2nd Generation biofuels a sure bet? A life cycle assessment of how things could go wrong |
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| Authors: | Rethabile Melamu Harro von Blottnitz |
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| Institution: | 1. School of Engineering and Applied Sciences, Frederick University, 7, Y. Frederickou Str., 1036 Nicosia, Cyprus;2. Laboratory of Heat Transfer and Environmental Engineering, Aristotle University of Thessaloniki, P.O. Box 483, 54124 Thessaloniki, Greece;3. Department of Business Strategy and Technological Innovation, Marconi University, Rome, Italy;1. Departamento de Engenharia Mecânica (DEM), Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Rio de Janeiro, Rio de Janeiro 22453-900, Brazil;2. Departamento de Engenharia Química e de Materiais (DEQM), Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Rio de Janeiro, Rio de Janeiro 22453-900, Brazil;3. Peugeot Citroën do Brasil Automóveis Ltda., Porto Real, Rio de Janeiro 27570-000, Brazil;1. College of Mechanical Engineering, Guangxi University, University Road 100, Xixiangtang District, Nanning City, 530004, PR China;2. Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology, Guangxi University, Nanning, 530004, China;3. BYD Auto Industry Company Limited, Shenzhen, 518118, China;1. College of Light Industry and Food Engineering, Guangxi University, Nanning 530004, China;2. School of Mechanical and Transportation Engineering, Guangxi University of Science and Technology, Liuzhou 545006, China;3. School of Mechanical Engineering, Guangxi University, Nanning 530004, China;4. Resource, Commonwealth Scientific and Industrial Research Organisation, 1 Technology Court, Pullenvale, QLD 4069, Australia;1. NEST – Excellence Group in Thermal Power and Distributed Generation, Institute of Mechanical Engineering, Federal University of Itajubá, Av. BPS 1303, Itajubá, Minas Gerais State, CEP: 37500-903, Brazil;2. IRN – Institute of Natural Resources, Federal University of Itajubá, Av. BPS 1303, Itajubá, Minas Gerais State, CEP: 37500-903, Brazil;3. ICIDCA – Instituto Cubano de Investigaciones de los Derivados de la Caña de Azúcar, Via Blanca y Carretera Central 804, San Miguel Del Padrón, A.P. 4036, La Habana, Cuba |
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| Abstract: | Biofuels are heavily debated as to their potential to reduce transport-related greenhouse gas emissions. Life cycle thinking gave rise to formal evaluations of the energy balance of such fuels, which led to the vigorously conducted “corn to ethanol” debates. Just as consensus was building on such evaluations came the “carbon debt” insights, a result of applying consequential Life Cycle Assessment (LCA) backed by advanced economic modeling. Increasingly, hopes have shifted to the 2nd generation biofuels, viewed as a “technological home run”. Could this also backfire? We investigate a simple South African case in which there might not be improvements in environmental performance: a sugar mill sells its bagasse, currently used at low efficiency to provide process heat, to an advanced biofuels producer, and buys an equivalent amount of coal without investing in efficiency improvements. Seven scenarios are generated, ranging from the status quo, where no bagasse is diverted, to 100% bagasse diversion, with one scenario including an energy efficiency improvement in the sugar mill. A consequential LCA is applied to the seven scenarios, covering global warming potential (GWP), non-renewable energy use, aquatic eutrophication and terrestrial acidification. A basic financial analysis of the proposed scenarios shows that they are realistic, with potentially lucrative returns. Results show that diverting bagasse without efficiency improvements from its current use to an ethanol bio-refinery would indeed backfire for all environmental impacts studied. The base case outperforms all the other scenarios, with the 100% bagasse diversion scenario emerging the worst. Investments into energy efficiency are therefore a precondition for diverting cellulosic residues into biofuel production. |
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