AN AQUAPONICS LIFE CYCLE ASSESSMENT: EVALUATING AN INOVATIVE METHOD FOR GROWING LOCAL FISH AND LETTUCE by REBECCA ELIZABETH HOLLMANN B.A., University of Denver, 2013 A thesis submitted to the Faculty of the Graduate School of the University of Colorado Denver in partial fulfillment of the requirements for the degree of Master of Science Integrative Biology 2017
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AN AQUAPONICS LIFE CYCLE ASSESSMENT: EVALUATING AN INOVATIVE METHOD
FOR GROWING LOCAL FISH AND LETTUCE
by
REBECCA ELIZABETH HOLLMANN
B.A., University of Denver, 2013
A thesis submitted to the
Faculty of the Graduate School of the
University of Colorado Denver in partial fulfillment
II. AQUAPONICS LIFE CYCLE ASSESSMENT……………………………… 29
2.1 Introduction………………………………………………………………. 29
2.1.1 Research objectives………………………………………………... 30
2.1.2 Study site…………………………………………………………... 30
2.2 Methodology……………………………………………………………... 32
2.2.1 Goal and scope……………………………………………………... 31
2.2.2 Life cycle inventory……………………………………………….. 36
2.2.3 Life cycle impact assessment…………………………………….. 43
Allocation……………………………………………………………. 44
Total resource use………………………………………………….. 44
Conversion…………………………………………………………… 44
2.3 Results…………………………………………………………………… 45
2.4 Discussion……………………………………………………………….. 51
2.4.1 Impact assessment…………………………………………………. 51
2.5 Conclusion……………………………………………………………….. 58
REFERENCES…………………………………………………………………... 59
APPENDICES
A. Flourish Farm’s delivery locations…………………………………….. 66
B. Flourish Farm’s produce production……………………………………. 67
C. Flourish Farm’s integrated pest management use in 2014…………….. 69
ix
LIST OF TABLES
TABLES
1. Nutrient waste in a levee-style catfish pond 13
2. Pre-farm, on-farm and post-farm inclusions and exclusions in the LCA 34
3. Life cycle inventory of Flourish Farms 35
4. Electrical operational equipment at Flourish Farms 38
5. Necessary infrastructure in Flourish Farm’s aquaponic system 41
6. The total global warming potential (kg CO2 e), energy use (mJ) andwater dependency (m3) for Flourish Farm lettuce and tilapia and hybridstriped bass per kilogram in 2014.
47
7. Comparison of annual land use, water dependency, and energy use inaquaponics, hydroponics and traditional agriculture for lettuceproduction.
49
8. Comparison of global warming potential, energy use, and waterdependency of various aquaculture systems with values in terms of onekg produced.
50
x
LIST OF FIGURES
FIGURES
1. The recirculating principles of the aquaponics life cycle 3
2. The University of the Virgin Islands deep water culture (DWC)aquaponic facility.
5
3. Media based aquaponic system 6
4. Deep water culture root system 7
5. Nutrient film technology (NFT) aquaponic system 8
6. Layout of Flourish Farms 17
7. Flourish Farm’s DWC and main fish tank 18
8. Boundaries of Denver, Colorado zip code 80216 20
9. Major Toxic Releasing Inventory (TRI) facilities and super fund sites inor next to zip code 80216
21
10. Denver County food desert 22
11. Phases of a life cycle assessment 25
12. System boundary for the Flourish Farm LCA 33
13. Life cycle assessment process flow for fish 36
14. Life cycle assessment process flow for lettuce 37
15. Skretting’s Pond LE fish feed components 39
16. The GrowHaus delivery route 40
17. Global warming potential of fish production at Flourish Farms 46
18. Global warming potential of lettuce production at Flourish Farms 47
19. Distribution of global warming potential kg of CO2 e/ kg of productionwithin Flourish Farms.
48
xi
ABBREVIATIONS
CO2 Carbon Dioxide
DM Dry Mass
DWC Deep-Water Culture
EPA Environmental Protection Agency
EU Electricity Use
GHG Greenhouse Gas
GWP Global Warming Potential
HSB Hybrid-striped bass
ILCD International Reference Life Cycle Data Systems
IOS International Organization for Standardization
IPCC Intergovernmental Panel on Climate Change
IPM Integrated Pest Management
LCA Life Cycle Assessment
LCIA Life Cycle Inventory Analysis
NFT Nutrient Film Technology
TRI Toxic Releasing Inventory
USDA United States Department of Agriculture
WD Water Dependence
WM Wet Mass
1
CHAPTER I
THE RELEVANCE AND BACKGROUND OF AQUAPONICS
1.1 Introduction
1.1.1 Inner workings of aquaponics
This research assesses efficiency and output of a commercial aquaponics system known
as “Flourish Farms” in Denver, Colorado. The global food production system is projected to
decline in crop output due to climate change (Nelson, 2009), and population growth will
continue to exceed the carrying capacity of the planet (Barrett & Odum, 2000), which will
lead to a greater percentage of the world’s population receiving inadequate nutrition on a
daily basis. Current agricultural methods are a primary contributor to climate change and
environmental degradation. If current agriculture is further invested in and expanded in order
to meet the increasing demand, environmental collapse is expected (Edenhoger et al., 2014).
Alternative food production systems, such as organic, hydroponics, aquaculture, urban
gardening, and local food production offer a solution to steer away from the global food
system, and towards healthier and more sustainable crop output while revitalizing the
environment. Aquaponics is a promising system design to produce protein and vegetables
using minimal resources and waste production. This technology is in the early stages of
development worldwide with few commercial systems. Completing a Life Cycle Assessment
(LCA) on one of the well founded commercial systems in Denver will elucidate the resource
use, global warming potential and waste production of this aquaponics system.
Understanding the system value may lead to better system management, and long-term
decisions on the viability of aquaponics as a potential for year-round local food production in
temperate climates.
2
Aquaponic farming is a promising technology for local, sustainable food production.
Aquaponics combines aquaculture (e.g. aquatic animal farming) and hydroponics (e.g.
soilless systems for crop production) in a recirculating engineered ecosystem to
simultaneously produce vegetables and protein. Aquaponics systems have a high yield and
can annually produce 41.5 kg/m3 of tilapia and 59.6kg/m2 of tomatoes in a 1.2m wide, 0.33m
deep and 0.86m long tank with 4 plant plots (McMurtry et al., 1997). Aquaponic farms
utilize the effluent from aquatic animals rich in ammonium by circulating it to nitrifying
rhizobacteria to fertilize hydroponic vegetables. Nitrosomona species oxidize the toxic
ammonia (NH3) into nitrite, and then Nitrospira bacteria convert nitrite (NO2-) into nitrate
(NO3-), which is less harmful to the fish, but fertilizes the plants. The water, now cleansed of
ammonia, nitrates, and other nutrients after flowing through the bacteria matrix and root
system, circulates back to the aquaculture subsystem (McMurty et al., 1997) (Fig 1.).
3
Figure 1. The recirculating principles of the aquaponics life cycle. The fish excrete waste
products which are turned into nitrates from bacteria species such as Nistrospira sp. The root
system is then able to absorb these nutrients, and quickly grow into a harvestable product.
The fish are then supplied with clean water and are another harvestable product within time
(Engle, 2013).
1.1.2 History of Aquaponic
Although the term ‘aquaponics’ was coined in the 1970s, the science of aquaponics
developed long ago. One of the earliest was the Aztec agricultural islands known as
‘chinampas’ that would float on top of shallow lakes about 1,000 years ago (Crossley, 2004).
Aztecs would fertilize the islands with nutrient rich mud from nearby canals. Additionally, in
South China, Thailand and Indonesia grew fish in rice fields approximately 1,500 years ago
4
(Coche, 1967). This polyculture practice still exists today as hundreds of thousands of
hectares of rice fields are stocked with fish (Coche, 1967).
Development of contemporary aquaponic systems is practiced in warm and temperate
climates with many variations in system construction and cultivated species (Bainbridge,
2012). Modern aquaponics was first influenced by researchers studying recirculating
aquaculture systems who were looking for solutions to eliminate accumulations of nitrogen
(Love et al., 2014). One of the solutions researchers identified was to combine a soilless plant
system into the aquaculture system as a way of withdrawing the nitrogen compounds out of
the water. Present-day systems now rely on many hydroponic growing methods, such as use
of a greenhouse, and similar growing technologies.
One of the major revolutions to the aquaponics industry was the work of Dr. James
Rakocy, known colloquially as the Father of Aquaponics. He began further investigation of
aquaponics systems while working on his PhD at Auburn University, graduating with a
degree in aquaculture in 1980. He then developed an aquaponics facility at the University of
the Virgin Islands (UVI). The system started small, but continued to expand into a
commercial system which contains six hydroponic tanks with a growing area of 2,303 ft2 and
four fish rearing tanks containing 7798 liters of water each. In 1999 Dr. Rakocy started a
training program with students from all over the Unites States and territories. The system has
become an important tool in training students and educators about aquaponics all over the
world, and has proven to be successful in producing high quantities of fish and vegetables
(Rakocy, 2012). Dr. Rakocy and Dr. Lennard now teach a commercial aquaponics workshop
at UVI two times a year, which has been instrumental for the development of large scale
systems worldwide (Rakocy, 2012; Fig. 2).
5
Figure 2. The University of the Virgin Islands DWC aquaponic facility. UVI has one of the
best established and deep water culture aquaponic systems where they offer intensive training
course (Rakocy, 2012).
1.1.3 Aquaponic system types
There are three main types of aquaponic system constructions: media-based growing,
deep-water culture (DWC), and nutrient film technology (NFT). At minimum, a system will
have some form of a tank containing aquatic species, grow beds, and a pump. Most systems
contain a solids removal system; however, in media-based systems scuds and/or worms can
be added as an effective solids removal mechanism. Within the media-based growing there
are several different designs that can be put into place. There are basic flood and drain
systems, designs with sump tanks, constant height one pump systems, and even systems
using barrels (Bernstein, 2011; Lennard & Leonard, 2006). There are pros and cons to adding
sump tanks to a system. Sump tanks are second tanks kept without fish, where water will
continuously drain from the grow beds before recirculation. Designs without a sump are
typically much more simple and easy to construct, however the changing water levels can
add stress to the fish. Designs with a sump tank are more difficult to construct, but will keep
6
the water in the fish tank at a continuous level, which is ideal for the fish (Bernstein, 2011;
Fig. 3).
Figure 3. Media based aquaponic system with sump tank. In farms using media, the water
will flood and drain the system. Some advantages for the media based solution are growing
more root intensive crops, solid entrapment, and some systems use detrivores in the media as
well (Lovatelli, 2015).
The seeds in media based systems can be planted directly into the media, or transplanted
from nurseries. The media and root matrix is an efficient solids filter, and no other removal
system is needed. Media based systems also provide ideal growth environments for the
necessary bacteria. Another advantage to a media based system is this design allows the
greatest flexibility for what crops can be grown.
DWC systems use water filled beds with floating rafts which support the shoots above the
waterline, as the roots hang into the water. The roots hang into the water directly and the
bacteria can usually grow onto these extensive root systems without further assistance (Fig.
7
4). In some farms, the bacterial will cultivate within the solids removal and dentrification
tanks as well.
Figure 4. Deep water culture root system. In DWC systems, the roots hang loose into the
water culture on floating rafts (www.ColoradoAquaponics.com).
DWC aquaponic farms are more limited in what they can grow, and do require further
solids filtration. However, these systems are typically used in commercial aquaponics
facilities as they are relatively inexpensive to set up compared to other system types, and the
crops are considerably more easy to harvest than in a media based system (Bernstein, 2011).
The last type of system, NFT, uses condensed channels into which nursery plants are
transplanted, where a more concentrated stream of water flows through the root systems (Fig.
5). These systems look characteristically more like hydroponic systems. They offer many of
the same advantages and disadvantages of DWC systems, in that the crops are easy to
8
harvest, but the varieties that can be successfully grown are limited (Bernstein, 2011). This
system is primarily used for leafy greens and herbs, as other plants develop extensive root
systems that can easily block the channels (St. Charles, 2013).
Figure 5. Nutrient film technology aquaponic system. NFT systems are one of the most
common growing practices for hydroponic systems, and the technique has carried over into
aquaponics (Lovatelli, 2015).
1.1.4 Comparison Systems
Hydroponics. The word hydroponics is derived from the Greek roots of hydro and
ponos, meaning ‘working water’. The history of hydroponics dates back to 1929 with Dr.
William Gerich from the University of California (Love et al., 2014). In essence, hydroponic
farming is the science of growing plants without the use of soil, in a liquid culture
(Wignarjah, 1995). In hydroponic systems, nutrient solutions, mainly chemical salts, are
added to the culture that contains all the essential elements needed by the plant for its normal
growth and development. Like aquaponics, hydroponics can be developed with several
different designs, including NFT as one of the most popular techniques for producing leafy
greens. However, media based options are still used to support a larger variety of vegetables.
Many hydroponic systems are operated in controlled environment facilities in order to
9
increase the yield of the crops. Additionally, since the roots can easily obtain the necessary
nutrients in the synthetic liquid cultures, the yield is often much higher than conventional
agriculture (Love et al., 2014). Hydroponics also recirculates the water in order to more
sustainably nurture and support plant production.
Aquaculture. Aquaculture is the breeding, rearing and harvesting of plants and animals
within a water environment, which can range from ponds, rivers, lakes and the ocean.
Aquaculture has a long history of practice, dating back to 2,500 B.C. in China, with the
cultivation of common carp (Cyprinus carpio) (Rabanal, 1988). Near 500 B.C. Fan Lai wrote
a monograph names “The Classic of Fish Culture”, which is the first known description of
aquaculture practices. Aquaculture can also be known as aquafarming, which implies
intervention in the natural rearing process in order to enhance production. These practices
can range from stocking, feeding, and protection from predators (FAO, 2011). Today with
the decline of wild fish populations, aquaculture is a massive industry with over one half of
consumed fish products supplied by aquaculture facilities (Stanford University, 2009).
Conventional Agriculture. The modern industrial agricultural practice has historically
been defined as growing crops with soil, without cover, and treating the crops with irrigation,
nutrients, pesticides and herbicides (Barbosa et al., 2015). These traditional agricultural
techniques became popularized in the 20th century, which was known as the Green
Revolution (Hazell, 2009). With these technologies, conventional agriculture produces great
yields, but also has intensive resource requirements. Conventional agriculture is often
juxtaposed to organic farming, which does not permit the use of synthetic fertilizers,
pesticides, genetically modified organisms, or ionizing radiation or sewage sludge (USDA,
2016). These standards were developed in the late 19th century in central Europe and Asia.
10
1.1.4 Aquaponic Production
Aquaponics technologies have records of successfully raising many different types of fish
including: several varieties and hybrids of tilapia such as red tilapia (Oreochromis spp) and
Nile tilapia (Ocheochromis niloticus), and many other species such as yellow perch (Perca
The boundaries of an LCA also include establishing the ‘scope’ of the environmental
issues that will be reported, such as greenhouse gases. GHGs are classified into three
different scopes based on the GHG Protocol Corporate Standard. Scope 1 emissions are
directly from sources that are owned or controlled by the system, such as vehicle emissions
or emissions from chemical production. Scope 2 emissions are indirect emissions from
sources that are purchased by the system, such as the emissions generated from purchasing
energy, where the emissions occur at the facility where the energy is generated. Scope 3
emissions are additionally indirect emissions that are not reported in Scope 2, that are in the
27
value chain of the reporting company, both upstream and downstream. Scope 3 emissions
include extraction and production of purchased materials. LCA software has Scope 3
emissions databases for all processes that are reported.
1.4.2 Inventory analysis description
The inventory analysis encompasses the task of collecting the necessary data in order to
perform the LCA. There are two types of data, foreground data which refers to data that
describe a particular product, and background data which are data for the production of
generic materials, energy, transport, and waste management. Foreground data must be
collected from the system itself, whereas LCA software, such as GaBi V5.0, contains the
necessary background data, such as the scope 2 and 3 emissions of certain processes. LCA
software helps to manage data and model the LCA within the ISO standards. GaBi V5.0 has
several options for creating process maps and flows and has several analyzing and
interpreting selections (www.GaBisoftware.com). Questionnaires are often helpful during
foreground data collection in order to gather all required information. In order to gain the
background data, the GaBi V5.0 software has a database covering 10,000 processes in the
EcoInvent and U.S. LCI databases (Goedkoop et al., 2013).
1.4.3 Impact assessment description
Impact assessment of an LCA is an analysis to determine environmental impacts
throughout a product’s lifetime. This phase is aimed at understanding and evaluating the
significance of impacts of the production system (Goedkoop et al., 2013). In order to do this
in compliance with the ISO, a classification and characterization need to take place. GaBi
V5.0 software has many available impact assessment methodologies built in to its program
that can be used depending on the goal and scope of the system. The results will typically
display which inventory items are contributing to the environmental factors, and to what
28
degree. The impact assessment analysis can have many stages, including; allocation, total
resource use calculations, library determination, and conversions. If necessary, allocations
will be determined by the end user. Library determination depends on what software
databases are available, and which elements the end user is trying to analyze. Conversions
into the same function output unit are typically done within the software.
1.4.4 Interpretation stage description
The interpretation stage is described by ISO 14044 as the number of checks to test
whether conclusions are adequately supported by the data (2006). In GaBi V5.0 software this
exists as a checklist that will review relevant issues mentioned in the ISO standard. These
exist mainly as uncertainty in the analysis, such as variation in the data, correctness of the
model, and incompleteness of the model. Once these aspects are evaluated, the model can be
looked at to see if any hot spots exist, or areas of consumption that are causing large
environmental impact. These hot spots can be recommended for system improvement design
changes in order to reduce environmental impact. This stage will also be used to compare the
results of an LCA to another applicable system or product in order to discern which system
can have more viability and less environmental impacts long-term.
29
CHAPTER II
AQUAPONICS LIFE CYCLE ASSESSMENT
2.1 Introduction
This research assessed the operational production and sustainability potential of Colorado
Aquaponic’s commercial system ‘Flourish Farms’ located in Denver, Colorado in the United
States. Aquaponic farming is a promising technology for local, sustainable food production.
Aquaponics combines aquaculture and hydroponics in a recirculating engineered ecosystem
that utilizes the effluent from aquatic animals rich in ammonium by circulating it to nitrifying
rhizobacteria to fertilize hydroponic vegetables. Nitrosomona species oxidize the toxic
ammonia (NH3) into nitrite, and then Nitrospira bacteria oxidize nitrite (NO2-) into nitrate
(NO3-), which is less harmful to the fish, and a nutrient for the plants. The water, now
stripped of most ammonia and nitrates after flowing through the bacteria matrix and root
system, circulates back to the aquaculture subsystem (McMurty et al., 1997) This system
design can annually produce up to 41.5 kg/m3 of tilapia and 59.6kg/m2 of tomatoes in a 1.2m
wide, 0.33m deep and 0.86m long tank with 4 plant plots (McMurtry et al., 1997).
The global food production system is projected to decline in crop output due to climate
change (Nelson, 2009), and population growth will continue to exceed the carrying capacity
of the planet (Barrett & Odum, 2000), which will lead to a greater percentage of the world’s
population receiving inadequate nutrition on a daily basis. Current agricultural methods are
some of the primary contributors to climate change and environmental degradation, and if
they are further expanded to meet the increasing demand, environmental collapse is expected
(Edenhoger et al., 2014).
In place of a global food production systems, hydroponics, aquaculture, urban gardening,
and local food production offer an alternatives, and aim for a healthier and more sustainable
30
crop output while revitalizing the environment. Aquaponic technology is a system designed
to produce protein and vegetables using minimal resources and waste production.
Aquaponics also offers a solution to the difficulties of acquiring protein locally and
affordably. One four ounce serving of tilapia incorporates 50% of the daily protein
requirements for men, and 60% for women (USDA SR-21, 2014). This technology is still
used as a niche farming method with only 257 systems out of the 809 United States systems
surveyed in 2014 operating on the commercial scale, with all others classified as backyard or
hobby systems (Love et al., 2014). However, aquaponics is a rapidly growing field as over
600 systems have been built in the United States from 2010 to 2013 (Love et al., 2014).
Completing a Life Cycle Assessment on one of the well-founded commercial systems in
Denver will elucidate the WD, EU and GWP of this aquaponics system.
2.1.1 Research Objective
In order to further examine and assess aquaponics as a method to grow high quality food,
we performed an LCA on the commercial aquaponics system in Denver, Colorado, which
compared the GWP, WD and EU to literature recordings of resource use in conventional
agriculture, aquaculture, and hydroponics. This analysis will enable the end users to take into
account where inefficiencies in the aquaponic process may exist, and how to improve
operations for a more sustainable system. The literature comparisons will help those
interested in the aquaponic field to understand the benefits and resource requirements for the
system, in contrast to other available options.
2.1.2 Study Site
The LCA took place at Flourish Farms, run by Colorado Aquaponics, within the
GrowHaus. The GrowHaus is in a historic 1,858 square meter greenhouse which functions as
a non-profit indoor farm, marketplace and educational center. They aim to create a
31
community-driven, neighborhood-based food system by serving as a hub for food
distribution, production, education, and job creation (www.GrowHaus.com). Food is
produced year-round at the GrowHaus with three separate sustainable and innovative
growing farms: hydroponics, permaculture and aquaponics. The scope of this study will
concentrate on the aquaponic farm ‘Flourish Farms’ which occupies 297 square-meters
within the GrowHaus.
Flourish Farms was founded in 2009 by owners and CEOs Tawnya and JD Sawyer. The
farm serves as a commercial production center and as a model system that has been
mimicked in schools, community buildings, correctional facilities, and homes. As part of
Colorado Aquaponics’ mission, they provide aquaponic training, curriculum, consultation
and support programs that can be delivered to individuals, schools, institutions and
communities looking to take charge of their own sustainable farming and food security
(www.ColoradoAquaponics.org).
The farm contains three types of aquaponic systems, deep water culture (DWC), nutrient
film technique (NFT) and media beds, as the owners showcase the various construction
designs for aquaponics systems. Flourish Farms used a tilapia and koi carp combination for
many years, due to their resilience and rapid growth under high stocking densities. However,
they gradually switched to hybrid striped bass (HSB) in 2014 and 2015, recognizing a greater
value and preference for this fish by their customers (Tawnya Sawyer, personal
communication 2015). They have also successfully raised catfish and bluegill. Since Flourish
Farms moved into the GrowHaus in 2012, they have grown hundreds of different varieties of
vegetables and have sold over 13,607 kg of food within an eight kilometer radius.
32
2.2 Methodology
The LCA follows the ISO 14040/14044 guidelines (ISO, 2006) and is separated into four
sections: (1) goal and scope definitions; (2) inventory analysis; (3) impact assessment and (4)
interpretation (as presented in the ‘Results’ and ‘Discussion’ section of this paper).
2.2.1 Goal and scope
This LCA is considered a streamlined LCA, as several processes in a cradle-to-grave
analysis were omitted for this study. However, streamlining the LCA process is an essential
element in the goal and scope definition, as few LCAs are full-scale due to time and cost
constraints, according to Todd & Curran (1999). Streamlining allows the study designers to
select an approach and level of rigor that is appropriate for the intended end users and
application of the study.
In this research, the goal of the study was to determine the life cycle GWP, WD and EU
from a commercial aquaponic system in Denver, CO. A second goal was to compare the
results from this study to other literature LCA values from hydroponics, aquaculture and
conventional agriculture to evaluate if any of these systems offer environmental efficiencies
for agricultural production. These goals were achieved by forming a functional unit,
constructing system boundaries, and gathering the required data.
In order to accommodate for the production of two products in this agricultural system,
two separate LCA analyses were completed with allocations for resource use. The functional
unit for the lettuce production is 1 kg WM lettuce. Dry mass (DM), although a more accurate
measure as it excludes fluctuations in water concentrations, was not used for this study as
Flourish Farm measures every full lettuce head weight right after harvest and before
delivering to the costumer. Flourish Farms produced 60 different types of leafy greens during
the 2014 year (Appendix B), which for this study will all be referred to as “lettuce”. Each
33
species of lettuce was weighed at harvest and recorded and the average sell weight was
calculated. The second LCA analysis focuses on the fish production of the aquaponic farm,
with a functional unit of 1 kg of fish. Flourish Farm produced two different species of fish
during 2014, tilapia and HSB which both together will be referred to as ‘fish’. For this
analysis, a fish mass estimation had to be used, as the farm currently sells their fish whole
and only occasionally weighs them. Fish mass was estimated from personal communication
with owner Tawnya Sawyer, as well as notes in the sales section of the data report indicating
approximate fish size and occasional weights. The weights were categorized into small
(~28gm), medium (~170gm) or large (~396gm) for each fish sold.
The system boundary is a single issue LCA approach, with an Order I analysis focusing
on the production cycle and transportation of the farm in order to ascertain the global
warming potential, energy and water use within the farm for the entire 2014 year. The scope
includes the energy carriers, natural gas consumption, water use, integrated pest
management, delivery transportation, and the input of fish feed into the system (Goedkoop et
al., 2013; Fig. 12).
34
Figure 12. System Boundary Colorado Aquaponic’s Flourish Farms LCA. The above figure
demonstrates a flow diagram of the boundaries of the LCA for this study. This study included
the fish feed production, water acquisition, water use, pump use, lighting use, integrated pest
management, heating and cooling mechanisms and the transport to the customers. Excluded
from the study were the nutrient additions and the background analysis of the capital units
used in production and transportation.
In order to clarify the system boundaries, the components were divided into ‘pre-farm’,
‘on-farm’ and ‘post-farm’, which will help elucidate the areas outside of the system boundary
(Table 2).
35
Table 2. Pre-farm, on-farm and post-farm inclusions and exclusions in this study.
Pre-Farm On-Farm Post-Farm
Inside
Study
Boundary
• Fish feed production
• Pest management
production
• Heating
• Cooling
• Lighting
• Pumps
• Water
additions
• Transport to
customer
Outside
Study
Boundary
• Infrastructure
production
• Capital production
• Nutrient production
• Materials transport to
farm
• Nutrient
additions
• Packaging
• Storage
• Consumption
stage
• Waste
generation
• Avoided
products
The WD and GWP were both calculated using GaBi Product Sustainability Software
version 5.0. GaBi V5.0 which generates the LCA of a product according to the ISO
14040/14044 regulations, and uses the PAS 2050 and GHG Protocol Product and Scope 3
Standard to specifically generate the carbon footprint. For this study, the GaBi V5.0
International Reference Life Cycle Data System (ILCD) was used, using the U.S. Life Cycle
Inventory and EcoInvent databases.
Outside of the scope of the study were the capital resources of the farm, which included
the ‘cradle’ production costs of greenhouse structure, tanks, piping, motors, heaters, fans,
lights and additional building materials. Additionally, the functionality of this study for
Colorado Aquaponics did not need the extensive rigor to include the capital, but rather
focusing on the production hot spots accomplished the goal. In future studies of the farm,
36
these elements could be inventoried and included. Also, many of the nutrient additions to the
farm in 2014 were not categorized for which chemicals were included. For instance, a
“homebrew” nutrient mixture compromised 90% of the total nutrient additions for 2014, but
this mixture was constantly changed and no notes were provided as to what was included in
each supplement. Because of these inconsistencies, the nutrient additions were excluded.
However, the main nutrient supply to the system is the fish effluent, which has zero
environmental impact, and allows comparison of this study to others that do include nutrient
additions. Other limitations were the specific integrated pest management chemicals that
were used were not available in either database. However, a general pesticide application was
found which was used for this study. The water use in this study was pulled from the Denver
Water meter bills, and included all of the use on the farm – not just the usage for production.
In future studies, calculations could be made to determine the water use just for production
and exclude all other operations.
2.2.2 Life Cycle Inventory
The life cycle inventory considers all of the necessary inputs and outputs that occur
during the life cycle of the product. The process data were collected directly from Flourish
Farms owners and within the detailed records of produce and fish species output, fish food
input into the system, pest management use, electrical use, water bills, natural gas
consumption, and necessary equipment for operational activity. The life cycle inventory
shows all of the inputs into the system in order to produce 1 kg of lettuce and 1 kg of fish
(Table 3).
37
Table 3. Life Cycle Inventory of Flourish Farms.
Inputs Value UnitsLCI of 1 kg fish Fish feed 0.69 Kg
Pesticide production 0.0332 KgMarket for tap water 272 KgMarket for electricity 0.00843 mW hMarket for natural gas 4.83 kg
LCI of 1 kg lettuce Fish feed 0.054 KgPesticide production 0.00259 KgMarket for tap water 130 KgMarket for electricity 0.00365 mW hMarket for natural gas 4.83 KgTransport to costumer 4,970 kgkm
These values correspond to the process flows created within the GaBi V5.0 software (Fig.
13 & 14).
Figure 13. Life Cycle Assessment Process Flow for Fish. This image, taken from GaBi V5.0
software, exhibits the inputs into the database for the production of 1 kg of fish from the
farm.
38
Figure 14. Life Cycle Assessment Process Flow for Lettuce. This image, taken from GaBi
V5.0 software, exhibits the inputs into the database for the production of 1 kg of lettuce from
the farm.
These values were calculated from monthly utility meter readings of the natural gas and
water use. Additionally, electrical consumption was calculated from the kWh operational
data listed on each piece of equipment for the foreground analysis. The operational
equipment background data was excluded from this study. The building uses equipment to
control temperature, humidity, lighting, and water flow. These include five horizontal airflow
fans, two vent fans, a wet wall pump, circulation pump, four HID metal halide lights,
intermediate bulk container power pumps, a main MDM Inc. ValuFlo 6100 water pump
(Colorado Springs, CO), two media bed water pumps, an NFT pump, three nursery pumps,
one tower pump, and an S31 regenerative air blower. The system also uses fish tank boilers,
known as ‘fish sweaters’ and two Modine heaters (Racine, WI) to heat the water and
greenhouse respectively. Each piece of electrical equipment was evaluated for the average
hours per day it would run, and seasonal variation was calculated as well (Table 4).
39
Table 4. Electrical Operational Equipment at Flourish Farms. The following equipment was
all researched for kilowatt hour capacity, seasonal use, daily use, and number of units. This
combined information was used to calculate the total kilowatt requirements for the farm, and
was then converted into megaJoules for the EU factor for this study.
Tilapia Tropical Aquaponics 9.52 123.46 -1.50 Boxman et al 2016
Turbot Recirculation 6.02 290.99 4.81 Aubin et al 2006
Rainbow trout Flow through 2.02 34.87 98.80 Roque d'Orbcastel et al 2009
Rainbow trout Flow through 2.75 78.23 52.60 Aubin et al 2009
Rainbow trout Recirculation 2.04 63.20 6.63 Roque d'Orbcastel et al 2009
Seabass Net pen 3.60 54.66 48,720.00 Aubin et al 2009
Arctic Char Recirculation 28.20 353.00 - Ayer and Tyedmers, 2009
Atlantic Salmon Net Pen 2.07 26.90 - Ayer and Tyedmers, 2009
2.4 Discussion
2.4.1 Impact Assessment
The field of aquaponic farming has been rapidly growing over the past decades, but there
have been very few rigorous, peer-reviewed systems research published on the topic.
Because of this, assessment of these systems is needed in order to provide stakeholders
information on the benefits and costs of aquaponics and the potential these systems have for
providing sustainable food production. In a study done by Farahipour et. al., (2014) LCA has
52
been shown to be capable of producing some nontrivial results that can be significantly
helpful when it comes to decision making. This LCA demonstrated that aquaponics has
beneficial reductions for some environmental impacts associated with food production, but it
has a higher impact in other categories. Aquaponics showed a great potential for increasing
yield per land area, while decreasing water use compared to conventional agriculture. The
lettuce production in aquaponics was also outperformed by hydroponics in regards to yields
and water use. However, this aquaponic system used less energy than the comparative
hydroponic studies from the Barbosa et al., study (2015). This study used data focusing on
agricultural practices in Arizona, US as 29% of lettuce production nationwide occurs in this
state (Barbosa et al., 2015). The conventional agriculture ranges were determined from an
“order of magnitude” study from Acker et al. (2008) that focused on the required energy and
water for all lettuce cultivation in Arizona (as well as other crops). The hydroponic data
from the Barbosa et al. (2015) study was from an enterprise model from the Ohio State
University, used to estimate the revenue, expenses, and profitability associated with
greenhouse lettuce production. Data was also taken from two more hydroponic studies to
estimate water and energy use. These comparative studies for hydroponics and traditional
agriculture in Arizona have a warmer climate than Denver, Colorado. In order to compare
how sustainable aquaponics is as a local food production system for this city, it would be
helpful to compare to agricultural systems within this state, which so far, have not been
completed. Rain fed agriculture, in comparison, had much lower yields than any other
production type. However, they had a corresponding low GWP value as well. Although
primarily rain fed, the farmers in the Hall et al., study did supplement with irrigation when
needed, which resulted in the slightly higher WD than hydroponics. The rain fed agriculture
WD was still lower than irrigated traditional agriculture and aquaponics. In regards to fish
53
production, aquaponics contributed more to GWP than all other types of aquaculture except
for an arctic char recirculation system (Ayer & Tyedmers, 2009). However, the EU and WD
for this aquaponic study was the lowest of all aquaculture systems, which has the potential
for natural resource conservation. The comparison between temperate and tropical
aquaponics shows that regardless of the climate, the GWP is still high for the production.
This is potentially from the University of Virgin Islands system focusing primarily on fish
production, while Flourish Farms primary product is lettuce. The Boxman et al., (2016) study
also used the basil production as a credit to their system, instead of using an additional
functional unit. This resulted in several avoided products, which is why there is a negative
WD for this system. However, the water additions for the Boxman system were 0.16 m3/kg,
which was 0.03 m3/kg higher than Flourish Farms. These comparisons suggest that although
it would be logical to assume gained production efficiencies from a tropical climate system
that does not need a greenhouse, this is not necessarily the case.
This study identified areas where efficiencies could be built into aquaponics in order to
have a more sustainable system. The GWP for aquaponics was higher than other agricultural
systems, and could be reduced by the farm considering alternative energy solutions, such as
purchasing wind energy from their source. The farm currently has plans to install solar panels
which will reduce both the GWP and the EU for the system. Presently 63% of Flourish
Farms GWP is from the electrical usage of the farm, and 26% from the natural gas
consumption, so this improvement could help reduce these electrical usage components from
the farm. One of the hot-spots for electrical consumption was the use of the halide lights for
six hours a day during the winter. In the future, converting to LED lights could reduce energy
use for this component by 60%, although the greater capital cost for the lights would need to
be considered. Part of this high natural gas consumption comes from the temperate
54
continental climate, which generates hot summers and very cold winters, requiring high
temperature mediation. The aquaponic water culture is kept consistently between 21ºC and
22.7ºC, and the greenhouse air temperatures range from 12.7 to 23.8ºC. This amount of
temperature control in a drastically changing climate in Colorado is energy intensive to
maintain. Another aspect to consider is the building where Flourish Farms is located is in a
repurposed historic greenhouse from the 1970s, which lacks modern infrastructure to more
efficiently retain heat. Solar thermal heating and water heating could be applied to the
building to reduce the GWP, as well as a climate battery, which could store hot air
underground to use during the cold weather. One advantage aquaponics has in comparison to
traditional agriculture is the local customer base. Flourish farms sells and delivers all of its
products within an 8 kilometer radius. One of the potential reasons that the GWP for
aquaponics exceeded that of traditional agriculture is the reliance on electricity and heat for
the system to operate. While conventional farms do irrigate and have machinery for tilling,
weeding and harvesting, rarely are all of these components operating twenty-four seven. In
an aquaponic system the water pumps, circulators, aerators, and heating or cooling
mechanism need to be on one hundred percent of the time. If one of these elements were to
fail, there would likely be a large fish die-off, as there was in this farm when the generators
failed. However, the benefit from the constant circulation is the increased yield and year
round production, which many Midwestern agricultural systems cannot offer.
During the course of this study, Flourish Farms harvested both tilapia and HSB. HSB was
thought to be beneficial because it can be raised in lower water temperatures than tilapia, and
therefore saving on water heating costs. However, tilapia and HSB both grow optimally from
23ºC to 27ºC. Flourish Farms typically kept water temperatures 1 to 2ºC lower than
optimally growing records. One recommendation was to reduce the water temperature further
55
while the HSB were the primary species, since they are more resilient under cold conditions
than tilapia. Flourish Farms actually did attempt this growing technique to reduce GHG and
heating costs. They lowered water temperatures to 10ºC and found that the HSB were still
sustained. However, because the reduced temperatures slowed the HSB growth, the
nitrification process slowed as well, doubling the amount of time for the lettuce production to
reach harvest size. The reduction in profit harvestable vegetables was actually far greater
than the costs saved in heating over the winter.
While the WD for aquaponics was lower than traditional agriculture and aquaculture, it
was still higher than the projected 10% of water usage of traditional agriculture that many
studies support (Somerville et al., 2014; Lennard & Leonard, 2006; Bainbridge, 2012). This
LCA indicated that aquaponics uses 24% less water than traditional irrigated agriculture and
in a desert climate. Flourish Farms going forward should carefully track where water is being
applied in the system, and look for any possible reductions. Another possible reduction is
Denver approved rainwater collection in 2015, which could be another water source the farm
could utilize instead of tap water (Gauldin, 2015). The Bainbridge aquaponic LCA predicted
that a 0 m3 WD could be achieved in their system by relying on rainwater collection alone
(2012). The farm also experienced several operational emergencies during 2014, which could
have caused a need for the system to be flushed and heavy water use during this time.
Additional years of data and notes of future notes of high water usage may prove that 2014
was an outlier in WD for Flourish Farms.
The lettuce yield for aquaponics shows promise as the production was 560% higher than
traditional irrigated agriculture and 16,838% higher than rain fed agriculture. Higher yields
can result in more effective land use planning and management, which will become
56
important as we continually try to feed more people with less space. Land that is saved from
intensive agriculture could be use for conservation, which could improve the environment.
Some points of consideration for this study that may contribute to uncertainty in the
results, is Flourish Farms, up until recently, did not weigh their fish. The method for sales
included estimating fish length at approximately 12.7 cm long or “plate size” and selling the
fish for an even five USD. Typical aquaculture studies meticulously weigh the protein
produced and sell the fish by weight which gives very accurate production numbers, instead
of the estimates used in this study. The farm also experienced a dramatic die-off during the
2014 year in which 491 fish died due to loss of electricity. In order to account for this die off,
this study added these fish weights into the protein produced, even though this protein was
not sold.
Additionally, many studies use the DM value of plant mass as a better indication of the
actual production. DM does not include the water accumulated while growing, and therefore
has a greater consistency than WM. As water has no nutritional components, it is not ideal to
use the water weight within the product as part of the production. However, since the data for
this study were taken from 2014 Flourish Farms had already weighed their products before
the viewing of the data and any alterations could occur. One recommendation for future data
collections would be to have DM values for each product that the farm is selling, in order to
have more accurate measure of the food produced. Another data collection recommendation
would be to have consistency in the metrics that are being collected. Not all data points in all
years had consistent utility readings or fish counts. Other helpful metrics would be daily
water temperature readings, air temperature readings, and more precise recordings of
equipment operation throughout the year.
57
One issue with comparing LCA results to other LCA literature studies is that rarely will
the study boundaries reflect the same exact inclusions and exclusions. Each LCA is
completed with individual goals, and therefore the studies can be difficult to compare equally
as some studies will include more of the process than others. This is a concern for this study
as some of the literature values, (e.g. Barbosa et al., 2014) used fewer production
components than this study, while others (e.g., cradle to grave aquaculture studies) used more
production and life cycle events than this study. Unfortunately, without completing a range
of LCA studies compromising of various study boundaries this issue cannot be avoided.
LCAs will usually only compare if the two systems analyses were completed by the same
researcher, so the variable for the study boundary will be consistent. In order to account for
this discrepancy, the values for this study are primarily used for the farm’s benefit, and not as
concrete comparative value. A confidence variation analysis could help to make the
comparisons more effective.
Additionally, the allocation methods for this study could be improved since the economic
production required some estimation in regards to fish weights and sales. A method involving
resource requirements or mass for each subcategory of production may generate better
allocation percentages and will be considered for future research. Ultimately, better systems
information will quantitatively address hypotheses about the relative efficiencies of
aquaponic vs. other alternative farming techniques.
Local year-round food production is becoming increasingly important to communities
looking to have higher food security and food sovereignty, and aquaponics is a mechanism
that communities can explore. LCA’s can help individuals and communities evaluate if this
food production system is the right fit for the goals they hope to achieve.
58
2.5 Conclusions
This study has shown that aquaponics possesses certain environmental benefits as
compared to other agriculture systems. If applied on a larger scale, aquaponics could have
significant positive environmental impacts on the food system. This production system also
shows promise in international development to increase access to affordable protein when
there are limited options available. This research demonstrated that there may be ways to
produce high quality protein and produce, that has potential to be less environmentally
wasteful and costly than traditional agriculture, hydroponics and aquaculture. Further
investigation and implementation of alternative food systems could be a step in increasing
local food production, and shifting away from the industrial global food market.
59
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APPENDIX A
Flourish Farm’s Delivery Locations
1. The Growhaus – 4751 York Street, Denver CO 80216
2. Blue Moon Brewing Company – 3750 Chestnut Place, Denver CO 80216
3. Comida at the Source – 3350 Brighton Boulevard #105, Denver CO 80216
4. Mondo Market – 3350 Brighton Boulevard #115, Denver CO 80216
5. The Populist – 3163 Larimer Street, Denver CO 80205
6. The Preservery – 3040 Blake Street #101, Denver CO 80205
7. Nocturne – 1330 27th Street, Denver CO 80205
8. Aloy Thai – 2134 Larimer St., Denver CO 80205
9. Vesta Dipping Grill – 1822 Black Street, Denver CO 80202
10. Cholon Modern Asian Bistro- 1555 Blake Street #101, Denver CO 80202
11. Squeaky Bean- 1500 Wynkoop Street #101, Devner CO 80202
12. Central Bistro – 1691 Central Street, Denver CO 80211
13. Western Daughters Butcher Shoppe – 3326 Tejon Street, Denver CO 80211
14. Linger – 2030 West 30th Avenue, Denver CO 80211
15. St. Kilian’s Cheese Shop – 3211 Lowell Blvd, Denver CO 80211
16. Charcoal Restaurant – 43 West 9th Avenue, Denver CO 80204
17. Marczyk’s Fine Foods (17th) – 770 East 17th Avenue, Denver CO 80203
18. Thump Coffee – 1201 East 13th Avenue, Denver CO 80218
19. SAME Café – 2023 East Colfax Avenue, Denver CO 80218
20. Denver Zoo – 300 Steele St., Denver CO 80205
21. Marczyk’s Fine Foods (Colfax) – 5100 East Colfax Avenue, Denver CO 80220
22. The Plimoth – 2335 East 28th Avenue, Denver CO 80205