Grantee Research Project Results
2016 Progress Report: Biomass Greenhouse-heating systems to extend growing seasons for resource-limited farmers
EPA Grant Number: SU835939Title: Biomass Greenhouse-heating systems to extend growing seasons for resource-limited farmers
Investigators: Yu, Ok-Youn
Current Investigators: Yu, Ok-Youn , Domermuth, David , Houser, James , Farrell, Jeremy , Arnold, Alex , Davis, Chelsea , Franco, Pedro , Neff, Eric , Schoonover, Christopher , Smith, Alan , Sanborn, Jared , Febos, Barry , Atkinson, Mason , Mull, Henry , Linck, Jon , Miller, Gordon , Wells, Aaron , Holder, Jordan , Phillips, Jay , Anderson, Nathan , Beshears, Tyler , Joyner, Joshua , Roden, Elizabeth , Batzko, Gabbie , White, Harrison , Toy, Jamen , Houpe, Christian , Holmes, Anna Marie , O’Neal, Johnny , Bradshaw, Aaron , Gaines, Rachel , Gaines, Rachel , Cyzman, Amy , O’Neal, Johnny , Bradshaw, Aaron , Cyzman, Amy
Institution: Appalachian State University
EPA Project Officer: Page, Angela
Phase: II
Project Period: October 1, 2015 through September 30, 2017 (Extended to August 31, 2019)
Project Period Covered by this Report: October 1, 2015 through September 30,2016
Project Amount: $74,555
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet - Phase 2 (2015) Recipients Lists
Research Category: Sustainable and Healthy Communities , P3 Awards , Pollution Prevention/Sustainable Development , P3 Challenge Area - Air Quality
Objective:
Description and Objective of Research: The purpose of the Appalachian State University Nexus Project is to develop greenhouse heating technologies that provide affordable means to improve the food-growing capacities and standard of living for farmer communities in rural Appalachia while eliminating the use of fossil fuels. The student-led initiative seeks to engage both university students and the greater community in educational opportunities that will ultimately promote greater environmental awareness and economic self-sufficiency throughout the region. The Department of Sustainable Technology and the Built Environment at Appalachian State University (ASU) in Boone, NC has built a 20 feet by 30 feet greenhouse, a bio-volatilization (BV) system, and an anaerobic digestion (AD) system. This ready-to-test site called “Nexus” is located at the Watauga County Landfill, in Boone, NC. BV and AD systems already existing at Nexus have been integrated into the research as sources of biomass energy. In addition, a compost heating and a solar thermal systems have been built with funds from the Phase I grant. Therefore, our biomass greenhouse heating system involves AD, BV, compost, and solar energy sources, utilizing all of the feedstocks typically available on a small farm. AD and compost generate energy from readily digestible materials and the BV system handles relatively indigestible biomass, such as wood scrap. Phase II of the P3 award allows us to advance the technologies we have developed in Phase I to a point that full technology transfer is possible. Our multi-disciplinary team will address three critical objectives that, once met, will allow the technology to be feasibly transferred to area farmers: 1) Complete integration of heating, storage, and delivery systems; 2) Development of an innovative, appropriate-scale cleaning and storage system for on-demand use of farm gasses; and 3) Outreach to farmers to assess needs and determine new greenhouse production capacities.
Progress Summary:
The on-going work of building out the integrated heating systems as well as general improvements to the research space have been made during this reporting period.
Greenhouse: The bottom three feet of the greenhouse sides open and close for ventilation during warm sunny days and during the summer season. A pulley and rope system was installed for ease of performing this duty which in the shoulder seasons, can be daily. In preparation for winter and lower average temperatures an internal layer of 3.5mm polyethylene sheeting was installed. This additional plastic sheet creates an insulating air layer while only reducing the thermal gain by 9%. The head houses (framed structures on the east and west side of the hoop house) were insulated with 2” foam board to mitigate freezing temperatures and provide a thermal break to those sides of the greenhouse. The north side of the greenhouse has been insulated with an R6.13 reflective foil (Reflectix). This radiant barrier will reduce heat loss from the greenhouse’s north side, up to the center line of the greenhouse, which does not provide any thermal energy during the winter months due to the low sun angle, 30 degrees at its lowest altitude angle on the winter solstice. Finally, improvements to the greenhouse include adding framing around the aquaponics raised beds, widening walkways, and applying EPDM rubber on walkways to act as a durable work surface.
Thermal Battery: The 1,500 gallon tank acts as our heat storage for the entire greenhouse. Modular lids, 4’x4’, were constructed this fall with 2” foam insulation (R-10) and treated plywood tops. Metal bands tying the long sides of the tank were also added for structural reinforcement since the lids were made to be removable to access the hot water piping. The lid of the thermal battery is at working height and will serve as an area to start and grow plants.
Heating Systems: Several heating systems were built out or improved over the reporting period in preparation for the winter heating season. An evacuated tube solar thermal collector (30 tubes at 6’ length) was previously installed on the east head house as a drainback style system. The collector had been leaking close to the header and the cause was investigated. The leak was found at the junction between the metric header (13/16” outer diameter) and the standard US ¾” type m copper pipe (7/8” outer diameter). The joint was remade with silver solder and has been holding. The solar thermal system is direct, meaning that is uses water directly from the thermal battery. This solar system alone is capable of adding over 10,000 BTUs/day to the greenhouse envelope. A secondary heating system, wood stove with firebox heat exchanger and flu wrap-around heat exchanger, was up-fitted this fall and piped to the thermal battery. Initial observations (4 gallon per minute flow rate and temperature delta of 30F) show a heating capacity exceeding 50,000 BTUs/hr. Finally a propane water (36,000 BTUs/hr) heater with 120 gallon propane fuel tank were added and the water heater was plumbed into the thermal battery for periods of cold cloudy weather when personnel is not available to maintain a wood fire.
Aquaponics System: In order to maximize the utilization of limited greenhouse space, increase farmers’ income, and diversify available local foods, we designed an aquaponics system and built it inside of our greenhouse. Heated water from the thermal battery has been circulated to the pond to keep the right temperature range for fish. The pond also acts as a thermal storage, and holds/distributes heat to the greenhouse. There are three tables for hydroponics over the pond. Air start syphon circulates the water between the pond and the hydroponics. The water with excretions from the pond has been cleaned by feeding it to the plants in the hydroponics.
Controls and Data Logging: We are continuing our work to automate, monitor, and log data to hone our model of energy inputs necessary to maintain this type of hoop greenhouse in our climate. At present the solar thermal and wood stove heating systems are controlled by a Caleffi iSolar plus differential controller. This programmable controller monitors the following temperatures: thermal battery, solar collector, and wood stove heat exchanger. It controls two relays to switch two pumps on when the logic is met. Our goal is to maintain the thermal battery above 80F throughout the winter. To control the propane water heater pumping loop, an Arduino was programmed to act to turn the pump on when the thermal battery is below 80F and turn the pump off when the temperature is about 84F. The Arduino acts as an aquastat and is a very affordable controller that our research team can reprogram depending on desirable conditions. The final pump to control is the circulator between the thermal battery and the aquaponics pond. An Arduino controller will be built and programmed to operate this pump over the winter. Our research team has set-up data logging for the following: greenhouse and ambient air temperatures and relative humidity, thermal battery temperature (in 4 places to see stratification), aquaponics pond and raise grow bed temperatures. These data will be logged for the entire winter season to inform our thermal envelope model of the greenhouse.
Nexus open house: The Appalachian State University (ASU) biomass energy project team (i.e., Nexus team) and Appalachian Energy Center hosted an open house for a biomass heated greenhouse project on Oct. 21, 2015. It was part of the third annual National Bioenergy Day event, and the first-ever open house of the project. We were pleased to have more than 70 people attend including sponsors, ASU staff and students, farms and organizations from the local area as well as other areas. The guided site tours provided an opportunity to learn about on-farm biomass energy and its benefits. The event was a great success and fulfilled its role to introduce the biomass energy research to the community and promote interest in the project. We gathered valuable feedback from the extension and local farmers, which will influence future research. We look forward to participating in this annual event to engage with our community and share the progress of the bioenergy research.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 11 publications | 1 publications in selected types | All 1 journal articles |
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Type | Citation | ||
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Yu O-Y, Harper M, Hoepfl M, Domermuth D. Characterization of biochar and its effects on the water holding capacity of loamy sand soil: comparison of hemlock biochar and switchblade grass biochar characteristics. Environmental Progress and Sustainable Energy 2017;36(5):1474-1479. |
SU835939 (2016) SU835939 (2017) SU835939 (Final) |
Exit Exit |
Progress and Final Reports:
Original AbstractP3 Phase I:
Biomass Greenhouse-Heating Systems to Extend Growing Seasons for Resource-Limited Farmers | Final ReportThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.