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Hydrothermal liquefaction is a promising technology for producing renewable advanced biofuels. However, some weaknesses could undermine its large-scale application, such as the significant carbon loss in the aqueous phase (AP) and the necessity of biocrude upgrading. In order to deal with these challenges, in this work the techno-economic feasibili...
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... the production of hydrogen needed for upgrading, the economic impact of replacing the H 2 derived from the APR section was evaluated. Steam reforming and electrolysis were the two H 2 -producing technologies compared with APR, since they represent respectively the most established way and the most investigated decarbonized option. Table 5 and Fig. 2 show the main inputs and outputs of the plant. As regards the production of biocrude, the two cases had a mass yield (dry biocrude/dry feedstock) of 39.0 wt% (LRS) and 29.0 wt% (CS); the biofuel yields after upgrading were 29.1% (LRS) and 23.4% (CS). The H 2 yield of the HTL-APR integrated plant was lower with LRS (0.039 Nm 3 / kg dry ...
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... The MFSP varied from $3.27 to $13.8 GGE − 1 , influenced by feedstock types and other factors. Bio-oil yield (or final product yield) and feedstock cost have been identified as the most influential parameters (Ranganathan, 2023;Ranganathan and Savithri, 2019;Tito et al., 2023). However, when considering specific feedstock, significant differences in product economics were observed. ...
... Among the technologies that produce advanced liquid biofuels which are suitable for long-haul applications, are gasification, pyrolysis and hydrothermal liquefaction (HTL) the common characteristic of which is the production of intermediate biocrudes needing further upgrading. HTL is a promising thermochemical process that converts biomass into liquid fuels using hot, pressurized water (sub-and supercritical conditions) to break down the solid biopolymeric structures 4 . It is advantageous compared to the other thermochemical technologies as it can be applied to a wide range of wet biomass feedstocks (lignocellulosic, algae, sewage sludge) avoiding costly energy requirements for the drying step of the feedstock. ...
The purpose of this study is the formulation of various scenarios based on two different conceptual design configurations for a sewage sludge-to-fuel pathway via HTL, co-located with a wastewater treatment...
... In a similar study, hydrothermal liquefaction was proposed as a promising technology for renewable advanced biofuel production [77]. The main constraints in its large-scale applications are the significant carbon loss in the aqueous phase (AP) and the necessity of biocrude upgrading. ...
... Therefore, a techno-economic feasibility analysis was followed, in which different lignocellulosic feedstocks, corn stover (CS) and lignin-rich stream (LRS) from cellulosic ethanol production were tested for the evaluation of hydrothermal liquefaction (HTL) coupling with aqueous-phase reforming (APR). Following the carrying out of the mass and energy balances, the equipment design and the capital and operating costs calculation, it was shown that the biofuel minimum selling price (in the case of 0% internal rate of return) was fixed at 1.23 (in the case of LRS) and 1.27 EUR/kg (in the case of CS), respectively [77]. Moreover, the fixed capital investment was devoted to heat exchangers, while electricity and feedstock sustained the highest share of the operating costs. ...
... It can be also be pointed out that, in the case of CS, a production of 107% of the required hydrogen was reported for biocrude upgrading, making the APR process particularly profitable. In this context, APR reduced the hydrogen production cost significantly (1.5 EUR/kg), making it a cost-effective and competitive technology compared with conventional electrolysis [77]. ...
The role of hydrogen as a clean energy source is a promising but also a contentious issue. The global energy production is currently characterized by an unprecedented shift to renewable energy sources (RES) and their technologies. However, the local and environmental benefits of such RES-based technologies show a wide variety of technological maturity, with a common mismatch to local RES stocks and actual utilization levels of RES exploitation. In this literature review, the collected documents taken from the Scopus database using relevant keywords have been organized in homogeneous clusters, and are accompanied by the registration of the relevant studies in the form of one figure and one table. In the second part of this review, selected representations of typical hydrogen energy system (HES) installations in realistic in-field applications have been developed. Finally, the main concerns, challenges and future prospects of HES against a multi-parametric level of contributing determinants have been critically approached and creatively discussed. In addition, key aspects and considerations of the HES-RES convergence are concluded.
... In this framework different polyols and sugars have been used as feedstock for aqueous phase reforming, such as ethylene glycol, glycerol, xylitol, fructose and glucose. [6,8,11,12,15,16,17,18,19] The latter is of particular interest as it can be directly obtained from cellulose by hydrolysis. [20,21,22,23] However, its conversion to hydrogen under the APR conditions is hindered by the production of polymerized side products (humins) above 200°C, which are temperatures usually needed when using metal-based heterogeneous catalysts. ...
Molecular ruthenium cyclopentadienone complexes were employed for the first time as pre‐catalysts in the homogeneously catalysed Aqueous Phase Reforming (APR) of glucose. Shvo's complex resulted the best pre‐catalyst (loading 2 mol %) with H2 yields up to 28.9 % at 150 °C. Studies of the final mixture allowed to identify the catalyst's resting state as a mononuclear dicarbonyl complex in the extracted organic fraction. In situ NMR experiments and HPLC analyses on the aqueous fraction gave awareness of the presence of sorbitol, fructose, 5‐hydroxymethylfurfural and furfural as final fate or intermediates in the transformations under APR conditions. These results were summarized in a proposed mechanism, with particular emphasis on the steps where hydrogen was obtained as the product. Benzoquinone positively affected the catalyst activation when employed as an equimolar additive.
... However, such a low feedstock price can only be attained if sorbitol is efficiently produced from lignocellulosic biomass (Sladkovskiy et al. 2018). Tito et al. (2023) considered in their work a combined process involving a first step of hydrothermal liquefaction followed by aqueous-phase reforming of the resulting aqueous phase. Hydrogen produced by aqueous-phase reforming was aimed to upgrade the biocrude obtained with hydrothermal liquefaction. ...
The rising adverse effects of climate change call for a rapid shift to low-carbon energy and reducing our dependence on fossil fuels. For that, biorefineries appear as promising alternatives to produce energy, chemicals, and fuels using biomass and waste as raw materials. Here, we review catalytic aqueous-phase reforming to convert biomass and organic waste carbohydrates into renewable hydrogen, with focus on reforming basics; catalyst design; reforming of model compounds, wastewater and biomass; economics and life cycle assessment. We found that platinum and palladium are technically highly effective, yet their high price may limit upscaling. Alternatively, addition of tin to nickel gives acceptable results and improves hydrogen selectivity from 35 to 90%. We observed that hydrogen production decreases from 14% for crude glycerol to 2% for pure glycerol, thus highlighting the need to do experiments with real wastewater. The rare experiments on real wastewater from brewery, juice, tuna, and cheese industries have given hydrogen production rates of up to 149.7 mg/L. Aqueous-phase reforming could be shortly competitive with prices around 3–6 USD per kg of hydrogen, which are nearing the current market prices of 2–3 USD per kg.
... In fact, the real sample has an ash content of 1.9 ± 0.5 wt.%, which is probably the main reason for solid yields; hence a slightly higher solid yield would be expected. Alternatively, the ash could be solubilized in the aqueous phase or in the oil, as observed for Na, Ca, Mg (Panisko et al., 2015;Tito et al., 2022;Rizzo and Chiaramonti, 2022), some of the most common inorganic elements found in post-consumer plastic waste (Agostini et al., 2022). Due to the very low amount of solid produced, it was not possible to quantify the amount of ash present in the solid sample and its elemental composition. ...
Multi-material layered plastic films are used in the food packaging industry due to their excellent properties; however they cannot be mechanically recycled. In this study, a two-stage hydrothermal liquefaction (HTL) process is proposed and tested for chemical recycling of a two-layer film made of LLDPE-PET. Experimental results showed that after a first subcritical stage at 325 °C, 94% of terephthalic acid (TPA) is recovered from the PET fraction as a solid and 47% of ethylene glycol in the aqueous phase. The unconverted PE was then used as feedstock for a subsequent supercritical HTL stage at 450 °C for 90 min, achieving mass yields of 47% and 29% in a naphtha-gasoline oil and in an alkane-rich gas, respectively. In conclusion, this work proved that a sequential HTL procedure can be used for chemical recycling of multilayer plastics, allowing the recovery of PET monomers to be recycled back to the PET industry and a paraffinic oil and hydrocarbon-rich gas phase that could be used as feedstock for steam cracking to produce virgin materials.
... Scheme 3 shows the process. To address these challenges, some researchers have proposed coupling hydrothermal liquefaction with aqueous phase reforming, which is a catalytic process capable of converting oxygenates dissolved in water into a hydrogen-rich gas that can be used to upgrade biocrude [96,97]. The reactors used can be batch or continuous. ...
... Due to these facts, no plant has been implemented on a commercial scale so far, and it is necessary to explore many factors, such as the reaction mechanism, thermal and kinetic behavior, optimization of process parameters, reactor design, and economic analysis [98,99]. Figure 4 shows the liquefaction process. address these challenges, some researchers have proposed coupling hydrothermal liquefaction with aqueous phase reforming, which is a catalytic process capable of converting oxygenates dissolved in water into a hydrogen-rich gas that can be used to upgrade biocrude [96,97]. The reactors used can be batch or continuous. ...
Hydrogen is considered one of the most important forms of energy for the future, as it can be generated from renewable sources and reduce CO2 emissions. In this review, the different thermochemical techniques that are currently used for the production of hydrogen from biomass from plantations or crops, as well as those from industrial or agro-industrial processes, were analyzed, such as gasification, liquefaction, and pyrolysis. In addition, the yields obtained and the reactors, reaction conditions, and catalysts used in each process are presented. Furthermore, a brief comparison between the methods is made to identify the pros and cons of current technologies.
... In order to proceed with the industrial implementation of these technologies, it is necessary to verify that technical, economic and environmental sustainability criteria are satisfied. A techno-economic assessment conducted by the authors pointed out the technical and economic feasibility of an HTL-APR integrated plant [21]. Two cases were evaluated based on two different lignocellulosic feedstocks: corn stover (CS) and lignin-rich stream (LRS). ...
... The material and energy balances, as well as the design of the main equipment, were performed in a separate work [21], and the main results are reported in Figs. S1 and S2 of the Supplementary Information. ...
... However, in all cases the impact related to the hydrogen product was negligible. Under a mass-basis, the hydrogen flowrate was only 0.4% of the biofuel flowrate (2.9 kg/h vs 841 kg/h); under an energybasis, the hydrogen power was 1% of the biofuel power (being H 2 LHV = 120 MJ/kg and biofuel LHV = 43 MJ/kg); under an economicbasis, hydrogen counted for 1.1% of the biofuel value (assuming the H 2 selling price as green H 2 -5 €/kgand the biofuel selling price as the one derived in our previous TEA -1.62 €/kg [21]). For all these reasons, it emerges that the impacts obtained in the CS-case can conservatively be attributed to the biofuel production only. ...
The use of biofuels in the transport sector is one of the strategies for its decarbonization. Here, the LCA methodology was used for the first time to assess the environmental impacts of a biorefinery where hydrothermal liquefaction (HTL) and aqueous phase reforming (APR) were integrated. This novel coupling was proposed to valorize the carbon loss in the HTL-derived aqueous phase, while simultaneously reducing the external H2 demand during biocrude upgrading. Corn stover (residue) and lignin-rich stream (waste) were evaluated as possible lignocellulosic feedstocks. The global warming potential (GWP) was 56.1 and 58.4 g CO2 eq/MJbiofuel, respectively. Most of the GWP was attributable to the electrolysis step in the lignin-rich stream case and to the thermal duty and platinum use in the corn stover case. Other impact categories were investigated, and an uncertainty analysis was also carried out. A sensitivity analysis on biogenic carbon, electricity/thermal energy source and alternative hydrogen supply was conducted to estimate their influence on the GWP. Finally, the two scenarios were compared with the environmental impact of fossil- and other biomass-derived fuels, also considering fuel utilization. HTL-APR allowed a 37% reduction compared to fossil diesel, further reduced to 80% with the lignin-rich stream when green energy was used.
Herein we report the production of high-pressure (19.3 bar), carbon-negative hydrogen (H2) from glycerol with a purity of 98.2 mol% H2, 1.8 mol% light hydrocarbons (mainly methane), and 400 ppm...
