Greenhouse agriculture enables food production across climate regions and seasons but consumes a substantial amount of energy for heating, cooling and supplemental lighting. The ultimate goal of this project is to make greenhouses energy neutral. Recognizing plants only use a narrow range of wavelength from the light spectrum for photosynthesis and growth, the PIs will develop semi-transparent organic solar panels to harvest the solar energy from the under-utilized spectrum that is not required for plant growth; another goal is to breed crop varieties that perform optimally under these conditions. The Solar Powered INtegrated Greenhouse (SPRING) systems can be self-sufficient in energy, while recycling water and fertilizer for environmentally sustainable food production. This project will include a number of K-12 outreach activities, K-12 summer camps that consider both energy and agriculture, and research experiences for high school and community college teachers that will translate research at the intersection of food, energy, and water to their curricular activities.
The PIs will develop energy-neutral greenhouses by integrating semitransparent solar power modules for energy production, plant selection and management for food production, and closed-loop greenhouse design for water and nutrient conservation. To achieve the self-sufficient SPRING system, the following interrelated research tasks will be undertaken: (i) synthesize and characterize polymer semiconductors with tuned absorption spectra, (ii) design semitransparent solar modules that incorporate the polymer semiconductors to achieve high power conversion efficiency and tuned optical characteristics, (iii) process large area solar modules for incorporation in growth chamber model systems, (iv) select and evaluate plants under modified spectrum lighting, (v) design the greenhouse structure including thermal balance, photovoltaic integration, and lighting, and (vi) conduct detailed life cycle assessment to estimate the economic and environmental impacts of the SPRING system. In organic solar power development, intellectual merit is found in synthesis of novel organic semiconductor compounds with tuned absorption spectra and high efficiency when integrated into a solar cell. Additionally, advances will be made in semi-transparent solar cell design to achieve tuned transmission and in the development of scalable solar module manufacturing methods. In plant production, new insights into the genetic basis for adaptation and responses to modified light spectra and nutritional characteristics of vegetable produce will be developed along with new insight into water and nitrate/phosphate use efficiencies in recycled hydroponic systems. At the SPRING system level, key elements are design of the combined system for optimal plant growth, renewable power generation, and thermal load balance assessment and design. New tools will be developed that are able to perform the multivariate optimization of the systems for various climates, food production schemes, and greenhouse structures. If successful, this project will significantly advance controlled environment agriculture, providing the means to significantly increase food productivity, while reducing water consumption, lowering fossil fuel consumption, and providing increased food and water security with lower environmental impact.