Conversion of vine shoots into bioethanol and chemicals: Prospective LCA of biorefinery concept

Vine shoots are the viticulture residues generated in high quantities after the grapevine pruning. They are lignocellulosic material poorly exploited as feedstock. These wastes are often dumped in the agriculture fields or burnt. Due to their availability and relatively low price, vine shoots are considered as potential feedstock for biochemical conversion into value-added products. In this work, two biorefinery scenarios using vine shoots as feedstock to co-produce chemicals are assessed from an environmental point of view: production of lactic acid, and co-production of lactic acid and furfural. A CHP area was considered to be annexed to the plants to produce heat and electricity for internal use. The Aspen Plus and SimaPro commercial software were used to perform the LCA of the selected scenarios. The assessed scenarios demonstrate significant reductions in climate change, fossil fuel depletion, freshwater ecotoxicity and eutrophication and human toxicity impacts compared to their counterfactual systems.

Transition of a South African sugar mill towards a biorefinery. A feasibility assessment

Edgard Gnansounou, Jegannathan Kenthorai Raman, Elia Mercedes Ruiz Pachon, Pavel Vaskan

The survival of the sugar industry in South Africa is under threat due to an unstable and low sugar price, high production cost and old infrastructure. At present, coal and sugarcane bagasse are used as fuels in an inefficient boiler to generate the heat and electricity required by the plant. Moreover, the residues produced during the sugarcane agriculture stage are burnt in the field causing serious concerns in the nearby rural areas. The progress in the conversion of lignocellulosic residues to valuable chemicals in the South African sugar mills would bring benefits in sustainability and both rural and industrial economic development. Sugarcane bagasse and green harvesting residues are the largest lignocellulosic wastes in the production of sugar from sugar cane. They are seen as promising feedstock to improve the long-term sustainability of the local sugar mill. Integrated biorefinery-sugar mill scenarios using sugarcane harvesting residues, bagasse and molasses as feedstock to co-produce chemicals and electricity are evaluated in this work for the first time. The integration of plants was designed in a way to provide both economic and environmental benefits. The following lignocellulOse biorefineries were simulated in Aspen Plus V8.8: (SM LE) Co-production of sugar and lactic acid, and (SM LF) co-production of sugar, lactic acid, and furfural. Surplus power was produced in both scenarios for export. Both scenarios were simulated based on literature and experiment data presented in this work. Experiments were conducted on the bagasse pretreatment using dilute acid, and the conversion of hemicellulose into furfural product. The results of techno-economic assessment showed that both scenarios are economically feasible under the considered conditions and provide strong economic benefits in comparison with an existing sugar mill. Among the biorefinery scenarios, the SM LF scenario has better economic performance than SM LE. In terms of environmental assessment, both scenarios demonstrate a significant reduction in climate change, fossil fuel depletion, freshwater ecotoxicity and eutrophication and human toxicity impacts in the South African context. In a nutshell, biorefineries demonstrate potential to be a feasible and more sustainable alternative to the existing sugar mills in the South African context.

ELSEVIER SCI LTD2018

Life Cycle Assessment of Vetiver-Based Biorefinery With Production of Bioethanol and Furfural

Edgard Gnansounou, Jegannathan Kenthorai Raman

Lignocellulosic biomass feedstocks are considered as one of the major alternative for fossil and food based transport fuel and chemicals for the reasons such as fuel/food security, depleting fossil reserves, climate change, mitigate pollution in agriculture and rural socio-economic development. In highly populated and agriculture based countries such as India, the conventional lignocellulosic feedstock such as rice straw and wheat straw are a major source for animal feed and hence non-conventional feedstock that could be cultivated in waste land has to be explored to fulfill the lignocellulosic feedstock supply in the coming years. In this context, this study deals with life cycle assessment of vetiver, a non-conventional lignocellulosic feedstock for bioethanol and biochemical production in India. A prospective LCA was performed to compare the environmental impacts of vetiver based biorefinery system with conventional system. The results reveal that the carbon dioxide and fossil oil consumption could be reduced by 145% and 77% respectively in case of bioethanol production, and 30% and 12% respectively in case of bioethanol and furfural production compared to its reference system. The sensitive analysis indicates that using vetiver biomass a source of energy in biorefinery plant further reduces the carbon dioxide emission and fossil oil consumption significantly by 100% and 60% compared to the coal used for process energy requirement in vetiver biorefinery.

Elsevier2017

Life cycle assessment of SNG from wood for heating, electricity, and transportation

Christian Ludwig, Bernhard Steubing

The conversion of wood to synthetic natural gas (SNG) via gasification and catalytic methanation is a renewable close to commercialization technology that could substitute fossil fuels and alleviate global warming. In order to assure that it is beneficial from the environmental perspective, a cradle to grave life cycle assessment (LCA) of SNG from a first-of-its-kind polygeneration unit for heating, electricity generation, and transportation was conducted. These SNG systems were compared to fossil and conventional wood reference systems and environmental benefits from their substitution evaluated. Finally, we conduct sensitivity analysis for expected technological improvements and factors that could decrease environmental performance.

Elsevier2011

Transition of a South African sugar mill towards a biorefinery. A feasibility assessment

Edgard Gnansounou, Jegannathan Kenthorai Raman, Elia Mercedes Ruiz Pachon, Pavel Vaskan

ELSEVIER SCI LTD2018