Hybrid, energy-efficient farming by combined greenhouse and vertical growth

Hybrid, energy-efficient farming by combined greenhouse and vertical growth (HybriGrowth) HybriGrowth is a collaborative research project between SINTEF (SINTEF Energi, SINTEF Ocean and SINTEF Industry), two greenhouse companies (Viken and Snarum Gartneri), and the Norwegian Growers Association (Gartnerforbundet). The overall aim of the project is to develop and explore the potential for a novel hybrid, energy-efficient greenhouse concept that combines vertical and traditional greenhouse farming. Vertical production systems have already been installed at the two greenhouses and are used in conjunction with traditional greenhouse facilities. In this hybrid concept, young plants initially grow in the vertical systems for a few weeks before they are being transferred to traditional greenhouses for the main growth and final stage. This allows the plants to grow in a consistent and controlled environment during their early and most vulnerable stage, while the traditional greenhouse provides better access to light, nutrients, and CO2 during the main growth phase. These hybrid greenhouses are unique in Norway, and the concept has only been tested to a limited extent internationally, with a demo center in China and a company in the USA focused on decentralized lettuce production as the only known examples. Viken and Snarum Gartneri serve as in-depth case studies in the project. A significant challenge is the considerable heat generated by the LED lights in the vertical growth systems, which requires efficient cooling to maintain optimal growing conditions. Additionally, it is crucial to make good use of this surplus heat in a balanced manner so that it does not go to waste. Operational data from the hybrid greenhouses are now being modeled to maximize the use of surplus heat for heating the adjacent traditional greenhouses. This will optimize operations, reduce energy consumption, and cut CO2 emissions by minimizing the use of fossil fuels (propane) for heating. Systems with integrated heat pumps are also being studied, along with the possibility of thermal energy storage to balance the energy consumption in the hybrid greenhouses. The goal is to demonstrate a sustainable concept for increased productivity and profitability in Norwegian greenhouses through energy-efficient operations and optimized growth conditions. So far, the project has identified the need for additional data for modeling and simulation. Flow meters for water pipes and power meters for electricity consumption have been installed at Viken Gartneri, and data are being logged to provide input for modeling and simulation of the energy system. Efforts are also underway to collect other technical data for model simulations. A literature review on greenhouse lighting, focusing on indoor vertical green production, has uncovered opportunities for new lighting solutions that have the potential to significantly reduce energy consumption. A simulation study using the IDA ICE software has evaluated the amount of surplus heat from the vertical system. The results were presented at the European Horticulture Congress in Bucharest in May 2024 with the presentation "Surplus heat generated from vertical greenhouse lighting." The study showed that around 2.1 MWh of heat could be extracted from the 600 m² vertical system per day during a period in January 2024. The project has also obtained visibility through several presentations and a blog post on SINTEF's website titled: Horizontal vs. Vertical Greenhouse Growing – or a Hybrid Combination?

At Viken and Snarum greenhouses, vertical farming systems have already been installed in combination with their traditional greenhouse facilities. The hybrid farming facilities are unique in Norway, and the concept has been tested and analysed to a limited degree around the world. In HybriGrowth, the Viken and Snarum facilities will act as in-depth case studies, and the potential of hybrid farming systems will be investigated in detail. The main challenge today is that the artificial growth lights in the vertical farming systems generate large amount of heat, which calls both for efficient cooling and an improved recovery of the surplus heat. In the project, operational data from the hybrid greenhouses will be modelled and analysed in detail to optimise the use of waste heat from the vertical section for heating of the adjacent traditional greenhouse. Specific measures will be applied for optimised operation and energy savings, in addition to a minimal carbon footprint by a reduced use of fossil fuels. Systems with use of integrated heat pumps will be studied, together with the feasibility of thermal energy storage to reduce the overall energy consumption in the greenhouses. The aim is to demonstrate a sustainable concept for increased productivity and profitability in Norwegian greenhouses by energy-efficient operation and optimised control of the indoor growth conditions.