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The progressive request for replacing fossil fuels and net-zero emissions by 2050 is forcing a change in the current paradigm and economy. Bioprocesses offer a significant alternative to conventional refineries, as they convert biomass into valuable platform chemicals, fuels, and/or heat and energy. The concept is disruptive, but the modelling is not straightforward due to the intrinsic complexity of the feedstock, the unconventional transformation (i.e., pre-treatment and chemical/thermal conversion, and product purification), and the number of species involved in the system. These aspects are of paramount importance and represent significant hurdles for modelling. In the present work, we review the main strategies used for bioprocesses modelling by highlighting advantages and drawbacks. Finally, the work presents a few applications applied in process design and preliminary assessment for biomass-to-X projects. [ABSTRACT FROM AUTHOR]

Ammonia, as one of the optimal carriers for green fuels, is frequently associated with substantial carbon emissions during its production. Ammonia feedstock can be produced stably, efficiently, and without pollution by solid oxide electrolysis cell (SOEC), which requires in-depth research. In this work, a green ammonia feedstock with a H 2 :N 2 ratio of 3:1 is successfully produced via N 2 /H 2 O decomposition by the SOEC. The results indicates that the SOEC operates stably for 500 h, maintaining a consistent proportion of synthetic ammonia feedstock. The ammonia feedstock production rate of this method reaches 4.08 × 10−6 mol/(cm2·s), the energy conversion efficiency (ECE) ranges between 66.86 % and 70.51 %. This work offers a novel and efficient method for the synthesis of green ammonia, characterized by fast production rates, excellent stability, and high energy utilization efficiency. • The SOEC was operated stably for 500 h with degradation rate of 2.26 %/100 h. • The ammonia feedstock production rate reached to 4.08 × 10−6 mol/(cm2·s). • The energy conversion efficiency (ECE) ranges between 66.86 % and 70.51 %. [ABSTRACT FROM AUTHOR]

With the rising concerns on environmental pollution and emission reduction, plastic waste disposal draws great attention from governors and scientists. Instead of landfilling and incineration, chemical treatments are considered less polluting and resources recovering. Hydrothermal processing is considered a prospective technology for this issue. To regulate the conversion process and improve efficiency, a key step is to know the dominant stages and clarify the controlled part of the reaction. However, there is very limited number of researches on the visualized exhibition of this process. In this paper, a hydrothermal process visualization measure is adopted, to intuitionally demonstrate the whole conversion process. Polyoxymethylene (POM) spheres are employed as the feedstock in this experiment. A fixed-focus camera records the plastic sphere particle undergoing three stages of heated, swelling and dissolution, under hydrothermal condition. At the heated stage, the solid sphere becomes transparent, then during the swelling stage, the transparent sphere expands to around 130 % of the original size (sectional area), finally the expanded sphere is dissolved into fragments dispersing in the water. During the hydrothermal conversion, the carbon component of the plastic sphere immigrated into the aqueous phase, carbon recovery rate of the process reached as high as 90 %. The visualized results well demonstrate the physical and chemical transition of hydrothermal process, which would be a promising direction for future study. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass is a key feedstock for the sustainable production of biofuels, biobased chemicals and performance materials. Biomass can be efficiently converted into pyrolysis liquids (also known as bio-oils) by the well-established fast pyrolysis technology. Currently, there is significant interest in the application of fast pyrolysis technology as principle biomass conversion technology due to its feedstock flexibility, low cost and high energy conversion efficiency, with many emerging commercial enterprises being established around the globe. Upgrading of the bio-oils is a requisite, and is complicated by its complex and heterogeneous organic nature. Pyrolysis liquids may be further separated by a simple water fractionation, yielding an aqueous sugar-rich phase and a water-insoluble pyrolytic lignin (PL) fraction. This separation step allows the use of dedicated conversion strategies for each fraction, which can be highly advantageous due to their differences in composition and reactivity. For example, the sugar-rich fractions can be used for fermentation, while the phenolic-rich PL is a particularly promising feedstock for the production of a wide range of platform chemicals and energy-dense streams upon depolymerization. To aid the emerging use of PL, novel characterization techniques and valorization strategies are being explored. In this review, the fast pyrolysis process and PL characterization efforts are discussed in detail, followed by the state-of-the-art regarding PL processing using both oxidative and reductive (catalytic) strategies, as well as a combination thereof. Possible applications are discussed and recommendations for future research are provided. [ABSTRACT FROM AUTHOR]

The excessive energy utilisation worldwide has prompted awareness of finding a new clean energy. Malaysia has large oil palm resources and releases huge amounts of oil palm biomass. Since oil palm biomass is abundantly available in Malaysia, it has the high potential of being utilised as fuel for gasification technology. Although many institutions in Malaysia are undertaking numerous research activities, the gasification technologies are not progressing as expected. The understanding of the potential and challenges faced by Malaysian industries are vital to evaluate the feasibility of gasification technology using oil palm biomass in Malaysia. [ABSTRACT FROM AUTHOR]

Abstract This work aims at estimating the biomass from agricultural residues of Calabria region (Southern Italy) for possible energy conversion in combined heat and power (CHP) systems. To this purpose, attention has been focused on agricultural residues, livestock sewage, and by-products and waste of the agro-food industry. The investigation has been based on statistical information from 2015, and an extensive literature review has been performed to define proper parameters for the analysis. The study highlights that an interesting amount of biomass residues is present in the investigated area, with about 820,000 t per year that can be conveniently used in small-scale CHP units to satisfy the thermal and electric request of regional users. Specifically, Organic Rankine Cycle (ORC) systems have been considered to exploit lignocellulosic residues through direct combustion, while anaerobic digestion and internal combustion engines (ICEs) have been adopted for the energy valorisation of the other investigated feedstock. The analysis demonstrates that the available biomass residues could satisfy the thermal request of more than 116,000 households and the electric load of about 178,000 families simultaneously. Highlights • Biomass residues in agricultural areas can be exploited in CHP systems. • Statistical and literature data allow assessment of biomass territorial availability. • In Calabria (Italy) about 820,000 t per year can be used in small-scale CHP units. • The energy demand of 116,000 households and 178,000 families can be satisfied. • The methodology can be extended to other rural contexts at different spatial scales. [ABSTRACT FROM AUTHOR]

Abstract Pyrolysis is one of the most efficient and environmentally attractive thermochemical processes for conversion of both biomass and wastes to energy products. This review focuses on the use of auger reactors, also known as screw reactors, for the pyrolysis of carbonaceous solids into liquid, gaseous and solid products that can be used in the production of fuels and other valued-added products. The auger reactor is attractive for its versatility in transforming a wide range of feedstocks, and has been recognized as one of the technologies with better strengths not only for fast pyrolysis, but also for slow or intermediate pyrolysis. Auger pyrolyzers are of relatively simple design and overcome some of the problems of conveying heat for pyrolyzing biomass or wastes. The mechanical forces associated with auger reactors enhance particle mixing and heat transfer, which are key to successful pyrolysis. This paper presents a comprehensive review of the advantages and challenges of this technology and identify the main characteristics of both single- and twin-screw auger technology. The effect of operating conditions on yield and some properties of pyrolysis products are also provided. The review includes examples of commercial/demonstration-scale auger pyrolysis plants operated around the world. Highlights • The literature on auger pyrolyzers is widely surveyed. • Auger technology is attractive for pyrolyzing a wide range of feedstocks. • Auger pyrolyzers are able to work for fast, intermediate and slow conditions. • Yields and products characteristics are described for different plants. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Biogas (CH 4 + H 2) production from L. minor by integrated approach has high potential. • Three-stage integration was effective for highest energy yield (38.7 ± 1 mol/kg TOC R). • Maximum biogas recovered resulting in recycling of 530.7 dm3 of CO 2 per kg TOC R. • Analysis of organic flux elucidated the effectiveness of each process on integration. Abstract Aquatic weed, Lemna minor was evaluated for its potential as a feedstock for gaseous fuel production (biohythane) in an integrated strategy. Three approaches viz., acidogenic fermentation (H AF), electrohydrogenesis (H MEC) and methanogenesis (M AD), were evaluated in single stage as well as in different combinations of two stage (H AF → H MEC , H AF → M AD) and three stage (H AF → H MEC → M AD , H AF → M AD → H MEC) to tap the maximum feasible energy. Compared to single and two-stage operations, three-stage operation evidenced higher biogas (H 2 + CH 4) yield with remarkable total organic carbon (TOC) reduction. Irrespective of the integration sequence, H AF in first stage depicted the possibility of harnessing higher energy by accumulation of volatile fatty acids (VFA) along with H 2 production. Similarly, integration of M AD in second stage showed the possibility of tapping higher energy rather than H MEC due to higher carbon loss as CO 2 coupled to more H 2 fraction in biogas in case of H MEC. Among, three-stage integrations, higher biogas yield and energy recovery was observed in H AF → M AD → H MEC (38.77 mol biogas/kg TOC R ; 25,415 KJ/kg TOC R) as compared to H AF → H MEC → M AD (37.79 mol biogas/kg TOC R ; 15,416 KJ/kg TOC R). Along similar lines, analysis of organic carbon flow exhibited significant substrate degradation in three stage integrations (72.5–81.4%) as compared to second (66.2–70%) and first stage (39.7–56.5%). [ABSTRACT FROM AUTHOR]

To gasify the biofuel of low ash melting temperature and overcome the high content of tar in bio-gas, a novel two-stage gasification concept is proposed. This concept enables the tar-free bio-gas generated in the gasification process under thermal cracking. On that basis, a demonstration project is introduced. Rice husk acts as the feedstock for its accessibility on-site in the commissioning period. System reliability has been confirmed for the stable operation of more than 60 days. Tests have been performed under some typical operating conditions. As the results suggest, the bio-gas of 6.7 MJ/Nm 3 LHV is generated with cold gas efficiency and carbon conversion of 67.5% and 87% respectively. Elementary economic evaluation of this concept is also made in accordance with the commissioning results. As a result, the annual net profit of 40.92 K USD is yielded without a subsidized price for biomass materials. [ABSTRACT FROM AUTHOR]

Under the framework of circular economy, agricultural wastes are an interesting carbon-based feedstock for thermal energy and power generation. Their use could extend the availability of biomass-based fuel and, at the same time, would reduce negative environmental effects. However, depending on the residues’ characteristics, their direct combustion in boilers presents some challenges which could be overcome with a carbonization pre-treatment. In this paper, the main mechanisms of thermochemical transformation of an abundant agricultural waste, olive stone, into biochar products via slow carbonization are analyzed, with emphasis on the effect of peak carbonization temperature. Thermogravimetric and differential scanning calorimetry analysis are used to evaluate the performance of the resulting biochars compared to raw olive stone in combustion processes and to assess the correlation between the peak carbonization temperature and compositional and fuel properties. Results show that with a prior treatment up to an optimum temperature of 800 °C the energy density is increased up to three times compared to the raw material. These findings suggest that carbonization of olive stones reduces the barriers to their direct use in current biomass boiler technology. [ABSTRACT FROM AUTHOR]

Abstract: An integrated biobased economy urges an alliance of the two realms of “chemical production” and “electric power”. The concept of electrobiorefineries provides a blueprint for such an alliance. Joining the forces of microbial and electrochemical conversions in electrobiorefineries allows interfacing the production, storage, and exploitation of electricity as well as biobased chemicals. Electrobiorefineries are a technological evolution of biorefineries by the addition of (bio)electrochemical transformations. This interfacing of microbial and electrochemical conversions will result in synergies affecting the entire process line, like enlarging the product portfolio, increasing the productivity, or exploiting new feedstock. A special emphasis is given to the utilization of oxidative and reductive electroorganic reactions of microbially produced intermediates that may serve as privileged building blocks. [ABSTRACT FROM AUTHOR]

Abstract: Microalgal biomass processing by continuous hydrothermal liquefaction (HTL) has recently received much interest and can be used to convert microalgal biomass to biocrude oil and drop‐in fuels. This review focuses on the conversion of microalgae biomass to energy production through continuous HTL processes. In addition, processes for upgrading feedstocks and biocrude are also discussed. The feed of the biomass slurry is treated according to size and moisture regulations. Following separation of the gaseous, liquid, and solid phases, the determination of elemental, physical, and chemical fragments, yield of energy, and other properties of the various products is carried out. Homogeneous or heterogeneous catalysts improve the biocrude yield and quality as does higher moisture content. The high percentage of N2 and O2 in the feedstock results in lower quality products. This may be resolved through pre‐processing of the biomass, controlling of HTL processes conditions, and post‐upgrading processing of the HTL products. The promising potential of microalgae biomass for biocrude and drop‐in fuels may have an important contribution to the world's renewable energy sources through HTL in the near future. [ABSTRACT FROM AUTHOR]

Upgrading of bitumen blended with microalgae Chlorella vulgaris was investigated in supercritical water (SCW) at 440 °C and 30 MPa in a home-made batch type bomb reactor. The effects of the water/feed ratio ranging from 2 to 10 and the effects of microalgae fraction in the feeds ranging from 0 (pure bitumen) to 100 wt.% (pure microalgae) were investigated. Pyrolysis experiments in the absence of water were also performed at the same conditions. SCW was found to suppress the coke formation. 25 wt.% microalgae addition to bitumen increased VR conversion 20% with a considerable increase in gas content and diesel yield. Increasing microalgae fraction in the feed to 50 wt.% resulted in increased light liquid yields due to increasing conversion of VR and also led to undesired increases in coke and gas formation. Water/feed ratio of 10 led to increased gas yields with a lower VR conversion. [ABSTRACT FROM AUTHOR]

With a major global emphasis on the management of waste, alternative resources and a shift to environmentally sustainable technologies, demand for large volumes of heterogeneous solid biomass feedstocks for energy or chemical use is expected to rise significantly. In transforming a sporadic supply of a low-value, highly variable product, to continuous and controlled high throughput systems, a thorough understanding of the feedstock properties will increase in importance. Appropriate characterisation tests are necessary to define technical specification and selection criteria for handling equipment and to appraise the requirement and location for additional processes or pre-treatment to be integrated into the handling chain. Such tests may also influence the material characteristics to be used in the conversion process. This paper discusses the main feedstock attributes associated with a number of handling chain phases and the approach to obtain them. The framework for a holistic approach to the characterisation and design of biomass feedstock handling systems for further development and practical implementation is also proposed. [ABSTRACT FROM AUTHOR]

Given the expected rise in the importance and rate of decisions being made in the biofuel sector and the complexity of the system, this paper is focused on an analysis that, although well-established in economic and environmental evaluation theory, has not been widely used yet to assess biodiesel production. The aim of this study, in particular, is to analyze, from a quantitative point of view, the water footprint resulting from the use of various types of crops for the production of Italian biodiesel, combining it with the import costs of these crops, based on the current trade partners, and the crop energy conversion efficiency. The problem from the importing country's point of view is to minimize the total cost related to the import of crop products and, at the same time, to minimize the overall water footprint, ensuring a quantity of biodiesel produced at least equal to the pre-defined target set by the European Union for 2020. The paper provides a first glance at addressing optimal resource allocation and the design of biodiesel imports in the EU regulation context, contributing to reducing the water footprint, without ignoring the economic aspects. The study represents an original contribution for the identification of potential environmental policy drivers in the context of an economic sector characterized by potential growth, serving as a guide for the resolution of the trade-offs between biodiesel demand, import costs of feedstocks and water impact. [ABSTRACT FROM AUTHOR]

Nowadays, biofuel production is a fast expanding industry and is facing a growing dilemma about a feedstock source capable of keeping up with demand. Recently, macroalgae have been attracting a wide attention as a source for biofuel. In the present study, ten macroalgae were collected and screened as biodiesel feedstocks. As a result of their high biomass production and relatively high lipid content, Ulva lactuca , Padina boryana and Ulva intestinalis showed the highest significant lipids and fatty acid methyl esters (FAMEs) areal productivities among the studied species. Saturated fatty acids (SAFs) showed insignificant differences in the selected species, with noticeably significant higher polyunsaturated fatty acids (PUFAs) content in U. lactuca by 4.2 and 3 times, with respect to P. boryana and U. intestinalis , respectively. The recorded increase in PUFAs was attributed to higher content of C16:4 n -3, C18:3 n -3 and C18:4 n -3. By lipid fractionation, P. boryana showed significant higher concentration of neutral lipids (37.7 mg g −1 CDW, representing 46.7% of total fatty acids) in comparison to U. lactuca and U. intestinalis , which showed 16% and 17% lower neutral lipid fractions, respectively. In addition, biodiesel characteristics of the studied macroalgae complied with that of international standards. Furthermore, oil-free residual biomass can be readily converted into fermentable sugars or biogas due to its high carbohydrates content, which adds to the economics of macroalgae as biofuel feedstock. In conclusion, the present study confirmed that macroalgae represent an attractive alternative renewable feedstock for biodiesel and other biofuels. [ABSTRACT FROM AUTHOR]

This study compares the techno-economic feasibility of five forest-based biofuel conversion pathways for road transportation in the Nordic countries with particular focus paid to feedstock cost effects on total costs in a partial equilibrium model environment. We present (I) a literature review of techno-economic estimates detailing biofuel costs at various capacities, (II) estimate a capacity-wise normalized cost-comparison of the conversion pathways, and (III) estimate the feedstock cost changes with increasing biofuel facility deployment in the Nordic Forest Sector Model. The results indicate that fast pyrolysis and hydrothermal liquefaction are the most cost-competitive options among the reviewed conversion pathways. We found average costs of FASTPYR and HTL to range from 0.84 € −L to 0.91 € −L (0.93 $ −L to 1.01 $ −L ) and 0.84 € −L to 0.88 € −L (0.93 $ −L to 0.98 $ −L ) depending on the techno-economic data used and forest biomass marked demand. Technology learning may reduce these costs further. The conversion pathways are not cost-competitive with current fossil alternatives but may be cost-competitive with current biofuel conversion pathways, given nth plant cost levels. At a biofuel production level corresponding to 20% of the Nordic fossil fuel consumption for road transport, feedstock costs increase 12.0–35.2%, depending on the conversion pathway and the restrictions imposed on what constitutes biofuel feedstock. This corresponds to an increase ranging from 9.9% to 26.2% on the total costs. Technology learning may outweigh the effect of feedstock cost increases on the total costs depending on the learning rate and the conversion pathway. The results of this study can potentially aid policy creation for conversion pathway evaluation and support schemes. [ABSTRACT FROM AUTHOR]

Seaweeds are considered a viable feedstock for producing energy through the anaerobic digestion conversion process. Its exploitation and use as an alternative renewable energy source; however, remains marginal in the EU. This study aims to evaluate BMP in batch tests of the brown algae Fucus vesiculosus from the Baltic Sea and collected from the Latvian coast. The lab scale BMP tests were oriented towards the evaluation of the effects of mechanical and microwave pre-treatment methods, as well as the impact of a different algae-to-inoculum (A/I) ratio using: i) cutting blades together with mortar and pestle (C&PM) in combination with the use of a 700 W capacity microwave, ii) 1:3 and 1:5 A/I ratios. The cumulative CH 4 yields show a value in the range of 68 ± 21 mL CH 4 /g VS – a trial with no microwave treatment and A/I of 1:3) and 144 ± 28 mL CH 4 /g VS – a trial including a microwave treatment for 3 min, and A/I ratio of 1:3. The results show effectiveness in the range of 7.8%–43.7%, when the microwave pre-treatment is applied for 1.5 min, and a range of 37.2%–45.2% when the pre-treatment is applied for 3.0 min. The results of this study suggest promising potential for F. vesiculosus for biogas production, especially in the Baltic region. [ABSTRACT FROM AUTHOR]

Biomass used in energy conversion processes is typically characterized by high variability, making its utilization challenging. Therefore, there is a need for a fast and non-destructive method to determine feedstock/product properties and directly monitor process reactors. The near-infrared spectroscopy (NIRS) technique together with advanced data analysis methods offers a possible solution. This review focuses on the introduction of the NIRS method and its recent applications to physical, thermochemical, biochemical and physiochemical biomass conversion processes represented mainly by pelleting, combustion, gasification, pyrolysis, as well as biogas, bioethanol, and biodiesel production. NIRS has been proven to be a reliable and inexpensive method with a great potential for use in process optimization, advanced control, or product quality assurance. [ABSTRACT FROM PUBLISHER]

Anaerobic digestion (AD) plants enable renewable fuel, heat, and electricity production, with their efficiency and capital cost strongly dependent on their installed capacity. In this work, the technical and economic feasibility of different scale AD combined heat and power (CHP) plants was analyzed. Process configurations involving the use of waste produced in different farms as feedstock for a centralized AD plant were assessed too. The results show that the levelized cost of electricity are lower for large-scale plants due to the use of more efficient conversion devices and their lower capital cost per unit of electricity produced. The levelized cost of electricity was estimated to be 4.3 p/kWhe for AD plants processing the waste of 125 dairy cow sized herds compared to 1.9 p/kWhe for AD plants processing waste of 1000 dairy cow sized herds. The techno-economic feasibility of the installation of CO2 capture units in centralized AD-CHP plants was also undertaken. The conducted research demonstrated that negative CO2 emission AD power generation plants could be economically viable with currently paid feed-in tariffs in the UK. [ABSTRACT FROM AUTHOR]

Success and acceptability of the bio energy conversion technology to a large extent depend upon management of the inevitable by-products generated during the conversion process. By-products can be considered favourable as organic fertilizer as they retain nutrients with varying composition depending upon input biomass. However, characteristics of these heterogeneous resources with respect to feedstock and processing conditions have to be assessed to state on their agricultural and environmental benefits. Therefore, 3 types of anaerobic digestion by-products (digestate) from surplus biomass viz. cow dung, Ipomoea carnea:cow dung (60:40 dry weight basis) and rice straw:green gram stover:cow dung (30:30:40 dry weight basis) and one gasification by-product (biochar) from rice husk are considered to understand the fertilizer prospects. Considering 3 potential application options, digestate from each feedstock option was further processed as separated solid, separated liquid and ash from solid digestates. Thus, a total of 10 by-products were investigated for understanding their prospects as fertilizer using Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X ray Spectroscopy (EDX) and phyto-toxicity test to have a broad insight in terms of their organic, mineral, elemental composition, morphological feature and potential phyto-toxicity. In general, irrespective of origin of feedstock, solid digestate, ash digestate and char showed similarity in terms of composition of functional groups with some degree of variation in relative content as reflected by FTIR analysis. Dominance of organic functional groups in separated solid digestates compared to liquid fraction indicated the former as favourable organic amendments. Quartz was the prevalent mineral phase in all separated solid, ash digestate and rice husk char. Digestates in ash phase represent more concentrated plant nutrient source with higher content of K, Ca, P, Na and Mg than their respective solid phase. Application of ash digestates and char is likely to improve adsorptive capacity of soil for water and nutrient due to presence of relatively uniformly distributed porous particles. Liquid fraction of Ipomoea digestates exhibited inhibitory effect on seed germination of greengram ( Vigna radiate) with significant reduction of germination index. Inhibitory effects of by-products were found to correlate negatively with their electrical conductivity and ammonia-nitrogen content. Understanding on spectroscopic, morphological and phytotoxic properties of different application options of bioenergy by-products would be useful for assessment of their appropriate use in agriculture. [ABSTRACT FROM AUTHOR]

The fixed bed slow pyrolysis of lemongrass (Cymbopogon flexuosus) is studied with the aim of determining the main characteristics of the bio-oil formed and the quantity of bio-oil produced. Variables investigated were temperatures between 350 and 550°C, particle sizes between 0.3–0.6 and 1.0–1.25 mm, and heating rate of 15 and 45°C/min. Under the conditions of this study, temperature was very significant parameter to determine the product yield. Whereas particle size and heating rate have less effect on the yield. Higher pyrolysis temperature resulted in higher fixed carbon content. At higher pyrolysis temperature, more volatiles have been removed, which resulted in lower char yield. The maximum bio-oil yield of 40.6 wt% was obtained at the final pyrolysis temperature of 450°C, particle size range of 0.71–1.0 mm, and heating rate of 45°C/min in a fixed-bed lab-scale reactor. Chromatographic studies on the bio-oil showed that the oil obtained from lemongrass can be used as a renewable fuel having heating value of 17.2 MJ/kg and chemical feedstock. [ABSTRACT FROM PUBLISHER]

Recent advancements in the microbial fuel cell (MFC) field have led to the deployment of pilot-scale autonomous sanitation systems converting the organic content of urine into electricity to power lights in decentralised areas. Two designs have been deployed successfully, namely ceramic cylinder based MFCs ( c -MFC) and membrane-less self-stratifying MFCs ( s- MFC) , but only one research has tested simultaneously these two designs under similar conditions. To complement this single study, the present work investigated the response of these two designs to the dilution of feedstock. Both designs were assembled as cascades, a configuration close to the conditions of implementation. The tested conditions were 100%, 75%, 50%, 25% urine diluted with tap water. Results have shown that under the 100% condition (neat urine), the s- MFC had a higher energy output (2.29 ± 0. 04 kJ d−1) and treatment (4.16 ± 0.15 g COD.d −1 ; 1.39 ± 0.15 g NH4.d −1 ) than the c -MFC. Under the 25% condition, the c -MFC had a higher energy output (0.75 ± 0. 04 kJ d−1) but a lower treatment (0.40 ± 0.05 g COD.d −1 ; 0.01 ± 0.02 g NH4.d −1 ) than the s- MFC. Both type of cascade designs could be fed a 75% concentration feedstock for a week without a significant performance decrease. Overall, the c -MFC cascade had higher energy conversion efficiency and the s- MFC had higher power generating performance. [Display omitted] • The ammonium removal rate positively correlated to the feedstock concentration. • The organic removal rate negatively correlated to the feedstock concentration. • Ceramic based designs have higher conversion efficiency than membrane-less designs. • Membrane-less designs have higher performance than ceramic based designs. • The presence of membranes limits the impact of urine dilution. [ABSTRACT FROM AUTHOR]

Consumption of renewable fuels from carbon rich urban refuse is attracting core attention in the ongoing as well as upcoming research works,among which agricultural waste and municipal solid wastes (MSWs) are deliberate substrates which have issues on disposal, that can be manipulated toward the production of cleaner and versatile fuels such as biohydrogen and biogas, and also these gaseous fuels make distribution effortless, since they can be transported easily. Biohydrogen is the only carbon free fuel which ultimately oxidizes to give water as a by-product, and also it is a flexible and safe energy resource which can be utilized in all sectors globally. Biohydrogen can be converted into energy either through combustion or fuel cells to generate electricity, and further it releases explosive energy in heat engines. Biogas is a combination of two-thirds of methane (CH 4 ) and the rest is mostly carbon dioxide (CO 2 ) with traces of hydrogen sulfide which can be enriched to produce natural gas. Not only the gas but also the spent slurry can be enriched to be utilized as fertilizer for agricultural crops and hence promoting sustainable biomass production in the world. Both biogas and biohydrogen can be utilized to produce centralized or distributed power supply in rural and urban areas and are considered to be cost beneficial. In this review we focus on the insights into these two prominent gaseous fuels in order to draw more research and development toward producing a sustainable environment. [ABSTRACT FROM AUTHOR]

The production of biofuels from lignocellulosic feedstock is attracting considerable attention in the United States and globally as a strategy to diversify energy resources, spur regional economic development and reduce greenhouse gas emissions. Because of the wide variation in feedstock types, compositions and content of convertible organics, there is a growing need to better understand correlations among feedstock quality attributes and conversion performance. Knowledge of the feedstock impact on conversion is essential to supply quality controlled, uniform and on-spec feedstocks to biorefineries. This review paper informs the development of meaningful feedstock quality specifications for different conversion processes. Discussions are focused on how compositional properties of feedstocks affect various unit operations in biochemical conversion processes, fast pyrolysis and hydrothermal liquefaction. In addition, future perspectives are discussed that focus on the challenges and prospects of addressing compositionally intrinsic inhibitors through feedstock preprocessing at regionally distributed depots. Such preprocessing depots may allow for the commoditization of lignocellulosic feedstock and realization of stable, cost-effective and quality controlled biomass supply systems. [ABSTRACT FROM AUTHOR]

Development of a new technology for conversion of residual biomass into a liquid fuel via pyrolysis–gasification–gas cleaning–synthesis is the overall objective of the on-going bioliq ® project. The present paper gives an overview on research activities dedicated to mathematical modelling of entrained-flow gasification for conversion of biomass-based suspension fuels into a medium calorific (LCV around 15 MJ/kg) synthesis gas. The objective is to identify knowledge gaps that currently prohibit a knowledge-based mathematical description of reacting high-pressure multi-phase flows so as to model the bioliq ® gasification reactor in particular and biomass conversion in entrained flow gasifiers in general. Substantial knowledge gaps for high pressure process conditions have been identified for atomization of high viscous liquids, gasification chemistry for biomass-based fuels, radiative heat transfer as well as slag formation mechanisms. The paper proposes an interdisciplinary research approach in a holistic manner to close these gaps. [ABSTRACT FROM AUTHOR]

• Recent Cu-based catalysts for CO 2 reduction to C 2+ products are summarized. • Mechanism of CO 2 RR on Cu surfaces are elaborated separately. • Recent approaches to catalyst design are summarized. • Challenges and outlooks in Cu-based catalysts towards CO 2 RR are highlighted. Electrochemical CO 2 reduction (CO 2 RR) driven by renewable energy is a promising strategy to close the anthropogenic chemical carbon cycle and simultaneously increase carbon feedstock production. Multi-carbon (C 2+) products from CO 2 RR are very attractive as they are important fuels, chemicals, and industrial raw materials. Copper has received wide attention as an excellent metal catalyst for the formation of C 2+ products through CO 2 RR. Although important advances have been made for Cu-based catalysts to produce C 2+ products, there are still challenges such as wide product diversity, poor yield, and high overpotentials. The structure and composition of catalysts affect the binding strength of key intermediates such as *CO and *OCCO during the CO 2 RR process. Therefore, it is necessary to have in-depth knowledge of the relationship between the structural components and performance to figure out reasonable design strategies. Here, we summarize the favored mechanisms for CO 2 RR and the possible pathways to produce C 2+ products on the surfaces of Cu-based materials. Recent approaches to catalyst design, including structure control, oxide-derived Cu, bimetallic strategy, surface modification, and atomic-level dispersion, are evaluated for their CO 2 RR performance. Finally, challenges and perspectives in this field are highlighted for further improvement of CO 2 RR. [ABSTRACT FROM AUTHOR]

The article presents an essay on the study to evaluate nitrogen and carbon chemistries as alternative routes for stationary chemical hydrogen storage. It focuses on the capture of N2 and CO2 from the atmosphere as feedstock to set a common basis for the comparison of the various chemical hydrogen storage routes. The minimum energy needed to separate a gas mixture can be examined from entropy considerations assuming ideal gases.

The present study aims to quantify the main biomass resources in South Tyrol (Northern Italy) and estimate the potential contribution for the energy sector. Moreover, four representative feedstocks have been tested in a domestic pellet boiler under standard conditions in order to assess its performance and pollutant emissions. The unexploited biomass potential for energy conversion applications, expressed as dry weight, has been estimated to be 135 000 t y −1 from forest, 14 950 t y −1 for apple pruning residues and 12 000 t y −1 from the industrial sector. The scenario of utilizing the unexploited local biomass resources – in energy systems such as the ones deployed in South Tyrol – would contribute with an annual bioenergy production contribution of 130–270 TJ of electricity and 1700–2100 TJ of heat. Finally, the tested feedstocks can be used in domestic boilers, however, some modifications are required when using agricultural residues. [ABSTRACT FROM AUTHOR]

Previous studies of cellulosic-ethanol production have shown that the cost of producing cellulase is surprisingly significant, and that reducing this cost is key to making cellulosic-ethanol economically viable. This study confirms that finding, and compares the costs of the three approaches for producing cellulase: off-site, on-site, and integrated. It finds that the integrated method is the lowest cost, primarily because it substitutes an inexpensive feedstock, biomass, for a relatively expensive one, glucose. This substitution also makes the ethanol a 100% second-generation biofuel, i.e., it uses no 'food for fuel'. This study also compares the activity of cellulase produced by the integrated method versus that produced by the off-site method. Laboratory trials of the two show the 'integrated' cellulase to be better or equal to commercially available 'off-site' cellulase in converting cellulose to sugar. © 2016 The Authors. Biofuels, Bioproducts, Biorefining published by Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This section offers news briefs related to the biofuels industry in the world as of March 2016. Topics covered include the greenhouse gas emission savings effort of Great Britain and the plan of Global Bioenergies to boost the feed-stock flexibility of isobutene process of Global Bioenergies. Also mentioned is the aim of the U.S. Department of Energy to offer funding to create biofuel conversion technologies.

HTC (hydrothermal carbonization) is a technically-attractive thermal conversion process for biomass to produce solid carbonaceous products at mild conditions. EB (eucalyptus bark) was used as a feedstock for producing hydrochar by HTC. Effect of process conditions on the yield and physicochemical properties of hydrochar was examined by varying carbonization temperature over the range of 220–300 °C and varying residence time over the range of 2–10 h. With increase in temperature, the hydrochar yield decreased slightly from 46.4% at 220 °C to 40.0% at 300 °C. The O/C and H/C atomic ratios reduced from 1.69 and 0.80 to 0.83 and 0.23, respectively, which was mostly related to dehydration, decarboxylation and demethanation reactions. The oxygen containing functional groups decreased with increasing temperature. HHV (higher heating value) of hydrochar was in the range of 20.2–29.2 MJ/kg. Thermogravimetric analysis showed that hydrochar products obtained at temperature over 220 °C exhibited almost the same thermal behaviors. In comparison, the influence of residence time on the yield, physicochemical properties and thermal behavior of hydrochar was marginal. [ABSTRACT FROM AUTHOR]

The thermal decomposition of woody biomass in the absence of oxygen, or pyrolysis, is a series of complex reactions involving hundreds of compounds. The species of residue, form of residue (bark, sawdust, and other residues), age, storage conditions, among other factors, will impact the composition of the residue which in turn impacts the pyrolytic reactions. The reaction rates must be understood to optimize the pyrolysis reactor. However, the determination of intrinsic kinetics in this system is complex (both due to feedstock composition and the nature of reactions at pyrolysis temperatures) and as such the approach has been to use an overall reaction rate or series of simplified reactions. In this study, a review of large scale pyrolysis process units, reactor mathematical models, mechanisms for conversion of woody biomass and overview of heat of pyrolysis is presented. In addition, the presented kinetic models have been compared to experimental data obtained from pyrolysis of different liginocellulosic biomass (i.e. sawdust, bark, and wood chips) in a lab-scale tube furnace reactor, to determine the “best” kinetic model for the fast pyrolysis of sawmill residues. The results show that the chemical percolation devolatilization model (Lewis et al. Energy Fuels 2013; 27:942–953. doi:10.1021/ef3018783) predicts the pyrolysis products most accurately. Furthermore, the competitive model (Chan et al. Fuel 1985; 64:1505–1513. doi:10.1016/0016-2361(85)90364-3) shows very good agreement for bio-oil experimental data. Although the pyrolysis of biomass has been widely investigated in recent decades, the models have some limitations which could limit their application to a broad spectrum of feedstock and pyrolysis operating conditions. [ABSTRACT FROM AUTHOR]

In this study, a well-controlled three-stage process was proposed for high ammonium removal from synthetic wastewater using selected promising microalgal strain UMN266. Three trophic modes (photoautotrophy, heterotrophy, and mixotrophy), two N sufficiency conditions (N sufficient and N deprived), two inoculum modes (photoautotrophic and heterotrophic), and different NH 4 + -N concentrations were compared to investigate the effect of trophic mode conversion and N deprivation on high NH 4 + -N removal by UMN266. Results showed that photoautotrophic inoculum with trophic mode conversion from heterotrophy to photoautotrophy and N deprivation in Stage 2 turned was the optimum plan for NH 4 + -N removal, and average removal rates were 12.4 and 19.1 mg/L/d with initial NH 4 + -N of 80 and 160 mg/L in Stage 3. Mechanism investigations based on algal biomass carbon (C) and N content, cellular composition, and starch content confirmed the above optimum plan and potential of UMN266 as bioethanol feedstock. [ABSTRACT FROM AUTHOR]

Municipal solid waste (MSW) can be viewed as a feedstock for industrial ecology inspired conversions of wastes to valuable products and energy. The industrial ecology principle of symbiotic processes using waste streams for creating value-added products is applied to MSW, with examples suggested for various residual streams. A methodology is presented to consider individual waste-to-energy or waste-to-product system synergies, evaluating the economic and environmental issues associated with each system. Steps included in the methodology include identifying waste streams, specific waste components of interest, and conversion technologies, plus steps for determining the economic and environmental effects of using wastes and changes due to transport, administrative handling, and processing. In addition to presenting the methodology, technologies for various MSW input streams are categorized as commercialized or demonstrated to provide organizations that are considering processes for MSW with summarized information. The organization can also follow the methodology to analyze interesting processes. [ABSTRACT FROM AUTHOR]

Fluid catalytic cracking (FCC) is one of the major conversion technologies in the oil refinery industry. FCC currently produces the majority of the world's gasoline, as well as an important fraction of propylene for the polymer industry. In this critical review, we give an overview of the latest trends in this field of research. These trends include ways to make it possible to process either very heavy or very light crude oil fractions as well as to co-process biomass-based oxygenates with regular crude oil fractions, and convert these more complex feedstocks in an increasing amount of propylene and diesel-range fuels. After providing some general background of the FCC process, including a short history as well as details on the process, reactor design, chemical reactions involved and catalyst material, we will discuss several trends in FCC catalysis research by focusing on ways to improve the zeolite structure stability, propylene selectivity and the overall catalyst accessibility by (a) the addition of rare earth elements and phosphorus, (b) constructing hierarchical pores systems and (c) the introduction of new zeolite structures. In addition, we present an overview of the state-of-the-art micro-spectroscopy methods for characterizing FCC catalysts at the single particle level. These new characterization tools are able to explain the influence of the harsh FCC processing conditions (e.g. steam) and the presence of various metal poisons (e.g. V, Fe and Ni) in the crude oil feedstocks on the 3-D structure and accessibility of FCC catalyst materials. [ABSTRACT FROM AUTHOR]

The production of diesel and gasoline range paraffins from both solid and liquid biomass is one of the promising alternatives being considered for ensuring sustainable fuel supply. Solid biomass gasification produces synthetic gas, which via subsequent Fischer-Tropsch reaction is converted into useful liquid hydrocarbon fuels. Similarly, pyrolysis generates oxygenated and bio-oil products with comparable fuel potentials. The liquid biomass such as vegetable oils, on the other hand can be upgraded by serial hydrogenation, cracking, deoxygenation, and decarboxylation. We have critically reviewed substantial literature on the various conversion processes and the hydroisomerization of the linear bioparaffins into isomerized products with enhanced fuel properties. Emphasis was given to the heterogeneous catalyst systems, operational parameters, reaction mechanisms, and identified challenges. The scope was extended to cover different porous catalysts with prospects in biomass-to-fuel conversion. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The hydrotreatment of different VGO feedstocks in a pilot plant is modeled using the continuous lumping approach. A model with five continuous families (paraffins, naphtenes, sulfur-containing aromatics, nitrogen-containing aromatics, and sulfur and nitrogen free aromatics) is proposed and validated in this work. The model considers the five families to be a continuous distribution. A reaction network, including hydrogenation, desulfurization, denitrogenation, and cracking is established and used to derive the kinetic rate expressions for each family. A total of 46 model parameters are adjusted, using data from 44 experimental runs, using a pilot plant. Three feedstocks of different origin and thus different characteristics (e.g. True Boiling Point, sulfur- and nitrogen content) were used in this study. The same set of parameters was used to simulate hydrotreatment of all three feedstocks, which extends the range of applicability of the model beyond the models which are typically proposed in literature, which rely on feedstock-specific parameters. The model was validated using 14 additional tests with 2 different feeds. The results show that this modeling approach is capable of accurately predicting the total hydrocarbon conversion and yield regardless of feed composition. Furthermore, insights into the underlying reaction mechanisms can be gained from the kinetic parameters. [ABSTRACT FROM AUTHOR]

Wheat straw has a vast potential as feedstock for biofuel production in China. However, little information is available regarding variation in cell wall composition and enzymatic digestibility of wheat straw. This study investigated cell wall compositions and biomass digestibility of the straw of 115 wheat accessions from central China using a 1% NaOH pretreatment and mixed enzymatic hydrolysis. Significant variation in cell wall composition and sugar release was observed, with a coefficient variation (CV) ranging from 4.7% to 21.2%. Cellulose, hemicelluloses, alkali detergent hemicelluloses (ADH), and acid insoluble lignin (AIL) positively correlated with each other, and they all negatively correlated with acid soluble lignin (ASL). Hexose yields had a negative correlation with ADH and AIL, and positive correlation with ASL. No apparent undesirable correlation was found between sugar release and grain yield, thus yield and biomass convertibility can be potentially improved simultaneously. Furthermore, the features of the cell wall constitutions were compared with other plants and their implication in determining the best possible conversion strategy was discussed. This initial study is essential to understand the cell wall composition of wheat straw and to explore the potential of wheat straw as feedstock for biofuel production. [ABSTRACT FROM AUTHOR]

The catalyst-free microwave-assisted conversion of free fatty acids (FFA) to alkyl esters in triglyceride feedstocks with a high acid content was studied. To this end, esterification of FFA with higher alcohols was investigated using the response surface modelling approach (RSM). A model was constructed using stearic acid and 1-butanol. The influence of reaction temperature and the FFA content in the triglyceride feedstock were studied by varying both parameters on 5 levels between 175 °C and 275 °C, and 30 mass% and 100 mass% FFA respectively. Afterwards, the general applicability of the model was verified using other FFA, fatty acid distillates (FAD) from industry and other alcohols. When using other FFA, FAD or primary alcohols other than 1-butanol, the model is able to accurately predict the actual conversion with a typical deviation between actual and predicted data of 2%. After 1 h of reaction at temperatures above 250 °C, conversions over 90% were reached. [ABSTRACT FROM AUTHOR]

Abstract: This paper proposes and tests novel supply chain designs for bioenergy and biobased products that result in logistical costs savings of 2–38%. The proposed supply chain design reduces the costs of: (1) purchasing logistical harvesting equipment; (2) operating logistical harvesting equipment; and (3) holding feedstock inventory, by using a multitude of crop types as feedstock, instead of just one, as is common in research and practice today. In so doing, this research challenges the prevalent assumption that monocultures, despite their known environmental concerns, are preferable from a costs perspective. Simulation/optimization is used to test supply chain designs, and then to find the environmental conditions where these new supply chain designs could be most profitably implemented. [Copyright &y& Elsevier]

SUMMARY In order to evaluate quantitatively the effect of syngas cooling modes of slurry feed gasification on the hydrogen production process, two processes of gasification for hydrogen with petcoke as the feedstock were developed in the paper, which were petcoke water slurry + total quench + high water/dry gas (W/G) and petcoke water slurry + radiant syngas cooler + quench + low W/G, named by cases 1 and 2, respectively. The two processes were simulated by using Aspen Plus. The results show that with the operating parameters used by the system, the energy conversion efficiency of cases 1 and 2 are the same, which is 74%. The exergy efficiency of case 2 is higher than that of case 1, which are 62% and 61%, respectively. The water consumption of cases 1 and 2 are almost the same. However, the proportion of high-quality steam produced in case 2 is higher, and the quantity of high-quality steam is larger than that of case 1. The system profit of case 2 is better than that of case 1. Thus, case 2 is better than case 1 and is more suitable for petcoke gasification for hydrogen taking the gasification performance, energy utilization analysis, system water utility analysis, and system performance yield rate into account. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Highlights: [•] A comprehensive overview of recent progress in enzymatic biodiesel production. [•] Critical assessment of merits and demerits of enzymatic biodiesel process. [•] Economic considerations and large scale developments in enzymatic biodiesel. [•] Current trends and future directions for enzymatic biodiesel R&D. [Copyright &y& Elsevier]

Abstract: Empty fruit bunch (EFB) from oil palm is one of the potential biomass to produce biofuels like bio-oil due to its abundant supply and favorable physicochemical characteristics. Confirming the assertion, this paper presents an overview of EFB as a feedstock for bio-oil production. The fundamental characteristics of EFB in terms of proximate analysis, ultimate analysis and chemical composition, as well as the recent advances in EFB conversion processes for bio-oil production like pyrolysis and solvolysis are outlined and discussed. A comparison of properties in terms of proximate analysis, ultimate analysis and fuel properties between the bio-oil from EFB and petroleum fuel oil is included. The major challenges and future prospects towards the utilization of EFB as a useful resource for bio-oil production are also addressed. [Copyright &y& Elsevier]

Highlights: [•] Energy demand of 122 microalgae biomass production scenarios were compared. [•] Choice of harvesting technology affected energy demand of other phases. [•] Raceway ponds, settling, and chamber filter press consumed the least energy. [•] Total energy demand for biomass production depends on final concentration. [Copyright &y& Elsevier]

Insufficient spatial coverage of existing land-cover data is a common limitation to timely and effective spatial analysis. Achieving spatial completeness of land-cover data is the most challenging for large study areas which straddle ecological or administrative boundaries, and where individuals and agencies lack access to, and the means to process, raw data from which to derive spatially complete land-cover maps. In many cases, various sources of secondary data are available, so that land-cover map assimilation and synthesis can resolve this research problem. The following paper develops a reliable and repeatable framework for assimilating and synthesizing pre-classified data sets. Assimilation is achieved through data reformatting and map legend reconciliation in the context of a specific application. Individual maps are assessed for accuracy at various geographic scales and levels of thematic precision, with an emphasis on the ‘area of overlap’, in order to extract information that guides the synthesis process. The quality of the synthesized land-cover data set is evaluated using advanced accuracy assessment methods, including a measure describing the ‘magnitude of disagreement’. This method is applied to derive a seamless thematic map of the land cover of eastern Ontario from two disparate map series. The importance of assessing data quality throughout the process using multiple reference data sets is highlighted, and limitations of the method are discussed. [ABSTRACT FROM PUBLISHER]

Abstract: This paper provides a literature review of articles on the primary forest fuel supply chain which have been published in English speaking peer-reviewed journals from 1989 to 2011. The focus is on the key issues of the transportation of primary forest fuel to heat and/or power plants: (i) transportation modes, (ii) terminal types, and (iii) forest fuel supply chain management, and provides basics on the logistically relevant characteristics of wood as feedstock such as on various feedstock assortments. The analysed supply chains include the transshipment, storage, handling (e.g. chipping) and transportation of primary forest fuel from the place of harvest to energy conversion plant. Due to spatial distribution, low mass density, low energy density and low bulk density, the transportation of primary forest fuel is crucial for economic efficiency as well as for reduced CO2 emissions. As a consequence of forests accessibility, road transportation (after hauling the biomass to the forest road) is the first step of the modern primary forest fuel supply chain. For longer transportation distances, rail or waterway is preferred because of lower transportation costs per volume transported and lower CO2 emissions. We highlight that some experience exists in multimodal transport, including truck, train or ship. Intermodal transport, however, has not been studied in the past and, therefore, an outlook for the research requirements is made here. [Copyright &y& Elsevier]

Highlights: [•] Decanter cake as a potential waste feedstock for biodiesel production. [•] Ultrasound-aided transesterification achieving nearly 86% conversion in 1h. [•] Boiler ash, a waste product, was successfully used as a catalyst. [ABSTRACT FROM AUTHOR]