Fat Beet Farm
During the spring of 2019 I have been doing an internship at Fat Beet Farm in Tampa, Florida. The Curci family have envisioned a sustainable commercial operation that includes a farm, food commissary, two restaurants and an event venue. They have been working for four years on establishing the farm where they are currently growing hydroponic lettuce, micro-greens, and soil-based vegetables, including cabbage, cauliflower, green onions, and of course BEETS. New projects on the horizon include a worm farm as well as an innovative mushroom growing system inside a shipping container!
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| Jerry Comellas and I digging the future beet field |
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| Fat Beet Micro-greens used at their partner restaurants Noble Crust |
My internship has revolved around building and getting the Biodigester up and running. As I excitedly talk about my project, I'm often met with quizzical looks . . ."Uh, sorry, but what EXACTLY is a biodigester?" I even recently had a friend ask, "Can it eat people?" Well, the short answer is - yes, yes it can!
What is a Biodigester?
An anaerobic biogas digester turns food, animal and agricultural “waste” into energy! Microbes break down organic materials into methane (CH4), carbon dioxide (CO2) and digestate, which can be used as fertilizer. Anaerobic (without oxygen) digestion is a simple process that occurs naturally in lakes and bogs, and consists of the following four steps:
Anaerobic Digestion
1. Hydrolysis: Organic matter is broken down to molecules such as sugars, amino acids, and fatty acids, becoming available for the bacteria2. Acidogenesis: Acidogenic bacteria convert these molecules into VFAs (volatile fatty acids) ammonia, hydrogen sulfide and carbon dioxide
3. Acetogenesis: Acetogenic bacteria continue breaking down matter to produce acetic acid, carbon dioxide and hydrogen
4. Methanogenesis: Methanogenic bacteria complete the break down process resulting in methane (biogas), carbon dioxide and water.
In these four simple steps you can take any organic material including food waste like meat and dairy products, grease, moldy bread, rotten fruit and veggies, as well as any kitchen scraps. Additionally, you can use animal waste of any kind - horse, cow, pig, human, and even dog and cat! Also agricultural waste, such as grass clippings, dead flowers, husks and shells, and weeds can be added. In the end, any leftover indigestible material left in the digestate makes for excellent natural fertilizer. This process creates a close-looped cycle, turning "waste" into energy and fertilizer input.
What we're doing at Fat Beet
At Fat Beet, there is an abundant amount of organic matter "waste," from the food processing facility for the Noble Crust restaurants and the agricultural processes. Although composting is currently an option, with future restaurant and agricultural expansion plans, there will be a surplus of organic waste.
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| TH Culhane & Josie Curci |
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| http://www.solarcities.eu/ |
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| http://en.puxintech.com/Home |
After constructing the concrete shell, we installed a 6" pipe to input food waste, a 4" pipe for digestate output, and the Puxin dome lid, for the biogas release. We made a steel stir pipe to prevent clogs. 
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| 500 ft. of PEX coils looped through cinder blocks, holding them in place and providing surface area for bacteria colonies. The coils connect to steel pipes we placed inside the concrete shell. |
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| PCGS students came out to help install the 60 evacuated tube solar system |
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Split solar water heater systemBringing It All Together
After the solar water system was installed, we needed to connect everything. We used CPVC pipes to connect the steel pipes that the PEX coils are connected to inside the digester to the solar tubes. Through trial and error, we realized the CPVC wasn't strong enough to withstand the piping hot water coming out of the solar tubes, so we had to refit the system with copper. We completed our plumbing system, with several pressure relief valves to hopefully deter any future explosions. We wrapped all the plumbing with foam insulation to prevent heat loss throughout the system.
Warped CPVC after system exploded from high temperatures
Jerry and I cutting copper pipes
I learned how to solder!
She's Alive!
After several weeks of inoculation and feeding the biodigester manure and food waste, she is now functioning. We have both biogas and digestate production. We have a temporary IBC tank system set up, capturing both byproducts. These will eventually be replaced with custom cone bottom tanks. The conical shaped tank will prevent a build up of sludge at the bottom of the slurry tank.
Liquid digestate aka slurry
Temporary digestate and biogas IBC holding tanks
Future cone storage tank
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Te Kā or Te Fiti?
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| Te Ka or Te Fiti
Anybody who knows me, knows I have a slight obsession with the greatest movie of all time, Moana. In the movie, the demigod Maui has stolen the heart of Te Fiti, i.e. Mother Nature, to give power to humanity. Moana's people are beginning to suffer with crop blight and dwindling fish populations. She embarks on a mission to return the heart to Te Fiti, overcoming many obstacles along the way. Her final battle is against Te Ka the volcanic fire-breathing demon. In the end, Moana realizes that Te Ka is Te Fiti who has been corrupted without her heart. Moana returns her heart, and Te Fiti reemerges as the green goddess, forgiving all and ending the blight.
The story of Moana can be aligned to our current world. We have abused Mother Nature to such an extent that we are suffering many consequences. We have extracted fossil fuels in order to obtain power, despite the ill effects of doing so. Perhaps, if we are able to have a paradigm shift, and turn to renewable energy sources, such as biogas, we can undo or at least prevent further damage. Our biodigester is both Te Ka and Te Fiti. She is currently black and capable of breathing fire, like Te Ka (and her dragon counterparts). In the future, Josie Curci envisions growing vining plants on her as she creates life with her fertilizer output and provides biogas energy, as Te Fiti.
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