Integrating Combined Heat and Power into Controlled Environment Agriculture

Controlled Environment Agriculture (CEA), while now only a minor source of food production, must play a larger role in a sustainable future in which critical natural resources—land, water and energy—are much more limited. CEA food production is expanding at a healthy rate driven by factors that include: (1) CEA has high per-acre crop yields that can be located close to the consumer providing almost immediate farm-to-table delivery, (2) CEA provides protection from animal and insect damage without the use of pesticides, and (3) CEA produces a high value crop, free from fungicides and herbicides with high nutritional content and genetic diversity that is often important to the consumer. Unfortunately, CEA grown crops can cost much more than field grown crops. The major reason for this difference is energy—CEA crops must pay for the energy to both drive photosynthesis and maintain a healthy, productive growing environment. The proposed technology will drive down the cost for CEA crops by making vertical farms more energy efficient. At the center of the proposed technology is a Combined Heat and Power (CHP) system. As its name implies, a CHP system supplies both electricity and thermal energy. One innovation of the proposed work is to use the recovered thermal energy from CHP to drive a liquid desiccant dehumidifier that maintains the grow room at a healthy, productive relative humidity. A second innovation is to cool, clean and dry a portion of the CHP engine’s exhaust so the CO2-rich gas can fertilize the grow room. And a third innovation is to again recover thermal energy but now use it to drive a distillation process that recycles up to 90% of the CEA facility’s wastewater. The innovations of the proposed technology will reduce energy use for CEA crops by 50%, thereby reducing growing costs and expanding the benefits of Controlled Environment Agriculture to a much broader segment of the population.