Hydrothermal carbonization of anaerobically digested maize silage
TL;DR: The hydrochars showed mainly amorphous macro-size features with a carbon content of 59-79% (ash-free, dry) and a higher heating value of 25-36 MJ kg⁻¹ and are potentially interesting for applications such as an alternative fuel or a soil conditioner.
About: This article is published in Bioresource Technology.The article was published on 2011-10-01. It has received 343 citations till now. The article focuses on the topics: Hydrothermal carbonization & Carbonization.
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TL;DR: An overview of biochar production technologies, biochar properties, and recent advances in the removal of heavy metals, organic pollutants and other inorganic pollutants using biochar is provided.
1,301 citations
Cites background from "Hydrothermal carbonization of anaer..."
...Higher temperatures increased the char’s carbon content but decreased its yield, volatile matter content, ion exchange capacity, O-containing functional groups and surface area (Mumme et al., 2011; Kang et al., 2012)....
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...…also the main influencing factor for the properties of biochar produced from HTC. Higher temperatures increased the char’s carbon content but decreased its yield, volatile matter content, ion exchange capacity, O-containing functional groups and surface area (Mumme et al., 2011; Kang et al., 2012)....
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...Hydrothermal carbonization (HTC) usually pyrolyze the biomass at 180– 300 C in water for 30 min to 16 h, resulting in 36–72% biochar yield (Table S1) (Rillig et al., 2010; Hoekman et al., 2011; Mumme et al., 2011; Kalderis et al., 2014)....
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TL;DR: In this paper, an updated review on the fundamentals and reaction mechanisms of the slow-pyrolysis and hydrothermal carbonization (HTC) processes, identifies research gaps, and summarizes the physicochemical characteristics of chars for different applications in the industry.
Abstract: Slow-pyrolysis of biomass for the production of biochar, a stable carbon-rich solid by-product, has gained considerable interest due to its proven role and application in the multidisciplinary areas of science and engineering. An alternative to slow-pyrolysis is a relatively new process called hydrothermal carbonization (HTC) of biomass, where the biomass is treated with hot compressed water instead of drying, has shown promising results. The HTC process offers several advantages over conventional dry-thermal pre-treatments like slow-pyrolysis in terms of improvements in the process performances and economic efficiency, especially its ability to process wet feedstock without pre-drying requirement. Char produced from both the processes exhibits significantly different physiochemical properties that affect their potential applications, which includes but is not limited to carbon sequestration, soil amelioration, bioenergy production, and wastewater pollution remediation. This paper provides an updated review on the fundamentals and reaction mechanisms of the slow-pyrolysis and HTC processes, identifies research gaps, and summarizes the physicochemical characteristics of chars for different applications in the industry. The literature reviewed in this study suggests that hydrochar (HTC char) is a valuable resource and is superior to biochar in certain ways. For example, it contains a reduced alkali and alkaline earth and heavy metal content, and an increased higher heating value compared to the biochar produced at the same operating process temperature. However, its effective utilization would require further experimental research and investigations in terms of feeding of biomass against pressure; effects and relationships among feedstocks compositions, hydrochar characteristics and process conditions; advancement in the production technique(s) for improvement in the physicochemical behavior of hydrochar; and development of a diverse range of processing options to produce hydrochar with characteristics required for various industry applications.
1,061 citations
TL;DR: In this article, the authors used the hydrothermal carbonization (HTC) process to convert sewage sludge into clean solid fuel without prior drying, and evaluated the fuel characteristics and combustion behaviors of hydrochars.
706 citations
Cites background from "Hydrothermal carbonization of anaer..."
...Currently, many biomass substrates, including cellulose [11], microalgae [12,13], anaerobically digested maize silage [8], municipal solid waste [14–16], distiller’s grains [17], and black liquor [18], have been applied in HTC to gain fuels or materials....
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...pressures (2–10 MPa) [8]....
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TL;DR: In this paper, the chemical and structural properties of cellulose, lignin, d-xylose, wood meal, and phenolic hydrochars were investigated, and the carbonization mechanism was proposed, and furfural was found to be an important intermediate product during d-Xylose hydrochar production.
Abstract: Hydrothermal carbonization of cellulose, lignin, d-xylose (substitute for hemicellulose), and wood meal (WM) was experimentally conducted between 225 and 265 °C, and the chemical and structural properties of the hydrochars were investigated. The hydrochar yield is between 45 and 60%, and the yield trend of the feedstock is lignin > WM > cellulose > d-xylose. The hydrochars seem stable below 300 °C, and aromatic structure is formed in all of these hydrochars. The C content, C recovery, energy recovery, ratio of C/O, and ratio of C/H in all of these hydrochars are among 63–75%, 80–87%, 78–89%, 2.3–4.1, and 12–15, respectively. The higher heating value (HHV) of the hydrochars is among 24–30 MJ/kg, with an increase of 45–91% compared with the corresponding feedstock. The carbonization mechanism is proposed, and furfural is found to be an important intermediate product during d-xylose hydrochar production, while lignin hydrothermal carbonization products are made of polyaromatic hydrochar and phenolic hydrocha...
548 citations
TL;DR: The main research directions in the hydrothermal conversion of biomass into fuels and carbon throughout gasification to produce H2 or CH4, liquefaction to produce crude oils and phenols from lignin as well as carbonization to produce carbonaceous materials which can be either used as fuels (carbon negative chars) or interesting energetic materials (hydrothermal carbons).
384 citations
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TL;DR: On the climate change mitigation front, the incorporation of ‘biochar’ into the soil is one idea gaining support, and Johannes Lehmann argues that trapping biomass carbon in this way is more effective than storing it in plants and trees that will one day decompose.
Abstract: Locking carbon up in soil makes more sense than storing it in plants and trees that eventually decompose, argues Johannes Lehmann. Can this idea work on a large scale? With the rash of IPCC reports in climate much in the news, geoengineering — the deliberate large-scale modification of the environment — is now being taken seriously in scientific and political circles that would previously have scoffed at the notion. Oliver Morton reports on the state of play in the field [News Feature p. 132] On the climate change mitigation front, the incorporation of ‘biochar’ into the soil is one idea gaining support. Johannes Lehmann argues that trapping biomass carbon in this way is more effective than storing it in plants and trees that will one day decompose. The latest IPCC report — round 3 — is covered in the News pages this week.
2,117 citations
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TL;DR: In this article, Flannery presented a Biochar Classification and Test Methods for determining the quantity of Biochar within Soils and its effect on Nutrient Transformations and Nutrient Leaching.
Abstract: Preface Foreword by Tim Flannery 1. Biochar for Environmental Management: An Introduction 2. Physical Properties of Biochar 3. Characteristics of Biochar: Microchemical Properties 4. Characteristics of Biochar: Organo-chemical Properties 5. Biochar: Nutrient Properties and Their Enhancement 6. Characteristics of Biochar: Biological Properties 7. Developing a Biochar Classification and Test Methods 8. Biochar Production Technology 9. Biochar Systems 10. Changes of Biochar in Soil 11. Stability of Biochar in Soil 12. Biochar Application to Soil 13. Biochar and Emissions of Non-CO2 Greenhouse Gases from Soil 14. Biochar Effects on Soil Nutrient Transformations 15. Biochar Effects on Nutrient Leaching 16. Biochar and Sorption of Organic Compounds 17. Test Procedures for Determining the Quantity of Biochar within Soils 18. Biochar, Greenhouse Gas Accounting and Emissions Trading 19. Economics of Biochar Production, Utilization and Greenhouse Gas Offsets 20. Socio-economic Assessment and Implementation of Small-scale Biochar Projects 21. Taking Biochar to Market: Some Essential Concepts for Commercial Success 22. Policy to Address the Threat of Dangerous Climate Change: A Leading Role for Biochar Index
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