LEI Sector enOndernemerschap, Wageningen UR Glastuinbouw, Wageningen UR Glastuinbouw
This environmental impact assessment of the current situation of Dutch tomato production in a Venlo greenhouse in a temperate climate was developed as part of the EUPHOROS project. The project aims to develop a more sustainable greenhouse system with a reduction of external inputs yet with high productivity and an efficient use of resources. The environmental impact analysis was based on using the Life Cycle Assessment (LCA) methodology as defined by the ISO 14040. The crop production system was structured in several stages and processes to facilitate the study and interpretation of results. The stages considered were structure, auxiliary equipment, climate control system, fertilizers, pesticides and waste. The main results and issues to be improved are described and presented in this paper. The use of a cogeneration system (CHP) and the consequent production of electricity create a methodological question on how to handle allocation between products. This paper shows two different methods for dealing with co-production: considering electricity as an avoided product and energy allocation at CHP. Depending on the approach considered values can range between 12 to 31 MJ/kg of tomato or 0.78 to 2.0 kg CO2 eq/kg of tomato for instance. Climate control system had a high energy demand with major contributions to all the impact categories (81.1 to 96.1% of the total) and the rockwool substrate accounted for 57.0 to 81.7% of the auxiliary equipment contribution. More effort should be made to recycle rockwool and reduce the high energy demand associated with the expansion of the mineral in the manufacturing processes. The structure was a major burden due to the high amount of steel and glass. Energy environmental impacts could be reduced, because of the avoided electricity production by the power plant, by using a combined heat and power plant to meet greenhouse electricity demands, resulting in a surplus which could be delivered to the public grid. Further research should also be oriented to developing efficient technologies to improve the intensive use of materials and energy.