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The latest research and development in hydrothermal carbonisation (HTC) processes are reviewed and the feasibility of application to small towns in the UK is assessed. The HTC process designed in this report is theoretically evaluated for the biodegradable municipal waste and sewage waste produced by the small town of Chirnside, in the Scottish Bor...
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... Especially when a brief residence time is implemented, the HTC process water creates favorable conditions for AD, which can generate biogas. Furthermore, the process water contains inorganic ions such as potassium and phosphate and short-chain carboxylic acids, both of which are beneficial for plant development (Bevan et al., 2021). ...
... Nevertheless, the liquid phase can potentially cause complications both within the HTC process apparatus and when it naturally discharges. Thirteen of the 680 organic contaminants assessed for their presence in the process water were detected in trace amounts (Bevan et al., 2021). To reduce the TOC and other nutrients, process water must be treated anaerobically or aerobically (Funke & Ziegler, 2010). ...
... However, the potential of the HTC process to predominantly generate carbon dioxide while minimizing the release of hydrocarbons like methane and hydrogen has been recognized for its environmental benefits (Child, 2014). Therefore, by utilizing an HTC plant, the production and discharge of substantial quantities of hazardous greenhouse gases that result from the landfilling or combustion of renewable biomass could be avoided (Bevan et al., 2021). ...
Hydrothermal carbonization (HTC) technology emerges as a sustainable method to convert wet biomass, including food waste and municipal solid waste into high‐energy dense biocoal. This process, conducted at temperatures ranging from 180 to 260°C and pressures of 10–50 bar, effectively transforms the organic material in wet biomass into solid, liquid, and gaseous outputs. The solid product, biocoal, possesses a high carbon concentration and heating values on par with lignite coal, presenting a cleaner alternative to traditional fossil fuels. Despite operational commercial‐scale HTC facilities globally, further adoption across various feedstocks can improve waste management and energy production. The process can achieve energy yields up to 80%, particularly at temperatures favoring the generation of secondary char with higher heating values. HTC not only aids in reducing greenhouse gas emissions through carbon sequestration in solid waste but also promotes environmental sustainability by yielding nutrient‐rich by‐products for agriculture. As a versatile and energy‐efficient solution, HTC technology is a pivotal innovation in waste‐to‐energy conversion, addressing the imperative for sustainable waste management. Other supplementary benefits are presented; they include higher employability, reduction of a nation's reliance on imported energy, and better waste control, therefore considering all pillars of sustainability. Future research should focus on optimizing process efficiency and exploring the broader applicability of HTC to various biomass feedstocks, enhancing its role in the global pursuit of sustainable energy solutions.
... HTC and slow pyrolysis have recently advanced to industrial scales [13]. European industrial entities are actively developing pyrolysis for bio-oil, pyrochar, and syngas production [14]. ...
... In this sense, pumpable or easily transported feedstocks with well-understood rheological properties are essential. However, it has been reported that this challenge can be overcome by recycling process water to low-moisture content feedstock [17]. ...
... The advantages and drawbacks between HTC and other technologies are discussed in the literature. Taking the two first and simplest methods (landfilling and composting), neither produces energy nor produces additional profits [17]. Moreover, these methods are sluggish when compared to HTC. ...
... Hence, they demand large areas and are related to substantial greenhouse gas (GHG) emissions. In addition, in 2014, the European Commission outlined landfilling as the least preferable option for waste disposal [17], even though it is still widely applied worldwide, particularly in developing countries. ...
This study assesses the status of hydrothermal carbonization (HTC) technology and identifies barriers hindering its commercial viability. Conducting a global survey among HTC companies (with a total of 24 surveys sent), the research evaluates the current landscape, challenges, and future prospects of large-scale HTC operations.
This paper also explores the potential of HTC in transforming waste management practices, carbon sequestration methodologies, and the development of new materials. Employing a thorough SWOT analysis, the paper advocates for a broader adoption of HTC, emphasizing its transformative capacity in fostering sustainable management of urban, industrial, and agricultural residues, promoting circular economy principles, mitigating climate change, and offering a robust foundation for informed decision-making and sustainable development strategies.
... HTC and slow pyrolysis have recently advanced to industrial scales [13]. European industrial entities are actively developing pyrolysis for bio-oil, pyrochar, and syngas production [14]. ...
... When biomass is thermally treated, carbon can be contained in solid form, and, in turn, sequestered from the carbon cycle. One of the emerging technologies for converting biomass into a carbon-and energy-dense solid is the Hydrothermal Carbonisation (HTC) process, where, under elevated temperatures (up to 260 ̊C ) and pressures (up to 40 bar) (Bevan et al., 2021a), a water-based reaction causes chemical and physical changes to the biomass structure (Sevilla and Fuertes, 2009). The solid product of HTC can be referred to as hydrochar referring to the water used in the conversion (hydro-), which is not used by any other thermo-chemical biomass conversion process. ...
... Hydrothermal carbonization (HTC) is a thermochemical process that takes place at pressures of 10-50 bar, residence times of 0.5-8 h, and temperatures usually around 180 and 250 C (Musa et al. 2022). Most studies on HTC concentrated on the solid product, thoroughly examining its qualities as a biofuel and soil enhancer, even when used in co-combustion with coal (Bevan et al. 2021). ...
... One of HTC's key benefits is that it does not require the raw material to be processed and dried. Instead, hydrogen and oxygen atoms in carbon molecules are released by the action of water at high pressures (about 20 MPa) and temperatures between 180 and 300 C (Bevan et al. 2021). This procedure can potentially increase the fuel quality of MSW by lowering the water content, removing chlorine, and densifying the energy. ...
... This procedure can potentially increase the fuel quality of MSW by lowering the water content, removing chlorine, and densifying the energy. As a result, carbon dioxide makes up the bulk of the mixture of gases, including a highly concentrated aqueous solution and an enriched solid carbon (Bevan et al. 2021). The mass of the product concerning the raw material used decreases due to the dehydration and decarboxylation reactions. ...
There has been a significant increase in global waste generation owing to rapid urbanization and industrialization. Anthropogenic activities associated with exploiting natural resources pose severe threats to the long-term resilience of ecosystems. The buildup of waste biomass in ecosystems causes various adverse environmental conditions, such as greenhouse gas emissions, global warming, bioaccumulation and biomagnification of hazardous chemicals, surface and groundwater pollution, and acid rains suppress and lessen biological diversity. According to the World Bank predictions, 3.4 billion tons of municipal solid waste will have been generated by 2050. Thus, effective waste biomass management through valorization is critical in circular bio-economy and meeting environmental feasibility. Due to its abundance and renewability, lignocellulosic waste biomass can be a beneficial substrate to produce many high-value goods such as biofuels, biofertilizers, composts, biochar, pharmaceuticals, bioplastics, and food additives. This chapter summarizes the potential of hydrothermal conversion processes, including hydrothermal carbonization, hydrothermal liquefaction, and hydrothermal gasification, in producing a range of value-added products from solid waste substances. Moreover, the future trends of biological conversions that use microbial bioconversion generate a number of eco-friendly valorized products like biopesticides, biohydrogen, organic acids, antibiotics, enzymes, food colors, amino acids, and single-cell proteins were discussed. Further, this chapter highlights the multidisciplinary approaches for waste biomass valorization combined with advanced bio-nanotechnology, enzymatic sequent biomass hydrolysis treatments that are becoming popular and research gaps to overcome the challenges of waste biomass valorization by enhancing the process efficiency.KeywordsBiomass valorizationLignocellulosic biomassBio-fertilizersBio-energyComposting
... A promising approach for the conversion of wet biomasses (such as algae, sewage sludge, crops, and animal manure) to hydrocarbon materials is hydrothermal carbonization (HTC) which is based on a variety of temperatures and pressures [181]. In fact, when pyrolysis is carried out in the presence of liquid water the process is redefined as HTC [182]. Compared to dry pyrolysis [58,172], HTC omits the energy-intensive pre-drying stage and produces hydrochar with substantial physicochemical diversity [183]. ...
Climate change is a growing threat to civilization. The major anthropogenic greenhouse gas is CO2, which is emitted principally from the combustion of mineral hydrocarbons. By 2100, the concentration of CO2 in the atmosphere is expected to rise twofold due to increased vehicular emissions, deforestation, chemical processes, and fossil fuel-fired power plants. To this end, there is an urgent demand for adopting CO2 emissions mitigation strategies. Worldwide efforts have resulted in developing new and affordable CO2 reduction methods. The significant levels of CO2 released into the atmosphere can be diminished using diverse liquid and/or solid materials. The commonly used liquid sorption routes require expensive regeneration and produce harmful by-products. Therefore, this review focuses on the use of carbon-based materials (CBMs) for CO2 capture. In principle, CBMs have the potential for industrial applications due to their cost efficiency, desirable regeneration, and ability to physically uptake considerable amounts of CO2. The present paper aims to discuss the fundamental mechanism of CO2 capture on the most commonly investigated CBMs in the last five years. Besides, it provides a comprehensive study of significant progress in designing and synthesizing CBMs, including nanotubes, aerogels, composites, and biomass derivatives, with their adsorption potential for CO2. Noteworthy, progress has been made in this subject; nevertheless, further investigations are still necessary. Finally, several perspectives are discussed in light of recent studies regarding sustainable CO2 capture development.
... A summary on the nano-catalytic conversion biomass to energy and material is tabulated in Table 8. Graphitic carbon supported Co catalyst was applied for catalytic steam reforming of tar [210]. The Co 0.1 /oxidized Shengli lignite char catalyst maintained a stable toluene conversion of 85% during the 30-h test of the steam reforming of tar. ...
We conceptualize bioresource upgrade for sustainable energy, environment, and biomedicine with a focus on circular economy, sustainability, and carbon neutrality using high availability and low utilization biomass (HALUB). We acme energy-efficient technologies for sustainable energy and material recovery and applications. The technologies of thermochemical conversion (TC), biochemical conversion (BC), electrochemical conversion (EC), and photochemical conversion (PTC) are summarized for HALUB. Microalgal biomass could contribute to a biofuel HHV of 35.72 MJ Kg-1 and total benefit of 749 $/ton biomass via TC. Specific surface area of biochar reached 3000 m2 g-1 via pyrolytic carbonization of waste bean dregs. Lignocellulosic biomass can be effectively converted into bio-stimulants and biofertilizers via BC with a high conversion efficiency of more than 90%. Besides, lignocellulosic biomass can contribute to a current density of 672 mA m-2 via EC. Bioresource can be 100% selectively synthesized via electrocatalysis through EC and PTC. Machine learning, techno-economic analysis, and life cycle analysis are essential to various upgrading approaches of HALUB. Sustainable biomaterials, sustainable living materials and technologies for biomedical and multifunctional applications like nano-catalysis, microfluidic and micro/nanomotors beyond are also highlighted. New techniques and systems for the complete conversion and utilization of HALUB for new energy and materials are further discussed.
... More importantly, the successful application and focus on generating HTC-based bioenergy from the organic parts of FW could ensure the creation of values from waste while also assuring local job opportunities as well as the security of energy. Particularly, hydrochar generation from the HTC of FW could guarantee energy security in areas that are dependent on importing coal and other kinds of fossil fuels (Bevan et al., 2020). Indeed, the HTC approach is a crucial method for avoiding the difficulties associated with facing wet waste like FW. ...
... Unlike other types of biomass, FW-based hydrochar is not regarded as a typical solid fuel. When redirected from incineration or landfilling, the HTC provided an effective waste disposal approach for waste biomass that could be degraded biologically, as well as the possibility of generating renewable energy, hence avoiding health risks and mitigating the detrimental impacts of global warming at the same time (Bevan et al., 2020). Accordingly, in order to make the entire bioenergy supply chain more economically viable, additional funds might be achieved from waste generators by charging an FW disposal fee . ...
Every day, a large amount of food waste (FW) is released into the environment, causing financial loss and unpredictable consequences in the world, highlighting the urgency of finding a suitable approach to treating FW. As moisture content makes up 75% of the FW, hydrothermal carbonization (HTC) is a beneficial process for the treatment of FW since it does not require extensive drying. Moreover, the process is considered favorable for carbon sequestration to mitigate climate change in comparison with other processes because the majority of the carbon in FW is integrated into hydrochar. In this work, the reaction mechanism and factors affecting the HTC of FW are scrutinized. Moreover, the physicochemical properties of products after the HTC of FW are critically presented. In general, HTC of FW is considered a promising approach aiming to attain simultaneously two core benefits on economy and energy in the sustainable development strategy.
... This process is performed in a biomass-water solution at temperatures of 180-300 °C and autogenous pressure (subcritical conditions) for several hours. Similar to pyrolysis, HTC presents significant biochar yields (50-80 wt.%), but also a liquid fraction composed of a bio-oil and water mixture (5-20 wt.%), and a gas phase that mainly includes CO2 (2-5 wt.%) [13]. The great interest in HTC for biochar production is that the process can avoid the energy-intensive drying step that is usually required for conventional pyrolysis, and thus minimize operational costs. ...
... Comparison of thermochemical processes for biochar production[9,12,13,[15][16][17]. ...
Biochar produced during the thermochemical decomposition of biomass is an environmentally friendly replacement for different carbon materials and can be used for carbon sequestration to mitigate climate change. In this paper, current biochar production processes and top market applications are reviewed, as well as emerging biochar uses gaining momentum in the market. Various application fields of biochar, including agricultural applications (e.g., soil conditioning), adsorption (for soil and water pollutants), carbon sequestration, catalysis, or incorporation into composites or construction materials, are also presented and discussed. According to this literature overview, slow pyrolysis is the preferred process for biochar production, whereas agricultural applications (for soil conditioning and fertilization) are the most studied and market-ready solutions for biochar use. The Alentejo region (Portugal) shows tremendous potential to be a major player in the developing biochar market considering feedstock availability and large areas for biochar agricultural application. Biochar’s production potential and possible benefits were also estimated for this Portuguese region, proving that agricultural application can effectively lead to many environmental, economic, and social gains.
