Environmental Assessment of Green Chemicals - LCA of Bio-Based Chemicals Produced Using Biocatalysis
Abstract: It is of at most importance that society reduces its impact on the environment. In the chemical industry the use of renewable resources will play a fundamental role in the transition to more sustainable chemical products. Also industrial biotechnology, i.e. the use of enzymes to convert raw material into valuable chemicals at low temperatures, leads to more sustainable processes. The research presented in this thesis has been carried out within the research programme “Greenchem - Speciality Chemicals from Renewable Resources”, which aims at developing a sustainable technology for chemical products, primarily through the use of renewable resources and the use of industrial biotechnology. The overall objective of the work presented in this thesis was to examine the environmental performance of these new, green chemicals. The method for evaluation was life cycle assessment (LCA), which means that the entire environmental impact throughout the life cycle of a product or process is investigated. The result of the LCAs presented in this thesis indicates that the implementation of renewable raw materials and biocatalytic production processes is promising from a sustainability point-of-view. However, several key parameters with a big impact on the overall environmental performance of the chemicals have been identified. For the cultivation of biomass used as raw material the key parameters identified are, the type of biomass cultivated, nitrous oxide emissions from fertiliser production, biogenic nitrous oxide emissions from soil, carbon dioxide emissions from the use of fossil fuels, and carbon dioxide emissions due to land use change. For the production process the key parameters identified are, yield, process energy demand and the source of the primary energy, solvent use, and toxicity. Also differences were identified for different types of chemicals. For bulk chemicals the production of raw material tends to have a significant impact on the overall environmental performance, and thus energy demand and the contribution to climate change and eutrophication are important. For fine chemicals and pharmaceuticals on the other hand, the contribution to the overall environmental impact originates mainly from the production process, and for these chemicals the key parameters identified for the production process are therefore often more important, as are the impact categories, energy use and toxicity. The key parameters and the methodological concerns presented can be used to facilitate LCAs of emerging technologies in the future. For the chemical industry the development of easy-to-use methods for evaluating different production options at an early stage have been identified as important. At an early-planning stage often numerous options are available and then an adapted method to decrease the number of options, still giving a reliable result, is required. The results presented in this thesis can be used to develop such a model based on the identified key parameters presented here.
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