Performing Department
COOPERATIVE EXTENSION SERVICE
Non Technical Summary
The food-energy-water (FEW) nexus is central to sustainable development. Demand for all three is increasing, driven by rising global population (current 7 billion to ~9.5 billion by 2050), rapid urbanization (current 54% to 66% of global population by 2050), changing diets and economic growth. Agriculture is the largest consumer of freshwater resources and uses over 25% of the energy expended globally. Competing for underutilized spaces, food production, energy production and stormwater management threaten the future of agriculture sites. To advance the National Institute for Food and Agriculture (NIFA) programs and the Sustainable DC goals, UDC land-grant researchers are developing and testing innovative solutions to help maximize land use including the CAUSES's Food Hub Concept. Central to this is the recent construction of a fully integrated agricultural production system for research consisting of solar photovoltaic canopy and rainwater harvesting on a half-acre site of Firebird Farm. In this proposal, a multidisciplinary team specializing in agriculture, stormwater management, and renewable energy will quantify the efficacy of this novel system at Firebird Farm to better inform local urban farmers. High value specialty crops will be tested in protected micro-climates using solar energy to pump water for drip irrigation. Different solar angles have been tested with mixed results in other areas but are yet to be tested in this region. Furthermore, the concept of rainwater harvesting from a solar panel for food production has not been well researched anywhere. The objectives of the project are to a) quantify a closed loop (water & energy) urban farming system, b) develop FEW guidelines and recommendation for optimal solar angles for i) Food production ii) Energy harvesting and iii) Rainwater harvesting, and c) develop life-cycle cost (LCC). If feasible, this concept could be University trademarked and developed to supply food-energy-water nexus (FEW) for commercial use globally.
Animal Health Component
35%
Research Effort Categories
Basic
35%
Applied
35%
Developmental
30%
Goals / Objectives
Achieve food security and fight hunger.Improve and increase the production of goods and services from working lands while protecting natural resources and the environment.Mitigate climate change impacts.Ensure the development of human capital, communities, and a diverse workforce. The global population is growing (current 7 billion to ~9.5 billion by 2050) and increasingly lives in cities (current 54% to 66% of global population by 2050). In the US, 8% of the US population lacks access to fresh fruit and vegetables such as lettuce and strawberries (TRF, 2012; USDA, 2019). This nexus of food-energy-water (FEW) is central to sustainable development. Demand for all three is increasing, driven by a rising global population, rapid urbanization, changing diets and economic growth (Dimond, 2017). Agriculture is the largest consumer of the world's freshwater resources, and more than one-quarter of the energy used globally is expended on food production and supply.Agriculture generates 25% of CO2, 65% of methane, and 90% of nitrous oxide emissions (O'Hara 2015). Moreover, the food supply transportation produces 11% of US greenhouse gas emissions (Canning et al. 2010; O'Hara 2015). At the same time, on average, it requires 1 acre (about half the area of a Manhattan city block) to feed a family of 4, and more land to power it through solar panels. A typical community development of (1,000 homes) would require approximately 16 city blocks of solar to power it. There is not enough land to meet both the demands of agriculture and solar. Similarly, solar panels are being used on rooftops to power buildings, however, green roofs are helping to reduce the building stormwater footprints. In the coming decades, climate change is projected to increase weather variabilities such as low and erratic rainfall, increased storms and floods, and extreme temperatures. According to an USAID study by Carew-Reid et al. (2013), higher temperatures will affect yield in addition to increasing demand for more water for irrigation. In addition to growing heat- and drought-tolerant species and varieties, developing novel and integrated production systems that enable efficient use of resources is critical to mitigate the effects of climate change and to feed the growing global population. It is equally important to standardize the production system and techniques before introducing them to growers.The hypothesis of the project is that an economically and environmentally self-sustained as well as energy neutral/positive sustainable food production is feasible in urban environment through high value specialty crops production in protected micro-climates using solar energy to pump water for drip irrigation and collect water through rainwater harvesting. The findings of this study can be extended to peri-urban or rural areas where farmers are converting land to solar fields or for urban rooftop installations. This project aims to test, develop and standardize the proposed system to make recommendations and introduce it to urban farmers in DC and surrounding areas. Some questions we plan to address through this work are: What is the best economical value for peri urban and urban farms? Is food production viable along with solar production? And if so, what is the best solar angle to optimize production under the FEW system? What are the plant species suitable for growth under solar panels? What are the environmental impacts of water consumption as compared to traditional farming, and renewable energy production compared to non-farming locations? Within UDC's focus on Urban Agriculture and Urban Sustainability, the proposed research aims to address the NIFA programs of improving food security and mitigating climate change, and the Sustainable DC goals (see table below) of increasing green-economy jobs and small businesses and bringing locally grown food within a quarter mile of 75% of DC residents. The production system will be introduced to farmers and the general public in the community through the following specific outreach events: by conducting location visits to view standing crop as part of the academic and certificate courses conducted by the investigators; by standing crop demonstration during field-days and other UDC events and by developing and distributing fact sheets to stakeholders.While different solar angles have been tested with mixed results in other areas, it is yet to be tested in this region. Furthermore, to the best of our knowledge, the concept of rainwater harvesting from a solar panel for food production has not been well researched anywhere. Initially, a drip irrigation system will be employed, and the best specialty crop species will be optimized under these conditions. Thus, the objectives of the project are to a) develop a closed loop (water & energy) urban farming system to develop guidelines and planting recommendation for growing specialty crops under solar panels for the DC region, b) develop guidelines and recommendation for optimal solar angles for i) food production, ii) energy harvesting and iii) rainwater harvesting, and c) to develop life-cycle cost (LCC) assessment tool for such innovative system to assess economic benefit. If effective, this concept could be developed across the globe to supply food-energy-water (FEW) nexus and can be practiced commercially.
Project Methods
This project will test nine species of specialty crops per year (3 per season) with one variety of each of the 9 species tested per year. In the third year, we will pick the best of the species and varieties from the preceding two years and confirm the results. Three experimental replicates for each test variety/species will be grown in plots measuring 35' x 16' to study the integrated food, energy and water system. Three solar angles will be used to harvest solar energy while collecting rainwater for drip irrigation. Thus, in this project, high value specialty crops will be grown in protected micro-climates using solar energy to pump the harvested rainwater. The solar panels may also benefit crop production by cutting down the amount of high intensity light that falls on plants. This unique approach will also use the solar panel as a water catchment area during rainfall increasing the percentage of fresh rainwater collected which will be directly usable for irrigation. Initially, a drip irrigation system will be employed. Consequently, there are some unique approaches to this triple yield project: a) specific solar panel installation to generate energy for supplemental use and to collect water during rainfall, b) use of solar energy generated to pump the rainwater as well as to collect rainwater in cisterns for subsequent irrigation, c) efficient balance of water use for irrigation collected directly from solar panels during rainfall or through solar energy induced pumping, and d) superior growth of specialty crops in the presence of solar installation. A seasonal performance matrix will be developed for each crop, and sensor data will be utilized to resources optimization for energy, water and plant productivity. Furthermore, activities (e.g. food/crops grown, water used, cost of solar panel, amount of energy generated etc.) causing direct costs or benefits to the decision maker during the economic life of systems will be identified in quantifiable monetary units. An excel based modeling tool will be developed for LCC.There will be specific procedures followed in this study for measuring different parameters and to control the system performance and crop productivity which have been listed below:Crop Productivity-Plant biomass will be weighed at the end of each growing harvest for different types of crop per set of 3. Fertilizer inputs (as recommended for each crop under normal growth conditions) will be tracked and considered in relation to biomass and effluent water quality. 2 different varieties in year 1 and 2 and the best variety in year 3 of the project.Energy Production- Electrical sub meters will be installed on each array (3 pairs) to measure energy production and solar radiation. This will be used to quantify the energy production per angle during given environmental conditions.Waterinflow/outflow-The inflow and outflow will be measured continuously (5-15-minute time steps expected) throughout the proposed study period. Flow will be calculated using a pressure transducer/water level logger. The outflow measurements will also provide water consumption values which will be validated with the irrigation control box.Water Quality- Water grab samples of influent and effluent will be tested using standard laboratory methods and will be compared against irrigation water quality requirements. The parameters include total nitrogen, total phosphorus, trace metals, alkalinity, pH, and salts.Weather- Weather parameters will be continuously (5minute time steps expected) measured throughout the proposed study period with a weather station located on site. Weather parameters include rainfall, air temperature, relative humidity, solar radiation, wind speed, and wind direction. An existing weather station will be used for the project.Weather station - The project will re-use an existing Meter Environment.The weather station parameters include precipitation (tipping rain gauge), atmospheric pressure (kPa), relative humidity (RH), wind speed and direction (M/S), Solar Radiation (W/m2), air temperature (F), barometric pressure.Weather parameters will be continuously (5-15-minute time steps expected) measured throughout the study period with a weather station located on each site.Time Domain Reflectometers (TDRs)-will be used to measure soil moisture. TDRs will be used from previous research projects. The sensors capture relative soil moisture percentage in soils. Collectively with irrigation data, we will be able to assess Evapotranspiration (ET). (18) sensors will be buried approximately 3-4" deep. Each set will have (3) three sensors per an array (18) total sensor. The field placement will be decided through a random matrix.Hydros-21-Pressure Transducers - will continuously monitor water level in the cisterns of the system. This will be used to continuously assess water levels. Each solar array has an individual cistern that will require a PT (6) six total. The irrigation control box has water use calculations. The Hydros 21 will continuously collect electrical conductivity and temperature data. The data will help to quantify the relative water collected from each angle of solar panel.UDC Lab Samples - Weekly composite grab samples will be collected from six cisterns. The samples will be tested for nutrients and metals.10% of total experimental trays will be randomly sampled as field duplicates for each storm event. The samples will quantify potential water contamination from the solar panels. This includes atmospheric deposition. The project will use laboratory facilities at Firebird Farm for testing. This would include the potential for analysis of onsite E. coli sampling.The soil will be analyzed in the UDC soil lab for nutrients (N, P, K), organic content, and the potential to absorb macronutrients (cation exchange capacity, base saturation). These characteristics are unlikely to change rapidly; 500 grams of soil samples will be collected at the beginning and end of the growing season from each set.CS310-Quantum (PAR) Sensor -(20) -The quantum sensors will express the photosynthetically active radiation (PAR) or typical radiation under the solar canopy. The quantum sensors will be set on a stand slightly above the plant layer. Due to potential variations in sun light, sensors will be placed directionally across the full range ensuring (edges and middle). We anticipate having (3) sensors per pair (one array per set will have sensors). Two additional Quantum Par sensors are required to assess the control.