Assessing the energy and environmental performance of vertical hydroponic farming

In this study, the sustainability of the vertical farming system at Grönska Stadsodling, hereafter referred to as Grönska, has been evaluated. Grönska is located in southern Stockholm and produces primarily basil in pots that are sold to retailers around the city using vertical-hydroponic techniques. The energy use and environmental impacts for the production of herbs (basil) were assessed using life cycle assessment (LCA) from a cradle-to-gate perspective

Summary

The global population is increasing rapidly, and the amount of people living in urban areas are expected to almost double within 30 years. With a rising population, the demand for food and pressure on arable land is also increasing. Currently, about 26 % of the greenhouse gases emitted from Sweden come from agricultural activities, and with an increasing population, it is essential to aim to reduce the emissions from food supply.

Vertical farming has seen increasing popularity as a way to reduce the need for arable land and grow crops where they are to be consumed. When farming indoors in a closed environment, the plants are protected from the weather, insects and pests. There are no leakages of nutrients in closed systems and the amount of water used is very limited in comparison to conventional farming. However, artificial lighting is needed in order for the crops to grow. Additionally, vertical farming is capital intensive and requires technical knowledge to be able to make use of the new techniques and equipment available.

In this study, the sustainability of the vertical farming system at Grönska Stadsodling, hereafter referred to as Grönska, has been evaluated. Grönska is located in southern Stockholm and produces primarily basil in pots that are sold to retailers around the city using vertical-hydroponic techniques. The energy use and environmental impacts for the production of herbs (basil) were assessed using life cycle assessment (LCA) from a cradle-to-gate perspective. This included the materials (e.g. soil, fertilizers) and energy consumption used for growing basil plants. The use (consumption), waste management and transportation to and from the company were not included in this study.

The results illustrated a large share of energy used for the manufacturing of gardening soil, which also resulted in the second largest environmental impact. The largest source of environmental impacts was the energy consumed for lighting, despite the use of LED lighting. There are possibilities to reduce these impacts by e.g. installing solar panels and optimizing the output of LEDs for the plant production. Furthermore, energy could be saved by changing the growing material, for something with less environmental impacts e.g. coir pith or by recycling the soil used. While extended transportation distances of food is one of the main arguments for urban agriculture, energy consumption and environmental impacts for transportation were found to be a minor part of the energy use and environmental impacts. Finally, the socio-economic implications of urban farming should be taken into account when reviewing sustainability aspects. This study only reviewed energy and environmental impacts, but the socio-economic benefits and resilience for the local community are important to highlight.

Coworkers: Michael Martin

Year: 2018.0

Report number: C299

Authors: Michael Martin, Elvira Molin

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