. Three or more protective layers
of pipe or tubing around the well shaft that goes into the injection
site ensure that the system will not leak into the surrounding
ground layers. Lastly, protective layers between the well and the
drinking aquifer will be established to also prevent leakage.
Below is a diagram of the deep-well injection set-up:
Figure 9: Deep-well injection set-up.
The alternative for deep-well injection for the disposal
of the brine waste water is to dump it offshore in the Atlantic
Ocean. Unfortunately, impacts on the marine ecology make this
scenario less appealing. Not only are salinity gradient changes
and chemical additives a possible problems, but also the weight of
the brine can cause it to sink rather than dissolve resulting in a salt
scar. A salt scar limits nutrient development and thus, life
development. Equipment corrosion can also occur resulting in the
release of titanium, copper, and nickel into the sea. These
substances directly harm marine organisms and humans
inadvertently due to consumption of contaminated fish and
shellfish. The most important environmental concern with
offshore-dumping is the impact on a potentially sensitive
ecosystem that would quickly diminish around the site of disposal.
The first to be affected would be the marine biota such as
phytoplankton and algae that provide the basis for organisms in
the ocean.
A third possible alternative would be to create an
evaporation pond. This concept involves placing the brine waste
water into a shallow pool of water and letting the sun evaporate it
until a salt substance remains that can be used as nutrients or for
other means. A problem with this alternative is the rainfall on
Florida’s east coast would make the process almost impossible;
therefore, deep well injection would be the most reasonable and
environmentally friendly method of disposing the waste.
PERMITS AND REGULATIONS
The Joe Mullins Reverse Osmosis Water Treatment
Plant must adhere not only to the standards and regulations set by
the Environmental Protection Agency (EPA), but must also obtain
the appropriate permits issued by the National Pollutant Discharge
Elimination Systems (NPDES), the Florida Department of
Environmental Protection (FDEP), and the St. Johns River Water
Management District in order to run its facility.
One permit that is necessary for water removal,
treatment, and exportation to consumers is the Consumptive Use
Permit (CUP). The St. Johns River Water Management District
requires all companies that utilize large quantities of water to
obtain this permit. Currently, Florida is divided into five
management districts. The St. Johns Water Management District
has jurisdiction over Brevard County including the Indian River
Lagoon, Eau Gallie River, and Lake Washington. The city of
Melbourne had been operating under CUP permit #50301 issued
on May 11, 1999 until recent concerns regarding brine disposal
from the reverse osmosis process was addressed. Since 2006,
however, the plant was issued a Temporary Consumptive Use
Permit (TCUP). Beginning that year, the processing plant was
required to filter greater amount than the permit allotment of
surface water from Lake Washington to meet the public supply
needs. The TCUP allows the plant to use up to 15.5 million
gallons per day of withdrawals and although the permit expired
October 11, 2006, Melbourne has continued to use this amount.
The expansion of the Joe Mullins Reverse Osmosis
Water Treatment Plant from three wells to ten requires additional
permits including the environmental resource permit (ERP). The
environmental resource permitting program is designed to ensure
that new construction will not adversely affect water flow or
storage, thus, preventing flooding. ERP combines two permits:
the former Wetland and Dredge Fill permit issued by the Florida
Department of Environmental Protection FDEP) and the
Management and Storage of Surface Waters permit issued by the
water management districts. An ERP is required by anyone
proposing construction including government agencies.
Once an ERP is obtained the Florida Department of
Environmental Protection must be contacted in order to obtain the
appropriate permits required for water well construction and for
the delegation of a contractor-licensing program in the St. Johns
River Water Management District. The District established these
construction standards to ensure that newly constructed water
wells do not cause uncontrolled water flow or water quality
degradation. The District also issues water well construction
permits to FDEP-delineated groundwater contamination areas.
Further permits are required for the operation of the Joe
Mullins Reverse Osmosis Water Treatment Plant. These permits
are applied for and granted under FDEP 62-4 permits: Drinking
Water and Ground Water Rules. Within these rules there are
further regulations that must be adhered to when operating a water
treatment plant including well dimensions, staffing, and brine
waste water disposal. The following permits would be necessary:
Under the FDEP Drinking Water Regulations
• 62-550: Drinking Water Standards, Monitoring and
Reporting
• 62-602: Drinking Water and Domestic Wastewater
Treatment Plant Operators
• 62-699: Treatment Plant Classification and Staffing
FDEP Ground Water Regulations
• 62-520: Ground Water Classes, Standards, and
Exemption
• 62-522: Ground Water Permitting and Monitoring
Requirements
• 62-528: Underground Injections Control
• 62-521: Wellhead Protection
In addition to permits required for the removal and
purification of the surface waters, construction permits required
by the FDEP include:
• 62-555: Permitting and Construction of Public Water
Systems
• 62-560: Requirements for Public Water Systems that are
Out of Compliance
• 62-531: Water Well Contractors
• 62-532: Water Well Permitting and Construction
Requirements
Regarding the disposal of brine waste water, The Joe
Mullins Reverse Osmosis Water Treatment Plant holds a shared
permit. This shared permit includes an Underground Injection
Control Permit from the FDEP along with a discharge permit
through the National Pollutant Discharge Elimination Systems.
The latter is authorized by the Clean Water Act under the EPA
and is responsible for the control of water pollution by regulating
point sources that discharge pollutants into the waters of the
United States. Currently, the water treatment plant is permitted to
dispose of 1.5 million gallons of the brine waste a day into the
Eau Gallie River.
In addition, the EPA prescribes regulations that limit the
amount of contaminants into the water provided by public water
systems. It further requires annual reports covering water quality
from the facility. These water quality tests must be performed by
a state-certified laboratory that continuously analyzes quality
throughout the entire treatment process to ensure the population of
no pollutants. These annual reports can be viewed at:
www.melbourneflorida.org. Also through the EPA, the
Underground Injection Control (UIC) program is responsible for
the regulation of all construction, operations, permitting, and
closure of injection wells that place fluids underground for
disposal or storage. Under the UIC, further permits are necessary
for expanding the existing water treatment plant.
The FDEP also performs water quality assessments
through another program: Source Water Assessment and
Protection Program (S.W.A.P.P.). This program ensures that the
drinking water is safe at its source. The Florida Department of
Environmental Protection is initiating the S.W.A.P.P. as part of
the federal Safe Drinking Water Act (SDWA). Results of this
assessment are located at the Florida Department of
Environmental Protection website:
http://www.dep.state.fl.us/swapp/.
CONCLUSION
Providing 33% of the energy needed to run the
expanded Joe Mullins Reverse Osmosis Water Treatment Plant is
technically feasible and economically viable. Of the two potential
solar power setups, option 2, which integrates batteries into the
design, is not only less expensive over the next 20 years but, it
requires no grants for funding and is able to produce the same
amount of power. Option 2 also utilizes less acreage, fewer solar
panels, and increased availability to utilize the maximum amount
of renewable energy. This is only feasible if the battery setup is
economically viable within the unit cost shown.
By installing 26,191 arrays over 16 acres and using
batteries, the company will essentially be profiting from the
expansion in a long term sense. The total cost for option 2 over
the next 20 years is $332.7 million dollars. This statistic
encompasses capital costs, costs to Florida Power and Light for
providing the additional 66% of the energy, the price and
installments of the PVs, and the maintenance required to run the
facility. By producing the drinking water for $3.56 per Kgal and
selling it for the standard $3.67 per Kgal, the company would
profit $0.11 per Kgal of water consumed.
After discussing various possibilities for disposing of an
extra 2.5 million gallons a day of brine waste water, the best
alternative suggested is deep well injection. Certain safety
precautions must be considered before initializing the deep well
injections to prevent possible sinkholes or brine backwash into
drinking aquifers. A poorly permeable layer must be placed
between the two and a soundly structured well must be
constructed.
To expand the R.O. plant from three wells to ten wells,
certain permits and regulations must be upheld to ensure safety,
quality, and habitat maintenance. The St. Johns River Water
Management District requires an Environmental Resource Permit,
certain water well permits, and a licensed contractor. The
Environmental Protection Agency must provide an Underground
Injection Control permit for proper brine disposal. Florida
Department of Environmental Protection requires over 11 permits
for optimum insurance over water quality, maintenance safety,
well soundness, and construction compliances related to both
drinking water and groundwater permits.
For future studies, perhaps a water turbine can be placed
in the reverse osmosis facility to create energy from the current
produced by the brine waste water. In upcoming years, the
demand by consumers for drinking water in Brevard County will
increase as Lake Washington slowly decreases. This expansion
must be viewed as only a temporary fix for the economic
problems at hand in the near future. We suggest a more reliable
source of drinking water supply by introducing a desalination
plant at a Melboure/Palm Bay site, which would take water from
the Indian River Lagoon and discharge it into the Atlantic Ocean.
Although this would be a billion dollar investment, it would
provide climate ready facilities, appropriate amounts of drinkable
water for many more years, and for a $3.17 K/gal unit cost
(Lindler and Aljure, 2009). required 11 KWh/K
ACKNOWLEDGMENTS
Our thanks to Mr. Frank Leslie for direction and
assistance in the overall outcome of the project. Mr. David
Phares, Assistant Superintendent, and Mr. Cody Wells,
Operations Supervisor, of Water Production for the City of
Melbourne for providing relevant data and information about the
current plants, and possible future scenarios for future solutions.
Ms. Colleen Lindler, Florida Institute of Technology graduate
student, for providing environmental issues information. Ms.
Krista Simon, Tampa Bay Water Records Manager, for providing
two CDs with information about the Tampa Bay desalination
plant.
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