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Ample interest for more efficient utilization of bio-based residues has emerged in the Nordic pulp and paper (P&P) industry, which uses virgin wood as feedstock. Although different bioenergy retrofit technologies for production of liquid, solid, and gaseous bioenergy products have been applied in the existing P&P mills, the number of installations remains small. The lack of profound knowledge of existing bioenergy retrofits hinders the replication and market uptake of potential technologies. This review synthesises the existing knowledge of European installations and identifies the key drivers and barriers for implementation to foster the market uptake of potential technologies. The bioenergy retrofits were reviewed in terms of technical maturity, drivers, barriers and market potential. Based on this evaluation, common drivers and barriers towards wider market uptake were outlined from political, economic, social, technical, environmental, and legal perspective. Technologies already commercially applied include anaerobic fermentation of sludge, bark gasification, tall oil diesel and bioethanol production, whereas lignin extraction, biomethanol production, hydrothermal liquefaction and hydrothermal carbonization are being demonstrated or first applications are under construction. The findings of this review show that a stable flow of residues at P&P mills creates a solid base for retrofitting. New innovative bio-based products would allow widening the companies' product portfolios and creating new businesses. Also, European Union's (EU) legislation drives towards advanced biofuels production. Wider uptake of the retrofitting technologies requires overcoming the barriers related to uncertainty of economic feasibility and unestablished markets for new products rather than technical immaturity.

Ample interest for more efficient utilization of bio-based residues has emerged in the Nordic pulp and paper (P&P) industry, which uses virgin wood as feedstock. Although different bioenergy retrofit technologies for production of liquid, solid, and gaseous bioenergy products have been applied in the existing P&P mills, the number of installations remains small. The lack of profound knowledge of existing bioenergy retrofits hinders the replication and market uptake of potential technologies. This review synthesises the existing knowledge of European installations and identifies the key drivers and barriers for implementation to foster the market uptake of potential technologies. The bioenergy retrofits were reviewed in terms of technical maturity, drivers, barriers and market potential. Based on this evaluation, common drivers and barriers towards wider market uptake were outlined from political, economic, social, technical, environmental, and legal perspective. Technologies already commercially applied include anaerobic fermentation of sludge, bark gasification, tall oil diesel and bioethanol production, whereas lignin extraction, biomethanol production, hydrothermal liquefaction and hydrothermal carbonization are being demonstrated or first applications are under construction. The findings of this review show that a stable flow of residues at P&P mills creates a solid base for retrofitting. New innovative bio-based products would allow widening the companies' product portfolios and creating new businesses. Also, European Union's (EU) legislation drives towards advanced biofuels production. Wider uptake of the retrofitting technologies requires overcoming the barriers related to uncertainty of economic feasibility and unestablished markets for new products rather than technical immaturity. Publishers version

Renewable energy production throughout low-voltage grids has gradually increased in electrical distribution systems, therefore introducing small energy producers - prosumers. This paradigm challenges the traditional unidirectional energy distribution flow to include disperse power production from renewables. To understand how energy usage can be optimized in the dynamic electrical grid, it is important to understand the behavior of prosumers and their impact on the grid’s operational procedures. The main focus of this study is to investigate how grid operators can obtain an automatic data-driven system for the low-voltage electrical grid management, by analyzing the available grid topology and time-series consumption data from a real-life test area. The aim is to argue for how different consumer profiles, clustering and prediction methods contribute to the grid-related operations. Ultimately, this work is intended for future research directions that can contribute to improving the trade-off between systematic and scalable data models and software computational challenges. This work is financially supported by the Danish project RemoteGRID, which is a ForskEL program under Energinet.dk with grant agreement no. 2016-1-12399.

Gasification of biomass is an industrial process utilized to produce product gas that can be used in electrical power generation with internal combustion engines. However, there remain huge challenges with regards to tar and other pollutants, thus their removal before further use is necessary. Non-thermal plasma method can be considered as a novel and efficient way for treatment of tar from product gas. In this work, a laboratory-scale, reverse vortex flow gliding arc plasma reactor was developed and tested for the removal of tar model compound using naphthalene as surrogate. Effects of total gas feed rate in the range of 20–60 L/min, applied voltage in the range of 50–220 V, hence, power input in the range of 300–460 W with initial naphthalene concentration of 610 ± 50 mg/m3 on removal and energy input were investigated. It was found the tar removal efficiency increased with increasing applied voltage. Maximum naphthalene removal efficiency of 85% was achieved at applied high voltage of 15 kV and specific energy input of 0.13 kWh/m3 with energy utilization efficiency of about 4.60 g/kWh. From the findings, non-thermal plasma technology appeared to offer great potential in the removal of biomass tar from gasification. The technology may be promising for possible application to real biomass tar cracking and upgrading of product gas from gasification.

Microbial fuel cells (MFCs) are a green technology that can directly convert electrical energy from chemical energy contained in organic wastewater. Rice is the most popularly consumed food in Asia. Rice washing before cooking produces an enormous amount of domestic sewage. Rice washing wastewater (RWW) contains various organic matters, minerals, and vitamins. Therefore, in this study, we utilized RWW as biofuel to operate a floating MFC (FMFC). The FMFC was designed with the air-cathode floating on the biofuel and the anode immersed in the biofuel. This design enables the device to float on wastewater sources and to harvest electricity directly from that source. Baker’s yeast and bacteria existing in a natural pond (natural bacteria) were used as biocatalysts. Experimental results showed that the FMFC could generate electricity from RWW using both the baker’s yeast and natural bacteria. The maximum power density ow the FMFC using the baker’s yeast was 1 mW/m2.

The objective of the research was to produce biogas by anaerobic co-digestion of biomass and urban solid waste, which made it possible to take advantage of these organic wastes, transforming them into a renewable energy source such as biogas being a fuel with an high calorific on an average of 19.6 to 25 MJ/m3. The methodology consisted of developing different experiments to evaluate the biogas performance in each of the selected biomasses. The percentage of CH4 and CO2 was determined by gas chromatography, from which the following results were obtained: by rinds of, potato (35.64% CH4), papaya (1.64% CH4), pineapple (0.11% CH4), pea (16.13% CH4), banana (0.39% CH4), bean (0.76% CH4), sugarcane bagasse (80.85% CH4), wet sugarcane bagasse (96.06% CH4), semi-dry sugarcane bagasse (91.39% CH4) and potato peel with sugarcane bagasse (58.74% CH4). After the methane quantification in the different codigestion, the sugarcane bagasse presented better results with a 15% increase in the generation of methane when it was pretreated. Subsequently, we worked with anaerobic biodigesters on a laboratory scale with 500 mL capacity, with a 75% feed (sediment, sugarcane bagasse and water 0.75: 1.5: 1.5). In experimentation 8 with 55% of methane and experimentation 9 with 32%, likewise the energy potential where 15.05 MJ/m3 in experimentation 8 and 16, 72 MJ/m3 in experimentation 9.

The rising amount of organic wastes (biomasses) generated annually constitute serious environmental concerns but hold enormous potentials in solving the increasing global energy demand. When properly harnessed, they are good renewable energy sources with capabilities of bridging the energy demand gaps and ameliorating environmental concerns of developing climes. In this study, the mixed-method approach of anaerobic digestion and thermogravimetry were used in the ranking of eighteen selected agro-industrial biomasses based on their energy (biomethane or thermochemical) conversion potentials. The ultimate and proximate properties of the substrates were determined, then the experimental biomethane potentials (BMP) were carried out via anaerobic digestion of feedstocks at mesophilic conditions for 30 days. The biomasses were also degraded thermally within a temperature range of 50 and 800 °C, torrefaction and the pyrolysis char yields were determined. The calorific values and the theoretical biomethane potentials (TBMP) were calculated from the elemental compositions of substrates. From the results obtained, lignocellulosic plant materials and the animal manures recorded lower methane yields and biodegradability. Although the animal manures had appreciable high heating values (HHVs), their BMP yields were poor with biodegradability as low as 25.8%. Consistent with agro-based biomasses, most of the biomass had low H/C eff , high H/C and O/C atomic ratios. Based on ranking criteria, waste samples from animal carcasses and oil crops were ranked topmost in both thermochemical and biochemical energy conversion. Co-digestion/degradation of high ranked biomass with others and enhancements of the substrate before energy conversion is recommended. Thermal upgrade of biomasses and co-pyrolysis with coal is also recommended.

Rapid industrialization has significantly increased the world’s energy usage. It has been visualized that petroleum-reserves will be scanty, and levels of pollution and global warming will be ample. One can solve these problems by using cleaner and renewable energy sources. Biodiesel can be easily prepared by renewable feed stocks. It is biodegradable and non-toxic as well as it can be used in pure state or by blending with diesel in a diesel engine without any major engine modifications. In this study, biodiesel is produced from tallow oil and blended in different ratios (10%, 20% and 30% abbreviated as B10, B20 and B30 respectively) with diesel and used as an engine fuel to compare combustion and performance characteristics e.g. in-cylinder pressure, rate of pressure rise, mean gas temperature, heat release rate, brake power, specific fuel consumption, brake thermal efficiency and torque. The experimental results showed that engine performance parameters support the use of biodiesel and its blends as fuel as the difference between maximum brake power values of diesel and biodiesel blends(B30) is 1.7% which is un-noticeable, considering its other benefits. The similar results obtained for other characteristics. However, specific fuel consumption was higher in the case of biodiesel blends because of its lower heating value relative to diesel. Considering the fact that animal fat is voluminous by-product of meat Industry and it has limited use otherwise, the present investigation illustrates that biodiesel from animal fat can be used with efficacy without modifications in engine design.

The ever-increasing need of the human beings to energy has brought about concerns regarding the decrease in the amount of energy resources. So, renewable energies have become very important and have obtained a special status in today's world. Using bioethanol as a renewable resource to be blended with other fuels in internal combustion engines has attracted many researchers to itself. Thus, in this study, we assess the amount of bioethanol extracted from cantaloupe waste (Magassi Neishabouri Cultivar) to be used as a fuel. To do so, considering the 15 kg capacity of the device's fermenter, 12 kg of refined cantaloupe sugar syrup and three kilograms of water (with the standard ratio of 4 to 1), i.e. a total of 15 kg of substrate with the brix degree of 20, as well as 75 g of saccharomyces cerevisiae yeast, cultured in standard conditions (5 g of yeast for each kilogram of substrate) were transferred into the fermenter. The tests were conducted in 35 h with three replications and at three different rotation speeds of the fermenter's mixer. Sampling took place every five hours. Fermentation temperature was set as 30 °C and distillation temperature was set to be 78.5 °C which is the standard temperature of bioethanol's boiling point. The results showed that about 49.5 g of bioethanol were extracted from each kilogram of cantaloupe syrup. In comparison to the results obtained by other researchers, it became clear that due to its high sugar level, cantaloupe waste is one of the appropriate options for the production of bioethanol. In addition, considering the rate of the alcohol produced and in order to optimize energy consumption, it was seen that the best speed for the fermenter's mixer, was 120 rpm. Keywords: Bioethanol, Renewable energy, Cantaloupe waste

Ex-situ biomethanation (CO2 + 4H2 → CH4 + 2H2O) can simultaneously achieve renewable electricity storage and CO2 valorisation. However, fluctuations in variable renewable electricity may lead to intermittent hydrogen supply, which is shown to adversely affect microbial activity and performance of the biomethanation process. Carbonaceous materials may act as an abiotic additive to enhance microbial robustness and improve system performance. Nanomaterial graphene and pyrochar were compared to assess their effects on biomethanation systems with an intermittent supply of hydrogen. Results revealed that intermittent gas supply caused deterioration in the restart performance with only 66% of theoretical methane production obtained in the control compared with 84% under steady state conditions. The addition of graphene in biomethanation led to 78% of the theoretical methane production after repetitive intermittent supply; this improvement is postulated to be due to its high electrical conductivity and large specific surface (500 m2/g). In comparison, pyrochar amendment did not lead to a significant improvement in upgrading performance. Microbial analysis showed that the OTUs affiliated to bacteria withinin the order SHA-98 (42.9% in abundance) and archaea from the genus Methanothermobacter (99%) may result in the establishment of a new syntrophic relationship to improve the robustness of biomethanation process.

In this paper, the implications of the use of hydrogen on product yield and conversion efficiency as well as on economic performance of a hydrogen enhanced Biomass-to-Liquid (BtL) process are analyzed. A process concept for the synthesis of fuel (gasoline and LPG) from biomass-derived synthesis gas via Methanol-to-Gasoline (MtG) route with utilization of carbon dioxide from gasification by feeding additional hydrogen is developed and modeled in Aspen Plus. The modeled process produces 0.36 kg fuel per kg dry straw. Additionally, 99 MW electrical power are recovered from purge and off gases from fuel synthesis in CCGT process, covering the electricity consumption of fuel synthesis and synthesis gas generation. The hydrogen enhanced BtL procces reaches a combined chemical and electrical efficiency of 48.2% and overall carbon efficiency of 69.5%. The total product costs (TPC) sum up to 3.24 €/kg fuel. Raw materials (hydrogen and straw) make up the largest fraction of TPC with a total share of 75%. The hydrogen enhanced BtL process shows increased chemical, energy and carbon efficiencies and thus higher product yields. However, economic analysis shows that the process is unprofitable under current conditions due to high costs for hydrogen provision.

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link. Growth in anaerobic digestion (AD) has expanded the use of silage to preserve crops intended for renewable energy generation. Preservation of seasonal crops and their residues is critical in a process that needs continuous feeding. Whilst the impact of different crops and harvesting times on methane formation is relatively well understood, to date the specific considerations for maximising methane yields through management practice have been largely ignored. The present paper reviews the current state of knowledge on silage practice for biogas production and specifically on the factors affecting methane yields of ensiled crops, as well as their influence on the silage quality, and provides suggestions for further research in the field. Data shows that ensiling is able to conserves 93% of crops gross energy when good practices are followed. Shorter chop length (7-10 mm), lower DM feedstock (20-35%) and lower compaction values (less than 250 kg/m3) are used to achieve higher biogas yields. Increase biogas production can also be obtained by managing the organic acids production with the preferential formation of acetic acid and ethanol instead of lactic acid via enzymatic or microbial additives. The review outcomes show that more research is required to provide a clear-cut distinction between the requirements for ensiling crops for AD versus crops for animal feed.

Corn stover (CS) has currently received great attention worldwide as a potential feedstock for the production of bioethanol as alternative renewable fuel or additive to gasoline. This work evaluates the quantities and chemical characteristics of the CS available in Ghana and their conversion into bioethanol. The average quantity of CS production in Ghana per year was estimated to be 1.77 × 106 t. The cellulose, hemicellulose, and lignin contents of CS obtained from Pioneer 30 W 40, a local maize variety, were found to be 37.72 %, 20.62 %, and 30.50 %, respectively. Alkali pretreatment and enzymatic hydrolysis of the CS yielded a reducing sugar concentration of 157.96 mg/ml within 24 h and an ethanol yield of 0.045 l/kg. It was estimated that 40 % of the average annual CS production has the potential of yielding 140.855 × 106 l of bioethanol.

Charred briquettes production is a sustainable way of producing cooking fuel from waste. Unsustainable harvesting of wood for fuel production has contributed immensely to the rapid deforestation in Ghana. This study determined the potential of charred briquettes of sawdust, rice and coconut husks in meeting cooking energy needs of households. In a further step, the acceptability of biomass users in the study to replace their current fuels with charred briquettes was established. The calorific value of the charred briquettes was found to be 24.69 MJ/kg. The highest combustion efficiency of briquettes was determined as 34.7% when a multi-feed gasifier stove (MFGS) was used. There were 14% and 80% reduction in particulate matter and carbon monoxide emissions, respectively when briquettes was used instead of charcoal in the MFGS. The analysis of the production cost of briquettes revealed that 1 kg of briquettes should be sold at Gh¢ 2.48 in order to make a 10% profit. The user acceptability survey indicated that about 40% of respondents are ready to patronize briquettes should it be sold at Gh¢ 2.48. This study established that briquette is a suitable replacement for wood and charcoal, if its full potential is harnessed and the energy utilization efficiency of biomass (sawdust, rice and coconut husts) briquettes is confirmed.

Mono alkyl fatty acid ester or methyl ethyl esters (biodiesel) are the promising alternative for fossil fuel or petroleum derived diesel with similar properties and could reduce the carbon foot print and the greenhouse gas emissions. Biodiesel can be produced from renewable and sustainable feedstocks like plant derived oils, and it is biodegradable and non-toxic to the ecosystem. The process for the biodiesel production is either through traditional chemical catalysts (Acid or Alkali Transesterification) or enzyme mediated transesterification, but as enzymes are natural catalysts with environmentally friendly working conditions, the process with enzymes are proposed to overcome the drawbacks of chemical synthesis. At present 95% of the biodiesel production is contributed by edible oils worldwide whereas recycled oils and animal fats contribute 10% and 6% respectively. Although every process has its own limitations, the enzyme efficiency, resistance to alcohols, and recovery rate are the crucial factors to be addressed. Without any benefit of doubt, production of biodiesel using renewable feedstocks and enzymes as the catalysts could be recommended for the commercial purpose, but further research on improving the efficiency could be an advantage.

The ever-increasing demand for global energy and the disadvantages related to the use of fossil fuels, mainly due to gas emissions during their combustion, are the main driving forces behind the development of renewable energy sources. In this regard, biodiesel is an interesting alternative, and its use could lead to a reduction in greenhouse gas emissions and their release to the atmosphere. In this study, research on heterogeneous catalysis was conducted in order to obtain a CaO catalyst that can be reused in the biodiesel production process. In addition, the transesterification reaction with the use of a heterogeneous catalysis, optimized by full factorial design, was performed. The reaction was conducted in a bench scale re-circulation reactor. The biodiesel obtained was characterized by gas chromatography, to evaluate the ester concentration and physical proprieties, such as density, viscosity and acid concentration. Initially, the best operational conditions were evaluated by data regression using STATISTICA 7.0 ® software. The results were then used to monitor the reaction progress and the catalyst deactivation over time and can verify that the quality of the biodiesel produced is preserved during the experiments. For this, we can conclude that the recycle reactor used in this study give good contribution to innovation in the biodiesel production.

Torrefaction is a promising biomass thermal conversion technology to produce biochar due to its ease of operation and mild operating conditions. In this study, cassava rhizome (CR) was torrified under various sweeping gas types (nitrogen (N2), carbon dioxide (CO2), mixture gas (N2 + CO2)) and flow rates (50, 150, 250 mL/min) at 200 – 300 °C for 30 min. The experimental results show that fuel properties of CR were remarkably upgraded after torrefaction. Sweeping gas has less effect on fuel properties of torrified CR than torrefaction temperature. Torrefaction under CO2 atmosphere produced the biochar with minimum ash content. Torrefaction at 300 °C under 50 mL/min CO2 was recommended as the promising condition to produce biochar replacing lignite coal. Thermal properties and chemical functional groups of the derived biochar suggested that torrefaction process removed mainly oxygen and hydrogen contents which could be achieved through decarbonization (DC), dehydrogenation (DH), and deoxygenation (DO) pathways. Economic feasibility revealed that the torrefaction of CR is cost-advantage under the proposed condition.

Biological wax esters offer a sustainable, renewable and biodegradable alternative to many fossil fuel derived chemicals including plastics and paraffins. Many species of bacteria accumulate waxes with similar structure and properties to highly desirable animal and plant waxes such as Spermaceti and Jojoba oils, the use of which is limited by resource requirements, high cost and ethical concerns. While bacterial fermentations overcome these issues, a commercially viable bacterial wax production process would require high yields and renewable, affordable feedstock to make it economically competitive and environmentally beneficial. This review describes recent progress in wax ester generation in both wild type and genetically engineered bacteria, with a focus on comparing substrates and quantifying obtained waxes. The full breadth of wax accumulating species is discussed, with emphasis on species generating high yields and utilising renewable substrates. Key areas of the field that have, thus far, received limited attention are highlighted, such as waste stream valorisation, mixed microbial cultures and efficient wax extraction, as, until effectively addressed, these will slow progress in creating commercially viable wax production methods.

Drop-in biofuels from forest by-products such as black liquor can help deliver deep reductions in transport greenhouse gas emissions by replacing fossil fuels in our vehicle fleet. Black liquor is produced at pulp mills that can increase their pulping capacity by upgrading some of it to drop-in biofuels but this is not well-studied. We evaluate the techno-economic and greenhouse gas performance of five drop-in biofuel pathways based on BL lignin separation with hydrotreatment or black liquor gasification with catalytic synthesis. We also assess how integrated biofuel production impacts different types of pulp mills and a petroleum refinery by using energy and material balances assembled from experimental data supplemented by expert input. Our results indicate that drop-in biofuels from black liquor part-streams can be produced for ~80 EUR2017/MWh, which puts black liquor on the same footing (or better) as comparable forest residue-based alternatives. The best pathways in both production routes have comparable costs and their principal biofuel products (petrol for black liquor gasification and diesel for lignin hydrotreatment) complement each other. All pathways surpass European Union's sustainability criteria for greenhouse gas savings from new plants. Supplementing black liquor with pyrolysis oil or electrolysis hydrogen can improve biofuel production potentials and feedstock diversity, but better economic performance does not accompany these benefits. Fossil hydrogen represents the cheaper option for lignin hydrotreatment by some margin, but greenhouse gas savings from renewable hydrogen are nearly twice as great. Research on lignin upgrading in industrial conditions is recommended for reducing the presently significant performance uncertainties.

Food stores can find themselves in the position of having to dispose of different types of products, such as snacks, confectionery, prepackaged food, drinks and others, Sweet Product Residue (SPR), which presents a great opportunity to produce energy through Anaerobic Digestion (AD), due to its high sugar, carbohidrate and fat contents. In order to valorise SPR, this paper takes into consideration the all necessary treatments; owing the fact that the refuses are constitute by an organic part and packaging (plastic, paper and their combinations), a pretreatment able to remove the latter is necessary. SPR refuse was initially subjected to novel pretreatment approach: extrusion at 200atm to remove the packaging, and a Basic Pre-treatment (BP) then tested through a Two-Stage AD (TSAD) process, for H2 and CH4 productions. The experimental results were analysed considering three parameters: Efficiency (ξ), which takes into account the quantity of the energy produced as hydrogen plus methane that the bioreaction is able to extract; Efficacy (η), which takes into account the efficiency of the actual test, compared with that obtained from a reference test carried out with glucose; Energy Sustainability Index (ESI), which takes into account the total amount of energy produced as H2 plus CH4, and the amount of energy consumed to pre-treat the refuse. The effectiveness of the extrusion process in removing the packaging was very high: about 80% of the organic part present in the SPR was recovered. The obtained results have pointed out that SPR is suitable for energy valorization process: ξ=50%, η=0.67 and ESI=24.4, without the need of basic pre-treatment.

Summary Traditional lignocellulosic feedstock research has focused on biomass characteristics essential for improving saccharification efficiency, yet the key biomass features underlying high-quality renewable lignin materials remain unknown. Nevertheless, modern biorefinery cannot achieve sustainability and cost-effectiveness unless the lignin stream can be valorized. We hereby addressed these scientific gaps by investigating biomass characteristics defining lignin-based carbon materials properties. Lignin from eight sorghum samples with diverse characteristics was fabricated into carbon fibers (CFs). Remarkably, only lignin uniformity was found to define CF mechanical performance, highlighting the new structure-property relationship. Contrarily, lignin content and composition did not impact on carbon material properties. Mechanistic study by XRD and Raman spectroscopy revealed that higher lignin uniformity enhanced CF microstructures, in particular, turbostratic carbon content. The study for the first time highlighted lignin uniformity as an important biomass structure determinant for renewable products, which opened up new avenues for feedstock design toward diverse products enabling sustainable and cost-effective bioeconomy., Graphical Abstract, Highlights • Lignin uniformity was discovered to define biomass-derived CF mechanical property • Traditional key feedstock characteristics do not significantly impact on CF property • Feedstock variants and growth conditions impact on lignin uniformity • Novel feedstock design needs to be developed for biomaterial manufacturing, Polymer Chemistry; Biomass; Materials Chemistry; Materials Property

A box-type reactor system with liquid inoculum has been studied for the dry anaerobic digestion of food waste. The food waste was processed without any pre-treatment to remove physical impurities, neither water addition to dilute and slurry the feedstock. The experiment was carried out with inoculum to substrate ratios of 1:1 (w/w) and 0.08:1 (VS basis). Previous acclimation of liquid inoculum enhanced the process, assuring a fast start up of the box digester and preventing from process failure by volatile fatty acids accumulation. The percolate recirculation strategy was shown to have a relevant effect on the progress of the process. The results suggest that the process can be optimized by providing low percolate recirculation rate during the start-up of the box digester followed by an increase in the percolate recirculation rate when volatile fatty acids decrease and methane content in the biogas increases. The methane yield obtained in the box digester from the food waste was in the range 460–477 L CH4 kg−1 VS, being the VS removal efficiency between 91.1 and 91.4%. Globally, the process operated at an organic loading rate of 2.5 kg VS m−3 d−1 and yielded a volumetric methane production rate of 1.0 m3 CH4 m3 d−1. These results show the high potential of food waste for its conversion in renewable energy by using the dry batch anaerobic technology.

Highlights • Biogas potential of hazelnut wastes and hazelnut shell residue in Giresun was evaluated. • Giresun city of the total electricity production potential of the biomass sources was 38.21 GW h/year. • The biogas potential of Giresun, which can be produced from these wastes, reduces CO2 emissions by 273,954 tons., In recent years, the world's natural energy resources unable to meet the increasing energy needs. In Turkey and in the world, there is an increasing need for renewable energy. One of the renewable energy sources is biogas energy. In this study, the biogas potential of Giresun, which is also known as coastal city, can be formed from 2 different organic wastes are experimentally calculated. Organic wastes included in the calculation; hazelnut shells (HS) and hazelnut wastes (HW). Production experiments were investigated in two ways: untreated and thermal pretreatment. In addition, biogas yield was examined at room temperature (23 °C), at mesophilic temperature (39 °C), and at thermophilic temperature (60 °C). As a result, the highest biogas yield was found at temperatures of 60 °C and under thermal pretreatment conditions. Under these conditions, annual biogas production potential of Giresun city was found as 38.21 GW h/yr.

Nowadays, microbial fuel cells (MFC) stand up as a promising renewable energy source. Due to the ability of the MFC to oxidize a wide spectrum of substrates, wastewater seems to be one of the most interesting fuels. Unfortunately, wastewater could contain electron acceptors such as nitrate, which could interfere with the electrical performance of the MFC. In this work, the influence of oxidised nitrogen forms on the electricity production of an air breathing MFC was studied. It was observed that power generation was not significantly influenced when operated at nitrate concentrations below 0.9 mg N-NO3 L−1. However, when the nitrate concentrations were above this value, the electricity generation was reduced. In order to investigate the causes of this reduction, an electrochemical characterization of the MFC was performed. The results of polarization curves were fitted to an empirical mathematical model. From the results it was observed that, when nitrate was present, the denitrifiers outcompeted the electrogenic microorganisms for substrate, causing mass transfer limitations to the electrogenic process., Hoy en día, las pilas de combustible microbianas (MFC) se erigen como una fuente de energía renovable prometedora. Debido a la capacidad del MFC para oxidar un amplio espectro de sustratos, las aguas residuales parecen ser uno de los combustibles más interesantes. Desafortunadamente, las aguas residuales podrían contener aceptores de electrones como el nitrato, lo que podría interferir con el rendimiento eléctrico del MFC. En este trabajo, se estudió la influencia de las formas de nitrógeno oxidado en la producción de electricidad de un MFC que respira aire. Se observó que la generación de energía no se veía significativamente influenciada cuando se operaba a concentraciones de nitrato por debajo de 0.9 mg N-NO 3 L -1. Sin embargo, cuando las concentraciones de nitratos estuvieron por encima de este valor, se redujo la generación de electricidad. Para investigar las causas de esta reducción, se realizó una caracterización electroquímica del MFC. Los resultados de las curvas de polarización se ajustaron a un modelo matemático empírico. A partir de los resultados se observó que, cuando estaba presente el nitrato, los desnitrificantes superaban a los microorganismos electrogénicos por sustrato, provocando limitaciones de transferencia de masa al proceso electrogénico.

The Swietenia macrophylla wood used for the study was sun dried for about 48 h, pulverized using a hammer mill and then sieved to a particle size of about 425μm using Wiley milling machine. The prepared materials were pyrolyzed in a fixed-bed pyrolysis reactor in the temperature range from 425 to 500 °C. The product yields were collected at an interval of 25 °C. The maximum yield of bio-oil was recorded as 69.5wt.% at the pyrolysis temperature of 450 °C. The physicochemical properties and compositions of the feed materials and produced bio-oil were measured in order to quantify their potential for bio-energy use and industrial applications. The properties specifically measured include density, moisture content, ash content, pH, refractive index, cetane index, elemental composition, viscosity, and heating values. The ultimate analysis of the product showed that the contents of carbon, oxygen, hydrogen, nitrogen, and sulfur were 50.2%, 42.6%, 6.6%

Atabani, Abdulaziz/0000-0001-6793-5589; Mostefa, khelafi/0000-0001-9321-4152; WOS: 000493911600058 The world is concerned with the degradation of the Saharan eco-system due to the absence of green spaces, emission of greenhouse gases and the burial of oases by sand beside the global energy crisis. This promoted the Algerian government to set a national strategy towards the use of renewable sources to cover 40% of its energy needs by 2030. In this article, a modern technique to simultaneously protect the environment and produce biofuels from the Saharan environment through cultivation of Moringa oleifera and valorizations of waste Phoenix dactylifera L. dates which are of not of satisfactory quality for the local market has been adopted. Characterization of Moringa oleifera oil, Moringa oleifera biodiesel and bioethanol produced from the waste date was done. Biodiesel-diesel-bioethanol blends were characterized by DSC, FT-IR, TGA and GC methods. Results show high oil content of Moringa oleifera seeds of 40%, biodiesel yield of 91% and bioethanol percentage of 96.83% with 3.17% of impurities. The properties of ternary blends of D80B5BE15, D80B10BE10 and D80B15BE5 exhibit similar densities and cold flow properties to Euro-diesel. Our analysis also proved that waste Phoenix dactylifera L. dates are useless as ruminant feed due to low protein content. In conclusion, the study proved the feasibility of cultivating Moringa oleifera to protect the environment and valorizing its seeds besides waste date seeds to produce both biodiesel and bioethanol in the Algerian Saharan.

International audience; In this study, the VOC emissions from a self-bonded coriander board originating from a coriander biorefinery, were investigated. These emissions mainly result from the presence of essential oil in the manufactured materials. Firstly, an extensive analysis of the essential oil obtained from French coriander fruits showed the presence of linalool as the major component (72%), with an absolute concentration in the essential oil of 412 g/L. A characterization of the enantiomeric distribution of linalool, which is important in terms of its bioactivity, resulted in an enantiomeric excess of (S)-linalool of 77%. Further, the presence of this volatile oil in the coriander boards was confirmed through identification of the terpenoid compounds in the VOC emission profile. The area specific emission rate of linalool and camphor was determined at 125 and 25 μg m−2 h−1, respectively, at 25 °C and 50% RH, while their emission was found to increase by a factor of 3 with an increase in temperature of 10 °C. The renewable self-bonded boards could thus present potentially interesting alternatives for less sustainable materials in the construction or agricultural industry, where they could provide a significant added value in terms of indoor air quality or storage of food and agricultural products.

In 2015, the Worldatlas recorded 50 countries whose source of income is fossil fuel and its derivatives. Surprisingly, these countries solely depend on this source of energy up to 100% (Omar, Qatar, Kuwait and Saudi Arabia) because of technology improvement. It's so sadden that apart from its adverse effect on the economics of the countries, fossil fuels harmful effects on the universe cannot be overlooked. Meanwhile, the use of renewable energy as a replacement for fossil fuel and its derivatives are faced by the high oil price, high cost of investment for alternative energy, and unfathomed electricity prices. This research work evaluates desirability of making use of alternative source of energy sources by making use of biomass oil over the use of fossil fuel and its derivatives for electricity generation. Lucky nut is an agricultural non edible seed that was employed as raw material for biofuel production. The non-edible oil was extracted from the seeds and the oil was further converted to Lucky nut biofuel via a heterogeneous based catalyst produced from calcinated pearl spar. For modelling and optimization, design expert coupled with genetic algorithms were used to generate experimental designs so as to correlate the variable factors considered for production. The extraction of Lucky nut seed revealed the optimum production yield of 50.80% (v/v) and the oil is highly unsaturated. Energy Dispersive X-ray Fluorescence Spectrophotometer analyses and scanning electron microscope (SEM) of the calcined catalyst obtained from pearl spar showed the major component found in the pearl spar was K with relative abundance of 58.48%, which favoured the yield of Lucky nut biodiesel (91.00% (v/v)). Based on predicted values, the optimum validated Lucky nut biodiesel by RSMED and ANNED were 89.68% (v/v) and 92.87% (v/v), respectively. Produced properties of biofuel conformed to the biofuel standard. The study concluded that Lucky nut seed is a good source of oil, and its transformation to alternative fuel via a using calcined catalyst proved its fitness as a replacement for fossil fuel.

We report on the thermochemical conversion of inedible crop residues using concentrated solar energy as the source of high-temperature process heat. Experiments were performed using a 5 kWth solar packed-bed reactor exposed to radiative fluxes up to 1788 suns. The waste biomass feedstock consisted of unprocessed batches of cotton boll, soybean husk, and black mustard husk and straw, which were pyrolysed and steam-based gasified at nominal temperatures in the range 879–1266 °C, yielding high-quality syngas with molar ratios in the range H2:CO = 1.43–3.25, CO2:CO = 0.28–1.40, and CH4:CO = 0.03–0.28. The solar-to-fuel energy conversion efficiency, defined as the ratio of the heating value of the syngas produced to the solar radiative energy input and the heating value of the feedstock, reached 18%. The heating value of the feedstock was solar-upgraded by 7%, thus outperforming autothermal gasification that typically downgrades by at least 15%. The ash contained 23% potassium. The solar-driven thermochemical process offers a sustainable and efficient path for the conversion of agricultural wastes into valuable fuels and soil fertilizers. ISSN:0378-3820

8 Figures, 3 Tablas.-- © 2017. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/, Chemical Looping Combustion (CLC) using renewable solid fuels appears as an important option to reach negative carbon emissions. In this work, three types of forest and agricultural residues (pine sawdust, olive stone and almond shell) were tested between 900–980 °C in a 0.5 kWth unit with an iron ore as oxygen carrier (Tierga ore) working under In situ Gasification-Chemical Looping Combustion (iG-CLC) mode. Specific solids inventories lower than 1000 kg/MWth were tested as they were consider more representative of what can be used in a larger CLC unit. CO2 represented about 70% in the fuel reactor outlet gas stream, followed by unburnt compounds: H2, CO and CH4. CO2 capture efficiencies increased with the fuel reactor temperature achieving almost 100% of capture with the three biomasses at temperatures above 950 °C. In contrast, no clear trend with the fuel reactor temperature was observed for the total oxygen demand, achieving values about 25%. The major contribution to this value comes from the unburned volatiles with a small contribution coming from tar (≈ 1%). Regarding tar, naphthalene was the major compound found at the different operating conditions. The present results support the consideration of the CLC process with biomass (bio-CLC) as a promising Bio-Energy with Carbon Capture (BECCS) technology., The authors thank the Spanish Ministry of Economy and Competitiveness (MINECO) for the funding received from the project ENE2014-56857-R) and FEDER for the financial support. A. Pérez-Astray thanks MINECO for the BES-2015-074651 predoctoral fellowship co-financed by the European Social Fund. T. Mendiara thanks for the ‘‘Ramón y Cajal’’ post-doctoral contract awarded by MINECO. The authors also thank PROMINDSA for providing the solid material used in this work.

World production of rice exceeds 750 million tonnes per year of which a fifth is removed in the form of rice husk during the milling process. The use of rice husks as a source of sustainable and renewable energy is often hindered by lack of capital and a poor understanding of rice husk combustion characteristics. This results in the selection of poor quality technology which generates significant quantities of harmful crystalline silica waste. Despite previous work in the area, detailed characterisation of the combustion of rice husk ash in a TORBED reactor across a wide temperature range has not yet been attempted and little effort has been directed towards assessing the economic viability of generating quality rice husk ashes. The use of a TORBED reactor enables low residual carbon after combustion without the generation of harmful crystalline material. Rice husk was combusted in a 400 mm reactor at temperatures between 700 and 950 °C. In the subsequent characterisation studies the resulting materials were shown to be fully amorphous high purity silica (> 95%) and were readily digested in a series of alkaline digestion experiments. Complete silica conversion was only possible using uneconomic Na 2 O/SiO 2 ratios and further optimisation of the combustion process to generate higher surface area material is necessary to increase the digestion rates further. Provisional economic analysis suggests that sales of the by-product enhance the returns from rice husk based power generation. TORBED reactors enable the combustion of rice husk with considerable operating flexibility and they generate products that could be used to displace resource intensive products and processes thus, added value from the by-products can be obtained by using TORBED reactor technology.

Used Cooking Oil (UCO) and pure Fatty Acids (FAs) derived from food processing represent sustainable feedstocks for biofuel production. The catalytic and non-catalytic pyrolysis of these residual oils is a possible pathway to advanced biofuel production, alternative to catalytic hydrotreatment, already commercially deployed in large-scale installations. The present work first carried out a literature review of previous research works in the field, which provided the key information to the following implementation of a pilot-scale dedicated experimental work aimed at producing bio-hydrocarbons from residual vegetable oils, with a special focus on paraffinic fuels. Based on the literature survey, 4 different catalysts were selected for the experimental investigation. Catalytic and non-catalytic pyrolysis of UCO was initially carried out in 1.5 kg h −1 (max) feed pilot unit, operated at 500 °C, with the catalytic reactor working at 4 and 2.5 h −1 Weight Hourly Space Velocity (WHSV). Liquid yields and corresponding hydrocarbon fractions were investigated: these initial results suggested to extend the study to catalytic pyrolysis of pure FAs. At T = 500 °C and with activated carbons as catalyst, the total observed hydrocarbon yield mass fraction on UCO and FA increased from 23% (UWHSV = 4 h −1 ) to 35% (UCO, WHSV = 2.5 h −1 ) and finally to 40% (FA, WHSV = 2.5 h −1 ). A slight reduction in the overall liquid yield mass fraction was also observed in this last experiment with FAs (from 63% to ≈49%). Even if the current work on the pilot pyrolyser did not aim at investigating energy and process optimization, including yield maximization and catalyst lifetime, experimental results indicated that catalytic pyrolysis could be a promising way for industrial production of hydrocarbons from low quality lipid-based materials (as it is the case of UCOs) and without requiring hydrogen for catalytic hydrotreatment.

The objective of this work is to provide a comprehensive study on algal biomass as feedstock for biogas production. Algae-derived biofuels are seen as one of the most promising solutions to mitigate climate change and as alternative to fast depleting of fossil fuels and oil reserves. Microalgae and macroalgae underwent an intense academic and industrial research, thanks to their capability to overcome the drawbacks related to the first and second generations of biomass resources. Major advantages of algae are: no competition with food crops for arable land, high growth rates, low fractions of lignin which reduces the need for energy-intensive pretreatment and compatibility with biorefinery approach implementation. However, some disadvantages such as the presence of high water content, seasonal chemical composition and the occurrence of inhibitory phenomena during anaerobic digestion, make algal biofuels not yet economically feasible although they are more environment friendly than fossil fuels.