Biomass Quality Research Articles

Pilot verification of a two-stage fluidized bed gasifier with a downer pyrolyzer using oxygen-rich air

A novel two-stage fluidized bed gasification system coupling a downer pyrolyzer and a riser gasifier was proposed, and a pilot facility of 15 kg/h of feedstock was further built and tested, by which the resulting technology gains its advantages of realizing the two-stage gasification principle in fluidized beds and having the large tolerance to biomass quality and size. Gasification of pine chips was in turn investigated at various equivalent ratios of air by changing the O2 concentration of gasifying agent composed of nitrogen and oxygen. The pilot facility was successfully operated at an ER value of 0.15, which generated 1.33 Nm3 product gas per kilogram of feedstock and containing 26.5% CO, 13.6% CO2, 8.89% H2, 12.6% CH4 and 0.63% CnHm. The LHV of the obtained fuel gas was as high as 9.35 MJ/Nm3 with a reasonably low tar content at 8.08 g/Nm3. By increasing the ER from 0.15 to 0.3, the temperatures of the pyrolyzer and gasifier were increased from 790 to 823 °C and from 881 to 925 °C, respectively. The gas yield was decreased to 1.1 Nm3/kg to have a reduced cold gas efficiency of 65.5% and a lower tar content of 4.35 g/Nm3 in the gas. These thus verified the technical feasibility of the proposed two-stage gasifier consisting of a downer and a riser.

Potential and Opportunity of Co-Firing Power Plant in Indonesia Through Torrefaction of Empty Fruit Bunch (EFB) - A Review

Electricity was an important requirement for various activities. Currently, the level of electricity consumption in Indonesia was around 1000 kWh/capita/year and is expected to continue to increase towards developed countries with a minimum electricity consumption level of 3000 kWh/capita/year. Along with the increasing demand for electricity, many new power plants were being built in Indonesia using coal as fuel. Coal was a non-renewable fuel so the CO 2 gas produced has an impact on global warming. Co-Firing was a technology for combining fuel of biomass and coal in order to reduce the use of coal. The difference in the quality of biomass and coal was an obstacle to getting a stable combustion performance so it is necessary to improve the quality of biomass. The torrefaction technology can be implemented to improve the quality of biomass in Indonesia so it can be used as fuel for a co-firing power plant. One of the most potential biomass was empty fruit bunch (EFB) from palm oil processing with a potential of around 48 million tons per year or equivalent to 30 GW. Every Oil palm mills plant that process 25 ton/hour of fresh oil palm fruit bunches can produce EFB around 5.25 ton/hour. With so many palm oil plants, torrefaction technology can be used to store EFB torrefied which can change the properties of biomass from hydrophilic to hydrophobic. The government's role to support the use of biomass, including EFB, is very much needed in increasing cooperation between palm oil mills and power plants.

CHARACTERIZATION OF OAT BIOMASS FOR ENERGY PRODUCTION1

ABSTRACT Biomass produced in agricultural areas stores energy that can be used, contributing to regional development. Among the widely cultivated agricultural species is oats, destined for the production of not only grains and forage, but also biomass. The objective of this study was to characterize oat biomass in terms of the potential for energy generation considering the genetic and cultivation environment variability. Four field experiments were conducted in the state of Paraná and one in the state of São Paulo, Brazil, with black oat (Avena strigosa) and white oat (Avena sativa) cultivars. At the milky grain stage, plants were collected to quantify the production of shoot biomass and its qualitative variables for energy production and energy potential. Biomass yield varied between cultivars and cultivation sites. The mean higher calorific value was 17.9 MJ Kg-1, varying more between cultivation sites than between cultivars, being inversely proportional to the ash content. The contents of carbon, fixed carbon, volatile materials and nitrogen in the biomass did not vary between oat cultivars. The power generation potential varied widely between cultivars and cultivation sites, from 1557 to 3091 KWh ha-1, influenced mainly by the biomass yield, which overlaps the effects of the variations found in biomass quality. We concluded that oats are a species with high potential for use as an energy product, and the selection of the most productive cultivars regionally is crucial.

The Subcooling Effect of the Flue Gas Flow Mixture Internal Dynamic and Heating Capacity

Growing environmental restrictions in energy production industry calls for greater efficiency and cleaner fuel burning processes. Biomass (wood chips) as a fuel is in great demand for boiler and power plants as it is considered widely available and relatively clean. While combining woodfuel flue gas and condensing economizers significantly raises the efficiency and makes it even more viable solution for energy production although the biomass fuel usage still has reservations in waste heat, which could be utilized. The calculation algorithm is presented for evaluation of subcooled biomass flue gas components concentration values which determine the leftover heat energy value carried by flue gas flow. Several cases of biomass quality (regarding moisture w=45%, 50%, 55% and 60%) and combustion process quality (regarding air excess value λ=1,2; 1,5; 1,8) in the flue gas temperature range of 50 to 20°C and effects for flue gas internal dynamic were examined. It was determined that water vapour amount depends only on temperature, while every other component concentration change with different air excess and temperature values. It was observed that further usage of biomass flue gas could result in up to 13% additional heat energy recovery for 1MW of fuel input, system combination together with condensing economizers could result in up to 31% of heat energy recovery.

Biomass Quantity and Quality from Different Year-Round Cereal–Legume Cropping Systems as Forage or Fodder for Livestock

The quantity and quality of forage and fodder crops is the major drawback of the livestock sector in the country. There is a need to bridge the gap between the supply and demand of fodder through the adoption of specific sustainable fodder production strategies. The field experiments were conducted during kharif (rainy, June–October), rabi (post-rainy, October–February), and summer (March–May) seasons of 2018–19 and 2019–20 to identify a sustainable fodder cropping system module in randomized complete block design with fifteen fodder cropping systems in three replications. The main objective of this research was to identify the most productive cereal–legume cropping system, both in terms of quantity and quality of biomass, to reduce the gap between supply and demand of quality livestock feed around the year. Among cropping systems, Bajra–Napier hybrid intercropped with lucerne, cowpea, and sesbania recorded significantly higher green fodder (163.6, 155.2, and 144.0 t/ha/year, respectively) and dry matter yields (32.1, 30.8, and 31.3 t/ha/year, respectively). Similarly, the same perennial systems also recorded higher quality yield and ash content. However, higher crude protein content was noticed in monocrop legumes, with the highest in sesbania (22.32%), while higher ether extractable fat was found in monocrop sesbania (3.78%). The monocrop oats recorded higher non-fiber carbohydrates (36.90%) while a monocrop of pearl millet recorded higher total carbohydrates (80.75%), however they were on par with other monocrop cereal cropping systems. Cultivation of legumes as a monocrop, and their inclusion as an intercrop with cereals resulted in lower fiber fractions and improved crude protein in intercropping systems. Furthermore, this improved the dry matter intake and digestibility of fodder. With higher sustainable yield index values and land-use efficiency, perennial intercropping systems were also found to be sustainable. Thus, cultivation of the Bajra–Napier hybrid with either lucerne, cowpea, or sesbania as an intercrop will help livestock farmers to achieve higher productivity in terms of quantity and quality, and forms a viable option for overcoming livestock feed scarcity.

A Recommendation for a Pre-Standardized Marine Microalgal Dry Weight Determination Protocol for Laboratory Scale Culture Using Ammonium Formate as a Washing Agent.

Simple SummaryMicroalgae are increasingly recognized as a source of valuable biomass with numerous health benefits. Cleaning of marine microalgal biomass is very crucial for microalgal studies as the salt on the microalgae cells will lead to overestimation of biomass determination. Incomplete washing of salt from microalgae could also interfere with the nutritional analyses. The biomass, especially dry weight, has been utilized for nutritional or compositional evaluation. Although standard methods of marine microalgal dry weight determination are available, these methods did not provide comprehensive details, and the parameters vary among themselves. Without a standard method, a comparison of results among previous studies can be misleading and unreliable. Therefore, the current study aimed to investigate and determine the ideal setting of several parameters in the marine microalgal dry weight determination for laboratory-scale culture. The present findings could assist in developing a standardized protocol to ensure a high quality of biomass for microalgal studies. Microalgal biomass is one of the crucial criteria in microalgal studies. Many reported methods, even the well-established protocol on microalgal dry weight (DW) determination, vary greatly, and reliable comparative assessment amongst published results could be problematic. This study aimed to determine the best condition of critical parameters in marine microalgal DW determination for laboratory-scale culture using four different marine microalgal species. These parameters included the washing process, grades of glass microfiber filter (GMF), GMF pretreatment conditions, washing agent (ammonium formate) concentrations, culture: washing agent ratios (v:v) and washing cycles. GMF grade GF/A with precombustion at 450 °C provided the most satisfactory DW and the highest ash-free dry weight (AFDW)/DW ratio. Furthermore, 0.05 M ammonium formate with 1:2 culture: washing agent ratio and a minimum of two washing cycles appeared to be the best settings of microalgal DW determination. The present treatment increased the AFDW/DW ratio of the four respective microalgae by a minimum of 19%. The findings of this study could serve as a pivotal reference in developing a standardized protocol of marine microalgal DW determination to obtain veracious and reliable marine microalgal DW.

An account of periphyton, plankton and water quality in Labeo fimbriatus culture tanks provided with feed and sugarcane bagasse as periphyton substrate in two orientations

An on-farm study with periphyton based culture systems was conducted for 90 days in 16 m2 soil-based and fertilized out-door cement tanks. The objective was to evaluate the effect of provision of feed and orientation of substrate on the water quality and taxonomic composition and biomass of periphyton and free plankton. Fertilization of tanks was done with cattle dung applied at 4.5 t/ha, followed by single super phosphate (SSP) and urea, each at 50 kg/ha. Fortnightly fertilization schedule included cow dung at 2.25 t/ha, urea and SSP, both at 50 kg/ha each. The treatments consisted of tanks receiving no feed and no substrate (NFNS), receiving only feed (FNS) and those receiving only sugarcane bagasse as periphyton substrate at 2 t/ha (3.2 kg/tank) either vertically suspended in water column (NFSV) or applied to tank bottom (NFSB). Fish in three tanks of FNS treatment were fed daily at 5% of body weight with a 25% crude protein pelleted feed. Fingerlings of Labeo fimbriatus were stocked at 10,000/ha 10 days after manuring. The percentage weight gain of fish was 425.08 ± 23.51, 597.41 ± 60.11, 659.17 ± 73.43 and 676.95 ± 22.41 g, respectively, in NFNS, FNS, NFSV and NFSB tanks. Principal component analysis revealed higher plankton density in FNS tanks and “moderate negative loading” of nitrate-N in NFSV tanks. The total planktonic genera attached as periphyton from NFSV treatment were 58 compared to 51 from NFSB treatment. The total number of free planktonic genera encountered in water from the NFSB treatment tank was the highest (87 numbers) followed by FNS (65), NFSV (64) and NFNS (42). The dry matter content of periphyton showed no difference (p > 0.05) between the substrate orientations. The study indicated that changing the orientation of substrate did not have any impact on the quality of culture water and periphyton biomass.

Advancing improvement in riverine water quality caused a non-native fish species invasion and native fish fauna recovery

The knowledge of biotic and abiotic drivers that put non-native invasive fishes at a disadvantage to native ones is necessary for suppressing invasions, but the knowledge is scarce, particularly when abiotic changes are fast. In this study, we increased this knowledge by an analysis of the biomass of most harmful Prussian carp Carassius gibelio in a river reviving from biological degradation. The species' invasion followed by the invasion's reversal occurred over only two decades and were documented by frequent monitoring of fish biomass and water quality. An initial moderate improvement in water quality was an environmental filter that enabled Prussian carp’s invasion but prevented the expansion of other species. A later substantial improvement stimulated native species’ colonization of the river, and made one rheophil, ide Leuciscus idus, a significant Prussian carp’s replacer. The redundancy analysis (RDA) of the dependence of changes in the biomass of fish species on water quality factors indicated that Prussian carp and ide responded in a significantly opposite way to changes in water quality in the river over the study period. However, the dependence of Prussian carp biomass on ide biomass, as indicated by regression analysis and analysis of species traits, suggests that the ecomorphological similarity of both species might have produced interference competition that contributed to Prussian carp’s decline.

Rapid indicators for monitoring the health of Chlamydomonas nivalis biomass during preservation

Microalgae are photosynthetic microorganisms that have increasingly attracted interest in the last decade due to their potential for industrial applications. One crucial aspect for the industrial-scale valorisation of algae biomass concerns the quality control during its preservation before being treated to obtain the end-product. Monitoring biomass quality is essential and can be potentially accomplished with the aid of specific biochemical indicators called biomarkers. In this context, the main aim of this work was to identify potential indicators of microalgae biomass viability that could be used as markers of its quality during storage/preservation for commercial operations. The health status of a suspension of Chlamydomonas nivalis was assessed at 4 ºC and 25 ºC during 10 days of storage. The use of the pulse-amplitude-modulation technique, based on chlorophyll fluorescence, was a valuable indicator of the culture viability. The measurement of DNA and of chlorophyll in the supernatant, indicative of cell lysis, also provided satisfactory results; in the case of the DNA, the limit of detection was 3.9 µg DNA·mL−1. The effect of different concentrations of a well-known and cheap preservative, acetic acid, was also evaluated at 4 ºC. This work identified three suitable biomarkers to be used as rapid indicators of the quality of the microalgal suspension prior to its reception for biorefinery activities.

Production of kale seedlings on substrates containing proportions of organic compost

One of the difficulties in the kale seedlings production in containers is to ensure the production of aboveground biomass with a limited portion of roots, restricted to a small volume of substrate. Thus, we investigated whether substrates with organic compost added to it associated with kale cultivars interfere in the quality of seedlings produced in a greenhouse. Here, we studied two kale cultivars and five substrates. The experiment was designed in randomized blocks, with treatments arranged in a bifactorial scheme (2 x 5), with three replications. We carried out the physical and chemical characterization of the substrates and evaluated attributes of the aerial part and root system of the kale seedlings. The results showed that the substrate with the highest water retention was the one without the addition of organic compost. The greater the proportion of organic compound added to the substrate, the higher the nitrogen, phosphorus and organic carbon values. Seedlings produced in the substrate with greater water retention capacity had better performance in relation to the morphology of the aerial part and the morphology of the root system. We conclude that seedlings of kale cultivars associated with substrates with higher water retention have better quality. Seedlings of the ‘Gaudina’ cultivar stand out for their better phytometric morphology, while seedlings of the ‘Manteiga’ cultivar have higher quality of root biomass.

Biomass production and nutritional quality of potato tuber as affected by blended fertilizer (NPSB), cattle manure, vermicompost and mineral NP in southwestern Ethiopia

Keeping in view the declining soil fertility and people’s nutritional issues, a research experiment on potato (Solanum tuberosum L.) was carried out in Belg (February to May) and Meher (June to October) seasons of 2020 at Abelo in Masha district, southwestern Ethiopia, to gauge the effects of blended mineral NPSB fertilizer, cattle manure (CM), vermicompost (VC) and mineral NP on growth, biomass and tuber nutritional quality. The fertilizer treatments consisted of 7.5 t CM ha-1 + 75 and 50% of recommended dose of NP fertilizers (RDF), 7.5 t VC ha-1 + 75, 50 and 25% of NP, 5 t VC ha-1 + 75% NP, 100 kg NPSB ha-1 + 61.5 kg P ha-1 + 146 kg N ha-1, 150 kg NPSB ha-1 + 53.7 kg P ha-1 + 138 kg N ha-1, 200 kg NPSB ha-1 + 46 kg P ha-1 + 128 kg N ha-1, 100% of NP (165 kg N ha-1 + 60 kg P ha-1) and one no-fertilizer treatment (control) making a total of 11 treatments. The effects of the treatments indicated that the application of 75% of NP and 7.5 t ha-1 vermicompost significantly increased the plant height, dry shoot and root yields, specific gravity, total soluble solids and starch. On the other hand, the highest crude protein content was recorded at the application of 200 kg NPSB ha-1 + 46 kg P ha-1 + 128 kg N ha-1. It was summarized that the use of 7.5 t VC ha-1 + 75% of NP (124 kg N ha-1, and 45 kg P ha-1) increased the biomass and improved the quality of potato fetching high economic return over the sole application of either 200% mineral NPSB ha-1 or 150% mineral NPSB ha-1 or 100% NP or no-application of fertilizer in the study area. In the light of present findings, there is a need to extend these studies using multiple combination ratios of NPSB fertilizer with vermicompost and cattle manure on different soils of varied agro-climatic zones to come up with conclusive recommendations.

Linking insect herbivory with plant traits: Phylogenetically structured trait syndromes matter

AbstractQuestionsHerbivory is a fundamental ecological interaction underlying energy and mass flow between primary producers and consumers. Ecological theory describes plant biomass quality in terms of food for herbivores as a functional effect trait. We asked how leaf functional traits affect insect herbivory in a species‐rich meadow community.LocationČertoryje National Nature Reserve, Bílé Karpaty (White Carpathians) Protected Landscape Area, Czech Republic.MethodsWe assessed herbivory of 24 plant species co‐occurring in a species‐rich semi‐natural grassland by measuring herbivore damage caused by leaf‐chewing insects. Identification of trait–herbivory links was conducted by a comparative analysis based on a phylogenetically informed regression.ResultsPlant species strongly differed in leaf‐chewer herbivory. Interspecific differences in herbivory and most traits displayed a strong phylogenetic signal associated with the deep evolutionary split between monocot graminoids and dicot forbs. There were also pronounced correlations among individual traits. Herbivory was tightly related to an intercorrelated trait set describing fibre composition and Ca content. There was also a less pronounced negative effect of leaf biomass C:N ratio on herbivory. However, the observed association between traits and herbivory was phylogenetically structured in agreement with the univariate tests of phylogenetic signal.ConclusionHerbivory was associated with a whole syndrome of intercorrelated traits, among which it is not possible to choose a single best trait predictor. Moreover, the principal pattern in this trait syndrome was related to a macro‐evolutionary singularity. Such linkage among an ecosystem process, traits, and phylogeny complicates linking ecosystem processes with particular functional traits and may also occur elsewhere in natural ecosystems.

Biomass Yield of Selected Herbaceous and Woody Industrial Crops across Marginal Agricultural Sites with Shallow Soil

Agricultural land in Europe is affected by low rooting depth (LRD) on 27.9 Mha. This marginal agricultural land can potentially be used to grow industrial crops without directly threatening food security or biodiversity conservation. However, little is known about the yield performance of industrial crops at LRD conditions. This study therefore compiles and discusses the meaningful data available in scientific literature. Twelve relevant industrial crops were identified for Europe. Currently, robust information on good growth suitability for LRD conditions is available for only one industrial crop, namely reed canary grass (RCG). Because this information was taken from field trial results from a single site, it remains unclear what role other growing conditions such as soil quality and climate play on both the yield level and the biomass quality of RCG under LRD conditions. These uncertainties about the quantitative as well as qualitative performance of industrial crop cultivation on marginal agricultural land characterized by LRD represent a major agronomic knowledge gap. Here, more knowledge needs to be compiled through both expanded crop science activities and improved international information exchange to make more optimal use of the large LRD areas available for the transition to a bioeconomy.

Optimizing a pellet supply system: Market-specific pellet production with biomass quality considerations

Renewable energy policies have driven the wood pellet market over the last decades worldwide. Among other factors, the returns from this business depends largely on how well the producers manage the uncertainty associated with biomass yield and quality. To serve this purpose, this study develops a two-stage stochastic programming model that optimizes different critical decisions (e.g., harvesting, storage, transportation, quality inspection, and production decisions) of a biomass-to-pellet supply system under biomass yield and quality uncertainty. The goal is to economically produce pellets while accounting for the different pellet standards set forward by the U.S. and European markets. Due to the difficulty in solving the optimization model in a real-world scenario, we develop a hybrid algorithm that combines Sample Average Approximation with an enhanced Progressive Hedging algorithm. We propose two parallelization schemes to efficiently speed up the convergence of the overall algorithm. We use Mississippi as a testing ground to visualize and validate the performance of the algorithms. Experimental results indicate that the biomass-to-pellet supply system is sensitive to the biomass quality parameters (e.g., ash and moisture contents). Results further reveal that the pellet production can drop up to 13.6% to 48.3%, respectively, if high ash or moisture content is available in the biomass.

Quantifying the boron demand of Pelargonium graveolens for optimum biomass yield and quality of essential oil under field conditions

Deficiency and toxicity of micronutrient boron (B) play a critical role in plant productivity. In this study, the evaluation of B supplementation on biomass and essential oil (EO) yield of rose-scented geranium (Pelargonium graveolens L.) and its distribution at different application rates (2.5, 5.0, and 7.5 kg ha−1) was performed in a field trial during the growing season of two consecutive years 2017–18 and 2018–19. Boron uptake, plant biomass, and EO yield along with EO constituent in leaves were determined at different time scales. Application of B significantly improved the biomass yield of P. graveolens and at B-II treatment (5.0 kg ha−1 dose) highest biomass and EO yield was recorded, however, B-III treatment (7.5 kg ha−1) demonstrated toxicity symptoms like the decline in protein and chlorophyll content and an increase in proline and stress enzymes (SOD, CAT) in plant leaves. The effects of B on EO constituents varied with the different developmental stages of P. graveolens. Furthermore, the application of B at 5.0 kg ha−1 acts as a stimulant in upgrading the quality and quantity of EO with improved main aroma constituent’s P. graveolens than the control without modulating odor quality i.e., citronellol:geraniol (C:G) ratio. Hence, the study revealed a balanced level of B as a crucial parameter for the enhanced productivity with the improved economic return of P. graveolens.

Carbonization of microalgae for bio-coal production as a solid biofuel similar to bituminous coal

The carbonization of Nannochloropsis gaditana microalgae biomass was found to produce bio-coal that is similar to bituminous coal used in thermal power plants. Currently, microalgae that capture CO2 while they are in the growth stage are considered a source for the production of biofuels. The carbonization of biomass for producing bio-coal has received attention for its ability to improve the biomass quality for producing solid biofuels. The research was focused on optimizing a fixed carbon index (FCindex), which allows finding operational conditions of carbonization to favor the fixed carbon content without significantly affecting the bio-coal yield. The optimization carried out by response surface methodology in a thermogravimetric analyzer allowed the prediction of optimal carbonization conditions to achieve an FCindex of 191% at 403 °C, 71 °C/min, and 60 min of residence time. The bio-coal produced under optimized conditions was characterized by 59% of fixed carbon and 41% of volatiles on a dry and ash-free basis, which is similar to bituminous coal. The promising results of dry carbonization producing bio-coal similar to bituminous coal could promote this technology, avoiding the necessity of hydrothermal carbonization. Because a high ash content was detected in the final product, further studies using the optimized conditions and a washing step should be conducted.

Elucidating the multifunctional role of the cell wall components in the maize exploitation

BackgroundBesides the use of maize grain as food and feed, maize stover can be a profitable by-product for cellulosic ethanol production, whereas the whole plant can be used for silage production. However, yield is reduced by pest damages, stem corn borers being one of the most important yield constraints. Overall, cell wall composition is key in determining the quality of maize biomass, as well as pest resistance. This study aims to evaluate the composition of the four cell wall fractions (cellulose, hemicellulose, lignin and hydroxycinnamates) in diverse maize genotypes and to understand how this composition influences the resistance to pests, ethanol capacity and digestibility.ResultsThe following results can be highlighted: (i) pests’ resistant materials may show cell walls with low p-coumaric acid and low hemicellulose content; (ii) inbred lines showing cell walls with high cellulose content and high diferulate cross-linking may present higher performance for ethanol production; (iii) and inbreds with enhanced digestibility may have cell walls poor in neutral detergent fibre and diferulates, combined with a lignin polymer composition richer in G subunits.ConclusionsResults evidence that there is no maize cell wall ideotype among the tested for optimal performance for various uses, and maize plants should be specifically bred for each particular application.

Year-Round Cultivation of Tetraselmis sp. for Essential Lipid Production in a Semi-Open Raceway System

There is increasing demand for essential fatty acids (EFAs) from non-fish sources such as microalgae, which are considered a renewable and sustainable biomass. The open raceway system (ORS) is an affordable system for microalgae biomass cultivation for industrial applications. However, seasonal variations in weather can affect biomass productivity and the quality of microalgal biomass. The aim of this study was to determine the feasibility of year-round Tetraselmis sp. cultivation in a semi-ORS in Korea for biomass and bioactive lipid production. To maximize biomass productivity of Tetraselmis sp., f medium was selected because it resulted in a significantly higher biomass productivity (1.64 ± 0.03 g/L) and lower omega-6/omega-3 ratio (0.52/1) under laboratory conditions than f/2 medium (0.70/1). Then, we used climatic data-based building information modeling technology to construct a pilot plant of six semi-ORSs for controlling culture conditions, each with a culture volume of 40,000 L. Over 1 year, there were no significant variations in monthly biomass productivity, fatty acid composition, or the omega-6/omega-3 ratio; however, the lipid content correlated significantly with photosynthetic photon flux density. During year-round cultivation from November 2014 to October 2017, areal productivity was gradually increased by increasing medium salinity and injecting CO2 gas into the culture medium. Productivity peaked at 44.01 g/m2/d in October 2017. Throughout the trials, there were no significant differences in average lipid content, which was 14.88 ± 1.26%, 14.73 ± 2.44%, 12.81 ± 2.82%, and 13.63 ± 3.42% in 2014, 2015, 2016, and 2017, respectively. Our results demonstrated that high biomass productivity and constant lipid content can be sustainably maintained under Korean climate conditions.

Chemical composition and calorific value of elephant grass varieties and other feedstocks intended for direct combustion

AbstractPerennial grasses display several positive attributes as suitable energy crops for use as a solid fuel for direct combustion, such as high annual production of dry matter per unit area, perennity and high harvest flexibility. This study aimed to characterize the chemical composition and calorific value of 18 elephant grass (EG) varieties (Pennisetum purpureum Schum.) and 10 other potential bioenergy feedstocks intended for direct combustion. Samples were obtained from 6‐month‐old EG and sorghum and 3‐year‐old eucalyptus, Mimosa caesalpiniaefolia, and bamboo plants. Sugarcane bagasse and straw, rice husk, corn stover, coconut husk, and fiber samples were also evaluated. The elemental composition, lower heating value (LHV), and cellulose (CEL), hemicellulose (HCEL), lignin (LIG) and ash contents (% dry matter) were analyzed. The results indicated that the EG genotypes showed significant differences when compared with other evaluated biomasses, but showed no differences among themselves. The EG varieties showed a mean LHV (16.7 MJ/kg) superior to that of rice husk, sugarcane bagasse, and sorghum and similar to that of sugarcane straw, coconut fiber, and corn stover. The EG varieties showed a mean ash content (4.74%) inferior to that of rice husk, sugarcane bagasse, coconut fiber, and sorghum; a mean CEL content (36.0%) similar to that of sugarcane straw, coconut fiber, corn stover, sorghum, and Mimosa caesalpinifolia; HCEL; a mean HCEL content (30.3%) superior to that of rice husk, bamboo, eucalyptus, M. caesalpinifolia, coconut husk, and fiber; and a mean LIG content (8.80%) superior to that of corn stover and similar to that of sorghum, sugarcane bagasse, and straw biomass. The significant capacity of EG to accumulate dry matter was associated with the biomass quality attributes (LHV and CEL, HCEL, LIG, and ash contents), thereby making it an excellent alternative to lignocellulosic feedstock for direct combustion.

Productivity and Biomass Properties of Poplar Clones Managed in Short-Rotation Culture as a Potential Fuelwood Source in Georgia

Georgian forests are very valuable natural resources, but due to the lack of affordable alternatives to firewood, people are forced to use forest resources illegally and unsustainably. The aim of this study was to determine the productivity and biomass properties of four poplar clones from Aigeiros and Tacamahaca and one control clone, considering their wood and bark characteristics and their proportion in the stems. Short-rotation woody crops with these clones represent a potential source of commercial fuelwood production in Georgia as an alternative to natural forests. These tree characteristics were evaluated after three years of growth. The survival of the clones was generally high. No significant differences in biomass production (dry matter, DM) were found among the four clones tested (DM of approximately 4 Mg ha−1 yr−1), while the control clone achieved significantly lower values for DM. The biomass specific density was exceptionally high, at 481–588 kg m−3, which was a result of the high proportion of bark mass in the stem (23.3–37.7%), with a density almost twice that of wood. On the other hand, the tested clones had a very high ash content in the biomass (2.6–4.5%), which negatively affected their energy potential expressed as a lower heating value (17,642–17,849 J g−1). Our preliminary results indicated that both the quantity and quality of biomass are important factors to justify the investment in an intensive poplar culture. The four clones should be further considered for commercial biomass production and tested at different sites in Georgia to evaluate the genotype-by-environment interactions and identify the site conditions required to justify such an investment.