Drying is one of the methods used for preserving fruits and vegetables. However, due to the lengthy process and elevated temperature of convective drying, other pretreatment and drying methods are studied to shorten the drying time and obtain high-quality products. This study aimed to examine the effect of ultrasonic (US) pretreatment and microwave−hot air drying (MW−HA) on the drying time, specific energy (SEC), qualitative properties (e.g., color, shrinkage, and rehydration ratio), and bioactive compound properties (e.g., antioxidant activity, phenolic, and flavonoid contents) of hawthorn fruit. Experiments were performed using ultrasound pretreatment and a microwave dryer (microwave power: 180, 360, and 540 W) at air temperatures of 40, 55, and 70 °C. Drying of hawthorn lasts from 35 min for the ultrasound-treated sample (dried at 540 W and 70 °C) to 180 min (dried at 180 W and 40 °C without US treatment). The lowest amount of SEC (24.11 MJ/kg) was obtained using the US−MW−HA air dr... [more]

This review article aims to describe the main applications of gas hydrates in industrial processes and the related advantages and limitations. In particular, gas storage, energy storage, gas transportation, final disposal of greenhouse gases, desalination, wastewater treatments, food concentration, and other technologies are described in detail. Similarly, the benefits and disadvantages of the solutions, currently adopted to improve the process efficiency, are discussed in the text. A particular focus on the use of additives and their capability to intervene during the formation of hydrates and on the replacement process is provided. The second part of the article deals with the use of small-chain hydrocarbons as aid gases during formation, to improve the efficiency and the competitivity of hydrate-based processes. First, the thermodynamic properties of hydrates, containing only these compounds, are described. Then, based on a collection of experimental data available elsewhere in the... [more]

One of the options for reducing harmful emissions in the production of heat energy is the use of biomass, including in combination with industrial waste (for instance, coal and coke dust). Recent studies demonstrate that a mix of biomass and coal makes it possible to obtain a bio-coal briquette with better characteristics, which is a motivating factor in the search for alternative sources of heat energy from local agricultural waste. The aim of this research is to study the properties of bio-coal briquettes from biomass (sunflower husks and leaves) and industrial waste (coal and coke dust). The raw material was grinded and used for the production of bio-coal briquettes of 20%, 30%, 40%, 50%, 60%, and 70% of biomass. The biomass was grinded to the size of no more than 2 mm for the fine fraction and no more than 6 mm for the coarse fraction. The briquettes were made mechanically using a hydraulic press with a compression pressure of 25 MPa without the use of any binder. The characteristi... [more]

The complex fault block oilfields in the craton basin contain vast reserves of oil and gas resources. During the development of an oilfield, the flow of oil, gas, and water, is controlled by faults and configuration boundaries. The distribution of remaining oil and gas depends on the interpretation of the reservoir’s architecture. However, recognizing the faults and the architecture boundary remains a challenge, hindering the efficient development of these resources. This study proposes a new idea for interpreting the configuration of thick sand bodies. This study was conducted in order to interpret the fine architecture of thick sand bodies in the Sangtamu area, using core samples, well logging, and production data, guided by sedimentation patterns from ancient to modern times. Results indicate that the Sangtamu area is a braided river delta front sedimentary system, dominated by the backbone underwater distributary channel and branch-type underwater distributary channels. The backbon... [more]

According to the needs of sustainability, a new sustainable banana chip value chain, which is a combination of the traditional banana chip value chain and the banana waste value chain, was designed. Scenarios were created assuming that an anaerobic digester would be implemented to produce biogas—which can act as a substitute for liquefied petroleum gas (LPG) used in banana processing—from banana wastes. The values of banana residues throughout the value chain were determined depending on farm gate tree price, transportation cost, and the final value of LPG substitution. The value chain was optimized using two objective functions: total chain profit maximization and factory profit maximization. The tree price at the farm gate was determined and assumed to be between USD 0.067 and USD 0.093 per tree, and the transportation cost of tree transportation was assumed to be between USD 0.31 and USD 0.39 per km. Different tree prices and transportation costs affected the profits of all stakehol... [more]

This paper presents the conceptual design of a technological solution for the efficient conversion of food waste into heat and power. The distribution and composition of food loss and waste at different stages of the food supply chain in Slovenia and their potential for biogas production were determined. It was found that more than 50% of food waste comes from households. Therefore, a small plant was designed to convert food waste into biogas, which was innovatively coupled with a combined heat and power (CHP) unit and a heat pump. This doubles the amount of heat generated compared to conventional cogeneration. Based on the capacity of a micro commercial CHP unit, 3330 households (about 8000 residents) would supply food waste. The heat generated could replace 5% of the natural gas used for domestic water heating. The payback period would be 7.2 years at a heat price of about 80 EUR/MWh, however, for municipalities with more than 40,000 inhabitants the payback period would be reduced to... [more]

The subject of the research involved fly ashes from several power plants in Poland, produced in the process of hard coal and lignite combustion. The objective of this article was to determine the concentration and distribution of elements strategic for the EU economy in ashes and in their two finest grain classes (below 20 µm and 45 µm). The differences in grain size of these ashes, as shown by granulometric tests, were significant. The concentrations of elements in the ashes and in grain classes were compared with the world average (Clarke value) for this raw material. For the majority of critical elements, a dependence of the concentration on the size of ash particles was observed. The content of REY (Rare earth elements and yttrium) and other critical elements in hard coal ashes increases with decreasing particle size. Despite the increase in the concentration of REY in the class below 20 µm, the Clarke value of these elements was not exceeded. Pearson’s correlation coefficients con... [more]

This paper describes examples of energy crops that are profitable to burn, and whose cultivation is not complicated or expensive. Rapid growth of biomass, especially the green mass of energy crops, is indicated, which means that, in relation to fossil fuels, energy crops are considered renewable raw materials. An assessment of Polish non-food energy agriculture was conducted in the context of the prospects of a renewable energy source, namely, biomass. Recommendations for crop cultivation, the size of possible yields and the most important parameters of the obtained biomass, which have the greatest impact on the suitability of energy use, are presented. Materials of biological origin for combustion are divided into three groups: wood waste, by-products and plant products for the energy industry. It is indicated that 2 tons (Mg) of dry wood or straw is energetically equivalent to 1 Mg of coal, and 1 m3 of biogas is energetically equivalent to 1 kg of Polish coal. A novelty of this artic... [more]

New strategies and market segments considering integrated approaches have emerged as critical components in the energy transition. Agrivoltaics is one approach that has shown a lot of promise for offering advantages in the food-energy-water nexus. The agrivoltaic system involves the installation of photovoltaic panels above agricultural lands to generate electricity while also allowing for crop production. The paper “SWOT and TOWS Matrix Analysis of Agrivoltaic System” comprehensively analyses the potential strengths, weaknesses, opportunities, and threats (SWOT) associated with implementing an agrivoltaic system. This study utilizes a SWOT analysis framework to identify and evaluate the internal and external factors that could impact the implementation and success of the agrivoltaic system. A TOWS matrix analysis is also conducted to formulate strategic recommendations based on the identified SWOT factors. The analysis results reveal that the agrivoltaic system has numerous strengths,... [more]

Anaerobic digestion is considered a beneficial treatment for biogas production (BP). To improve the performance of this bioprocess, the addition of well-selected inocula could be an interesting approach that affects the overall efficiency of the BP. In this study, the reactor performance and energy analysis of liquid-state anaerobic digestion of cattle manure (CM) at high solids concentration (TS%) (94.87%) with six different inocula—two cellulosic (C.I1, C.I2), one lipidic (Li.I), two lactic (La.I1, La.I2), and one saccharidic (Sacc.I)—were investigated. The results showed that inocula improved the biogas production and yield during anaerobic digestion of CM by 109%, 86%, and 52.4%, respectively, when the cellulosic (C.I1), lipidic (Li.I), and lactic (La.I1) inocula were added, compared with the substrate production alone at a substrate/inoculum (S/I) ratio of 5:3 (v/v). The addition of inocula in an appropriate range is useful for the performance of the anaerobic digestion process. I... [more]

The influence of impellers system, baffles system and type of liquid on gas hold-up in a vessel has been presented in this paper. The analysis of gas hold-up was conducted on the basis of the data obtained in the vessel. The vessel used in the study was of inner diameter D = 0.288 m, and it was filled with liquid up to a height of H = 0.576 m. The vessel used in the study was equipped in four planar standard baffles or 24 vertical tubular baffles located on the circuit. A high-speed impellers system, consisting of two impellers located on the shaft, was used to agitate the liquid. The six gas−liquid systems were tested. The gas used in the study was air. The liquids were distilled water, aqueous solutions of NaCl (concentration c = 0.4 kmol/m3 or 0.8 kmol/m3), aqueous solution of sucrose (concentration c = 2.5% mass., 5% mass.), 5% mass. aqueous solution of sucrose and yeast suspension concentration ys = 1% mass. The obtained set of over 1600 experimental points allowed to derive the e... [more]

This paper proposes a methodology for plant root system and soil moisture analysis through the geoelectrical prospecting method. Overall, bench and field experiments are implemented to analyze the behavior of electrical conductivity of the soil in relation to moisture content and plant root system growth. Specifically, Wenner array and lateral profiling technique are used to stratify the soil in horizontal layers, performing in-depth analysis. Millet (Pennisetum glaucum L.), bean (Phaseolus vulgaris L.) and sorghum (Sorghum bicolor L. Moench) are used to analyze the root system behavior. Results show that the soil water dynamics can be observed through soil stratification in horizontal layers and the plant root system is correlated with apparent electrical conductivity of the soil. Thus, geoelectric prospecting methods can be used as an analysis tool, both of soil moisture dynamics and of plant roots, to support decision making regarding soil and crop management.

This study was a preliminary investigation of solid recovered fuel production from spent coffee grounds using the hydrothermal carbonization (HTC) technique. The spent coffee grounds (SCGs) were subjected to HTC at 170 to 250 °C. The biochar was characterized by proximate analysis, ultimate analysis, capillary suction time, time to filter, suspended solids, and particle size distribution. The biochar yields decreased with increasing HTC temperature and time. However, the higher heating value (HHV) of biochar increased with the HTC temperature and time. The H/C slop relative to the O/C atomic rate of spent coffee grounds was 0.10 with low decarboxylation selectivity. Considering the HHV of biochar and dehydration capacity depend on ratio of H/C vs. O/C, the optimum reaction temperature of HTC was 200 °C, and the biochar from SCGs is an attractive biochar.

This work aims to systematically investigate the influence of process temperature, biomass-to-water ratio, and production scales (laboratory and pilot) on the chemical composition of aqueous and gaseous phases and mass production of chemicals by hydrothermal processing of Açaí (Euterpe oleraceae, Mart.) seeds. The hydrothermal carbonization was carried out at 175, 200, 225, and 250 °C at 2 °C/min and a biomass-to-water ratio of 1:10; at 250 °C at 2 °C/min and biomass-to-water ratios of 1:10, 1:15, and 1:20 in technical scale; and at 200, 225, and 250 °C at 2 °C/min and a biomass-to-water ratio of 1:10 in laboratory scale. The elemental composition (C, H, N, S) in the solid phase was determined to compute the HHV. The chemical composition of the aqueous phase was determined by GC and HPLC and the volumetric composition of the gaseous phase using an infrared gas analyzer. For the experiments in the pilot test scale with a constant biomass-to-water ratio of 1:10, the yields of solid, liqu... [more]

In this study, coffee waste (CW) and empty fruit bunches (EFB) were employed as precursors for the production of activated carbons by a chemical activation method. KOH, ZnCl2, and H3PO4 were used as activating agents along with their three mixing ratios of 1:0, 1:1, 1:3, w/w, and carbonization temperatures of 600 °C, 700 °C, and 800 °C were used to prepare these activated carbons. The highest yields of produced activated carbons were observed at 600 °C with a value of 45.20% for coffee waste and 48.20% for empty fruit bunch, with a 1:3 w/w (H3PO4) ratio. However, the maximum specific surface area was 3068 m2 g−1, and 2147 m2 g−1 obtained at 800 °C for coffee waste and empty fruit bunch activated carbons, respectively. The surface features of these products exhibited acute morphological changes, as were clearly noticed via SEM studies. Moreover, in the Van Krevelen diagram, it was also observed that both the H/C and O/C ratios were dramatically decreased to 0.0019 and 0.0759, and 0.0066... [more]

The influence of moisture content on substrate thermal conductivity at different temperatures was investigated for four different commercially available substrates for green roofs. In the unfrozen state, as moisture content increased, thermal conductivity increased linearly. In the phase transition zone between +5 and −10 °C, as temperature decreased, thermal conductivity increased sharply during the transition from water to ice. When the substrate was frozen, thermal conductivity varied exponentially with substrate moisture content prior to freezing. Power functions were found between thermal conductivity and temperature. Two equally sized, green roof test cells were constructed and tested to compare various roof configurations including a bare roof, varying media thickness for a green roof, and vegetation. The results show that compared with the bare roof, there is a 75% reduction in the interior temperature’s amplitude for the green roof with 150 mm thick substrate. When a sedum mat... [more]

Yeasts were isolated from four potential sources, sweet sorghum juice, sugar cane juice, grapes and rambutan. The 27 yeast isolates were tested for their ethanol tolerance (15% v/v of ethanol) and ethanol fermentation performance in a synthetic ethanol production medium (200 g/L of total sugar). Only five isolates, SCJ04KKU, SCJ07KKU, SCJ09KKU, SCJ14KKU and SSJ01KKU could tolerate 15% ethanol and produce ethanol at levels higher than 55 g/L. The ethanol production efficiency from sweet sorghum juice under high gravity (HG, 200 and 240 g/L of total sugar) and very high gravity (VHG, 280 g/L of total sugar) conditions of the five isolates was tested. Saccharomyces cerevisiae NP01 and S. cerevisiae ATCC4132 were used as reference strains. The results showed that the SSJ01KKU isolate gave the highest ethanol production efficiency under all conditions. Ethanol concentration (PE), yield (YP/S) and productivity (QP) values were 98.89 g/L, 0.50 and 1.18 g/L·h, respectively, with sugar consumpt... [more]

The paper presents the results of the pelletization (agglomeration) tests of post-harvest tobacco waste as a feedstock for fuel pellet production. The experiment was conducted on a prototype pelleting−briquetting device with a flat matrix. The influence of the tobacco waste moisture content (17, 21 and 25wt.%) and the rotational speed of the agglomerating rolls (120, 170 and 220 rpm) on the power demand and on the pellet’s kinetic durability and density were determined. It was found that the moisture content has a significant impact on the pellet’s density but slightly affects its kinetic durability. The obtained pellets were characterized by a high density above 1000 kg·m−3 and kinetic durability above 97%. In order to examine the exhaust composition, the obtained pellets were combusted in a 25 kW fixed great boiler. High amounts of CO, SOx, NO and HCl were obtained, which suggests that the selection of a different technology for tobacco waste pellet combustion should be made.

Sicily is characterized by rural buildings, Palmenti, destined to wine production, which are scattered along the countryside and part of the local historical heritage. There are different types of rural buildings, but all have in common the use of ancient and well-established bioclimatic techniques for wine conservation and aging. Most of them were built with the double function of living space for the owner and productive spaces for all the activities correlated to the cultivations. Indeed, many rural houses, destined to the wine production, are characterized by wineries and wine cellars (the first for the wine production, the second to store the wine for the aging process). The growing production of high-quality Sicilian wines, very appreciated all over the world, leads to upgrade the ancient Palmenti to seek optimal hygrothermal conditions and, therefore, to guarantee high performance of the produced and stored wines. The purpose of this study is to investigate how the retrofit meas... [more]

With the recent increase in biomass pellet consumption, the mechanical degradation of pellets during transport and handling has become more important. ISO standard 17831-1 is an accepted global standard that is commonly used amongst researchers and industries to determine the mechanical durability of pellets. However, the measured mechanical durability sometimes fails to match the certificate accompanying the shipment. In such cases, pellet length specifications are suspected to play a role. This paper studies the effect of pellet length on mechanical durability for various types of commercially produced biomass pellets. In addition, the effect of test conditions and torrefaction on the mechanical durability of biomass pellets has been investigated. To study the effect of pellet length, pellets were classified into three groups: shorter than 15 mm, 15 to 30 mm, and longer than 30 mm, and their length distributions were measured using an in-house image processing tool. Then, the mechani... [more]

Upgrading biomass waste streams can improve economics in wood industries by adding value to the process. This work considers use of a hydrothermal carbonization (HTC) process for the residual feedstock after lignin and hemicelluloses extraction. Batch experiments were performed at 200−240 °C temperatures and three hours residence time with an 8:1 biomass to water ratio for two feedstocks: Raw spruce and spruce after lignin extraction. The proximate analysis and heating value showed similar results for both feedstocks, indicating that the thermochemical conversion is not impacted by the removal of lignin and hemicelluloses; the pretreatment processing slightly increases the heating value of the treated feedstock, but the HTC conversion process produces a consistent upgrading trend for both the treated and untreated feedstocks. The energy yield was 9.7 percentage points higher for the treated wood on average across the range temperatures due to the higher mass yield in the treated experi... [more]

spp. are among the most suitable species for biomass production, even for the firewood derived from medium-rotation coppice (MRC). The general problem of wood is that it cannot be utilized immediately because of the high moisture content, which in the combustion process would reduce remarkably the yield of energy. In this context, outdoor storage of whole stems without branches (WS), outdoor storage of whole stems with branches (WSB), open shed storage of firewood logs in mesh bags (OSF), and outdoor firewood logs in mesh bags (ODF) of Eucalyptus spp woody biomass were compared in term of moisture and dry matter loss to evaluate the most convenient form of storing biomass deriving from a medium-rotation coppice. During the storage period, ODF showed higher moisture values than OSF, WSB, and WS, underlining that moisture reduction is related to local climatic conditions, pile size and permeability (compaction). However, at the end of the storage period, the four options reached a simila... [more]

The present study considers evaporative cooling and desiccant unit-based air-conditioning (AC) options for livestock AC application. In this regard, proposed systems are investigated by means of experiments and thermodynamic investigations. Air-conditioning requirements for animals are theoretically investigated and temperature-humidity index (THI) is estimated. A lab-scale heat mass exchanger based on the Maisotsenko-cycle evaporative cooling conception (MEC) is set up and its performance is evaluated at different ambient air conditions. In addition, a desiccant-based air-conditioning (DAC) unit is thermodynamically evaluated using a steady-state model available in the literature. The study focuses on the ambient conditions of Multan which is the 5th largest city of Pakistan and is assumed to be a typical hot city of southern Punjab. The study proposed three kinds of AC combination i.e., (i) stand-alone MEC, (ii) stand-alone desiccant AC, and (iii) M-cycle based desiccant AC systems.... [more]

Economies have begun to shift from linear to circular, adopting, among others, waste-to-energy approaches. Waste management is known to be a paramount challenge, and food waste (FW) in particular, has gained the interest of several actors due to its potential impacts and energy recovery opportunities. However, the selection of alternative valorization scenarios can pose several queries in certain contexts. This paper evaluates four FW valorization scenarios based on anaerobic digestion and composting, in comparison to landfilling, by applying a consistent decision-making framework through a combination of linear programming, Life Cycle Thinking (LCT), and Analytic Hierarchy Process (AHP). The evaluation was built upon a case study of five universities in Costa Rica and portrayed the trade-offs between environmental impacts and cost categories from the scenarios and their side flows. Results indicate that the landfill scenario entails higher Global Warming Potential and Fresh Water Eutr... [more]

The aim of this study was to compare the aromatic profile of plum spirits, obtained from the Požegača and Stanley varieties, as affected by different combinations of pre-distillation steps used in traditional and six modified production methods that are common in Serbian distilleries. Traditional plum spirits (produced from spontaneously fermented mashes of crushed plums with stones distilled after two months of storage) had the highest contents of ethyl acetate, benzaldehyde, and total acids, which resulted in the occurrence of an unpleasant solvent-like and stone-like odour and acidic taste. These sensory defects were overcome by the distillation of fermented mashes immediately after the completion of alcoholic fermentation. Depending on the combination of the pre-distillation steps, plum spirits from mashes distilled immediately after alcoholic fermentation were characterized by different aromatic profiles: closer to traditional (from spontaneously fermented crushed plums with/witho... [more]