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Report, 1993

Miljökonsekvensbeskrivning av termiska ogräsbekämpningsmetoder för hårdgjorda ytor : en jämförelse mellan flamning med gasol och frysning med flytande kväve och kolsyresnö

Larsson, Sigvard


In order to find non-chemical methods of controlling weeds on hard surfaces, the Department of Agricultural Engineering at the Swedish University of Agricultural Sciences at Alnarp has carried out trials to freeze weeds with liquid nitrogen and carbon dioxide snow. An environmental impact assessment has been carried out to investigate whether the environmental aspects motivate further studies of` this method. As a control alternative, flaming with liquefied petroleum gas has been chosen, because this is the established non-chemical method that freezing might be able to replace. Flaming has been compared to two different methods of freezing: one using liquid nitrogen and the other using carbon dioxide snow. Flaming has been carried out using conventional commercially available equipment, whereas a piece of simple trial equipment was used for freezing. The environmental impact assessment analyses the net surplus of carbon dioxide to the atmosphere, energy consumption in production, transport and use of the different methods. The difference between the consumption of LPG and freezing media is large for the same effect on weeds. For 1 m2 the consumption of LPG was 0,003 kg, the consumption of liquid nitrogen was 1,3 kg and 2,7 kg for carbon dioxide. The total energy consumption is much higher for freezing than for flaming. The net contribution of carbon dioxide to the atmosphere during the production phase and during use is greater for LPG than for the freezing media. This is on condition that the electricity used in production of freezing media is derived from hydroelectric power (H.E.P.) or nuclear power. However, since large quantities of freezing media are required, the carbon dioxide emissions during transport from the point of production to the point of use are decisive for whether freezing can be classified as "environment friendly". The environmental impact assessment shows that weed control by freezing is more environment friendly than flaming if the transport distance for liquid nitrogen does not exceed 100 km with diesel truck. The maximum transport distance for carbon dioxide is approximately 50 km. However, this is bearing in mind only the net emission of carbon dioxide to the atmosphere.


koldioxidutsläpp; transporter; miljökonsekvensanalys; miljökonsekvensbeskrivning; gasol; energiförbrukning

Published in

Rapport - Sveriges lantbruksuniversitet, Institutionen för lantbruksteknik
Publisher: Institutionen för lantbruksteknik, Sveriges lantbruksuniversitet

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