RESUMO
RESUMO A principal destinação de resíduos sólidos urbanos (RSU) coletados no Brasil tem sido aterros controlados e sanitários. Em raros casos, são aplicadas outras soluções, que poderiam trazer benefícios adicionais para as localidades. O aproveitamento do RSU é uma alternativa promissora. De imediato, apresenta-se a alternativa de geração de energia elétrica. Nesse caso, embora não se trate de potencial com dimensão suficiente para sustentar uma estratégia de expansão da oferta de energia elétrica do país em longo prazo, a geração de eletricidade mediante RSU é elemento importante de uma estratégia regional ou local e, portanto, não deve ser desconsiderada. Nesse cenário, este trabalho procurou estudar a viabilidade de implementação de tecnologias alternativas e complementares de destinação de RSU com geração de energia elétrica, levando em consideração seus impactos ambientais e utilizando como ferramenta a Avaliação de Ciclo de Vida (AVC). Os resultados mostraram que, entre as alternativas levadas em conta neste estudo, a geração de energia elétrica por intermédio dos processos combinados de tratamento mecânico biológico e incineração é a mais atraente em termos de impactos ambientais. A geração de energia elétrica por meio do processo de incineração mass burning mostrou-se também atraente no tocante a impactos ambientais. Como conclusão geral deste estudo, identificou-se a existência de alternativas e oportunidades para a implementação de projetos relacionados à geração de energia elétrica no Brasil por RSU, especialmente pelo processo de incineração, embora ainda existam barreiras econômicas, políticas e sociais que precisam ser vencidas.
ABSTRACT The main destination of municipal solid waste (MSW) collected in Brazil has been landfills and sanitary landfills. In rare cases, other solutions are applied, which may bring additional benefits to localities. The use of MSW is a promising alternative. At once, it is an alternative of generating electricity. In this case, although it is not sufficient to support a strategy to expand the Brazilian electricity supply, in the long term, the generation of electricity through MSW is an important element of a regional or local strategy and therefore should not be disregarded. In that context, this study sought to study the feasibility of implementing alternative and complementary technologies for the disposal of MSW with generation of electricity, taking into account its environmental impacts and using the Life Cycle Assessment (LCA). The results showed that, among the alternatives taken into account in this study, the generation of electric energy by combined biological and mechanical Treatment and Incineration is the most attractive in terms of environmental impacts. The generation of electricity by means of the mass burning incineration process showed to be also attractive in terms of environmental impacts. As a general conclusion of this study it was identified the existence of alternatives and opportunities for implementation of projects related to the generation of electric energy in Brazil especially by the incineration process, although there are still economic, political and social needs that must be overcome.
RESUMO
Photosynthetic microalgae are unicellular organisms that, during their cultivation, can fix carbon dioxide efficiently from various sources, including the air and exhaust gases from industrial processes. This feature can lead to economic benefits in the production process of biodiesel by way of the clean development mechanism, for which carbon credits for environmental benefits may be granted and which will contribute towards reducing costs in the production process. This study seeks to quantify the contribution of carbon credits in the operating costs of a route for biodiesel production from microalgae, as proposed by Davis et al. [Techno-economic analysis ofautotrophic microalgae for fuel production. Appl Energy. 2011; 88:3524-3531]. The results showed a reduction in annual operating costs by around 5%. This figure may be conservative, since the production process considered can be further improved to reduce operating costs and thus increase the contribution margin of carbon credits, which will reduce costs. On the other hand, the price of carbon may also rise in the future, thereby increasing its contribution towards a reduction in operating costs.
