Identifying potential applications for residual biomass from urban agriculture through eco-ideation: Tomato stems from rooftop greenhouses

Considering that urban agriculture (UA) is currently on the rise due to its multiple benefits in addition to environmental ones, it would also be necessary to foresee the flow of solid waste it generates, which if not properly managed or used, could become a new waste problem within the cities. The main objective of this study is to take advantage of agro-urban solid waste (AUSW) from the perspective of Circular economy (CE) in order to, in addition to reducing the volume of AUSW within cities, to close the life cycle of UA allowing to continue with its multiple benefits. Starting from a previous study on the classification and quantification of the AUSW generated in rooftop greenhouse (RTG) tomato crop, where it was determined that the waste with the greatest potential for use was tomato stems, in this study a methodology is proposed that part of the eco-design to take advantage of the tomato stems adding value (upcycling) through the approach of “do-it-yourself” (DIY) for local use. First, the physical, chemical and mechanical characterization of the tomato stems was carried out and the materials with similar properties were identified using Ashby graphs. Afterwards, a creative session was held where specialists in order to identify possible applications of the stems through group techniques for the generation of ideas and the evaluation of concepts. Finally, tests were carried out with the material and a semi-quantitative evaluation of the resulting concepts was carried out using an eco-design metric. The resulting concepts were “Fences and trellises”, “Packaging” and “Boards, panels and blocks". In addition to the results obtained on the possible applications of the stems in situ, this study provides data on the characterization of the stems of tomato plants that could also be used for the use of biomass in other contexts and scales such as conventional agriculture.