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Abstract(s)
Este trabalho teve como objetivo avaliar e comparar os impactes ambientais da produção do
butanol considerando três processos produtivos: um que usa fontes fósseis e dois que usam
fontes renováveis, nomeadamente palha de trigo e milho. Para o primeiro caso considerouse
o processo oxo e os restantes usaram o processo de produção ABE (acetona, butanol e
etanol).
Na primeira etapa estudaram-se e descreveram-se os diferentes processos referidos. A
análise do ciclo de vida foi depois aplicada efetuando as quatro fases nomeadamente
definição do âmbito e objetivo, inventário, avaliação de impactes e interpretação dos
resultados obtidos. O inventário foi efetuado tendo em conta a bibliografia existente sobre
estes processos e com o auxílio da base de dados Ecoinvent Versão3 Database™. Na
avaliação de impactes utilizou-se o método Impact 2002 + (Endpoint). Concluiu-se que a
produção do butanol pelo processo ABE utilizando o milho é a que apresenta maior impacte
ambiental e a que produção do butanol pelo processo ABE usando a palha de trigo é a que
apresenta um menor impacte ambiental, quando o processo de alocação foi efetuado tendo
em conta as massas de todos os produtos produzidos em cada processo.
Foi efetuada uma análise de sensibilidade para a produção de butanol usando palha de trigo
e milho relativa aos dados de menor qualidade. No processo da palha de trigo fez-se variar
a quantidade de material enviado para a digestão anaeróbia e a quantidade de efluente
produzida. No processo relativo ao milho apenas se fez variar a quantidade de efluente
produzida. As variações tiveram um efeito pouco significativo (<1,3%) no impacte global.
Por fim, efetuou-se o cálculo dos impactes considerando uma alocação económica que foi
executada tendo em conta os preços de venda para o ano 2013 na Europa, para os produtos
produzidos pelos diferentes processos. Considerando o valor económico verificou-se um
aumento do peso relativo ao butanol, o que fez aumentar significativamente o impacte
ambiental. Isto deve-se em grande parte ao baixo valor económico dos gases formados nos
processos de fermentação. Se na alocação por massa for retirada a massa destes gases os
resultados obtidos são similares nos dois tipos de alocação.
The goal of this work was to analyse and compare the environmental impact of three production methods of butanol. One of them using fossil fuels and the other two using renewable sources such as wheat straw and corn. The first one uses the oxo synthesis and the others use ABE (acetone, butanol and ethanol) fermentation. First of all, the mentioned processes were studied and described. Then, the life cycle analysis was applied involving four steps: goal and scope definition, inventory analysis, impact assessment and interpretation. The inventory analysis was executed attending to existing studies regarding each process and the Ecoinvent version3 Database. To assess the impacts it was used the Impact 2002+ (endpoint) method. It was possible to conclude that the ABE fermentation using corn presents the highest environmental impactand the ABE fermentation using wheat straw is the one that presents the lowest environmental impact, when the allocation method was based on mass. A sensitivity analysis was performed for the production of butanol using wheat straw and corn for the lower quality data. In the process using wheat straw it was analysed the variation of the material's amount sent for the anaerobic digestion and the amount of wastewater produced. In the process using corn it was analysed the variation of the amount of wastewater produced. The variations had no meaningful effect in the global impact (<1,3%). Finally the impacts were assessed using an allocation method based on the economic value of the products considering the selling prices for 2013 in Europe, for the products produced in the different processes. Considering the economic value, the relative weight of butanol raised which increased considerably the environmental impact value. This is due to the low economic value of the gases formed in the fermentation process. If the mass of these gases is not considered in the mass allocation method, the results obtained are similar in the two types of allocation.
The goal of this work was to analyse and compare the environmental impact of three production methods of butanol. One of them using fossil fuels and the other two using renewable sources such as wheat straw and corn. The first one uses the oxo synthesis and the others use ABE (acetone, butanol and ethanol) fermentation. First of all, the mentioned processes were studied and described. Then, the life cycle analysis was applied involving four steps: goal and scope definition, inventory analysis, impact assessment and interpretation. The inventory analysis was executed attending to existing studies regarding each process and the Ecoinvent version3 Database. To assess the impacts it was used the Impact 2002+ (endpoint) method. It was possible to conclude that the ABE fermentation using corn presents the highest environmental impactand the ABE fermentation using wheat straw is the one that presents the lowest environmental impact, when the allocation method was based on mass. A sensitivity analysis was performed for the production of butanol using wheat straw and corn for the lower quality data. In the process using wheat straw it was analysed the variation of the material's amount sent for the anaerobic digestion and the amount of wastewater produced. In the process using corn it was analysed the variation of the amount of wastewater produced. The variations had no meaningful effect in the global impact (<1,3%). Finally the impacts were assessed using an allocation method based on the economic value of the products considering the selling prices for 2013 in Europe, for the products produced in the different processes. Considering the economic value, the relative weight of butanol raised which increased considerably the environmental impact value. This is due to the low economic value of the gases formed in the fermentation process. If the mass of these gases is not considered in the mass allocation method, the results obtained are similar in the two types of allocation.
Description
Keywords
ABE Butanol Análise do ciclo de vida Alocação económica Análise de sensibilidade Biocombustíveis Life cycle assessment Sensitivity Analysis Market Value Biofuels