Betzabet Morero

Life cycle assessment of biomethane use in Argentina

Renewable substitutes for natural gas, such as biogas, require adequate treatment to remove impurities. This paper presents the life cycle and environmental impact of upgrading biogas using absorption-desorption process with three different solvents: water, diglycolamine and polyethylene glycol dimethyl ether. The results showed that water produces a minor impact in most of the considered categories, and an economic analysis showed that water is the most feasible solvent for obtaining the lowest payback period. This analysis includes three different sources for biogas production and two end uses for biomethane. The use of different wastes as sources results in different environmental impacts depending on the type of energy used in the anaerobic digestion. The same situation occurs when considering the use of biomethane as a domestic fuel or for power generation. Using energy from biogas to replace conventional energy sources in production and upgrading biogas significantly reduce the environmental impacts of processes.

Environmental impact assessment as a complement of life cycle assessment. Case study: Upgrading of biogas.

This work presents a comparison between an environmental impact assessment (EIA) and a life cycle assessment (LCA) using a case study: upgrading of biogas. The upgrading of biogas is studied using three solvents: water, physical solvent and amine. The EIA follows the requirements of the legislation of Santa Fe Province (Argentina), and the LCA follows ISO 14040. The LCA results showed that water produces a minor impact in most of the considered categories whereas the high impact in the process with amines is the result of its high energy consumptions. The positive results obtained in the EIA (mainly associated with the cultural and socioeconomic components) make the project feasible and all the negative impacts can be mitigated by preventive and remedial measures. From the strengths and weaknesses of each tool, it is inferred that the EIA is a procedure that can complement the LCA.

Assessment of biogas production in Argentina from co-digestion of sludge and municipal solid waste

In Argentina, there is an important potential to utilize organic waste to generate bioenergy. This work analyzes the environmental impacts and the energetic and economic requirements of the biogas produced by digesting the sewage sludge (SS) produced in a wastewater treatment plant in a medium city in Argentina. The SS is co-digested with the organic fraction of municipal solid waste (OFMSW), and the basis of this study is the life cycle assessment (LCA). The LCA is performed according to ISO 14040-44 using the SimaPro simulator. First, the transport of the raw materials to the biogas plant was defined. Then, the co-digestion and the biogas treatment for final use were evaluated. The co-digestion was improved with glycerol, and the generation of biogas was estimated using the GPS-X software. Two alternatives for the end use of biogas were considered: combined heat and power (CHP) and biomethane generation. For the first, H2S and water vapor were removed from the raw biogas stream, and for the second, also CO2 was removed. The H2S removal process was simulated in the SuperPro software by anaerobic biofiltration. The same software was used to simulate the removal of CO2 absorption-desorption with water as solvent. Finally, the environmental impacts related to the end use of biogas (CHP and biomethane) were evaluated. The environmental, energetic and economic analyses showed that the co-digestion of SS and OFMSW has great potential for reducing the environmental impacts and increasing the economic and energetic value of the substances via the production of biomethane, electricity and, potentially, fertilizer.

Simulación del Proceso de Absorción Química con Soluciones de Aminas para la Purificación Biogás

The influence of some key operating parameters and of different types of amines in biogas purification is analyzed. For this a conventional single-loop absorber-stripper process configuration was simulated using four types of amines (monoethanolamine, diethanolamine, diglycolamine and methyldiethanolamine) and two mixtures of them. The process simulator ProMax® was used. The variables studied were methane, carbon dioxide, hydrogen sulphide and water concentrations in the sweetened gas, process energy consumption, absorption temperatures and reboiler steam rates. The simulation results showed good levels of purification in all cases with best results for diglycolamine (97.3% de CH4) which also has the lowest reboiler energy consumption. Prior knowledge of natural gas absorber-stripper processes allowed using the technology in the particular case of biogas.

Simulation of the Process of Chemical Absorption using Amine Solutions for Biogas Purification

The influence of some key operating parameters and of different types of amines in biogas purification is analyzed. For this a conventional single-loop absorber-stripper process configuration was simulated using four types of amines (monoethanolamine, diethanolamine, diglycolamine and methyldiethanolamine) and two mixtures of them. The process simulator ProMax® was used. The variables studied were methane, carbon dioxide, hydrogen sulphide and water concentrations in the sweetened gas, process energy consumption, absorption temperatures and reboiler steam rates. The simulation results showed good levels of purification in all cases with best results for diglycolamine (97.3% de CH4) which also has the lowest reboiler energy consumption. Prior knowledge of natural gas absorber-stripper processes allowed using the technology in the particular case of biogas.

Integrated Process Design Optimization Accounting for Co-Digestion of Sludge and Municipal Solid Waste

Abstract This work presents an optimization model for the integrated design of waste treatment facilities, accounting for co-digestion of sludge and municipal solid waste. The superstructure of alternatives includes anaerobic digestion under mesophilic or thermophilic conditions, composting, recycling, and final disposal in a landfill. Anaerobic digesters can be fed with different mixing ratios of sewage sludge ( SS ) and the organic fraction of municipal solid waste ( OF ). A mathematical formulation derived from disjunctive programming is proposed to find the optimal process design. It comprises nonlinear equations to estimate digestion yields according to substrate mixing ratios. Results show that joint treatment increases the profitability, especially in small cities. Co-digestion of SS and OF leads to an integrated waste-to-energy process that maximizes the economic value of waste by producing electricity, heat and fertilizer.

Simulación del Proceso de Absorción Química con soluciones de Aminas para la purificación de biogás

The influence of some key operating parameters and of different types of amines in biogas purification is analyzed. For this a conventional single-loop absorber-stripper process configuration was simulated using four types of amines (monoethanolamine, diethanolamine, diglycolamine and methyldiethanolamine) and two mixtures of them. The process simulator ProMax® was used. The variables studied were methane, carbon dioxide, hydrogen sulphide and water concentrations in the sweetened gas, process energy consumption, absorption temperatures and reboiler steam rates. The simulation results showed good levels of purification in all cases with best results for diglycolamine (97.3% de CH4) which also has the lowest reboiler energy consumption. Prior knowledge of natural gas absorber-stripper processes allowed using the technology in the particular case of biogas.