Biomass Feedstock For Production Research Articles

Proportion of Nonindustrial Private Forest Lands That Potentially Can Be Leased to Bioenergy Enterprises to Grow Short Rotation Woody Crops

Abstract Determining how much nonindustrial private forest (NIPF) land could potentially be allocated to growing short rotation woody crops (SRWCs) is critical for estimating the future supply of woody biomass for biofuels and overall bioenergy production. This study estimated the proportion of the land NIPF landowners would be willing to allocate to SRWC cultivation. In view of the bounded nature of the dependent binary variable [0,1] and model performance, a fractional logit regression model was used to estimate model parameters. The estimated proportion of land allocated to SRWCs was positively influenced by the rental rate per acre, owning land for investment or fee-access hunting purposes, and the landowner’s age. In contrast, size of the ownership, owning land for the production of agricultural products, and residing on the land negatively influenced the proportion of land allocated to SRWCs. Lease contract duration, location of the largest tract owned, owning land for personal recreation or ecosystem services, and landowner familiarity with the concept of alternative fuels production did not influence the proportion of land allocated to SRWCs. These results will contribute to a better understanding of SRWC biomass supply from NIPF land and provide important benchmark information for conducting feasibility analyses of biofuel and biopower manufacturing in Mississippi and other states with abundant woody feedstocks. Study Implications: To achieve targeted levels of bioenergy production and carbon dioxide (CO2) emission reductions and diversify NIPF landowner income, participation of NIPF landowners in woody biomass feedstock production will be critical, because they own a majority of forestland in the region. Moreover, they have diverse reasons for owning land which has extensive implications not only in terms of incentive types or monetary compensation levels they might require for cultivating SRWCs but also policies related to the development of the bioenergy sector in Mississippi, the location of individual bioenergy processing facilities, and feedstock types that will be developed. Thus, forest managers and biomass procurement foresters might need to decide whether to focus their efforts on maximizing the land area allocated to growing SRWCs or considering a mix of SRWCs at lower lease rates per acre and material obtained from thinnings, which might be more amenable to landowners who value environmental amenities.

Design and characterization of a new pressurized flat panel photobioreactor for microalgae cultivation and CO2 bio-fixation

Microalgae-based biorefinery processes are gaining particular importance as a biotechnological tool for direct carbon dioxide fixation and production of high-quality biomass and energy feedstock for different industrial markets. However, despite the many technological advances in photobioreactor designs and operations, microalgae cultivation is still limited due to the low yields achieved in open systems and to the high investment and operation costs of closed photobioreactors. In this work, a new alveolar flat panel photobioreactor was designed and characterized with the aim of achieving high microalgae productivities and CO2 bio-fixation rates. Moreover, the energy efficiency of the employed pump-assisted hydraulic circuit was evaluated. The 1.3 cm thick alveolar flat-panels enhance the light utilization, whereas the hydraulic design of the photobioreactor aims to improve the global CO2 gas-liquid mass transfer coefficient (kLaCO2). The mixing time, liquid flow velocity, and kLaCO2 as well as the uniformity matrix of the artificial lighting source were experimentally calculated. The performance of the system was tested by cultivating the green microalga Acutodesmus obliquus. A volumetric biomass concentration equal to 1.9 g L−1 was achieved after 7 days under controlled indoor cultivation conditions with a CO2 bio-fixation efficiency of 64% of total injected CO2. The (gross) energy consumption related to substrate handling was estimated to be between 27 and 46 Wh m−3, without any cost associated to CO2 injection and O2 degassing. The data suggest that this pilot-scale cultivation system may constitute a relevant technology in the development of microalgae-based industrial scenario for CO2 mitigation and biomass production.

The Potential of Marine Microalgae for the Production of Food, Feed, and Fuel (3F)

Whole-cell microalgae biomass and their specific metabolites are excellent sources of renewable and alternative feedstock for various products. In most cases, the content and quality of whole-cell biomass or specific microalgal metabolites could be produced by both fresh and marine microalgae strains. However, a large water footprint for freshwater microalgae strain is a big concern, especially if the biomass is intended for non-food applications. Therefore, if any marine microalgae could produce biomass of desired quality, it would have a competitive edge over freshwater microalgae. Apart from biofuels, recently, microalgal biomass has gained considerable attention as food ingredients for both humans and animals and feedstock for different bulk chemicals. In this regard, several technologies are being developed to utilize marine microalgae in the production of food, feed, and biofuels. Nevertheless, the production of suitable and cheap biomass feedstock using marine microalgae has faced several challenges associated with cultivation and downstream processing. This review will explore the potential pathways, associated challenges, and future directions of developing marine microalgae biomass-based food, feed, and fuels (3F).

Industrial Development and Economic Impacts of Forest Biomass for Bioenergy: A Data-Driven Holistic Analysis Framework

A data-driven holistic analysis framework was developed to aid the industrial development of forest biomass for bioenergy to promote the regional bioeconomy. Leveraging the existing but fragmented multi-source data, four components of industrial bioenergy development were integrated into the framework including spatial statistical analysis of biomass feedstock and bioenergy production, machine learning-based suitability assessment, bioenergy plant sites identification and ranking, and socio-economic impacts assessment. A case study was conducted for forest biomass to pellet fuel in the U.S. Mid-Atlantic region. Our results indicate that the great potential of forest biomass with high variation at the county level is primarily clustered in western Pennsylvania and eastern North Carolina. Integrating the datasets of biomass feedstock, road conditions, employment status, income status, population, and current bioenergy production, the machine-learning model demonstrates good performance for bioenergy industry suitability assessment, with the high-suitable areas accounting for 19.76%, medium-suitable areas for 34.74%, and low-suitable areas for 54.49% in the region. Forest biomass availability and distance to major roads are the two top factors affecting bioenergy industry development. We identified 65 industrial sites within the suitable areas and their rankings were derived as a reference of the bioenergy development priority. The socio-economic impacts assessment indicates that the one-year construction of a medium-size pellet fuel facility (75,000 dry tons/year) could create 127 jobs, $8.78 million of labor income, while the operation could create 202 jobs, $10.52 million of labor income, $14.66 million of value-added, and $33.61 million of output in total per year for the state-level economy.

Biofuel supply chain management in the circular economy transition: An inclusive knowledge map of the field

Investment in biofuels, as sustainable alternatives for fossil fuels, has gained momentum over the last decade due to the global environmental and health concerns regarding fossil fuel consumption. Hence, effective management of biofuel supply chain (BSC) components, including biomass feedstock production, biomass logistics, biofuel production in biorefineries, and biofuel distribution to consumers, is crucial in transitioning towards a low-carbon and circular economy (CE). The present study aims to render an inclusive knowledge map of the BSC-related scientific production. In this vein, a systematic review, supported by a keywords co-occurrence analysis and qualitative content analysis, was carried out on a total of 1,975 peer-reviewed journal articles in the target literature. The analysis revealed four major research hotspots in the BSC literature, namely (1) biomass-to-biofuel supply chain design and planning, (2) environmental impacts of biofuel production, (3) biomass to bioenergy, and (4) techno-economic analysis of biofuel production. Besides, the findings showed that the following subject areas of research in the BSC research community have recently attracted more attention: (i) global warming and climate change mitigation, (ii) development of the third-generation biofuels produced from algal biomass, which has recently gained momentum in the CE debate, and (iii) government incentives, pricing, and subsidizing policies. The provided insights shed light on the understanding of researchers, stakeholders, and policy-makers involved in the sustainable energy sector by outlining the main research backgrounds, developments, and tendencies within the BSC arena. Looking at the provided knowledge map, potential research directions in BSCs towards implementing the CE model, including (i) integrative policy convergence at macro, meso, and micro levels, and (ii) industrializing algae-based biofuel production towards the CE transition, were proposed.

A multi-criteria land suitability assessment of field allocation decisions for switchgrass

With the goal of evaluating biomass resource availability in certain regions in the United States, the Department of Energy, Department of Agriculture, Environmental Protection Agency, national laboratories, and Forest Service research laboratories, together with academic and industry collaborators, performed a resource analysis study, 2016 Billion-Ton Report: Advancing Domestic Resources for a Thriving Bioeconomy, Volume 1: Economic Availability of Feedstocks, using POLYSYS model to estimate biomass potential. The study provided county- and state-level biomass potential projections, with biomass feedstock production estimates and suitability assessment of lands acreage likely to transition to energy crops. For this analysis, we estimate biomass supply by year 2028, more specifically, lands acreage transition to switchgrass in the Midwest of the United States, across 50 counties in 3 states (Nebraska, Kansas, and Colorado). We propose a multi-criteria site suitability framework, to determine the potential acreage and production for switchgrass, at the field level. Site selection criteria span agronomic and ecosystem services such as previous land cover, crop rotation, soil water holding capacity, crop productivity, field efficiency, topography, soil organic matter, soil leaching propensity, distance to surface water bodies, and soil erosivity. Efficient agricultural field selection for dedicated energy crops field allocation is critical to evaluate biomass resource availability, and it is our position that estimation at the field level would provide a more accurate and useful estimation to support an emerging bioeconomy. Using field suitability scores and county-level assessments, we model land allocation decision for energy crop in the future, estimating the spatial distribution of dynamics of energy crop adoption with priority to fields scoring the highest. Compared with POLYSYS results from the report mentioned above, our method shows good performance overall, with about 2% and 1.2% of difference in switchgrass acreage allocation and crop production, respectively.

Automated Agricultural Robot and Sensor Data Collection and Analysis through a Biomass Feedstock Production Information System

The increasing environmental pollution resulting from the use of non-renewable fossil fuels as well as the development of economic dependencies among countries because of the lack of such types of fuels underline the intense need for the use of sustainable forms of energy. Biomass derived biofuels provide such an alternative. The main tasks of biomass feedstock production are planting and cultivation, harvest, storage, and transportation. A number of complex decisions characterize each of these tasks. These decisions are related to the monitoring of crop health, the improvement of crop productivity using innovative technologies, and the examination of limitations in existing processes and technologies associated with biomass feedstock production. Other critical issues are the development of sustainable methods for the delivery of the biomass while maintaining product quality. There is the need for the development of an automated integrated research tool based on resilience and sustainability which will allow the coordination of different research fields but also perform research on its own. The specific tool should aim in the optimization of different parameters which specify the research done and in the case of biomass feedstock production; such parameters are the transportation of biomass from the field to the biorefinery, the equipment used, and the biomass storage conditions. This optimization would enhance decision making in the field of bioenergy production. Based on the need for such an automated integrated research tool, this paper presents an information system that provides automated functionalities for better decision making in the bioenergy production field based on the collection and analysis of agricultural robot and sensor data.

Tradeoffs between yield, disease incidence and conversion efficiency for selection of hybrid poplar genotypes as bioenergy feedstocks

Lignocellulosic biomass is an alternative source of energy that can reduce our dependency on fossil fuels and limit greenhouse gas emissions. Several techno-economic analyses have consistently shown that all the steps in biomass-to-bioproduct processes needs improvement. Simultaneous assessment of genotypes for multiple productivity characteristics and integrating information across production stages has seldom been the focus of research efforts. To address this gap, we first determined the agronomic performance of 10 poplar genotypes. Differences between genotypes in height, diameter at breast height (DBH), tree mass and yield were consistently observed. Correlation analyses revealed that height and DBH are positively correlated with tree mass and yield, whereas bark content is negatively correlated with tree mass, yield and disease incidence. Four highest-yielding genotypes were subjected to proximate, ultimate, targeted chemical analyses, along with assessment of sugar production by acid hydrolysis and enzymatic saccharification. Despite having only marginal changes in overall chemistry, the genotypes showed differential conversion efficiencies of enzymatic saccharification. Interestingly, the genotype that showed highest cellulose conversion efficiency had the lowest estimated sugar yields due to its low biomass yield, whereas the genotype with lowest conversion efficiency had the highest estimated sugar yields. These results show the importance of integrating information across the stages of biomass production and bioconversion. These results also demonstrate the complexity of biomass feedstock production and the need for future studies to assess whether these tradeoffs can be genetically separated to guide the selection of genotypes that can maximize the overall biomass feedstock production efficiency.

ASSESSMENT OF ECOLOGICAL AND ECONOMIC EFFICIENCY OF COMPOSITE FUEL PRODUCTION FROM THE PEAT AND BIOMASS

The goal of investigation was assessment of environmental impact and economic efficiency of composite briquette production on the base of peat and renewable biomass. Biomass for composite briquettes was obtained from straw (cereal crops and rape) and wood residues (sawdust, chips) Experimental composite briquette were produced from the mixture of peat and biomass in relation to – 25 : 75, 50 : 50, 75 : 25. The technological cards of biomass feedstock production for 6 variants were developed. Technological cards were used for calculation of emission into the atmosphere during life cycle of biomass production and prime cost of biomass. The lowest volume of gas (SO2, NOx, CO2)
 and particulate matter (PM) emission was installed for biomass production from the sawdust. The highest volume of
 emission was installed for production of biomass from the straw with pressing it in standard bale. The volume of CO2
 emission for the sawdust production was 6 kg per ton of biomass and for the standard bale of straw was 19 kg per ton of
 biomass. Prime cost of sawdust production (lowest) was 11 belarusian rubles per ton of biomass, for the wood chips was 19 rubles per ton and for the straw varied from 26 to 33 rubles per ton in depend of technology. It was installed that
 growth of biomass rate in composite briquette had a good influence on number of basic fuel characteristics (contents of
 ash, sulfur and moisture). The variation of calorific value of briquette was not significant in depend of biomass contents.
 In accordance with assessment of all characteristics the better briquettes was obtained from the peat and sawdust.

Study of the impacts of supplements on the specific methane production during anaerobic digestion of the West African Gamba and Guinea Grass

Nutrient supplementation could improve the biomethane production of different biomass feedstocks during anaerobic digestion. In this study, the impact of nutrient supplementation on the anaerobic digestion of the West African Gamba and Guinea Grass for biomethane production is presented. This was undertaken in 6 separate continuous stirred tank reactors for a hydraulic residence time of 25 days under supplementation regime with trace elements (TE), cocoa pod (CP) ash-extract, and commercial cellulase from Aspergillus niger (CCA) or Trichoderma reesei ATCC 26921 (CCT). The results showed that TE inhibits the specific methane production (SMP) with about 5% lower SMP than the control. In contrast, the other supplements namely CP, CP + CCA, CCA, and CCT + TE showed about 13, 28, 18, and 12% higher SMP than the control respectively. This study is the first demonstration of the impacts of different supplements on SMP during the anaerobic digestion of the West African Gamba and Guinea grass.

KnowVolution of a GH5 Cellulase from Penicillium verruculosum to Improve Thermal Stability for Biomass Degradation

Understanding the thermostability of cellulases is of high importance for their application in lignocellulosic biomass degradation, feedstock, and pulp and paper production. Cellulases have to with...

Optimization of the Biofuel Supply Chain With Capital-Constrained Farmers Under Government Subsidies

China’s biofuel industry faces the problem of insufficient supply of biomass feedstock because farmers lack the funds to carry out their planting plans. Moreover, natural disasters can easily expose farmers to bankruptcy risks, making it difficult for farmers with limited capital to obtain financing from banks. This paper studies the government’s subsidy programmes for helping farmers obtain financing: a poverty alleviation programme (PAP) and a social welfare programme (SWP). We construct a biofuel supply chain model including the government, the bank, farmers, and companies, which optimizes the biomass feedstock production and the government subsidy in different subsidy programmes. We find that high planting efficiency leads to a lower subsidy interest rate for farmers in PAP, while in SWP, high planting efficiency can promote the government to set higher subsidy interest rate when the competitive intensity between bioenergy companies is weak. Furthermore, the total biomass feedstock planting area and the optimal subsidy interest rate in SWP are larger (smaller) than those under PAP when the planting efficiency is higher (lower) than a certain threshold. An extension of our model shows that the government’s subsidy policy for the farmer with financial constraints will reduce the benefits of the farmer who does not need to borrow from the bank. The government’s failure to implement subsidy programmes can sometimes lead to a higher total income for farmers.

Bioethanol supply chain network design considering land characteristics

Biomass is becoming an increasingly widespread source of energy. Yet land, as one of the most important resources in biomass production, is surprisingly understudied in the literature of biomass supply chain planning. This study proposes a novel framework that combines the literature of bioethanol supply chain design with agricultural land planning to simultaneously address optimal supply chain planning and sustainable land use in a bioethanol supply chain. A bi-objective mixed-integer linear programming (MILP) model is proposed to formulate the optimal design and planning of a bioethanol supply chain network considering competition of food and biomass feedstock over the available croplands. The proposed model is capable of making strategic decisions (i.e. locations and capacities of facilities, sourcing and allocation of biomass feedstocks to biorefineries), along with some tactical decisions (i.e. land planning, inventory and production of both biomass feedstock and bioethanol). The model incorporates the two objectives of minimum cost and maximum suitability of crops with their assigned croplands. A novel integration of the FAO framework, the best-worst multi-criteria decision-making method, PROMETHEE II and GIS is used to determine the suitability of available croplands according to the croplands’ soil and topographical characteristics. The performance of the proposed model is demonstrated through a multi-feedstock bioethanol supply chain in Fars province, Iran. It is concluded that the proposed integrated land planning-network design framework outperforms hierarchical approaches in which network design and land planning problems are solved separately in a sequential manner. Also, the case study shows that conditional on implementing second generation bioethanol production, Fars province has the potential to satisfy three percent of the fuel demand for transportation in the country.

Potential Economic Impacts of Allocating More Land for Bioenergy Biomass Production in Virginia

The growing attention to renewable energy and rural development has created greater demand for production of biomass feedstock for bioenergy. However, forest growth rates and the amount of land in most existing forests may not be sufficient to sustainably supply the forest biomass required to support existing forest products industries and the expanding bioenergy industry. Additionally, concerns about agricultural land use competition have dampened expansion of biomass production on agricultural land base. One of the ways to meet the growing forest biomass feedstock demand for bioenergy production is by allocating currently marginal non-forested land for growing bioenergy feedstocks. In Virginia, about 80% of forestland is under nonindustrial private forest ownership. The land use allocation decisions of these private owners are critical for the supply of the forest biomass feedstock to support bioenergy production. We apply a computable general equilibrium model to assess the economy-wide impacts of forestland owners’ willingness to plant pine on non-forested land for woody bioenergy in Virginia. We consider three counterfactual scenarios of biomass feedstock supply increase as intermediate demand for bioenergy production based on forestland owners’ willingness to accept biomass bid prices to set aside more non-forested land for biomass production in Virginia under general equilibrium conditions. Overall, the results show an increase in social welfare and household utility but a marginal decline in GDP. However, increased demand of biomass from logging sector depressed the manufacturing sector (the wood manufacturing sub-sector particularly), which also relies on the logging sector for its intermediate inputs. Results from this study provide insights into the bioenergy land use competition debate, and pathways towards sustainable bioenergy feedstock supply.

Biomass Production of Monocultures and Mixtures of Cup Plant and Native Grasses on Prime and Marginal Cropland

To date, most candidate systems for producing herbaceous cellulosic biomass have been composed of monocultures of perennial or annual grasses. Ecosystem goods and services provided from these biomass feedstock production systems could be increased dramatically with mixing of one or more forb species that would increase biodiversity and provide habitat for pollinators. Cup plant (Silphium perfoliatum L.) is featured with many desirable characteristics, such as high biomass potential, adaptation to marginal soils, and attractiveness to pollinators, desirable in a dicot species to grow in mixtures with perennial warm-season grasses. The objective of this study was to compare cup plant, switchgrass (Panicum virgatum L.), and prairie cordgrass (Spartina pectinata Link) monocultures to their mixtures for biomass production on prime and poorly drained marginal crop land for two years in both South Dakota and Wisconsin. In Wisconsin, monocultures of prairie cordgrass and cup plant and their mixture produced more biomass (8.1 Mg·ha-1) than the switchgrass monoculture and switchgrass/cup plant mixture (5.3 Mg·ha-1) on both prime and marginal land. While in South Dakota, drought and meristem destruction by the cup plant moth (Eucosma giganteana Riley) caused large reductions in biomass production (1.7 Mg·ha-1) in both years, with the switchgrass/cup plant mixture on marginal land having the highest yield (2.1 Mg·ha-1). Our study showed binary mixtures of cup plant and native warm-season grasses have great potential for increasing biodiversity and other ecosystem goods and services, relative to monocultures, for sustainable biomass feedstock production on poorly drained marginal land in the northcentral USA.

A low-cost and scalable process for harvesting microalgae using commercial-grade flocculant.

A low-cost and scalable harvesting process was demonstrated for Chlorella sp. FC2 IITG, which offered an improved process economy for the production of a microalgal biomass feedstock via (i) the utilization of a cheaper commercial grade chemical flocculant; (ii) the recycling of post-harvested nutrient-rich spent water for the successive growth of the FC2 cells and (iii) the modulation of the flocculant dose, resulting in the non-requirement of a pH adjustment of the spent water and separate inoculum development step. Ferrous sulphate and ferric chloride were screened from a pool of four commercial grade flocculants, resulting in high harvesting efficiencies of 99.83% and 99.93% at the lower flocculant doses (g of flocculant g of dry biomass−1) of 2.5 and 3, respectively. The effect of the recycled nutrient-rich spent water and treated non-flocculated microalgal cells after harvesting was evaluated for the growth performance of the FC2 cells in six successive batches. It was found that ferrous sulphate was superior over ferric chloride in terms of the recyclability of the spent water for more number of batches, offering similar growth kinetics and nutrient recovery efficiency as compared with that of the control sample. The scale-up feasibility of the harvesting process was evaluated with a 5 L photobioreactor under indoor conditions and a 350 L open raceway pond under outdoor conditions with a modulated flocculant dose of 1.5 g ferrous sulphate. g dry biomass−1. The harvesting cost of 1 kg biomass using commercial grade ferrous sulphate was estimated to be in the range of 0.17–0.3 USD and was significantly lower as compared to that of analytical grade ferrous sulphate.

The sustainability of woody biomass feedstock production and landscape management: land use, phytoremediation, biodiversity, and wildlife habitats

Woody biomass feedstock is suitable for direct combustion, gasification, pyrolysis, ethanol or methanol production yielding heat, charcoal, pyrolysis oil, green electricity and bio-propellants. There are several issues concerning the environmental, socio-cultural and economic sustainability of woody biomass production connected to land use, protection and/or creation of wildlife habitats, conservation and remediation of wastelands and derelict cultural landscapes. Establishing energy plantations on arable lands or on grasslands is against nature conservation, while setting up them in depleted agricultural lands of inferior quality, polluted areas or wastelands could be advantageous for land reclamation and wildlife, because of - root filtration, phytoremediation, less chemicals and improved soils; - possibilities to establish organic production by combining irrigation with biologically cleaned, pathogen-free wastewater, - application of biosolids for fertilization connected to short rotation forestry (SRF) or short rotation coppicing (SRC), agroforestry (AF) or polycyclic arboriculture; - more permanent cover that provides shelter and biomass for feeding, which is especially important in winter; - higher architectural complexity of vegetation provides more place for nesting and feeding; - forbs in the undergrowth and young shots could provide better quality food for wildlife than the intensive monocultures. Biomass production is very complex and includes a vast variety of feedstocks suitable for a range of energy production technologies and many other products depending on the species and the conditions of cultivation. Therefore, the solution is a complex management system, including land use, phytoremediation, solid waste and wastewater management and ecosystem-based planning combined with other renewable energy sources such as geothermal energy, solar cells, wind turbines, hydroelectric power plants and non-polluting high-tech waste incinerators in one dynamic system.

Production of microbial biomass feedstock via co-cultivation of microalgae-bacteria consortium coupled with effective wastewater treatment: A sustainable approach

A sustainable process was demonstrated towards production of biomass feedstock coupled with wastewater treatment. Sustainability was endeavored to be achieved via symbiotic growth of microalgae and bacteria coupled with utilization of wastewater as cheap source of nutrient and water. The best microalgae-bacteria consortium comprised of two microalgae Chlorella sorokiniana strain DBWC2 &Chlorella sp. strain DBWC7 and two bacteria Klebsiella pneumoniae strain ORWB1 &Acinetobacter calcoaceticus strain ORWB3. When the consortium was characterized on artificial wastewater and raw dairy wastewater, a significant improvement in the microalgal growth, total biomass titer, chemical oxygen demand (COD), and nitrate removal efficiency was observed as compared to microalgae alone. Total biomass titer, nitrate removal, COD removal efficiency was found to be 2.84 g L−1, 93.59%, 82.27% and 2.87 g L−1, 84.69%, 90.49% in artificial wastewater and raw dairy wastewater respectively. The selected microalgae-bacteria consortium may be a potential platform towards sustainable production of microbial biomass using wastewater.

CFD modelling of biomass gasification with a volatile break-up approach

Gasification thermochemical processes of biomass in a 20 kW downdraft gasifier are investigated using a robust two-dimensional (2D) computational fluid dynamics (CFD) modelling method. The model includes all the four zones of the gasifier namely drying, pyrolysis, oxidation and reduction. A step-by-step approach is proposed to evaluate the composition of different gas species as a result of the volatile break-up during gasification. However, selecting suitable chemical reactions for the CFD modelling becomes challenging as the commonly used reactions in kinetic study showed discrepancy in predicting the synthesis gas compositions. A revised set of chemical mechanisms is therefore proposed in the study and the robustness of the approach is examined with results validated against data from literature. The study reports how the air equivalence ratio (ER) affects the gasifier temperature and also the composition of producer gases. The model is then applied to investigate the syngas production of various biomass feedstocks sourced from Scottish agricultural sites.

Investigating the Efficacy of Integrating Energy Crops into Non-Profitable Subfields in Iowa

Within-field spatial variability reduces growers’ return on investment and overall productivity while potentially increasing negative environmental impacts through increased soil erosion, nutrient runoff, and leaching. The hypothesis that integrating energy crops into non-profitable segments of agricultural fields could potentially increase grain yield and biomass feedstock production was tested in this study using a statewide analysis of predominantly corn- and soy-producing counties in Iowa. Basic and rigorous controls on permissible soil and soil-carbon losses were imposed on harvest of crop residues to enhance year-to-year sustainability of crop and residue production. Additional criteria limiting harvesting costs and focus on large-area subfields for biomass production were imposed to reduce the impacts of energy crop integration on grain production. Model simulations were conducted using 4 years (2013–2016) of soil, weather, crop yield, and management practice data on all counties in Iowa. Miscanthus (Miscanthus x giganteus), switchgrass (Panicum virgatum), and crop-residue-based bioenergy feedstock systems were evaluated as biomass. Average energy crop and plant residue harvesting efficiencies were estimated at 50 and 60%, respectively. Because of higher potential yields, average logistics costs for miscanthus-based biomass production were 15 and 23% lower than switchgrass-based and crop residue-based biomass productions, respectively, under basic sustainability controls, and 17 and 26% lower under rigorous sustainability controls. Subfield shape, size, area, and harvest equipment size were the dominant factors influencing harvesting cost and efficiency suggesting that in areas where subfields are predominantly profitable or harvesting efficiencies low, other options such as prairie strips, buffer zones around fields, and riparian areas should be investigated for more profitable biomass production and sustainable farming systems.