Comparison of the biochemical and thermochemical routes for bioenergy production: A techno-economic (TEA), energetic and environmental assessment

Abstract

This paper addresses the techno-economic, energetic and environmental assessment of the indirect and direct production of bioenergy using Pinus patula (PP) as raw material. Ethanol and synthesis gas are evaluated as main products through biochemical (fermentation) and thermochemical (gasification) routes, respectively. The complete characterization of the raw material was performed aiming to determine the chemical, proximate and elemental composition of the PP that is used as starting point for the simulation procedure. Mass and energy balances were obtained from the simulation of both processes using the software Aspen Plus v9.0. Different economic criteria such as Net Present Value (NPV) and Payback Period (PBP) were used to determine the profitability of both processes. The overall energy efficiency was calculated considering the relation between the energy content of the products and the energy content of the inputs (raw materials and utilities). The environmental assessment involves an attributional life-cycle assessment (LCA) of different systems such as seedlings production, PP cultivation, harvesting and collection, and the evaluated processes using a cradle-to-gate approach. As a result, the production of ethanol evidenced a low production cost (0.549 USD/L), higher energy efficiency (45.1%) and higher CO2 emissions (0.17 kg per MJ EtOH) in comparison to the biomass gasification.