CLEMSON — Clemson students are learning how rainwater and compost can be used to create a self-sustaining heated water system.
The project, Bio-Integrated Season Extension Techniques for Vegetable and Freshwater Prawn Production, is one of many Creative Inquiry projects on campus. Led by Student Organic Farm manager Shawn Jadrnicek, the students are building a compost heat-extraction system and learning how the system can be used to grow vegetables and freshwater prawn.
The system is located at the greenhouses on the Calhoun Field Research Area on the main campus. It recycles energy and water throughout the entire greenhouse complex. A concrete slab with embedded pipes connected to a hydronic heating system create a closed-loop water system.
Compost, comprised of wood chips from pruning operations around campus and food wastes from the cafeterias surround the pipes. The wood chips and food waste are combined in a manure spreader and spread around the pipes. During the process, the mixture is aerated and produces heat. This system integrates agriculture with water to moderate temperature extremes as well as provide nutrients and soils for the plants.
“We get really high temperatures,” Jadrnicek said. “It peaks at about 160 (degrees F) and then we usually get around 140 (degrees F) for four or five weeks.”
Heat is generated by bacteria eating and digesting the compost.
“Bacteria are primary decomposers feeding on the waste material,” Jadrnicek said. “Carbon and nitrogen are the two main components. As the bacteria feed, they grow exponentially and they reach a really high population concentration. It’s like if you get a massive amount of people in a room and they all start moving, that room is going to get really hot. The same kind of thing happens in a compost pile. You have billions of bacteria in (the compost) and they’re consuming and digesting the waste material. This whole process generates heat.”
Students involved in the project are learning how natural processes are used to generate and recycle energy and resources. Meredith McSwain, a sophomore biochemistry major from Charlotte, said she got involved with the project because it “…seemed like a really cool, fun thing to do” and offered her an opportunity to explore other areas of science.
“I’ve gotten to do a lot of hands-on designing, such as the substrate for the prawns, which was really cool,” McSwain said. “I’ve also gotten to help the water barrel system, which has also been cool. It’s fun to be able to do the hands-on part as well as learning the book part of the process.”
McSwain said working on the project has emphasized what she has learned in the classroom.
“Plants and other living things require specific conditions to thrive,” she said. “Knowing the conditions and understanding the conditions and how to alter the conditions is a lot of chemistry. You can learn to do it based on a set of instructions, but having a chemistry background lets you know what’s happening and why you’re using what you are to get the results you do.”
Other skills learned in the classroom that have helped her on this project include collecting and tracking data and determining how much energy is being pulled from the compost and how much money is being saved by not having to use additional heaters or a generator to heat the greenhouses.
McSwain and other students involved with the Calhoun Field project are investigating the Bio-Integrated Season Extension (BISE) greenhouse system and associated elements, including aquaculture ponds, nursery crops, mushroom logs and black soldier fly composting system. By participating in the project, Jadrnicek said students will gain hands-on experience with HOBO data logger and software, greenhouse system operations and maintenance.
The students also are monitoring how the season extension systems are integrated with natural processes to generate and recycle energy and resources. They are gaining experience with operation of all components of the system, including seed-starting, transplanting, high tunnel prep and maintenance, composting, irrigation, hydronic heating systems, aquaponics and vegetable production. They are collecting data using sophisticated sensors, data loggers and computer software to measure air and water temperature, light intensity, humidity and carbon dioxide levels to evaluate system efficiency and energy savings among different greenhouse/high tunnel systems, such as hydronic heating, passive solar, heat gain from fish ponds and compost heating.
The second semester involves the students analyzing and interpreting the previous semester’s data. The students continue to collect data and observe trends so that they can test and optimize system components and crop production.
“This exercise gives students confidence with data collection and analysis,” Jadrnicek said. “The students interpret the results and evaluate trends in the data to develop new experiments for future semesters.”
The students are expected to participate in two subsequent semesters, or preferably three or four, so that they can gather enough data to write articles for professional publications. They also are expected to create a poster about their project and display it at the Clemson Focus on Creative Inquiry Poster Forum, as well as at meetings or conferences related to sustainable agriculture and greenhouse management.
Clemson students are building a compost heat-extraction system and learning how the system can be used to grow vegetables and freshwater prawn as part of a Creative Inquiry project.
This story was written by Denise Attaway, Clemson University.