Exponential Population Growth

In SENS 100, our introductory sustainability course, we study the mathematics of exponential growth and apply those principles to current world population and growth rates. Worldwide, population growth is “only” about 1.1% per year, but using the “rule of 70″ we see that at 2013 growth rates, world population would double in less than 64 years. (The rule of 70 is a simplified version of calculating exponential growth. Seventy divided by the growth rate in percent gives the approximate doubling time.)

Mouse over the figure below to see the detailed results of 50 years of exponential growth at 2013 growth rates for 12 countries in the top 20 of world population. Our population growth calculations are based on demographic data from the CIA World Factbook.



Back From Basic: An Overview of the Aquaponics Workshop at Kentucky State University

Author: Candace King

On Friday April 10, 2014 I attended an aquaponics workshop in Frankfort, Kentucky. The conference lasted through Saturday the 11th,, but the applicable knowledge that I attained will last a lifetime. The workshop was hosted by Kentucky State University in conjunction with the Ohio State University “Aquaculture Boot Camp” 12 month course. The workshop actually took on a tone of an educational boot camp of sorts, with plenty of intensive information that was specifically geared at folks who are trying to get into aquaponics for hobby, business, and research.

To kick off the workshop Dr. Jim Tidwell (KSU) and Dr. Laura Till (OSU) gave everyone a warm welcome, and FOOD! Thus, things were off to a great start. The visiting scientist Dr. Charlie Shultz, who is a highly exalted aquaponics expert, and one of the few people in his field, took over the show from there and away we went to basic training.

 Jim TidwellDr. Jim Tidwell of KSU Aquaculture

The vast wealth of knowledge that was laid out on the first day was a lot to absorb, but that’s kind of the way of aquaponics; there is always a lot to absorb, or a lot being absorbed, or things you don’t want to be absorbed.  Charlie Shultz and crew went over all of those categories plus some throughout the 7 hours of aquaponics that followed. From the very basic principles of raising fish and growing plants, to the nuances of operating a balanced system, the economics of aquaponics for business, and the regulatory process for individuals wishing to be certified to sell their harvest.

As an Economics major, I was definitely holding a bias on this, but I think my favorite part of the first day of boot camp was hour long lecture by KSU’s Dr. Sid Dasgupta, on “Business aspects and Record Keeping” for small scale agriculture. He and his team of agriculture economists have devised a user-friendly excel data sheet is available for download on his biography page at this link:



Other Highlights from the first day were:

  • Aquaponics design: A lecture about what and how to build in order to support your needs;
  • The basic principles, chemistry and some nuances of raising fish, and plants in and out of an aquaponics system;
  • The importance and methods behind maintaining good water quality;
  • Harvesting, storing and marketing goods according to USDA standards;
  • GAP and HACCP- Good Agricultural Practices  and Hazard Analysis Critical Control Point methods of safe food production;
  • How to become certified as an organic grower;
  • How to get a grant to grow organics, even for aquaponics; and
  • A lovely social where the people attending the workshop got to know each other and do quite a bit of networking.

paddlefishA KSU scientist retrieving a dead paddlefish from the aquaculture facility.

 For day two of the workshop, the attendees were informed that we should wear something that were okay with getting dirty  because it was going to be hands on! My favorite quote from the day came from Charlie Shultz, who said “Hyroponics is clean, sanitary in fact, aquaponics is anything but that;” he wasn’t lying either. The first half of the day was spent inside of KSU’s million dollar aquaponics research facility, where the experts along with a few KSU grad students showed us the ropes of what it means to raise plants and fish in a closed loop system, indoors.  There were several experiments in operation, the goal of which is to combine the results to derive best practices for aquaponics under different conditions. For the sake of the workshop, the facility was a living example of what the attendees hope to get into on some scale.

 Laura TillDr. Laura Till catching some fish for the sexing demonstration.

Luke OliverKSU Grad student, Luke Oliver, talking about how to grow plants in an aquaponics system.

Charles ShultzDr. Charles Schultz talking about water chemistry


After all of the intensive learning workshops of the previous day and a half, the second half of day two was a great treat for the attendees, as we all gathered our druthers (which I’m sure we lost somewhere between the immense amount of information and sexing fish by hand) and drove to Lexington, where we enjoyed a tour of the AWESOME Food Chain facility. Food Chain is a 501C3 (non-profit) facility, that was launched in May of 2012, as a project of individuals who were interested in “closing the loop” between food and commerce, by bringing food production within feet of the consumers. They have been pretty successful at doing so, in cooperation with Lexington’s West Sixth Brewery and a new restaurant Smithtown Seafood, all located in the same building, a former bread factory, right in the heart of downtown Lexington, KY. Smithtown sources their Tilapia and fresh greens from  Food Chain, and Food Chain sources the grain for their feed from the brewery (beginning in 2014). If one has time while in Lexington, they should visit this facility for two reasons:

  1. Food Chain has a great model: the people who work there are inspirational and innovative, and they need support from everywhere, so pay $10 for the tour, and you will be performing a good deed as well as learning a great deal.Food chain
  2. It’s efficient! If you are hungry, have a hankering for a nice local beer, and you want to live more sustainably, just being a purveyor of this one building in Lexington, KY is one way to boost your level of sustainability; plus it’s neat!Tilapia

Please excuse all of the exclamation points, but they are warranted. Aquaponics is fairly new, and it’s definitely exciting. The workshop in Frankfort was much more exciting than I expected it to be, and it was certainly informative. I would recommend KSU’s aquaponics workshop to anyone interested in getting into aquaponics and OSU’s aquaculture boot camp to anyone interested in doing it on a commercial scale.


If you are interested in finding out more information about future Aquaponics events like this one you should check out this link: http://aquaponics.com


Also, if you reside in or around Ohio, you can join next the OSU Aquacuture Boot Camp by following this link: http://southcenters.osu.edu/aquaculture/aquaculture-extension/boot-camp.



Patriotic Aquaponics

Author: Richard Olson

The Berea College Aquaponics Facility just received a shipment of 80 red Nile tilapia (Oreochromis niloticus) fingerlings and 80 White Nile tilapia (the Rocky Mountain White variant). Combined with the Blue tilapia (Oreochromis aureus) already in the system, we are ready for the Fourth of July! And after a two-year hiatus, we are once again adding channel catfish (Ictalurus punctatus) to our mix. What could be more patriotic than this widespread and popular North American native? Our last cohort of channel cats produced several individuals in the 12 to 15 pound range, but since this is way past optimum feed conversion efficiency, we will shoot for one to two pounds with this group.

Adult Red Tilapia

All the fingerlings will live together in our rearing tank for the next six to eight weeks before being transferred to their own tank in the main aquaponics system. Our summer aquaponics manager Candice King will be providing strict parental oversight during this important stage in these young fish lives.


Reduce, Reuse, Recycle

In a trash survey by Berea College SENS students, around 60% of what Bereans throw away can be recycled! Our recycling rate is only around 20%. This is almost half of the national average. Berea College has a commitment to sustainability, but we as students need to invoke a sustainable culture. So what can you do to help?

Recycle: Did you know that recycling one aluminum can produces the amount of energy needed to run a television for 3 hours? Recycling not only saves energy, but conserves valuable resources. If we all recycled our newspapers we could save 250,000,000 trees a year.

Reuse: It doesn’t even have to be ‘regular’ recycling. Think outside the box–get creative. Got a cool looking glass bottle ready for the trash pile? You can turn that into a cup! Old t-shirts can be recycled into bags, bracelets, headbands, etc. You can find all sorts of creative ideas. Even food can be reused in the form of compost.

Waste Capture MSW

Reduce: The most important of these three is to reduce. Our planet is plagued by a steady increase in waste. If we can cut down on the amount of plastics, aluminum, and glass we use we can really make a difference. Use a reusable water bottle, take cloth bags with you to the store, and try to buy things with less packaging.

It might seem insignificant that one person recycles their soda can, but when an entire campus changes their habits it can make a real difference. For more information about recycling and waste see the links below!



FoodChain: A New Link between Aquaponics and Local Business

Author: Brittany Schroeder


On February 9th, a group of Berea aquaponics folk drove to Lexington for the regular Saturday afternoon tour of the FoodChain aquaponics facility (FoodChainLex.org). FoodChain is part of The Bread Box (BreadBoxLex.com), a mixed-use development located in the 90,000 ft2 former Rainbo Bread bakery in North Lexington. Other tenants include West Sixth Brewing Company, a community bike shop, a roller derby rink, an art studio, and a seafood restaurant.

The aquaponics unit has been in operation for about six months now, with four months’ worth of harvests. In that short amount of time, FoodChain has made a name for themselves in the local community with their educational programs and how quickly their fish sells out: usually within a few days of each weekly harvest.

fig 1

Figure 1: Food Chain’s raft unit operation—that’s a whole lot of lettuce!

 Like the Berea College aquaponics facility, Food Chain’s system is modelled after the University of the Virgin Island’s aquaponics system with the use of floating raft units, a clarifier, fine particle filter, bio-filters, and sump pump. Water circulates between six 250-gallon fish tanks and four 40-foot hydroponic raft units. Fish tanks and raft units are aerated with air-stones, calcium/potassium bases and chelated iron are added to adjust pH and provide limiting nutrients, and bacteria purify the water and break down fish wastes into plant-available nutrients.

Unlike the Berea and UVI systems, FoodChain’s aquaponics units are housed indoors in a windowless room. Energy-efficient tracking grow-lights that mimic sunlight are on for 18 hours a day. These lights also provide the benefits of accelerated growth and minimize the chances of tip burn. The lack of sunlight also allows for low level light in the fish tanks, which is ideal in tilapia production.

fig 2

Figure 2: Check out the root growth on that lettuce!

The system is designed to yield nearly 80 lbs of lettuce, 5 lbs of herbs, and 7 trays of microgreens per week, and about 150 pounds of tilapia every month. All produce is sold to Smithtown Seafood, which is literally located on the other side of one of the aquaponics facility walls. No restaurant has fresher ingredients.

As with any aquaponics operation, FoodChain is continuously working to improve the efficiency and productivity of its system. For example, to reduce the cost of tilapia fry for restocking, they are setting up their own breeding and nursery tanks.

fig 3

Figure 3: Kentucky State University’s Aquaculture program has equipped them with tanks to begin breeding their own fish fingerlings.


When FoodChain’s founder, Becca Self, was designing the system, she visited Berea to view our aquaponics setup and perhaps get a few ideas. Now she has been able to return the favor as we have learned some new techniques from her. We will be trying a coconut coir-based growing media for our seedlings, and lining our net pots with burlap. We are also looking forward to growing some micro-greens on coir mats.

fig 4

 Figure 4: Microgreen production by use of coconut coir mat media.

FoodChain’s mission goes far beyond aquaponics. They are working to re-localize agriculture, support a local economy, and build community. If you are a Berea College student and would like to be a part of this great effort this summer, FoodChain has an internship available. Contact Rebecca Self rebecca@foodchainlex.org or Richard Olson olsonr@berea.edu for more information.

An Appalachian Future Without Coal

Since last summer I have been focusing much of my attention onto mountaintop mining practices and the various way in which it affects the environment. I completed an internship with Dr. Sarah Hall studying the microbial properties of different spoil types – the soil/rock residue resulting from blasting, digging, etc. – and wrote an extensive literature review considering the effects and alternatives of coal waste impoundments, more commonly known as “slurry ponds”.

I found through much of my research that the number of studies on the health effects from mountaintop mining on adjacent communities has increased considerably since 2011. It is nice to see an increase in scientific interest of a subject that has drastically impacted the Appalachian region for decades. I also found several economic analyses that specified the high dependence Appalachian economies have on the coal industry, particularly in eastern Kentucky.

Many Kentuckians call for an immediate end to mountaintop mining practices. Regardless of how loud that call is, effective legislation change, that would protect the people and the environment, cannot be made without 1) an abundance of scientific data proving the effects of the mining are inherently harmful and 2) alternative economic proposals that would ease coal out of Appalachian economies with causing havoc.

The former is already in the works, thanks to hundreds of scientists in the region working hard to prove with numbers what can be seen with our eyes: highly polluted waterways, toxic drinking water, severely degraded ecosystems, etc. The latter however requires more discussion and deliberation in all spheres; governmental, scientific and public.

Economic proposals have ranged from restoring degraded mining lands into economically productive ecosystems (i.e. beekeeping, permaculture, etc.) to renewable energy production via wind and solar to increased support for local entrepreneurs. Through the SOAR initiative, which stands for Shaping Our Appalachian Region, developed by the Kentucky state government, funding is being allocating for economic development summits and further economic research that could generate ideas to diversify the local economies of eastern Kentucky.

An “Appalachian Proud” marketing brand is currently being developed to promote the agriculture and agritourism of the region. The Appalachian Wildlife Foundation has proposed the construction of a conservation and education center on reclaimed mine land that would include elk- and bird-watching, wildlife conservation education, agriculture research, astronomy and other programs.

There is a lot of promising work leading to the removal of coal production in the Appalachian region. I encourage you to research for yourself the variety of initiatives that are stirring in the coalfield counties. What do you think will improve the economies of these areas? And what can you do to improve the economies of these areas? The time for change is now.

Aquaponics Fish Harvest

Author: Richard Olson

Responding to a request by Sean Clark for tilapia to use in his Farm to Table course (ANR 386), we harvested 33 Nile tilapia from one of the 2000-gallon tanks in the aquaponics system. Using a large homemade net, we captured four or five fish at a time and placed them in an ice bath to “chill kill.”


 A sampling of the tilapia harvest.

A sampling of the tilapia harvest.

We captured 33 fish with a total weight of 53 pounds (1.6 pounds average weight per fish). The remaining tilapia in the system will continue to eat, grow and provide nutrients for the hydroponic vegetables (mostly lettuce and basil at the moment). We do need to get some younger replacement fish in the system, so will be making another purchase of tilapia fingerlings in March. After a couple of months in our grow-out tank, these will occupy one of the production tanks in the main system.
Cleaning some of the tilapia for use by the SENS House.

Cleaning some of the tilapia for use by the SENS House.

Freezing February brings forth Great Greens

Author: Richard Olson

It may be 24 degrees outside, but the SENS Aquaponics Facility is warm, and the greens are growing. Janet Meyer, Horticulture Manager for the Agriculture and Natural Resources Program, turned to Aquaponics to augment the production of her hoop houses and greenhouse.

Janet Meyer and Caleb Krebs harvest greens from the semi-deep aquaponic raft unit.

Janet Meyer and Caleb Krebs harvest greens from the semi-deep aquaponic raft unit.

Janet and student aquaponics operator, Caleb Krebs harvested six pounds of Tatsoi (a Chinese green) and almost 20 pounds of Yankee Hardy lettuce mix. After washing and bagging, the greens will be available at the Berea College Farm Store (check out their website here: http://bereacollegefarmstore.com/). In trade, Janet provided two flats of lettuce seedlings that will be transplanted into net pots and used to refill the floating raft units.

Caleb Krebs harvesting aquaponic lettuce

Caleb Krebs harvesting aquaponic lettuce

Next week the “aqua” portion of the system will come to the fore as we harvest some of our Nile tilapia. Check back soon for more information on that!

Recycling Maniacs and Energy Cut-Backs

Recycling does not lend itself to be a common topic in the Berea College SENS program. To be sure, recycling is mostly second nature to many of those who are wholly integrated into the program. But for the campus at large, recycling isn’t exactly held in as high esteem as it could be. To remedy this, a new spin has been put on an established approach, and SENS once again has a part to play in overall campus sustainability.

This year, through collaboration with the Sustainability Department, a new brand was created to encompass two national college competitions: RecycleMania and Campus Conservation Nationals (CCN). Berea has participated in both competitions in the past, but if one were to approach an average student about either their likely reaction would be a genteel “Huh?” followed by, “Sorry, but I gotta run; I’m late to Peanut Butter and Gender.”

Thus, (as this did often happen) it became obvious that getting people to recycle would take more than a few extra recycling bins, a couple flyers plastered in CPO and Alumni, and an email blast reminding everyone about the competitions. New Sustainability Director Joan Pauly let no time go to waste in figuring out just how Berea could live up to its reputation of sustainability while getting more students than ever educated and excited about making campus a little greener.

As a result, Berea College Eco-Challenge was born: an integrated approach to tackle both RecycleMania and its counterpart competition CCN with greater-than-ever coverage of on-going achievements, a real sense of community involvement, greater awareness of the issues themselves, and incentives to spur students on. The goals for the competitions were set at four pounds per person of recycled materials by the end of eight weeks (for RecycleMania) and placement in the top ten overall for CCN (based on comparison with baseline scores from last year’s readings of energy output). Various incentives were decided upon with stipulations on how neighborhoods (grouping of campus residence halls) could win and how individual responsibility could be played up to get everyone in on the fun.

The final logo for Berea College Eco-Challenge

The final logo for Berea College Eco-Challenge

But will it all work? In eight weeks will you be able to ask our obscure student what they can recycle, how to cut back on energy waste, and what great prizes they won through Eco-Challenge 2014 and actually get a reply? We can certainly hope so. Maybe by then their hurried response to your queries will be, “Yeah, Eco-Challenge is great, but I gotta run and recycle this before my next class.”

Friday Night Lights-out


Author: Richard Olson

Sleep, as usual, is elusive. Turning to check the time, he finds the digital display flashing as it does after a power outage. His watch shows 1:15am. The outage was brief.

Wide awake, he considers the implications. Does this mean that the power went out at the Aquaponics Facility, one block away? Is it back on there? The air pumps and natural gas heaters require electricity to run. And the air blower needs to be reset manually after a power outage. It is a cold January night, but the thermal mass of the water and gravel will slow the drop in water temperature. No air to the fish tanks is a more pressing issue. The stocking rates are low enough that fish won’t start dying in 10 minutes the way they would in some commercial aquaculture tank systems, but how long is too long? This is not an experiment he wishes to try.

Dressing warmly, he leaves the house. Hopefully, a push of the reset button and back to a warm bed. Cutting through the block he emerges to find trucks, spotlights, people. A large tree has chosen tonight to fall and take out power and phone lines. A quick trip is not in the cards. Sigh.

Entering the aquaponics greenhouse, he is struck by the silence. No blower, fans or running water. Dark, quiet, and starting to chill. The feel of a crypt.

Battery-powered lanterns and flashlights on, he rolls the generator outside, and runs the extension cord back inside. The generator is exercised weekly by the students to keep it primed. It starts on first pull.  Silence flees.

A generator and air pump: essential backup for the aquaponics system

A generator and air pump: essential backup for the aquaponics system

Inside, the backup air pumps are lugged into place, and the air lines and stones tossed into each tank. Bubbles rise. The fish are safe. The air is cooling but for now the water isn’t, so he decides not to fire up “Mr. Heater” just yet. He settles in to wait.

If the main heat goes out, Mr. Heater stands ready to step in

If the main heat goes out, Mr. Heater stands ready to step in

6 a.m.   Lights, fans, heaters! Electricity, and a greater appreciation for its value, returns. As does an appreciation for preparation, redundancy, resilience. But insomnia can’t be counted on to give warning. An alarm system is needed.

A request is made to the Technology and Applied Design Program, a member of the Division of People Who Do Things. And they do. A $30 smart phone knows when it is being charged. Plug it in at the aquaponics facility, and if the power goes out it calls a service provider and a phone tree is initiated. If a number is answered, the message says “The fish are in danger. If you can save them, press 1.  If you can’t, press 2.” When someone presses 1, they are told “The fate of the fish is in your hands,” and no further calls are made. One less thing to lose sleep about.