Vine Prunings Research Articles

A technical-economic analysis of integrating vine prunings energy conversion systems for CHP production in local wineries

This study proposes the energy conversion of vine prunings to supply energy to local wineries, with a focus on the Riunite & CIV branch winery located in Carpi (Modena, Italy), exploring the possibility of generating both electricity and heat through biomass gasification. A Matlab-Simulink model is used to evaluate the energy savings that can be achieved when an energy storage system is coupled with the combined heat and power generation system. Within this context, the results showed that it is possible to save ≈\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\approx $$\\end{document}30% of the electricity and ≈\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\approx $$\\end{document}60% of the thermal energy demanded by the winery. However, the economic viability of the project is hindered by high investment and operation costs. DPB is strongly affected by the cost of biomass and the energy prices, resulting in a profitable investment for electricity prices higher than 0.30 ÷>\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\div>$$\\end{document}0.57 €/kWh according to the different scenarios investigated.

Mild isolation and characterization of surface lignin from hydrothermally pretreated lignocellulosic forestry and agro-industrial waste biomass

Within the biorefining concept, the lignocellulosic biomass wastes can serve as feedstock to produce value-added chemicals and fuels. The sustainable valorization of biomass is based on integrated processes that aim to the utilization of “whole biomass”. To this end, the first step of the efficient biomass pretreatment towards selective isolation of cellulose, hemicellulose and lignin, is of paramount importance. Hydrothermal pretreatment of biomass in neat water is a green and well-established process that enhances hemicellulose removal and recovery in the liquid fraction, affording a cellulose and lignin enriched solid which can be enzymatically hydrolyzed to glucose. A simple and efficient method to facilitate the hydrolysis is the prior extraction of the formed “surface” lignin which hinders the action of enzymes. Within this context, in this work, forestry (beechwood sawdust) and agro-industrial (vine prunings, apricot kernel shells) wastes were hydrothermally pretreated in neat water (at 220 °C, 15 min) and the formed surface lignin was extracted via soxhlet or reflux methods under mild conditions, with the use of green solvents (ethanol, acetone). The delignification degree of the pretreated biomass was in the range of 35–67 wt%, depending on the solvent and biomass feedstock. The recovered surface lignins were of high purity and exhibited similar physicochemical and structural characteristics with the organosolv lignin. The fast pyrolysis of surface lignins afforded bio-oils enriched in alkoxy-phenols and oxy-aromatics. The biomass solids recovered after lignin extraction are enriched in cellulose (70%) and exhibit high relative crystallinity and improved textural properties, thus increasing their potential valorization.

Enhancement of Yield, Phytochemical Content and Biological Activity of a Leafy Vegetable (Beta vulgaris L. var. cycla) by Using Organic Amendments as an Alternative to Chemical Fertilizer.

This study evaluates the effect of a chemical fertilizer (ammonium nitrate), a compost (vermicompost from cattle manure) and two biochars (from vine prunings and wood chips, respectively), applied to the soil alone or in mixture, on the yield, phytochemical content and biological activity of Beta vulgaris L. var. cycla (Swiss chard). The respective treatments, each replicated four times, were arranged according to a completely randomized block design. Results showed that vermicompost, both alone and in mixture with vine pruning biochar, significantly increased yield parameters (plant height and leaf area) and yield over the untreated soil and the biochars alone, similar to ammonium nitrate. Moreover, vermicompost, both alone and in mixture, respectively, with the two biochars, determined lower total N and NO3- contents than ammonium nitrate, both alone and in mixture, respectively, with the two biochars. In particular, NO3- content was within the safe thresholds fixed for leafy vegetables by the European Commission to prevent any adverse implication on human health from dietary NO3- exposure. The biochars alone resulted in very low yield and leaf total N content, likely due to a limited release of N for plant uptake, also evidenced by the undetectable NO3- leaf content, similarly shown by plants grown in untreated soil. Vermicompost, alone or in mixture, respectively, with the two biochars, increased the content of specialized metabolites, with a positive effect on antioxidant activity. The organic amendments, particularly compost, could be an alternative to chemical fertilizers to reach a trade-off between yield, nutritional and health qualities in Swiss chard, meeting the needs of farmers and consumers as well as the targets for sustainable food production.

Optimization of Experimental Parameters in the Solvent Extraction of Trans-Resveratrol from Pruning Waste of Vitis vinifera, Fetească Neagră Variety

The past few decades have seen a marked expansion in market demand for food supplements with therapeutic value. Due to this demand, the recovery of vine waste for obtaining certain phytochemicals or plant synthesized compounds with health-promoting activities can be an important economic component, principally with the agreement of the European Union for resveratrol as a new food ingredient. For the sake of economic capitalization, it is necessary to determine optimum extraction parameters for maximum recovery. In this paper, we have determined the optimum parameters for the solvent extraction of trans-resveratrol from vine prunings. We tested different extraction conditions: 35 different types of solvents, 10 types of solid-to-liquid ratios, 10 extraction times, 10 types of granulosity of the ground material and 7 consecutive extractions on the same material. The optimal parameters determined were: solvent ethanol:diethyl ether 4:1 ratio, 1:35 solid liquid ratio g/mL, 4 days for extraction time, 500 µm–350 µm granulosity of powdered material and one extraction on the material. These findings are confirmed by optimization of extracting parameters according to Box–Behnken design.

Pretreatment/fractionation and characterization of winery waste streams within an integrated biorefinery concept

The aim of this work was the characterization of the main winery wastes, e.g. vineyard prunings, grape stalks, grape pomace and wine lees, and the utilization of the hydrothermal pretreatment towards selective fractionation and recovery of hemicellulose (and related sugars, furans and acids), increased cellulose enzymatic hydrolysis, and isolation of “surface” and hydrothermal/acid hydrolysis lignin, discussing also the potential valorization of each stream into value-added chemicals. Two varieties from Greece were investigated, i.e. Grenache Rouge (Vitis vinifera L. cv. Grenache Rouge) and Malagouzia (Vitis vinifera L. cv. Malagouzia). Three hydrothermal pretreatment severities were applied, i.e. logRo 3.24, 4.32 and 4.71 (corresponding to 170oC-15 min, 170oC-180 min, and 220oC-15 min), all leading to enhanced enzymatic hydrolysis of cellulose in the vine prunings to glucose. The composition of the recovered aqueous product contained mainly glucan and xylan, which were converted to monomeric sugars and eventually to furans (furfural, HMF) and organic acids (formic, lactic) at more intense conditions. The grape stalks and mainly the grape pomace which comprises of grape skins and seeds, contained less carbohydrates compared to vine prunings, but can be considered as an abundant source of lignin that can provide fast pyrolysis oils enriched in phenolic compounds. Similarly, the extracted surface lignin from the hydrothermally pretreated vine prunings may offer highly phenolic/aromatic bio-oils. The extractives of the parent lignocellulosic wastes (15–50 wt%) contain water soluble sugar monomers and oligo-saccharides and ethanol soluble fatty acids (palmitic, tridecanoic, a-linoleic, oleic, stearic acids). The wine lees can be considered as a source of value-added polyols and phenyl alcohols, such as glycerin (1,2,3-propanotriol), 2,3-butanediol and phenylethyl alcohol.

Valorization of Vine Prunings by Slow Pyrolysis in a Fixed-Bed Reactor

The paper aimed at studying the slow pyrolysis of vine pruning waste in a fixed bed reactor and characterizing the pyrolysis products. Pyrolysis experiments were conducted for 60 min, using CO2 as a carrier gas and oxidizing agent. The distribution of biochar and bio-oil was dependent on variations in heat flux (4244–5777 W/m2), CO2 superficial velocity (0.004–0.008 m/s), and mean size of vegetal material (0.007–0.011 m). Relationships among these factors and process performances in terms of yields of biochar (0.286–0.328) and bio-oil (0.260–0.350), expressed as ratio between the final mass of pyrolysis product and initial mass of vegetal material, and final value of fixed bed temperature (401.1–486.5 °C) were established using a 23 factorial design. Proximate and ultimate analyses, FT-IR and SEM analyses, measurements of bulk density (0.112 ± 0.001 g/cm3), electrical conductivity (0.55 ± 0.03 dS/m), pH (10.35 ± 0.06), and water holding capacity (58.99 ± 14.51%) were performed for biochar. Water content (33.2 ± 1.27%), density (1.027 ± 0.014 g/cm3), pH (3.34 ± 0.02), refractive index (1.3553 ± 0.0027), and iodine value (87.98 ± 4.38 g I2/100 g bio-oil) were measured for bio-oil. Moreover, chemical composition of bio-oil was evaluated using GC-MS analysis, with 27 organic compounds being identified.

Soil management in semi-arid vineyards: Combined effects of organic mulching and no-tillage under different water regimes

Optimizing water use in vineyards is crucial for ensuring the sustainability of viticulture in semi-arid regions, and this may be achieved by minimizing direct water evaporation from the soil through the use of mulching. In this context, the current study aimed at assessing the combined effects of the vine-row application of an organic mulch (vine prunings) and no-tillage under two water regimes on soil properties, plant water and nutritional status, yield and must composition of grapevine (Vitis vinifera L.) cv. Bobal grown under semi-arid conditions. For this purpose, a field experiment in a split-plot design was carried out for three years (2016–2018) in a mature Bobal vineyard located in Eastern Spain. Two soil management strategies (tillage and organic mulching with no-tillage) were assessed under two water regimes (rainfed and deficit drip irrigation) with four replications per combination. Vine responses were determined by measuring midday stem water potential, leaf nutrient concentrations, pruning weight, yield components and grape composition. Soil properties were assessed at the end of the experiment. Mulching and no-tillage positively affected vine water status under both water regimes, resulting in reductions in grape phenolic composition. Interactive effects of both water regime and soil management on water use efficiency were found. Regardless of soil management practice, irrigation increased yield and pruning weight when compared to rainfed conditions. Soil management had slight effects on vine nutritional status. At the end of the experiment, soil compaction increased and infiltration decreased as a consequence of mulching and no-tillage. Organic mulch and no-tillage improved vine water status, however, considering the final soil surface compaction and low water infiltration rate, longer-term studies are necessary to assess the sustainability of combining both practices.

Analysis of the Thermal Insulation and Fire-Resistance Capacity of Particleboards Made from Vine (Vitis vinifera L.) Prunings.

In Europe, vine (Vitis vinifera L.) prunings are one of the most abundant types of agricultural waste. It is, therefore, essential to organize the removal of vine waste from the fields in order to prevent the spread of fires, pests, or diseases. Using plant biomass in buildings will help achieve greater energy efficiency and cause less environmental pollution. The objectives of this work were to minimize burning of agricultural waste, reduce the use of natural wood, and obtain a product by using vine pruning waste to manufacture particleboards, assessing their use as an insulating material and their fire-resistance qualities. Eight types of boards were manufactured with vine prunings (two particle sizes, two times, and two pressures), using 9% by weight of urea-formaldehyde as a bonding resin. Experimental tests were conducted to determine the physical, mechanical, thermal, and fire-resistance properties. In general, the panels manufactured performed well as a thermal insulating material with a conductivity between 0.0642 and 0.0676 W/m·K and a classification of Bd0 according to the European standards on fire resistance; some of them may be used to manufacture furniture, interior décor, and load-bearing panels in dry conditions.

Biomass estimation and physicochemical characterization of winter vine prunings in the Chinese and global grape and wine industries

The residual biomass of winter vine prunings (WVPs) in the Chinese and global grape and wine industries was investigated and estimated, and the physicochemical characteristics of Chinese WVPs were analyzed. The eight regions investigated within China showed a total annual regional WVP yield of 201–842 kt FW, with R1 and R6 region showing the highest and the lowest region yields, respectively. The R4 and R2 regions showed the highest and the lowest yield per tree. Table grapes showed considerably higher WVP yields than wine grapes, whereas the pergola systems showed considerably higher WVP yields than the hedge systems. In addition, older vines showed higher WVP yields than younger vines. Overall, the average WVP yield in China was 2.35 kg/tree FW with a range of 1.33–3.21 kg/tree FW. Globally, the estimated WVP yield has decreased gradually from 2000 to 2017 to 42.31 million ton FW; in contrast, estimated WVP yield in China has increased substantially over the same period to 6.04 million ton FW. Winter vine pruning was the leading source of solid grape waste in the grape and wine industry, both absolutely and proportionally, and was characterized by such properties as a high dry matter content, mild acidity, high levels of organic matter and nutrients, and low fat. It is clear that WVP represents a resource of immense value for generating additional wealth in China and in the global grape and wine industry.

Experimental and Modeling Analysis of Brewers´ Spent Grains Gasification in a Downdraft Reactor

The first part of the current reported work presents experimental results of brewers’ spent grains gasification in a pilot-scale downdraft gasifier. The gasification procedure is assessed through various process characteristics such as gas yield, lower heating value, carbon conversion efficiency, and cold gas efficiency. Power production was varied from 3.0 to 5.0 kWh during the gasification experiments. The produced gas was supplied to an internal combustion engine coupled to a synchronous generator to produce electricity. Here, 1.0 kWh of electricity was obtained for about 1.3 kg of brewers’ spent grains pellets gasified, with an average electrical efficiency of 16.5%. The second part of the current reported work is dedicated to the development of a modified thermodynamic equilibrium model of the downdraft gasification to assess the potential applications of the main Portuguese biomasses through produced gas quality indices. The Portuguese biomasses selected are the main representative forest residues (pine, eucalyptus, and cork) and agricultural residues (vine prunings and olive bagasse). A conclusion can be drawn that, using air as a gasifying agent, the biomass gasification provides a produced gas with enough quality to be used for energy production in boilers or turbines.

Vine prunings biomass as fuel in wood stoves for thermal power production

Vine prunings biomass as fuel in wood stoves for thermal power production

Thermal decomposition of agricultural and food residues: Comparison of kinetic models

Agricultural and food residues are sustainable biofuels and their utilization in combustion, carbonization, and gasification reduces greenhouse gas emissions. In this work, the thermal decomposition of corn cobs, rice husks, vine prunings, and palm kernel shells was studied in thermogravimetric tests to elaborate reliable pyrolysis kinetics, which are basic parameters for fixed beds and grate reactors. The adequacy and predictability of different models (single first order reaction model, n‐order, distributed activation energy, and a structural model based on the decomposition of cellulose, hemicellulose, and lignin) were quantified. The single first order reaction model had low computational cost but poor accuracy (mean discrepancy 5–8 %, maximum discrepancy > 30 %), while the accuracy increased when a further parameter (reaction order) or a distribution in the exponential factor was introduced. The best accuracy (mean discrepancy 1–2 %, maximum discrepancy 5 %) was found for the structural model, with common kinetic parameters of the chemical components.

Gasification of agricultural residues in a demonstrative plant

Small size (<1 MW) thermochemical plants producing electricity and heat are a convenient option for biomass-to-energy scenarios. It is required to improve these systems in terms of efficiency and flexibility, extending the feedstock specification and plant reliability. In this work the experimental results of the recent campaigns in the CRIBE gasification plant with out-of-specification feedstocks (pellets, vine prunings, rice husks, corn cobs, miscanthus) are described and discussed. The biomass properties are investigated and related to the technological operations and plant performance for defining the suitable ranges of their characteristics. The morphological parameters (size/shape), density, thermal and mechanical consistency of the material are crucial for the safe operation in the downdraft gasifier. The pretreaments (drying, size reduction, pelletization, mixing of different feedstocks) are necessary for operability and should be optimized considering the overall plant efficiency and costs. This will be evaluated with a process study.

Fuel Characteristics of Vine Prunings (Vitis vinifera L.) as a Potential Source for Energy Production

Seven varieties of vine prunings (Vitis vinifera L.) grown under Riyadh conditions were considered as renewable sources for fuelwood. Significant effects (P<0.01) were found for total extractives, benzene-ethanol extractives, cellulose, hemicellulose, lignin, cold water solubility, and hot water solubility among the seven vine varieties. Highly significant positive correlations (P<0.01) were observed between the higher heating value (HHV) and benzene-ethanol extractives (r=0.74) and lignin content (r=0.94). Additionally, elemental composition (C, H, N, O, and S) exhibited a significant effect on HV (P<0.01) and ash content of the seven vine varieties. There were highly significant positive correlations (P<0.01) between the HV and C (r=0.96) and H (r=0.93). Ash content showed a highly significant effect (P<0.01) on HV with a negative coefficient (r=-0.93). The heating value of vine prunings ranged from 18.74 to 19.19 MJ/kg, i.e. higher than some well-known biomass fuels. The results suggested that the vine prunings could be suitable as a source for energy production in Saudi Arabia.

Assessment of syngas composition variability in a pilot-scale downdraft biomass gasifier by an extended equilibrium model

A new simplified approach based on equilibrium modeling is proposed in this work to describe the correlations among syngas species experimentally observed in a pilot scale downdraft biomass gasifier operated with different feedstocks (biomass pellets and vine prunings). The modeling approach is based on experimental evidence on the presence of devolatilization products in the syngas and fluctuations of syngas composition during stationary operation, accounted for by introducing two empirical parameters, a by-pass index and a permeability index. The simplified model correctly reproduces the correlations among the main syngas species (including methane and ethylene) resulting from experimental data of pilot tests with different feedstocks and under a wide range of operating conditions.

Numerical and experimental investigation of downdraft gasification of woody residues

A pilot scale throated downdraft gasifier was operated with vine prunings as feedstock to assess the effect of biomass loading rate on process performance. A distributed 1D model of mass and heat transfer and reactions was applied to aid the interpretation of experimental evidence. The model takes into account peculiar gasifier design features (air inlets and throat) and it reproduces satisfactorily the temperature profiles and the mass fluxes of gaseous species at different biomass loading rates. The integration of pilot-scale experiments and numerical simulations provides sound indications for the gasifier operation. In particular, simulations performed at different loading rates and feedstock humidity show that steady state operation and stable performance of the gasifier rely on the thermal balance between the enthalpy of cold biomass moving downward and the counter-current radiative heat fluxes moving upward from the oxidation zone. This balance can be destabilized by high loading rate and moisture contents.

The correlation of chemical characteristics and UF-Resin ratios to physical and mechanical properties of particleboard manufactured from vine prunings.

In this study, the relationship between chemical characteristics of chips, UF-Resin ratios and physical, mechanical properties of particleboard manufactured from vine prunings was investigated. Before particleboard manufacturing, the chips produced from vine prunings were subjected to chemical pre-treatment such as cold water treatment (CW), 1% NaOH treatment (N) and 1% CH3COOH treatment (A). FTIR spectra of chips were demonstrated that, the content of OH groups was increased by pre-treatments. Therefore, organic chemical component contents (extractives, holocellulose and lignin) of chips were determined. After producing particleboards, physical and mechanical properties namely; water absorption (WA), thickness swelling (TS), modulus of elasticity (MOE), modulus of rupture (MOR) and internal bond strength (IB) were studied. The multiple linear regression models were developed using physical and mechanical properties of particleboard as dependent variables and extractive, holocellulose, lignin contents and UF-Resin ratio as independent variables. The correlation coefficient (R2) values of 0.90 and 0.92 for estimating TS and WA confirmed that models produced more accurate results for physical properties than mechanical properties (R2 values of 0.64, 0.85 and 0.89 for estimating MOE, MOR and IB, respectively). Key words: Chemical pre-treatments, Chemical compounds, particleboard, physical and mechanical properties, vine pruning.

Characterization and utilisation of vine prunings as a wood substitute for particleboard production

The vine has been a traditional cultivation in Greece for many years. Every February after pruning, large quantities of vine prunings remain as byproducts in the field, non-utilized properly. The average amount of prunings per year reaches ≈5 t/ha, which is higher than the average yield of forests in temperate zones. The aim of the present work was to investigate the suitability of vine prunings as a raw material for particleboards. After pruning, prunings from several varieties were chipped with an automobile chipper and re-chipped in a hammermill. Vine pruning particles and industrial wood particles in various proportions were used as the raw material for one-layer and for the core and surface layer of three-layer particleboards. In addition, material from vine prunings stored for 6 months in outdoor conditions was tested for its quality for particleboard production. A commercial urea–formaldehyde (UF)-resin was used as binder. Vine pruning particles were characterized by higher bulk density and lower slenderness ratio than industrial wood particles. The evaluation of the mechanical and hygroscopic properties of experimental panels showed the following results: partial substitution of wood by vine prunings negatively affects all board properties. However, the mechanical properties of three-layer boards, even those containing up to 100% vine pruning particles in the core, exceed the minimum requirements of the relevant European Standards (EN 312, Part 3, 1996) set for interior boards in dry conditions. The same happened with the hygroscopic properties. With the exception of the screw holding strength and formaldehyde release, the properties of boards made of vine prunings did not change substantially in comparison to those made of vine prunings stored for 6 months in outdoor conditions.