Energy and exergy analysis of a supercritical water gasification system for the simultaneous production of hydrogen, heat, and electricity from sugarcane bagasse

Next Energy Pub Date : 2025-03-25 DOI:10.1016/j.nxener.2025.100266

Thiago Averaldo Bimestre , Thais Santos Castro , José Ramon Copa Rey , Valter Bruno Reis e Silva , José Luz Silveira

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Abstract

The search for sustainable energy sources and the use of agricultural waste have contributed to an increase in bioenergy research. Promising alternatives include supercritical water gasification (SCWG), which can be used to convert biomass into a hydrogen-rich synthesis gas, along with other value-added products such as bio-oil and process heat. In this context, sugarcane bagasse (SCB), an abundant by-product of the Brazilian sugar-alcohol industry, emerges as a strategic feedstock due to its wide availability and economic potential. This study focuses on hydrogen production by SCWG of SCB and evaluates the cogeneration of electricity, heat, and bio-oil as a secondary by-product by modeling a plant in DWSim. Key parameters such as temperature, biomass concentration, and residence time were evaluated to determine the hydrogen yield of the system as well as its energy and exergy efficiency. In the optimal scenario (700 °C, 25 MPa, 15 wt% biomass), the process achieved a hydrogen production rate of 8.86 mol/kg, generating 38 kW of electricity, 145 kW of heat, and 41 wt% of bio-oil. Overall, this scenario resulted in an energy efficiency of 61.45% and an exergy efficiency of 52.80%, with an eco-efficiency of 394 g CO₂-eq/kWh. The largest energy losses (79.80%) occurred in the supercritical water reactor, in the heat exchangers, and in the combustion chamber, which underlines the need for further optimization of the design. The results confirm the potential of SCWG as a viable pathway for hydrogen production and advanced energy conversion from residual biomass, which is essential for highly efficient and low-carbon utilization of these resources.

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用蔗渣同时生产氢、热、电的超临界水气化系统的能量和火用分析

寻找可持续能源和利用农业废物促进了生物能源研究的增加。有希望的替代方案包括超临界水气化（SCWG），它可用于将生物质转化为富氢合成气，以及其他增值产品，如生物油和工艺热。在这种情况下，甘蔗渣（SCB）作为巴西糖酒精工业的丰富副产品，由于其广泛的可获得性和经济潜力而成为一种战略原料。本研究侧重于SCB的SCWG制氢，并通过在DWSim中模拟工厂来评估作为二次副产品的电、热和生物油的热电联产。评估了温度、生物质浓度和停留时间等关键参数，以确定系统的产氢率及其能量和火用效率。在最佳条件下（700 °C, 25 MPa， 15 wt%生物质），该工艺的产氢率为8.86 mol/kg，产生38 kW的电，145 kW的热和41 wt%的生物油。总体而言，该方案的能源效率为61.45%，能源效率为52.80%，生态效率为394 g CO₂-eq/kWh。超临界水堆、热交换器和燃烧室的能量损失最大（79.80%），需要进一步优化设计。研究结果证实了SCWG作为剩余生物质制氢和先进能源转化的可行途径的潜力，这对这些资源的高效低碳利用至关重要。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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Next Energy

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