Process Analysis of Hydrogen Production via Biomass Gasification under Computer-Aided Safety and Environmental Assessments

Abstract

The growing awareness to advance new ways to transform renewable materials for producing clean fuels, under technical and sustainable viability, is evident. In this regard, hydrogen arises as one of the cleanest and energetic biofuels in the market. This work addresses the modeling and evaluation of a biomass gasification topology employing process simulation along with an environmental and inherent safety analysis. The presented pathway considered two renewable raw materials (cassava and rice waste) based on their vast availability in north Colombia regions. We employed Aspen Plus process simulation software to model the process, setting biomasses (and ash content) as nonconventional solids in the software and inclusion of FORTRAN subroutines for handling solid properties. Otherwise, the environmental evaluation was performed applying the waste reduction algorithm (WAR). At the same time, safety assessment involves a comprehensive approach based on the inherent safety index (ISI) and the process route index (PRI) methods. Data generated from the implementation of rigorous process simulation of biomass gasification allowed us to determine the needed aspect for performing process analysis methodologies. Results revealed that this topology generates a total flow of 3944.51 kg/h with more than 97% vol of H₂, from the sustainable use of 19,243 kg/h of cassava waste and 15,000 kg/h of rice straw. From the environmental viewpoint, the process showed moderately to a high overall rate of potential environmental impacts (PEIs), with a higher contribution from process sources than energy sources. It indicates that most of the generated impacts would come from self-operation than from the energy supply generation. In the case of process safety, the topology obtained an ISI score of 35, which represents that modeled gasification would operate below 50% of the expected neutral standard for a physical-chemical process. Complementing the safety evaluation, the obtained PRI suggests that compared to other processes, the analyzed topology shows relatively adequate performance considering the nature of this type of process.

Figure 1

Simulation process flowsheet diagram of biomass gasification.

Figure 2

Global environmental impacts of the biomass gasification process.

Figure 3

Comparison of the rate of impacts derived from process and energy contributions.

Figure 4

Rates of environmental impacts for toxicological categories in the biomass gasification process.

Figure 5

Rates of environmental impacts for atmospheric categories in the biomass gasification process.

Figure 6

Proposed block and simulation diagram of the biomass gasification process.