Environmental and energy performance of residual forest biomass for electricity generation: Gasification vs. combustion

Bioenergy systems have a great potential worldwide to substitute fossil fuels mainly because they may contribute to greenhouse gas emissions reduction. In Portugal, several biomass combustion-based power plants have been built in the last decade. Biomass gasification is a potential alternative to combustion but its environmental impacts should be evaluated. The goal of this study is to assess and compare the environmental and energy performance of direct gasification and combustion (both in fluidized bed) using residual forest biomass (RFB) from eucalypt in Portugal. In order to achieve the goal, life cycle assessment was applied, complemented with the Energy-Returned-On-Energy-Invested (EROI) indicator. The boundaries of the systems comprise three stages: (1) forest management, (2) collection, processing and transportation, and (3) electricity generation. The results indicate that gasification performs environmentally better than combustion in 5 out of 8 impact categories addressed. Conversely, combustion has greater EROI than gasification. After running a sensitivity analysis where the efficiency of the gasifier was changed from 53% in the base scenario to 57%, it is shown that the environmental performance of gasification improved in the range of 2-8%. The study concludes that gasification may be a good alternative to current combustion systems in Portugal. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The study evaluates and compares the environmental and energy performance of direct gasification and combustion using residual forest biomass in Portugal. Gasification performs environmentally better than combustion in most impact categories, but combustion has a higher Energy-Returned-On-Energy-Invested ratio. The study concludes that gasification may be a good alternative to current combustion systems in Portugal.