This study aimed to produce biochar with an energy value in the range of sub-bituminous carbon by investigating the effect of oxidative and non-oxidative torrefaction on the torrefaction yield and fuel properties of wheat straw. Three independent variables were considered at different levels: temperature (230, 255, 280, 305 °C), residence time (20, 40, 60 min), and reaction atmosphere (0, 3, 6 vol% O2; N2 balance); and three dependent variables: mass yield, energy yield, and percentage increase in higher heating value (HHV). The results showed that it is possible to produce a sub-bituminous carbon type C biochar using oxidative torrefaction, significantly reducing time and temperature compared with non-oxidative torrefaction. The optimum torrefaction conditions were 287 °C−20 min−6.0% O2, which increased the HHV of wheat straw from 13.86 to 19.41 MJ kg−1. The mass and energy yields were 44.11 and 61.78%, respectively. The physicochemical and fuel properties of the obtained biochar were... [more]

Land-based gas turbines (GTs) are continuous-flow engines that run with permanent flames once started and at stationary pressure, temperature, and flows at stabilized load. Combustors operate without any moving parts and their substantial air excess enables complete combustion. These features provide significant space for designing efficient and versatile combustion systems. In particular, as heavy-duty gas turbines have moderate compression ratios and ample stall margins, they can burn not only high- and medium-BTU fuels but also low-BTU ones. As a result, these machines have gained remarkable fuel flexibility. Dry Low Emissions combustors, which were initially confined to burning standard natural gas, have been gradually adapted to an increasing number of alternative gaseous fuels. The paper first delivers essential technical considerations that underlie this important fuel portfolio. It then reviews the spectrum of alternative GT fuels which currently extends from lean gases (coal b... [more]

This review investigates the effects of the Brazilian agriculture production and forestry sector on carbon dioxide (CO2) emissions. Residual biomasses produced mainly in the agro-industrial and forestry sector as well as fast-growing plants were studied. Possibilities to minimize source-related emissions by sequestering part of carbon in soil and by producing biomass as a substitute for fossil fuel were extensively investigated. The lack of consistency among literature reports on residual biomass makes it difficult to compare CO2 emission reductions between studies and sectors. Data on chemical composition, heating value, proximate and ultimate analysis of the biomasses were collected. Then, the carbon sequestration potential of the biomasses as well as their usability in renewable energy practices were studied. Over 779.6 million tons of agricultural residues were generated in Brazil between 2021 and 2022. This implies a 12.1 million PJ energy potential, while 4.95 million tons of for... [more]

Bioenergy with Carbon Capture and Storage (BECCS) technologies are fundamental to reach negative CO2 emissions by removing it from the atmosphere and storing it underground. A promising solution to implement BECCS is pressurized Chemical Looping Combustion (CLC), which involves coupling a pressurized CLC reactor system to a turboexpander. The typical configuration chosen is to have an air reactor and a fuel reactor based on coupled circulating fluidized beds. The fluidization regime in both reactors is preferred to be fast fluidization to enhance gas particle contact and solids circulation among reactors. To design the two reactors, Aspen Plus software was used, given that the new version has a module for fluidized bed modeling. At first, the oxygen carrier was designed ex novo, but given that it is a composite compound mainly made by nickel oxide freeze-granulated on alumina (Ni40Al-FG), the molecular structure has been inserted in Aspen Plus. Then, based on the power of the gas turbi... [more]

Jordan’s energy situation is in a critical state of dependency, with the country relying heavily on imports to satisfy its ever-increasing energy requirements. Renewable energy is a more competitive and consistent source of energy that can supply a large proportion of a country’s energy demand. It is environmentally friendly and minimizes atmospheric pollutant emissions. Thus, bioenergy has the potential to be a crucial alternative energy source in Jordan. Biomass is the principal source of bioenergy; it accounts for approximately 13% of the primary energy demand and is anticipated to supply half of the total primary energy demand by 2050. Nanotechnology has emerged as an important scientific research area with numerous applications, including biofuels. This review summarizes the application of nanoparticles to improve the properties and processes of biofuels. It presents the availability and viability of nanotechnology-supported bioenergy production in Jordan. Jordan generates up to 5... [more]

Lignin is a polymer found in the cell walls of plants and is an important component of wood. Lignin-derived fuels have attracted attention as a means of producing biofuels from biomass in recent years. There are two basic methods for converting lignin into fuel: thermochemical and catalytic. Lignin-derived fuels have the potential to reduce dependency on fossil fuels and reduce greenhouse gas emissions. However, more research is needed to optimize the production of lignin-derived fuels and to determine their environmental impact. This review aims to evaluate the development of lignin-derived fuels from an economic and environmental point of view while presenting a broad perspective.

The fuel qualities of several biodiesels containing highly saturated, mono, and poly unsaturated fatty acids, as well as their combustion and exhaust emission characteristics, were studied. Six biodiesel samples were divided into two groups based on their fatty acid composition, including group 1 (coconut, castor, and jatropha) and group II (palm, karanja, and waste cooking oil biodiesel). All fuels (in both groups) were tested in a single-cylinder off-road diesel engine. Castor and karanja biodiesel, both rich in mono-unsaturation level, have a high viscosity of about 14.5 and 5.04 mm2/s, respectively. The coconut and palm biodiesels are rich in saturation level with cetane numbers of 62 and 60, respectively. In both groups, highly saturated and poly-unsaturated methyl esters presented better combustion efficiency and less formation of polluted emissions than mono-unsaturation. At full load, coconut and palm biodiesel displayed 38% and 10% advanced start of combustion, respectively, w... [more]

One of the anaerobic digestion process products in an agricultural biogas plant is digestate (digested pulp). Large quantities of digestate generated in the process of biogas production all over the world require proper management. Fertilization is the main management of this substrate, so it is essential to look for new alternatives. The work aims to determine and discuss the possibilities of using digestate solid fraction (DSF) for pellets as biofuel production. Pellets from DSF alone and pellets with sawdust, grain straw additives were analyzed. The lower heating value (LHV) based on the dry matter for all analyzed pellets ranged from 19,164 kJ∙kg−1 to 19,879 kJ∙kg−1. The ash content was similar for all four samples and ranged from 3.62% to 5.23%. This value is relatively high, which is related to the degree of fermentation in the anaerobic digestion process. The results showed that the DSF substrate after the anaerobic digestion process still has energy potential. Analyzing those r... [more]

For international civil aviation to be able to significantly reduce its greenhouse gas (GHG) emissions, the use of Sustainable Aviation Fuels (SAF) needs to be made feasible. This paper presents the results of an assessment of the feasibility of production of SAF in Brazil, considering three certified routes, based on the dedicated production of eucalyptus, soy, sugarcane and corn. The results presented here refer to the production of biomass in selected locations, aiming to reduce GHG emissions and minimise production costs. Considering that the opportunity costs of feedstocks were not observed, the minimum selling price (MSP) of SAF in the reference case was estimated at 13.4 EUR·GJ−1 for the production based on soybean oil (HEFA-SPK route), 21.0 EUR·GJ−1 for the production based on ethanol from sugarcane and corn (ATJ-SPK) and 32.0 EUR·GJ−1 from eucalyptus (FT-SPK). These values refer to SAF’s nth industrial plant and biomass costs that are compatible with the current agricultural y... [more]

Gelatin production is the most industry polluting process where huge amounts of raw organic materials and chemicals (HCl, NaOH, Ca2+) are utilized in the manufacturing accompanied by voluminous quantities of end-pipe effluent. The gelatinous wastewater (GWW) contains a large fraction of protein and lipids with biodegradability (BOD/COD ratio) exceeding 0.6. Thus, it represents a promising low-cost substrate for the generation of biofuels, i.e., H2 and CH4, by the anaerobic digestion process. This review comprehensively describes the anaerobic technologies employed for simultaneous treatment and energy recovery from GWW. The emphasis was afforded on factors affecting the biofuels productivity from anaerobic digestion of GWW, i.e., protein concentration, organic loading rate (OLR), hydraulic retention time (HRT), the substrate to inoculum (S0/X0) ratio, type of mixed culture anaerobes, carbohydrates concentration, volatile fatty acids (VFAs), ammonia and alkalinity/VFA ratio, and reactor... [more]

Hydrothermal liquefaction is one of the common thermochemical conversion methods adapted to convert high-water content biomass feedstocks to biofuels and many other valuable industrial chemicals. The hydrothermal process is broadly classified into carbonization, liquefaction, and gasification with hydrothermal liquefaction conducted in the intermediate temperature range of 250−374 °C and pressure of 4−25 MPa. Due to the ease of adaptability, there has been considerable research into the process on using various types of biomass feedstocks. Over the years, various solvents and co-solvents have been used as mediums of conversion, to promote easy decomposition of the lignocellulosic components in biomass. The product separation process, to obtain the final products, typically involves multiple extraction and evaporation steps, which greatly depend on the type of extractive solvents and process parameters. In general, the main aim of the hydrothermal process is to produce a primary product... [more]

The negative impact of transport on climate has led to incentives to increase the amount of renewable fuels used in internal combustion engines (ICEs). Oxygenated, liquid biofuels are promising alternatives, as they exhibit similar combustion behaviour to gasoline. In this article, the effect of the different biofuels on engine efficiency, combustion propagation and emissions of a gasoline-optimised direct injected spark ignited (DISI) engine were evaluated through engine experiments. The experiments were performed without any engine hardware modifications. The investigated fuels are gasoline, four alcohols (methanol, ethanol, n-butanol and iso-butanol) and one ether (MTBE). All fuels were tested at two speed sweeps at low and mid load conditions, and a spark timing sweep at low load conditions. The oxygenated biofuels exhibit increased efficiencies, even at non-knock-limited conditions. At lower loads, the oxygenated fuels decrease CO, HC and NOx emissions. However, at mid load condit... [more]

Biochar is a co-product of advanced biofuels production from feedstocks including food, agricultural, wood wastes, or dedicated energy crops. Markets for soil amendments using biochar are emerging, but little is known about consumer preferences and willingness to pay (WTP) for these products or the depth of the products’ market potential for this product. This research provides WTP estimates for potting mix amended with 25% biochar, conditioned on consumer demographics and attitudes about product information labeling. Data were collected with an online survey of 577 Tennessee home gardeners. WTP was elicited through a referendum contingent valuation. Consumer WTP for an 8.81 L bag of 25% biochar potting mix is $8.52; a premium of $3.53 over conventional potting mix. Demographics and attitudes toward biofuels and the environment influence WTP. Biochar amounts demanded are projected for the study area’s potential market. Optimal prices, profits, and market shares are estimated across dif... [more]

In this paper, we address the classical problem of testing for stationarity in the prices of energy-related commodities. A panel of fourteen time series of monthly prices is analyzed for the 1980−2020 period. Nine of the series are classical nonrenewable, GHG-emissions-intensive resources (coal, crude oil, natural gas), whereas the remaining, low-emission group includes both uranium and four commodities employed in biofuels (rapeseed, palm, and soybean oils, and ethanol). A nonparametric, bootstrap-based stationarity testing framework is employed. The main advantage of this procedure is its asymptotically model-free nature, being less sensitive than parametric tests to the risks of misspecification and detection of spurious unit roots, although it has the potential limitation of typically requiring larger samples than mainstream tools. Results suggest that most of the series analyzed may be trend stationary. The only exception would be crude oil, where different conclusions are obtaine... [more]

Nowadays, the transport sector is trying to face climate change and to contribute to a sustainable world by introducing modern after-treatment systems or by using biofuels. In sectors such as road freight transportation, agricultural or cogeneration in which the electrification is not considered feasible with the current infrastructure, renewable options for diesel engines such as alcohols produced from waste or lignocellulosic materials with advanced production techniques show a significant potential to reduce the life-cycle greenhouse emissions with respect to diesel fuel. This study concludes that lignocellulosic biobutanol can achieve 60% lower greenhouse gas emissions than diesel fuel. Butanol-diesel blends, with up to 40% butanol content, could be successfully used in a diesel engine calibrated for 100% diesel fuel without any additional engine modification nor electronic control unit recalibration at a warm ambient temperature. When n-butanol is introduced, particulate matter em... [more]

In comparison to lignocellulosic biomass, which is suitable for thermo-chemical valorization, the organic fraction of municipal solid waste (OFMSW) is mainly treated via composting or anaerobic digestion (AD). An efficient utilization of OFMSW is difficult due to variations in its composition. Based on the characteristics of OFMSW, hydrothermal treatment (HTT) experiments at temperatures < 200 °C as an alternative OFMSW-processing were evaluated in this study. The raw OFMSW was characterized with a dry matter (DM)-based organic dry matter (oDM) content of 77.88 ± 1.37 %DM and a higher heating value (HHV) of 15,417 ± 1258 J/gDM. Through HTT at 150, 170 and 185 °C, the oDM contents as well as H/C and O/C ratios were lowered while the HHV increased up to 16,716 ± 257 J/gDM. HTT led to improved fuel properties concerning ash melting, corrosion stress and emission behavior. Negative consequences of the HTT process were higher contents of ash in the biochar as well as accumulated heavy me... [more]

The article presents the results of research on the influence of two fuel additives that selectively affect the combustion process in a diesel engine cylinder. The addition of NitrON® reduces the concentration of nitrogen oxides (NOx), due to a reduction in the kinetic combustion rate, at the cost of a slight increase in the concentration of particulate matter (PM) in the engine exhaust gas. The Reduxco® additive reduces PM emissions by increasing the diffusion combustion rate, while slightly increasing the NOx concentration in the engine exhaust gas. Research conducted by the authors confirmed that the simultaneous use of both of these additives in the fuel not only reduced both NOx and PM emissions in the exhaust gas but additionally the reduction of NOx and PM emissions was greater than the sum of the effects of these additives—the synergy effect. Findings indicated that the waveforms of the heat release rate (dQ/dα) responsible for the emission of NOx and PM in the exhaust gas diff... [more]

Analyses of statistical data were made and their results discussed in this article to identify the level of Poland’s energy security and to determine the role of agriculture in ensuring it. It has been demonstrated that coal continues to be the staple resource for the generation of energy in Poland. The current demands and requirements concerning the reduced consumption of non-renewable resources and Poland’s obligations towards the European Union regarding the production of energy from renewable resources—all these considerations contribute to the promotion of a skillful development of energy crop farming, which, in Poland, is likely to be very successful. Agriculture plays an important role in ensuring Poland’s energy security, and this branch of farming can grow dynamically provided adequate legal regulations and promotion are in place. The chief resource for renewable energy generation is biomass. Straw and biogas production in agricultural biogas plants are two solutions whose ful... [more]

The increasing world population generates huge amounts of wastewater as well as large energy demand. Additionally, fossil fuel’s combustion for energy production causes the emission of greenhouse gases (GHG) and other pollutants. Therefore, there is a strong need to find alternative green approaches for wastewater treatment and energy production. Microalgae biorefineries could represent an effective strategy to mitigate the above problems. Microalgae biorefineries are a sustainable alternative to conventional wastewater treatment processes, as they potentially allow wastewater to be treated at lower costs and with lower energy consumption. Furthermore, they provide an effective means to recover valuable compounds for biofuel production or other applications. This review focuses on the current scenario and future prospects of microalgae biorefineries aimed at combining wastewater treatment with biofuel production. First, the different microalgal cultivation systems are examined, and the... [more]

Biofuel produced from biomass pyrolysis is a good example of a highly complex mixture. Detailed understanding of its composition is a prerequisite for optimizing transformation processes and further upgrading conditions. The major challenge in understanding the composition of biofuel derived from biomass is the wide range of compounds with high diversity in polarity and abundance that can be present. In this work, a comprehensive analysis using mass spectrometry is reported. Different operation conditions are studied by utilizing multiple ionization methods (positive mode atmospheric pressure photo ionization (APPI), atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) and negative mode ESI) and applying different resolving power set-ups (120 k, 240 k, 480 k and 960 k) and scan techniques (full scan and spectral stitching method) to study the complexity of a pyrolysis biofuel. Using a mass resolution of 960 k and the spectral stitching scan technique gives... [more]

Artificial fuels have been researched for more than a decade now in an attempt to find alternative sources of energy. With global climatic conditions rapidly approaching the end of their safe line, an emphasis on escalating the change has been seen in recent times. Synthetic fuels are a diverse group of compounds that can be used as replacements for traditional fuels, such as gasoline and diesel. This paper provides a comprehensive review of synthetic fuels, with a focus on their classification and production processes. The article begins with an in-depth introduction, followed by virtually classifying the major synthetic fuels that are currently produced on an industrial scale. The article further discusses their feedstocks and production processes, along with detailed equations and diagrams to help readers understand the basic science behind synthetic fuels. The environmental impact of these fuels is also explored, along with their respective key players in the industry. By highlight... [more]

Artificial fuels have been researched for more than a decade now in an attempt to find alternative sources of energy. With global climatic conditions rapidly approaching the end of their safe line, an emphasis on escalating the change has been seen in recent times. Synthetic fuels are a diverse group of compounds that can be used as replacements for traditional fuels, such as gasoline and diesel. This paper provides a comprehensive review of synthetic fuels, with a focus on their classification and production processes. The article begins with an in-depth introduction, followed by virtually classifying the major synthetic fuels that are currently produced on an industrial scale. The article further discusses their feedstocks and production processes, along with detailed equations and diagrams to help readers understand the basic science behind synthetic fuels. The environmental impact of these fuels is also explored, along with their respective key players in the industry. By highlight... [more]

The production and use of terpene-based fuels represents a renewable source of energy in the transportation sector, especially in the aviation sector. The literature on the conversion of terpenes into valuable compounds is not new but has been based on the production of products for cosmetics and pharmaceutics. Several established chemical routes are also a way to develop drop-in fuels. The present work explores all the main chemical processes that can transform terpenes into more valuable fuels or additives, focusing on the use of heterogeneous catalysis, catalyst type, operating conditions, and reaction performance. α-pinene is the most studied catalyst, since it is the main component of turpentine. Isomerization is the most frequently applied chemical pathway used to enhance fuel properties, and a wide group of heterogeneous catalysts have been reported, with sulphonic acid resin catalysts, transition metals, alumina, and silicates being the most used. This work also explores the cu... [more]

The most common fuel used for powering compression ignition engines is diesel, whose main components are petroleum products. The constantly growing energy demand involves the implementation of new technical solutions and applying alternative fuels, including renewable ones, such as rapeseed oil, sunflower oil, peanut oil, and animal fats. The most commonly used biofuels are those obtained from chemically processed rapeseeds (transesterification) to provide them with physical−chemical properties similar to diesel fuel. The study presents the results of tests of a power unit fueled with different mixtures of diesel oil and fatty acid methyl esters. The experiment was carried out for a compression ignition engine of 81 kW power with direct fuel injection. Performance parameters of the vehicle power unit and its computer software were modified for the needs of the tests. Those modifications involved increasing the fuel dose and the fuel injection pressure. The test results were statistical... [more]

Energy-storage metabolites such as neutral lipids and carbohydrates are valuable compounds for liquid biofuel production. The aim of this work is to elucidate the main biological responses of two algae species known for their effective energy-rich compound accumulation in nitrogen limitation and day−night cycles: Nannochloropsis gaditana, a seawater species, and Parachlorella kessleri, a freshwater species. Lipid and carbohydrate production are investigated, as well as cell resistance to mechanical disruption for energy-rich compound release. Nitrogen-depleted N. gaditana showed only a low consumption of energy-storage molecules with a non-significant preference for neutral lipids (TAG) and carbohydrates in day−night cycles. However, it did accumulate significantly fewer carbohydrates than P. kessleri. Following this, the highest levels of productivity for N. gaditana in chemostat cultures at four levels of nitrogen limitation were found to be 3.4 and 2.2 × 10−3 kg/m2·d for carbohydrat... [more]