Our current industrial food system is unsustainable. Demand for food continues to grow while soil erosion, groundwater depletion and climate change are constricting supply. In addition, intensive use of synthetic fertilizers, pesticides, water, fossil fuels, and genetic engineering are eroding human, community, and environmental health. The rise of local, sustainable food systems present solutions to many of these problems, but these approaches are unable to consistently provide quality food on an annual basis. Aquaponics holds the promise of solving this fundamental problem of local food systems, and does so while requiring far less land, water, fertilizers, pesticides, fossil fuels, and genetic engineering. This article reports on a novel, sustainable, and economically viable model for aquaponic food production year-round, even in locations with harsh winter climates.
Our current industrial food system is environmentally and socially unsustainable.
The rise of local, sustainable food systems presents solutions to many of these environmental and social problems, but most are unable to provide consistent supply on an annual basis.
Aquaponics holds the promise of solving this fundamental annual supply problem while requiring far less land, water, energy, fertilizer, pesticide, and herbicide inputs than conventional farming.
Victus Farms is a large aquaponic facility designed to serve as a research, educational, and proof of concept system that has been operational for two years.
Wicked Fin Aquatic Farms has emerged from lessons learned with Victus Farms. It was designed to serve as a small, inexpensive, efficient, and economically viable model of aquaponic production to be duplicated around the world in an effort to strengthen local and sustainable food systems. This replication has already begun.
Global food production is having a hard time keeping up with demand, and trends suggest that it is only going to get more difficult.1 Global demand for food is growing as human and grazing animal populations increase, as more people are changing their diets to include more meat, and as more crops are used for biofuel production. On the other hand, it is getting more difficult to continuously increase annual agricultural yields as the downward pressure of soil erosion/degradation, aquifer depletion, and irrigation water supply complications due to melting glaciers begin to outpace technological advances in agricultural production.2 Many new problems have arisen as producers try to meet these challenging trends by squeezing ever more production from remaining agricultural lands.
The majority of our food and animal feed now comes from large-scale industrial crop production using a mono-cropping approach. This involves growing a single crop over a large area of land. This method became widespread in most industrialized countries in the 1940s and 1950s, at the expense of the small family farm, as farming became more commodity- and less subsistence-based. This approach increases mechanization, and demands the use of fossil fuels, fertilizers, pesticides, herbicides, irrigation water, and genetic engineering. All of these factors decrease the need for human labor, and ultimately reduce crop prices. While proponents of industrial agriculture claim to have modernized and streamlined the production of food in the United States, such evolution has been at the expense of environmental, human, and community health.3
Industrial farming practices have generated numerous environmental impacts including soil erosion and degradation, water pollution, air pollution, and biodiversity loss. These environmental impacts have led to numerous human health problems, including the ingestion of pesticides, herbicides and hormones, increased allergens and antibiotics-resistant bacteria, infectious disease incubation and dispersal, and a wide range of respiratory problems from exposure to air pollutants (including particulates, hydrogen sulfide, and ammonia). Finally, industrial farms typically import most necessary inputs and export products, leading to local economic stagnation. Surrounding property values also decline significantly as the result of odor, pollution, and their associated human health problems. When these local economies degrade, their community infrastructure (schools, parks, etc.) soon deteriorates as well. In this vicious cycle, environmental and human health problems work together to degrade the communities surrounding these large-scale farming operations.4
More sustainable food production techniques offer many solutions to the problems of industrial farming outlined above, but have difficulty generating reliable, adequate production (amount and variety) for a given region over the course of an entire calendar year. This is where the aquaponic solution enters the equation. Aquaponics offers the potential to reliably generate large quantities and varieties of food from very small urban spaces, in any season. If aquaponic food production methods can be made environmentally sustainable and economically viable, this approach could be used in combination with more typical sustainable farming methods to bring us far closer to a more competitive local food system. There are currently many groups in the Midwestern United States attempting to do just that.5
Aquaponics refers to the combined production of fish and plants in what is known as recirculating aquaculture.6 Nutrient-rich wastewater from fish supports plant growth, while plants clean the water so that it can be safely returned to the fish. The concept has grown increasingly popular in the last few decades, and aquaponics is now regarded by many as the future of food production. It holds the promise of becoming an economically viable way to consistently grow sustainable, local, and organic food.
Modern aquaponics dates back to early work at the New Alchemy Institute and three key university projects. The first physical project undertaken by the New Alchemy Institute was a geodesic dome greenhouse that contained fish and plants growing synergistically. William McLarney published a series of articles and, ultimately, a book documenting this pioneering work from 1974-1984.7,8,9,10 Mark McMurtry and Doug Sanders from North Carolina State University began their aquaponics system in the mid-1980s. Their system contained tilapia along with tomatoes and cucumbers growing in a sandy medium which doubles as a reciprocating bio-filter. They have used this system to demonstrate sand culturing of plants on fish wastewater,11 water use efficiency, and the economic improvements of combined fish and plant operations versus either in isolation.12,13 Also in the mid-1980s, Dr. James Rakocy developed a modified aquaponic system at the University of the Virgin Islands. Dr. Rakocy added rotating mechanical bio-filters between the fish tanks and the plant growth troughs to replace the sand medium, and developed the first raft aquaponic system. Raft aquaponics refers to growing plants on floating rafts with roots extending into the water below. Dr. Rakocy has made numerous contributions (fish feed, key scaling metrics, nutrient dynamics, pest/disease control, solids removal, and bio-filtration) to auquaponic knowledge over the past two decades.14,15,16
Dr. Nick Savidov, at the University of Alberta’s Crop Diversification Center in Brooks Alberta, started an aquaponic system in the mid-1990s modeled after Dr. Rakocy’s, but modified for cold-climate applications. Savidov developed a method for recycling all solids in-situ, eliminating the difficulties of sediment removal and disposal, and regenerating more internal nutrient to support plant growth. Savidov also demonstrated that plants grew better on fish wastewater than on conventional hydroponic nutrient solutions, and continues to this day in his search for the ‘missing ingredient.’17 Researchers for the University of Minnesota, Duluth visited Dr. Savidov and his system in the summer of 2011, and designed Victus farms using his as a model.18
In addition, numerous private aquaponic ventures have recently emerged. A few major examples from the Midwestern US include Future Farms, which was started by Steve Meyer, Chad Hebert and John Vrieze in Baldwin, Wisconson.19 As dairy farmers, the three have slowly developed a large and profitable working raft aquaponic system fueled by methane from the farm’s animal waste. More recently, they have begun to make the transition away from aquaponics in favor of hydroponic methods. Garden Fresh Farms was created by Dave and Bryan Roesers in Maplewood, Minnesota.20 The operation is located in an old warehouse, and is totally dependent on artificial light. They have been experimenting with alternative plant growth techniques such as vertical walls and drums rotating around a single tube of light.
Nelson and Pade, Inc. was founded by Rebecca Nelson and John Pade in Motello, Wisconson.21 They have a working aquaponic system and design and sell aquaponic production systems and system components around the world. They also do a great deal of educational training and coordinate an online aquaponics journal.
Growing Power was founded by Will Allen in Milwaukee, Wisconson.22 Growing Power’s mission is to inspire communities to build sustainable food systems by providing hands-on training, on-the-ground demonstration, outreach, and technical assistance. Finally, Urban Organics, founded by Dave Haider and Fred Haberman in 2013, is located in an old brewery in St. Paul, Minnesota.23 This operation uses a closed loop, recirculating agriculture system to produce a variety of produce exclusively indoors. Each of these operations has an established track record and all have become major contributors to advancing aquaponics.
Version 1.0: Victus Farms
The University of Minnesota, Duluth’s new aquaponic system located in Silver Bay, Minnesota was modeled after the systems described above, but has several key distinctions.24
The first is the attempt to integrate algae and duckweed into the conventional fish/plant symbiotic relationship. The algae hold the promise of introducing a bio-fuel revenue stream while also serving as a source of valuable oxygen and high protein fish feed. The inclusion of duckweed significantly reduces the need (and thus costs) for external fish feed. Our system is also approximately four times larger, allowing it to better serve as a research, training, and proof of concept facility.
The farm has received over USD $1.7 million in funds to date for project feasibility, design, construction, research, and early operations. The aquaponic production system is housed in a 9,000-square-foot facility. One third of this space contains a well-insulated building to house the fish tanks and filtration equipment, along with a lab, bathroom, utility room, and processing area. The other 6,000 square feet are devoted to an attached greenhouse. The fish are grown in nine 2,000-gallon tanks at high density (up to .5 lbs/gallon). The fish tank water requires constant treatment (60 minute residence time) to prevent oxygen depletion and ammonia toxicity. The fish wastewater flows through four 7,500-gallon troughs to support the hydroponic growth of basil, tomatoes, peppers, and lettuce as well as algae and duckweed.
Together, the plants, algae, and duckweed remove nutrients and add oxygen to the water before it is returned to the fish to complete the cycle. Currently, algae are harvested on only a very small experimental scale, and used to explore various methods of algal harvest, oil separation, and biodiesel production, as well as their use as a potential direct food source for the fish. Duckweed is also grown and harvested on a very small scale to explore its use as a potential feed source for the fish. Suspended sediments resulting from undigested food and fish feces are re-mineralized within the system. This integrated production system contains approximately 30,000 gallons of water.
Victus Farms has three primary project outcomes. The first is to demonstrate a local, job-creating, economically viable, and environmentally sustainable method for producing healthy food and clean bio-fuel. The second is to develop and deliver a range of educational opportunities for a wide variety of potential learners. Educational efforts at the technical college and university level will be aimed at training the workforce required to fuel the anticipated commercial expansion of this concept. The third is to continuously monitor and report system performance, as well as to develop an interdisciplinary research team to attract funds and conduct research aimed at improving system performance, sustainability, and economic viability.
System inputs include heat, electricity, water, fish feed, and solar energy. Two biomass boilers (and a backup natural gas boiler) heat the water to 80 degrees Fahrenheit. Electricity use will be offset by a 20-kilowatt wind turbine scheduled for installation in spring 2015. Daily water loss (two percent, or 600 gallons) from evaporation and harvest will be replaced by filtered rainwater stored in large tanks (37,000 gallons) located under the plant and algal troughs. The algal remains (after oil extraction), along with duckweed, are used to offset the use of external organic fish feed. Passive solar energy is used for space/water heating and growing plants and algae. Future research efforts will be aimed at minimizing these heating, electricity, water, and external feed demands, and ensuring renewable energy sources can completely cover these needs. System outputs include only fish, produce, and soil. The system generates no waste other than compostable plant and fish remains after harvest, plus any emissions from our natural gas and biomass boilers.
In more water-scarce environments, any wastewater generated from washing produce could easily be recaptured and treated for use in the system. The system requires no nutrient additives, herbicides, pesticides, or hormones. All produce has been organically certified by the Midwest Organic Services Organization, and is sold and delivered daily to local restaurants, grocery stores, and individuals. The project is truly a model of sustainable community development.
Economic Viability: Capital and Operational Costs
The current building/production system requires the following utilities and operational costs: water use currently averages 7,000 gallons of water per month with approximately 70 percent supplied by filtered rainwater. The energy required for heating (using the natural gas boiler) currently averages 1,100 therms per month. In addition, propane is used for supplemental greenhouse heating on an as-needed basis. Propane use averages 600 gallons per month. Current electricity use averages 5,500kwh per month. Finally, fish feed inputs average 400 lbs per month, with 20 percent of this need covered by algae and duckweed produced internally. Therefore, the current building/production system requires the following costs per month in USD: $150 for water, $900 for natural gas heating, $300 for propane heating, $450 for electricity, and $400 for fish feed. This results in total input costs of $2,200 per month. In addition, approximately $600 per month is spent on travel costs to cover the 100 mile round trip from Duluth to Silver Bay five days per week, and $800 per month is required for basic operational maintenance and supplies. Finally, $6,000 per month is spent on labor costs. The average total monthly costs comes to $9,600.
Economic Viability: Production and Sales Revenues
Victus Farms currently produces the following yields, with all costs listed in USD: 2,000 heads (at $1.25/head) and 200 pounds of lettuce (at $4/lb), 100 pounds of basil (at $12/lb), 200 pounds of fish (at $4/lb), 100 pounds of tomatoes (at $3.50/lb), and 100 pounds of cucumbers (at $1.5/lb). This core production is being sold wholesale to local restaurants and grocery stores. Total sales revenue from this core production sums to $5,700 per month.
In addition, a ‘Saturday Morning Market’ sells directly to consumers at retail prices approximately 80 heads of lettuce (at $2.00/head), 40 ounces of basil (at $3/ounce), 40 pounds of fish (at $4/lb), 20 pounds of tomatoes (at $4/lb), and 20 pounds of cucumbers (at $2/lb). Direct consumer sales total $560 per month. Therefore, average total sales revenues from current production systems sum to $6,260 per month, and continue to increase steadily as production is increased. Several research and operational grants now bridge the gap between sales revenues ($6,260/month) and total operational costs ($9,600/month).
Version 2.0: Wicked Fin Aquatic Farms
New Greenhouse and Production System Design
A great deal has been learned from the first two years of operations at Victus Farms, resulting in dramatic improvements in both production system design and the building that contains it. Using horizontal columns instead of the conventional raft approach improves both growth rates and plant quality. This substitution allows for the growth of approximately ten times more plants per square foot of greenhouse space, and enables the relocation of the fish from individual tanks to growth troughs beneath the horizontal plant columns. These simple improvements eliminate the need for large and expensive fish tanks, as well as the associated plumbing. It also allows for a dramatic reduction in water volume for the overall production system, resulting in far less water to circulate and heat. Finally, it reduces the required space for the production system by approximately 75 percent.
In Duluth, a new building was recently designed and constructed to take full advantage of the improvements outlined above.25 This building is far smaller, less expensive, and more efficient than the existing facility in Silver Bay. The installation of the new fish/plant production system described above is currently being completed. The building is a very simple 1,152 square foot greenhouse. In-floor heating is provided with a conventional 40-gallon hot water heater. Additional space heating and de-humidification is provided by a woodstove as needed.
The simplified production system consists of three (10′ x 12′ x 1′) troughs. The troughs will be constructed with two layers of green treated 2″ x 12″ lumber planks and lined with a dense pond liner. Each trough will contain 1,000 gallons of water (to support approximately 200 pounds of fish) and have its own simple filtration system as well as an electric in-line heater. Four PVC horizontal column racks (each containing eight 10-foot-two-inch PVC pipes with 12 plant holes each) will be suspended from the ceiling above each trough for lettuce and basil growth. A single pump running five minutes every hour will feed trough water into the top of the horizontal columns. The water will cascade through the horizontal column racks and return to the trough below by gravity. Another pump supplies water to 80 feet of four-inch PVC lines along the south wall of the greenhouse for tomato, pepper, and cucumber growth.
The production system also contains a 100-square-foot warm room for seedlings, and a 36-square-foot cold room for produce storage. The warm room is heated to 78 degrees Fahrenheit by heat generated from grow lights. The cold room is cooled using a small air conditioner coupled with a ‘cool-bot’ controller. Supplemental lighting, which will only be needed in the four winter months, is provided by LED grow lights. Finally, an 800 gallon rainwater storage tank and associated filtration system provides needed water additions to compensate for evaporation and transpiration losses.
Capital and Operational Costs
The greenhouse and the fish plant production system contained within was constructed on a heated gravel floor for under USD $25,000, plus labor costs. This smaller and far more efficient building/production system will dramatically reduce utility needs and operational costs. Water use will be reduced from 3,500 to 900 gallons of water per month with 80 to 90 percent supplied by filtered rainwater. The energy required for heating will be reduced from an average of 1100 therms to 300 therms per month. Heating will be supplied by a small electric hot water heater and three in-line electric spa heaters running as needed. Electricity will be reduced from 5,500 to 3,000 kwh per month, despite the shift from natural gas and propane to electric heat. Finally, fish feed will be reduced from 400 to 100 lbs per month with an additional 40 pounds per month coming from algae and duckweed produced internally. Therefore, the new building/production system will require only water (USD $50/month), electrical (USD $400/month) and food (USD $100/month) inputs.
Total utility and feed costs will be reduced from USD $2,200 to $550 per month. In addition, travel costs are reduced from USD $600 to $50 per month, and basic operational maintenance and supply costs are reduced from USD $800 to $400 per month. Finally, the labor requirement is reduced to one full time job at a cost of USD $4,000 per month.
Total costs for our new production system are reduced from USD $9,600 to $5,000 per month.
Production and Sales Revenues
We expect our new production system will generate the following, with all costs listed in USD: 1,200 heads of lettuce (at $2/head), 40 pounds of basil (at $12/lb) and 80 ounces of basil (at $3/ounce), 120 pounds of fish (at $4/lb), 80 pounds of tomatoes (at $4/lb), 80 pounds of cucumbers (at $2/lb), and 80 pounds of peppers (at $3/lb). This core production will be sold mostly to individuals and groups at retail prices. Total sales revenue from this core production sums to $5,040 per month.
A Promising Solution
Therefore, a USD $25,000 capital investment plus approximately USD $25,000 worth of expert labor to design, construct, install, and train new users, generates a facility capable of producing USD $60,000 per year in fish and produce sales revenues. Of this revenue, approximately USD $12,000 per year covers operational costs, leaving USD $48,000 per year for labor costs. These facilities are showing initial promise that may lead to economic viability, based on minimal fish feed, electrical, and water inputs. They generate only rich compost as a waste product. No fertilizers, pesticides, herbicides, or growth hormones are required. A production facility can be located in any urban or rural setting as long as electricity, water, and sunlight are available. In the cold Midwest region, demand for these small-scale, local production systems is rapidly intensifying. Similar systems are already being installed for individuals, restaurants, hospitals, schools, and community groups in Northern Minnesota. If it works in Northern Minnesota, it can work anywhere!
The authors would like to thank the following organizations for providing significant project funding: Minnesota Pollution Control Agency (MPCA); Iron Range Resources and Rehabilitation Board (IRRRB); Minnesota State Legislature; Minnesota Department of Employment and Economic Development (MN DEED); Minnesota Lake Superior Coastal Program; the University of Minnesota’s Northeast Region Sustainable Development Partnership (NMSDP), Healthy Foods Healthy Lives Institute (HFHL) and the Institute for Renewable Energy and the Environment (IREE); University of Minnesota, Duluth’s College of Liberal Arts; Lake County, Minnesota; Silver Bay, Minnesota; and the Lloyd K. Johnson Foundation. We would also like to thank our project partners from Silver Bay, Minnesota for their continuous project efforts: Lana Fralich, City Administrator; Bruce Carmen, City Project Consultant; and, Mayor Joanne Johnson. Finally, we would like to thank all the students from the University of Minnesota Duluth that have worked at Victus Farms.