Abstract

This work aimed to analyze and compare the environmental impacts of hydrothermal carbonization (HTC) process performed on olive pomace, aimed at energy recovery. Twelve alternative pathways, considering variable process conditions in terms of temperature (260, 280 and 305 °C), heat recovery layouts and the subsequent combustion of the generated solid product, were analyzed. Results, related only to the processing phases (i.e. without including avoided effects), showed, as expected, that the final environmental performance depends on the HTC process temperature. Moreover, it was noted that the resulting impacts are from 1.4 to 2.0 lower for the layouts with heat recovery, for all the analyzed impact categories, with exception of Freshwater Toxicity. It was also reported that by substituting the fuel in marginal processes of heat production, environmental load reduction potential, regarding all impact categories, can be achieved. The highest benefits were achieved by substituting coal with HTC pellet in the heat production, followed by wood pellets and natural gas. Concerning the contribution analysis, the combustion processes of HTC and wood pellet represent the major contributions to the Climate Change and Acidification impacts, the combustion processes of HTC and wood pellet represent the major contributions, around the 95% and the 75% of the total, respectively, for the cases with the highest HTC temperature and no recovery scheme. For the Eutrophication potential, biomass production contributes significantly to the final effect. Regarding the Freshwater Ecotoxicity, the major part of the impact is coming from the HTC process and the relative liquid phase emissions assumed to be composed by phenols and furfurals released from the process. However, this part of the system needs to be further analyzed in detail.

Graphic Abstract

中文翻译：

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假设的工业规模通过水热碳化从橄榄果渣中回收能量：LCA观点

摘要

这项工作旨在分析和比较对橄榄渣进行热液碳化（HTC）过程对环境的影响，旨在回收能量。分析了十二种替代途径，其中考虑了温度（260、280和305°C），热回收布局以及随后产生的固体产物燃烧方面的可变工艺条件。正如预期的那样，仅与处理阶段有关的结果（即不包括避免的影响）表明，最终的环境性能取决于HTC处理温度。此外，要注意的是，除淡水毒性外，对于所有分析的影响类别，带热回收的布局所产生的影响要低1.4至2.0。另据报道，通过在边际产热过程中替代燃料，就所有影响类别而言，都可以实现减少环境负荷的潜力。通过在热生产中用HTC颗粒代替煤炭，然后是木质颗粒和天然气，可以实现最高的收益。关于贡献分析，HTC和木屑的燃烧过程是对气候变化和酸化影响的主要贡献，HTC和木屑的燃烧过程是主要的贡献，约占总数的95％和75％，分别针对HTC温度最高且没有恢复方案的情况。对于富营养化潜力，生物量生产对最终效果有显着贡献。关于淡水的生态毒性，影响的主要部分来自HTC工艺，而相对液相排放被假定为由该工艺释放的苯酚和糠醛组成。但是，系统的这一部分需要进一步详细分析。

图形摘要