Hydrochar as an Alternative to Coal: A Comparative Study of Lignocellulosic and Nonlignocellulosic Biomass

IF 3.6 Q2 ENVIRONMENTAL SCIENCES

Resources Pub Date : 2024-03-31 DOI:10.3390/resources13040049

Numan Luthfi, Takashi Fukushima, Xiulun Wang, Kenji Takisawa

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Abstract

Hydrothermal carbonization (HTC) is a widely used process for converting biomass with a wide range of moisture. Biomass selection poses challenges in producing hydrochar with desired properties because of their different constituents. In this study, we investigated the fuel properties of hydrochar of sorghum bagasse (SB) and microalgae (MA) at different severity factors (SFs = 4.08, 4.43, 5.56, 5.90, and 6.63) and their potential as alternatives to coal. The results show that during HTC, both biomasses underwent dehydration, in addition to the noticeable decarboxylation of MA. Fixed carbon increasingly developed in the SB hydrochar, in contrast to the MA hydrochar, which formed volatile hydrocarbon; thus, the MA hydrochar released heat values of 26.7–36.2 MJ·kg−1, which was higher than that of SB at 19.7–28.0 MJ·kg−1. However, owing to the stable hydrocarbons, SB hydrochar is assumed to combust more stably and ignite more decently, as indicated by its fuel ratio (0.83), approaching 0.9–1.5. Moreover, the greater number of solids recovered in SB after carbonization makes its conversion more techno-commercially viable, retaining 1.8 times more of the original energy. Conflating these fuel properties reveals that SB hydrochar (SF = 6.63) is a promising alternative to steam coal, and MA hydrochar is an attractive alternative to both steam (SF = 4.08–5.90) and coking coals (SF = 6.63). Concisely, both biomasses are practically promising as value-added hydrochars, but only SB can be developed beyond the current HTC severity owing to the thermal stability of its hydrocarbons.

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水碳作为煤的替代品：木质纤维素和非木质纤维素生物质的比较研究

水热碳化（HTC）是一种广泛应用的生物质转化工艺，其水分范围很广。由于生物质的成分各不相同，因此生物质的选择给生产具有理想特性的水炭带来了挑战。在本研究中，我们研究了高粱蔗渣（SB）和微藻（MA）在不同严重系数（SFs = 4.08、4.43、5.56、5.90 和 6.63）下的水炭燃料特性，以及它们作为煤炭替代品的潜力。结果表明，在 HTC 过程中，除了 MA 明显脱羧外，两种生物质都发生了脱水。SB 水碳中的固定碳越来越多，而 MA 水碳则形成了挥发性碳氢化合物；因此，MA 水碳释放的热值为 26.7-36.2 MJ-kg-1，高于 SB 的 19.7-28.0 MJ-kg-1。然而，由于碳氢化合物比较稳定，SB 水炭的燃料比（0.83）接近 0.9-1.5，这表明 SB 水炭的燃烧更稳定，点火更容易。此外，碳化后 SB 中回收的固体数量更多，使其转换更具技术商业可行性，保留的原始能量是原来的 1.8 倍。综合这些燃料特性可以看出，SB 水碳（SF = 6.63）是一种很有前途的蒸煤替代品，而 MA 水碳则是蒸煤（SF = 4.08-5.90）和焦煤（SF = 6.63）的理想替代品。简而言之，这两种生物质都很有希望成为具有附加值的水煤浆，但由于其碳氢化合物的热稳定性，只有 SB 可以在目前的 HTC 严重程度之外进行开发。

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来源期刊

Resources Environmental Science-Nature and Landscape Conservation

CiteScore

7.20

自引率

6.10%

发文量

审稿时长

11 weeks

期刊介绍： Resources (ISSN 2079-9276) is an international, scholarly open access journal on the topic of natural resources. It publishes reviews, regular research papers, communications and short notes, and there is no restriction on the length of the papers. Our aim is to encourage scientists to publish their experimental and theoretical research in as much detail as possible. Full experimental and methodical details must be provided so that the results can be reproduced. There are, in addition, unique features of this journal: manuscripts regarding research proposals and research ideas will be particularly welcomed, electronic files or software regarding the full details of the calculation and experimental procedure, if unable to be published in a normal way, can be deposited as supplementary material. Subject Areas: natural resources, water resources, mineral resources, energy resources, land resources, plant and animal resources, genetic resources, ecology resources, resource management and policy, resources conservation and recycling.