Environmental Impact of Bioethylene

Life cycle assessment (LCA) is one method within the broader field of environmental system analysis. Environmental system analysis is concerned with the assessment of technical systems, in a broad sense, with regard to their impact on the environment and 

The fermentation of biomass to ethanol and its subsequent use as a fuel has been investigated in numerous projects (e.g. Concawe/EUCAR 2007 and the BrewProject) [32, 33]. Different biomass feedstocks, e.g. wheat, sugar beet, wood and sfraw, have been taken into account in these studies. However, when comparing separate studies of the same raw material results vary between studies. Some possible reasons are variation in geographical scope, different alcohol contents (anhydrous or hydrous, if stated at all) under different methodological choices such as allocation and how the alternative use of the material for other purposes has been dealt with. 

Apart from its use as a fuel, biomass gains increasing interest as feedstock for the chemical indusfry. The Brew project in which different biomaterials were assessed focus towards their potential in that sector [33]. A special role is played by the integration into the production of plastics, for which bio-based ethanol and subsequently polyethylene presents one alternative. As already stated, ethanol can be obtained from different sources. However, it seems that all data in the literature on greenhouse gas emissions and energy use for fermentation of Brazilian sugar cane and subsequent refinement to ethanol are based on the reports of one single researcher [34]. This is of course a limitation for the LCA. 

As several of the processes ethylene from ethanol do not yet exist, at least not on an industrial scale, process simulation and other data for LCA need to be estimated to understand how ethylene from ethanol compares to a conventional ethylene from fossil route. For reasons of data availability today s LCAs will also probably have to be limited to certain impact categories, i.e. emissions of greenhouse gases and resource use (in terms of raw materials, land use, water use and energy use). For a complete LCA everything from extraction of resources to ultimate disposal must be included and well defined. 

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