Miljöpåverkansbedömning vid tillverkning av etanol från cellulosabaserade råvaror
ekologisk gård självförsörjande med drivmedel
Fuel produced from renewable resources is of big interest. In this project the difference between a few different renewable materials are compared on the matter of environmental load when ethanol is produced. The renewable materials that are compared are Salix, straw and reed canary-grass (rörflen). The cellulose in the material is cut down to small pieces and then hydrolysed so that the sugar from the cellulose can be fermented into ethanol.
Tha amount of ethanols that is studied in this work is the smount of ethanol needed to cultivate 1000 ha. The functional unit in the report is 1000 ha. All the regulas crops and the crops for ethanolproduction in the system are organically cultivated.
The goal for this study is to compare the final environmental load for the whole system of ethanol production, cultivation and usage of the ethanol in the end. This is assessed by calculation of global warming potential (GWP), acidification potential (AP) and eutrophfication potential (EP).
The impact of GWP is dependant of the amount of CO2, CH4 and N2=. The fuel that are used for cultivation is based on ethanol with addition of some ignition improver of fossil origin. Since ethanol is produced from renewable sources the impact of GWP is small despite the ignition improver. The emissions from soil have the largest impact on GWP.
The two sources that have the largest impact on AP is emissions from soil and the emissions from the steamproduction. Steam is needed during the ethanol production process.
The emissions from the soil have the largest impact on EP. More than 90 percent of the total EP comes from the soil emissions.
A comparison of the three different systems shows that the system with straw has the lowest environmental load.