Solid Biofuel Production Research Articles

Relative fuel property variation of gas-pressurized and conventional torrefaction for biochar performance assessment

Exploring biochar from gas-pressurized torrefaction for solid biofuel production is of great concern for the process performance assessment. This study conducts several relative indexes of biochars produced from gas-pressurized and conventional torrefaction, identifying the merits of the former. The results suggest that a higher pressure is more feasible for reducing biochar volume and enhancing energy efficiency. The results of the relative higher heating value (1.01–1.07) and relative enhancement factor (1.00–1.06) indicate that gas-pressurized torrefaction is more efficient for energy density improvement. Furthermore, gas-pressurized torrefaction dramatically facilitates biochar grindability, with the relative Hardgrove grindability index value ranging from 1.20 to 2.40. The proximate and elemental analysis results suggest that a higher pressure facilitates biochar carbonization and deoxygenation with a higher carbonized component. The energy consumption, efficiency, and expense calculation results imply that gas-pressurized torrefaction is more energy-efficient and cost-saving, with the relative upgrading energy index range of 1.00–1.12.

Energy valorization of solid residue from steam distillation of aromatic shrubs

The interest for essential oils is increasing, alongside ongoing scientific research into distillation techniques. This process generates significant solid residue that could be revalorized as energy source. This study explores the energy recovery of the solid fraction produced during the distillation of three aromatic plants: Cistus ladanifer, Juniperus communis and Rosmarinus officinalis. Two conventional energy recovery technologies were considered and compared through an energy balance: solid biofuel production and biogas generation. In case of solid biofuels, the fractionation of biomass allowed for generation of three different qualities that meet the regulation standards of solid fuels, except for the dust fraction. According to the energy balance, the alternative use of these substrates for biogas production showed competitive production in case of Cistus ladanifer and Juniperus communis, while Rosmarinus officinalis biomass presented inhibition of the anaerobic digestion and null energy recovery.

Comparative advantages of gas-pressurized torrefaction for corn stalk conversion to achieve solid biofuel production

Torrefaction is a feasible approach to produce biochar. Several new torrefaction methods have been conducted for biochar production. Among them, gas-pressurized torrefaction is considered a new technology to produce solid biofuel with better fuel performance, without carrier gas, and higher deoxygenation. This study conducts a comparative analysis between conventional torrefaction and gas-pressurized torrefaction to identify the potential applications of the latter. The results indicate that increasing reaction pressure can achieve biochar volume reduction and HHV improvement, thus leading to a higher energy density. The conventional torrefied biochar yield is in the range of 54.13–90.11%, and it is 48.59–80.13% for gas-pressurized one. Moreover, a more extensive surface area, higher carbonization degree, and more stable pyrolysis characteristics are obtained compared to conventional torrefaction. The carbonization index values of conventional and gas-pressurized conditions are 1.04–1.42 and 1.06–1.48. The correlation analysis results suggest that biochar grindability is highly correlated to carbonaceous properties, regardless of torrefaction methods. The expense and environmental impact analysis indicates that gas-pressurized torrefaction possesses lower cost and environmental pollution potential for biochar production.

Production of a high-energy solid biofuel from biochar produced from cashew nut shells

The aim of the study is to produce a solid biofuel of high physico-mechanical and energetic quality from heat-treated cashew nut shells. Raw cashew nut shells are heat treated at 300 °C for 120 min at a heating rate of 1 °C/s. The resulting biochar is milled to 74 μm. Sugar cane molasses was incorporated into the biochar powder at a rate of 10% without the addition of water. The mass yields of solid, liquid and gaseous products obtained were 46.5%, 27.6% and 25.9% respectively. The solid biofuel produced has slightly improved physicochemical and energy properties over biochar, except ash and moisture content. Thus, the addition of binder and densification increased the ash and moisture content of the solid biofuel compared to the biochar obtained. With a higher calorific value of 33.02 MJ/kg, the solid biofuel has high water resistance and meets the quality requirements of class A1 of the NF EN ISO 17225-6 standard in terms of density and mechanical strength. Solid biofuel is ideal for use in households and biomass power stations.

Sustainable Solid Biofuel Production: Transforming Sewage Sludge and Pinus sp. Sawdust into Resources for the Circular Economy

Sustainable Solid Biofuel Production: Transforming Sewage Sludge and Pinus sp. Sawdust into Resources for the Circular Economy

Biochar-plastic co-conversion as an economic strategy in energy production and enhanced plastic waste transformation from walnut and polystyrene waste

In Iran, waste management can be improved through strategies of converting wastes into energy. Their exploitation is still abandoned due to oil economy and lack of environmental motivation. In this study, co-conversion of polystyrene waste (PS) with walnut shell (WS) biochar for solid biofuel production was conducted to develop a new sustainable economic waste-to-bioenergy strategy. The co-pyrolysis of PS and WS provided solid biofuel (WPS) with a yield of 43 % and HHV of 32.10 MJ/kg. To increase the HHV, PS was co-pyrolyzed with WS non-activated biochar (non-AC), resulting in a yield of 78 % and HHV of 33.03 MJ/kg. To enhance the yield, it was co-pyrolyzed with WS activated biochar (AC), leading to a yield of 93 % and HHV of 29.79 MJ/kg. The yield was increased because AC entrapped melted PS into its porous structure to avoid its vaporization. Interestingly, it successfully enhanced the PS conversion from 38 % (in pyrolysis alone) to 77 % (in the co-pyrolysis). Ultimate analysis of all three solid biofuels revealed a sulfur-free fuel as a clean energy source. The economic evaluation indicated that the production of non-ACPS could make it suitable for future commercialization by net profit of 0.085 $/kg and payback time of 1.12 year.

Assessment of the grindability and component variation of torrefied agricultural wastes for industrial furnace application

The utilization of agricultural solid biowastes is essential for resource saving and bioenergy conversion. By this way, the demand of industrial furnace for biomass would be compensated, and the energy structure would also be greener. Among them, torrefaction is a hopeful technology for solid biofuel production. This study investigates the grinding performance of torrefied biochar to achieve the grindability and component variation analysis of torrefied agricultural wastes for fluidized bed boiler, and thus realize pulverized biochar injection for industrial application. Totally crystallinity index (CrI), average particle size distribution, energy input for grinding process, component analysis, and elemental carbon state are adopted and analyzed around Hardgrove grindability index (HGI). The values of HGI are in the range of 45–120, 45–105, 60–120, and 60–135, respectively. The results indicate that torrefaction is conducive for biochar properties upgrading, especially for a higher temperature, and thus contributes to a higher HGI, lower particle size and grinding energy input, as well as better elemental carbon state. The produced powder from torrefied biochar is highly correlated to torrefaction temperature and biochar component, and thus leads to an excellent industrial application potential. Overall, this study is conducive for the agricultural biowastes conversion and solid biofuel production.

Pyrolysis as a Method for Processing of Waste from Production of Cultivated Tobacco (Nicotiana tabacum L.)

Because of the current energy crisis, researchers are looking into new potential substrates for production of biofuels and for possible ways to enhance their parameters. In line with such efforts, the current study focuses on the feasibility of processing waste from the production of cultivated tobacco. The aim of this study was to assess the potential of tobacco waste as a raw material for the production of solid biofuels, such as biochar produced through pyrolysis, and to determine its basic physicochemical properties, compared to other materials used for the production of green fuels. The analyses showed calorific values of 16.16 MJ kg−1 for the raw biomass and those in the range of 24.16–27.32 MJ kg−1 for the products of pyrolysis conducted at temperatures of 400–500 °C and with a heating time in the range of 5 to 15 min. To address the safety-related issues, the study also measured the explosion index (Kst max), which, in the raw biomass, amounted to 72.62 bar s−1 and in the biochar was in the range between 82.42 and 88.11 bar s−1. The registered maximum explosion pressure was 7.37 bar in the case of raw biomass, whereas in the biochars, the value ranged from 8.09 to 8.94 bar. The findings show that tobacco waste has parameters comparable to those identified in the case of other solid biofuels, whereas the process of pyrolysis enhances the energy-related parameters without increasing the explosion class of the product.

Comparison of torrefaction and hydrothermal carbonization of high-moisture microalgal feedstock

A comprehensive comparison is conducted to explore the conversion performance of torrefaction and hydrothermal carbonization of high-moisture microalga for producing solid biofuel with low expense and environmental impact. The results suggest that when their solid yields are close, the hydrochar has higher HHV (higher heating value) (21.10–25.39 MJ kg−1) and energy yield (72.48–92.29%) than the biochar. The graphitization degrees of the biochar and hydrochar are 1.298–3.107 and 2.193–3.049, respectively. Considering fuel grade, the biochar is in biomass and peat zones, but the hydrochar is only in the biomass zone. The biochar's elemental valence transformation and graphitization degree are better than hydrochar's. The pyrolysis and combustion characteristics of the hydrochar are better than those of the biochar when considering the thermodegradation data, leading to a lower expense and environmental impact. The results are conducive to efficiently figuring out a solution with a comparative advantage for microalgal thermochemical conversion. The hydrothermal carbonization conditions at 160 °C for 2 h are the best operation for microalgal solid biofuel production.

Effects of water washing and KOH activation for upgrading microalgal torrefied biochar

Torrefaction is an effective pathway for microalgal solid biofuel upgrading, and alkali metal activation is also an efficient method to enhance fuel properties. This study explores the comparison of torrefaction alone and KOH activation combined with torrefaction to determine a better operation for biochar production from the microalga Nannochloropsis Oceanica. The results indicate that the HHV ranges of KOH-activated biochar and unactivated biochar are 25.611–32.792 MJ·kg−1 and 25.024–26.389 MJ·kg−1, respectively. Furthermore, KOH-activated biochar is better than unactivated biochar, with less residue, broader pyrolysis and combustion temperature ranges, higher elemental carbon, and less combined carbon. Moreover, KOH-activated biochar is close to the unactivated one from the viewpoint of expense calculation and life cycle assessment and thus possesses a better comprehensive performance. Overall, KOH activation is an efficient method for upgrading microalgal solid biofuel. The results are conducive to exploring further modification of microalgal solid biofuel production with better properties, thus leading to a greener and more efficient approach for upgrading fuel performance.

Solid Biofuel Production from Biomass: Technologies, Challenges, and Opportunities for Its Commercial Production in Nigeria

Producing durable and efficient solid biofuels should be an important consideration in Nigeria’s present economy due to the numerous advantages associated with it. It offers the benefit of energy generation, particularly in rural areas, and could potentially replace fossil fuels. However, the adoption and production of solid biofuels at commercial scale in Nigeria is limited by some challenges, including the lack of a developed supply chain structure, inadequate facilities, and air pollution. The present study summarizes the types of solid biofuel production technologies deployed in Nigeria as well as the biomass feedstock utilized in the production of fuel briquettes and pellets. While opportunities exist in the gasification of biomass in Nigeria, direct combustion is a readily applicable fuel conversion process that can be utilized to generate electricity from solid biofuel. The major challenges surrounding the full adoption of solid biofuel production and utilization in Nigeria are highlighted. Among others, promotion of clean energy alternatives, investments and financial incentives, sustainable renewable energy policy and energy transition plan, and legislative backing are identified as factors that could accelerate the commercial production and adoption of solid biofuel in Nigeria.

Changes in Commercial Dendromass Properties Depending on Type and Acquisition Time

Forest dendromass is still the major raw material in the production of solid biofuels, which are still the most important feedstock in the structure of primary energy production from renewable energy sources. Because of the high species and type diversity of production residues generated at wood processing sites, as well as at logging sites, the quality of commercial solid biomass produced there has to be evaluated. The aim of this study was to assess the thermophysical characteristics and the elemental composition of ten types of commercial solid biofuels (pinewood sawdust; energy chips I, II, and III; veneer sheets; shavings; birch bark; pine bark; pulp chips; and veneer chips), depending on their acquisition time (August, October, December, February, April, and June). Pulp chips had the significantly lowest moisture content (mean 26.92%), ash content (mean 0.39% DM—dry matter), nitrogen (N) content (mean 0.11% DM), and sulfur (S) content (mean 0.011% DM) and the highest carbon (C) content (mean 56.09% DM), hydrogen (H) content (6.40% DM), and lower heating value (LHV) (mean 13.61 GJ Mg−1). The three types of energy chips (I, II, and III) had good energy parameters, especially regarding their satisfactory LHV and ash, S, and N content. On the other hand, pine and birch bark had the worst ash, S, and N contents, although they had beneficial higher heating values (HHVs) and C contents. Solid biofuels acquired in summer (June) had the lowest levels of moisture and ash and the highest LHV. The highest moisture content and the lowest LHV were found in winter (December).

Breeding of sorghum hybrids for solid biofuel

Purpose. Today, the search, research and implementation of new technologies for the production of solid fuel is important for the agro-industrial complex and renewable energy. Sorghum is considered as a strategic crop in the provision of feedstock for bioenergy and reclamation of degraded soils. The purpose of the study was to study and select the material for the creation of high-yielding hybrids of sugar and grain sorghum for the production of solid biofuel.
 Materials and methods. The two-year results of the sorghum variety test at the Synelnykivska Experimental Station are highlighted. 68 samples were studied. They had a yield of green mass in the range of 23–79 t/ha.
 Results. F1 hybrids (Nyzk.93s x Karlykove 45) formed the highest average yield of green mass — 65.2 t/ha; F1(Early776s x Karlykove 45) — 61.4 t/ha and F1(Dn71s x Karlykove 45) — 60.1 t/ha. The yield of hybrids Mammoth and F1(A158x Karlykove 45) was slightly lower, and amounted to 53.3 and 52.8 t/ha, respectively. F1 (Nyzkorosle 93s x Karlykove 45) stood out according to the average yield of dry matter of green mass — 17.6 t/ha; F1 (Dn17s x Karlykove 45) — 13.8 t/ha. According to the average indicators of the yield of solid fuel from 1 ha, the combinations F1 (Nyzk.93s x Karlykove 45) were the best — 12 t/ha; F1 (Dn17s x Karlykove 45) — 8.2 t/ha; F1 (Early 776s x Karlykov 45) — 7.9 t/ha. The best indicators in terms of energy output were the following combinations: F1(Low 93s x Karlykove 45) — 197.7 Gj/ha, F1(Dn71s x Karlykove 45) –135.5 Gj/ha, F1(Early 776s x Karlykove 45) — 129 Gj/ha.
 Conclusions. High-yielding sorghum hybrids are the most economical and energetically expedient measures to provide feedstock for the bioenergy industry. A selected hybrid for the bioenergy application F1 (Nyzkorosle 93s x Karlykove 45) differs from the standard in terms of productivity and manufacturability. The value of the Karlykove 45 variety as a pollinator for the creation of hybrids for solid biofuel was also clarified. The agricultural sector of Ukraine has enough potential resources for biofuel production.

Hydrothermal carbonization of mixture waste Gingko leaf and wheat straw for solid biofuel production

Co-hydrothermal carbonization (co-HTC) of ginkgo leaf residues (GLR) and wheat straw (WS) were conducted to investigate the possibility for mutually benefitting the two residues as feedstock to produce solid biofuel pellets. The mass yield, proximate, and elemental analysis of the hydrochar were characterized. The energy consumption during pelletization, pellet density, pellet durability, water resistance ability, and pyrolysis characteristics of hydrochar pellets were evaluated. The results show that when WS blended with 50%, the energy density of pellet increased from to the highest of 26.7 GJ/m3. The ash content decreased from 7.7% to 6.3% when the WS blended with 30%− 70%, while HHV showed a opposite trend. As the WS blended ratio increased from to 30–70%, the high lignin content in WS helped to enhance the mechanical properties of pellet including pellet density, durability, and hardness. The hydrochar pellets from high ratio WS had high devolatilization index indicating increased devolatilization ability. These findings imply adding WS in co-HTC would potentially promote the GLR to manufacture high quality solid biofuel. Overall, the co-HTC of WS and GLR is a promising alternative to transfer solid wastes to renewable fuels.

Peculiarities of plant growth, development, and chemical composition of the Paulownia biomass

Purpose. To establish the peculiarities of plant growth, development, and chemical composition of the paulownia biomass of two species in the Right Bank Forest Steppe of Ukraine. Methods. Field, laboratory, measuring and weighing, mathematical and statistical. Results. The biological properties of two Paulownia species, namely Clone in vitro-112 and Paulownia tomentosa, were studied. The maximum number of leaves per plant at the end of the vegetation season was 24–26 in Clone in vitro-112 and 22–24 in Paulownia tomentosa. Leaf area per plant was 5.0–5.5 m2 and 4.0–4.5 m2, respectively. The main period of wood accumulation falls during the first three years of vegetation, and during this period, biomass productivity indicators are the highest. Five-year wood yield per tree was about 0.35 m3 in Clone in vitro-112 and 0.24 m3 in Paulownia tomentosa. The research determined the optimal content of nutrients, the lack or excess of which negatively affects biomass quality. Nitrogen is mostly concentrated in leaves (2.3–2.6%) and petioles (0.67–1.1%). The content of phosphorus was quite low: 0.33–0.36% in leaves and 0.22–0.23% in petioles. Plants contain a significant amount of potassium in the leaves: 1.25% in Clone in vitro-112 and 0.75% in Paulownia tomentosa. Conclusions. Clone in vitro-112 can be recommended for cultivation in the Right Bank Forest Steppe Zone of Ukraine. One hectare can produce 200–250 m3 of industrial wood and the same amount of branch biomass for 5–6 years. Branches are suitable for the production of fuel pellets and chips with low ash content (0.8–1.5%). At the same time, leaves and petioles of paulownia have an increased ash content (3.9–7.1%) due to the higher content of nutrients, in particular nitrogen. Therefore, it is not advisable to use them as feedstock for the production of solid biofuel, but they are suitable for the production of biogas.

Comparative techno-economic assessment of production of microcrystalline cellulose, microcrystalline nitrocellulose, and solid biofuel for biorefinery of pistachio shell

The biorefinery of pistachio shell (PS) for producing microcrystalline cellulose (MC), microcrystalline nitrocellulose (MNC), and biochar (PSB) was techno-economically assessed. A rapid recyclable nitric acid treatment purely isolated 32–41 % of PS as MC particles (crystallinity index of 86 %) at 80 °C for 90 min. A facile synthesis obtained MNC particles (crystallinity index of 79 %) with a nitrogen content of 10.81 % from the MC. The PSB with the HHV value of 27.82 MJ/kg and 24 % production yield was achieved as biocoal via pyrolysis at 400 °C for 30 min. The incorporation of sulfuric acid pre-dehydration with pyrolysis temperature and time improved the PSB yield up to 28 %, while lowering the HHV to 24.12 MJ/kg. The NPV, IRR, ROI, and payback time indicated that the MC and MNC production from PS could make them suitable for future commercialization; however, the PSB production was not profitable because it could not compete with coal.

Agricultural biomass feedstock for biofuels production in Ukraine

Ukraine has a large potential of biomass available for the production of solid, gaseous and liquid biofuels. According to 2021 data, the bioenergy potential is about 25 Mtoe, of which 49% is agricultural residues and 30% is energy crops (in case of growing on 2 mln ha). Of the agriresidues, only sunflower husk is now widely used for energy, while the potential of straw, corn stalks and sunflower stalks is practically untapped for this purpose. For Ukraine, one of the promising directions is priority use of corn stalks for the production of energy and solid biofuels such as briquettes and pellets. Another prospective area is growing energy crops. Ukraine has 3-4 mln ha of unused (marginal) agricultural land, which can be engaged for growing energy crops such as willow, poplar, miscanthus (for solid biofuels) and corn silage for biogas. Growing energy crops as biomass feedstock and its further use for the production of heat and power becomes competitive in light of growing prices of natural gas and issues with providing security of its supply. An important but less-developed sector of Ukraine’s bioenergy is motor biofuels. Having such a big potential of agribiomass, the country could produce bioethanol and biodiesel including the advanced biofuels from lignocellulosic feedstock. It is necessary to create favourable conditions for the development of domestic production of motor biofuels. This may include a reduction in the excise tax, the abolition of compulsory tax bill for the full rate of excise duty when transporting bioethanol, the introduction of an export duty on rapeseed, and some other measures.

Life cycle assessment and techno-economic analysis for biofuel and biofertilizer recovery as by-products from microalgae

Although there are several studies on the hydrothermal carbonization of microalgae biomass for value-added products and their potential environmental impacts, the feasibility of scaling-up and the environmental and economic analysis need to be investigated. This study produced solid biofuel and biofertilizer under two operating conditions (170 °C, 10 min, 7 bar; or 130 °C, 50 min, 2 bar, respectively). Also, investigated the environmental performance and techno-economical viability of producing solid biofuel and biofertilizer from microalgae. Scale-up modeling used Aspen Plus software to obtain optimized production processes, energy data, equipment requirements, and costs, which were used to support the economic and environmental analyses. The Recipe Midpoint method showed that the solid biofuel had a higher environmental impact than the biofertilizer, especially in the Freshwater Eutrophication category (almost 7 times higher), Fossil Resource Scarcity (4.2 times higher), Global Warming, and Marine Ecotoxicity (both around 2.7 times higher). The damage assessment results showed that the production of solid biofuel was more impactful, with Human Health impacts 2 times higher, Ecosystem 1.6 times higher, and Resource 4.3 times higher than those caused by biofertilizer production. The biofertilizer production scenario emerged as the most economically viable option for hydrothermal carbonization valorization. The negative net present value and the inability to achieve the return on investment within a 30-year timeframe made the solid biofuel production scenario unviable. Thus, biofertilizer production from hydrothermal carbonization of microalgae biomass cultivated in wastewater is technically, economically, and environmentally feasible, whereas the same cannot be said for the biofuel evaluated.

DIRECTIONS OF USE OF FOOD AND PROCESSING INDUSTRY WASTE

Every year, there is more and more waste on our planet. This leads to soil, water and air pollution, which negatively affects people’s health and quality of life. Therefore, the task of reducing production and consumption waste, as well as choosing effective directions for their use, becomes urgent. During the production of food products, waste is mainly of plant and animal origin. The main types of waste generated at processing and food enterprises have been determined: in the fruit and vegetable and canning industry – apple, berry and vegetable pomace, as well as vegetables and fruits that cannot be processed as the main product; in the grain processing industry – wheat bran; in the sugar industry – molasses, pulp; in the dairy industry – whey; in the oil and fat industry – husks, cakes, etc. It is noted that the most valuable waste is sold abroad or processed into food products. The list of products by areas of use (food, medicine, chemical industry, fertilizers, cosmetic industry, animal feed, fertilizer, energy) that can be obtained from organic waste is given. The types of waste, which are valuable raw materials for chemical, pharmaceutical and cosmetic production, and energy production, have been determined. It is substantiated that in modern conditions in Ukraine it is necessary to intensify the use of waste from processing and food industries as energy carriers – for the production of solid biofuel (briquettes, pellets), biogas, etc. This will help compensate for the lack of energy resources due to damage to traditional energy facilities during Russia's hostilities against Ukraine. However, there is still a large amount of waste in Ukraine that is buried or poured into the sewers, which causes pollution of water bodies, soils and emissions of greenhouse gases into the atmosphere. With a comprehensive approach and a joint solution to the problem of waste management of various industries, it is possible to ensure the saving of raw materials, the creation of new jobs, and the protection and improvement of the environment.

Evaluation of Sugarcane Cutting Residues for the Production of Solid Biofuel

Due to pollution and environmental deterioration, man needs to find other alternatives as energy sources, including biomass. The present research was conducted to evaluate the sugarcane-cutting resi-due; this biomass has no use and can be burned to obtain energy. Manufacturing pellets reduces the environmental impact of animals and plants on crops. To characterize, for the first time, physical treat-ments such as cleaning raw materials are carried out, drying, grinding, and sieving to have the optimal characteristics to be used in the pelleting stage. Then a proximal analysis was conducted based on the ASTM -3172-89 Standard and the determination of the calorific value using the ASTM D-240 Standard. Likewise, the pellets were analyzed in their final stage. This method analyzes the parameters of mois-ture content, volatile material, ashes, and fixed carbon. It was obtained as a result that for the raw mate-rial, the % Hydrogen=3.543, %Volatile matter =86.53, %Cz=6.939, % Fixed carbon= 2.987, and Calorific value= 15.702 KJ/kg; and for the elaboration of the pellets it was carried out using the mixing propor-tion, 53% sugarcane cutting residue with 47% binder, this was determined using the proximal analysis and the determination of the calorific value, from which the results of % Humidity=5,768 were obtained., %Volatile matter=82.313, %Ash=6.376, %fixed carbon= 5.543 and Calorific value= 15.635 KJ/kg. Sugarcane cutting residues meet the physicochemical properties to be used as raw material in producing solid bio-fuel.