During the past five to six years, faculty and students at Appalachian State University have researched and developed different technologies to help local farmers extend their crop’s growing season.
The research project — named Nexus — is located at the Watauga County Landfill at 591 Landfill Road in Boone. The site at the landfill is used as a biomass and renewable energy testing location, according to Ok-Youn Yu — an associate professor and assistant chair of the Sustainable Technology and the Built Environment Department at App State.
Yu said the greenhouse space was available but unused for several years. Around 2013-14, faculty and students started using the space to conduct research. Nexus is a collaboration between the Sustainable Technology and the Built Environment Department and the Appalachian Energy Center.
Yu explained that the Nexus project aims to develop affordable technology to help farmers extend a growing season, which could mean more access to local food, an increase in income for farmers and less need to bring in products from outside the area, which could decrease the emissions by delivery trucks.
The research students and faculty have conducted so far centers around various heating technologies for greenhouses. Different technologies have been created at the Nexus site, including a small scale pyrolysis system, solar thermal heating system, compost heating system, an anaerobic digestion system and aquaponics, according to the university.
One of the technologies Nexus participants created was a 1,500-gallon water storage tank that they called a “thermal battery.” The heat would increase the water temperature in the thermal battery and it would radiate heat to the greenhouse.
This takes place after biomass materials are placed into a heat chamber and warmed up by firewood, thus creating the heat that flows into the thermal battery. Biomass can be items such as waste wood chips, sorghum waste, animal bone and switch grass.
Yu said those in the project have also been working on growing biomass crops that can be used to make bioenergy fuel. A bioenergy crop example Yu gave was arundo donax — a reed-type plant. He said plants used for bioenergy are often fast growing and found in warmer areas. However, the project has had luck growing bioenergy plants in Boone even with the higher elevation.
Next the group created a root zone heating concept, which includes tubing installed underneath benches that crops sit on in a greenhouse. Heated water is distributed through the pipes from the thermal battery, and it circulates through the tubes to heat the roots. The team upgraded this system last year to incorporate covers over the benches to trap the heat around the plants to keep it from escaping.
According to the university, root zone heating usually allows the operator to have a lower nighttime setting temperature by 5 to 10 degrees, which can result in an overall energy cost savings.
Several years ago the program received grant funding to be able to take their equipment from the testing site to local farms. Since then, Nexus has partnered with Against the Grain farm in Zionville and Springhouse Farm in Vilas. The team worked with the farmers individually to see what specific technologies would be best for their farms, since Against the Grain used an air-tight passive greenhouse and Springhouse Farm used a conventional hoop greenhouse.
According to Yu, the owner of the Springhouse Farm had a 50 percent cost savings in 2018 compared to using propane to heat the greenhouse in 2017. Once the Nexus team added the root zone heating covers, Yu said this added additional savings as well.
For Against The Grain farm, Nexus researchers noticed that when the root zone heating system was running, the air temperature inside the vertical rack holding the crops exceeded greenhouse air temperature by as much as 15 degrees, Yu said.
During summer, farmers do not need to heat up the greenhouse. The Nexus technologies are then converted for use by a food dehydrator. Heat from the biochar kiln — while it makes biochar — and a solar thermal collector can be diverted through a heat exchanger to circulate through the food dehydrator. A valve can determine if the heat is used for the food dehydrator during the summer and the thermal battery during the winter.
Additionally, those with Nexus have worked to create biochar — a byproduct after biomass materials are put into a heated kiln. Biochar is a charcoal-type product that can be used as a soil amendment that is said to have benefits such as improved soil fertility. Nexus received a $98,599 grant from the North Carolina Department of Agriculture and Consumer Sciences in 2018 to study the effects of biochar combined with anaerobic digestion on crop growth.
Last year, with grant funding Nexus brought on another partner — Heritage Homestead Farm in Crumpler — to create a bio-digester to convert organic waste into cooking fuel and fertilizer. The digester uses manure and cheese production whey from the farm to create energy to run a stove or other items. In the next year Yu said Nexus may try to reach out to Ashe County Cheese to potentially partner to make a bigger scale digester.
Nexus currently consists of four App State faculty members, one staff member from the university’s Appalachian Energy Center, five graduate students and four undergraduate students. Over the years, 17 graduate and 18 undergraduate students have actively participated with the project since 2014.
Looking to the future, Yu said students are eager to dig into research about greenhouse lighting and cooling systems. With crop covers, Yu said plants could benefit from supplemental lighting, and research would look at what color and intensity of light is best for each phase of growing the crops. As for cooling, Yu said the inside of a greenhouse can get up to 120 degrees during the summer, and cooling technology could be helpful for farmers.
Nexus’ work and its farm partnerships have been grant funded with some university support as well as labor by students and staff. Nexus would be interested in bringing on more partners, but farmers may have to be willing to pay for the technology or be willing to give labor.
Yu said there isn’t a simple answer regarding the cost of what these technologies may cost, due to variations existing infrastructure, which technologies would be installed and labor needed. For questions regarding cost, contact the Appalachian Energy Center at (828) 262-7289.