| 1. |
- Steinhagen, Sophie, et al.
(författare)
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Harvest time can affect the optimal yield and quality of sea lettuce (Ulva fenestrata) in a sustainable sea-based cultivation : Seasonal Cultivation of Ulva fenestrata
- 2022
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Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Seaweed biomass is a renewable resource with multiple applications. Sea-based cultivation of seaweeds can provide high biomass yields, low construction, operation, and maintenance costs and could offer an environmentally and economically sustainable alternative to land-based cultivations. The biochemical profile of sea-grown biomass depends on seasonal variation in environmental factors, and the optimization of harvest time is important for the quality of the produced biomass. To identify optimal harvest times of Swedish sea-based cultivated sea lettuce (Ulva fenestrata), this study monitored biomass yield, morphology, chemical composition, fertility, and biofouling at five different harvesting times in April - June 2020. The highest biomass yields (approx. 1.2 kg fw [m rope]-1) were observed in late spring (May). The number and size of holes in the thalli and the amount of fertile and fouled tissue increased with prolonged growth season, which together led to a significant decline in both biomass yield and quality during summer (June). Early spring (April) conditions were optimal for obtaining high fatty acid, protein, biochar, phenolic, and pigment contents in the biomass, whereas carbohydrate and ash content, as well as essential and non-essential elements, increased later in the growth season. Our study results show that the optimal harvest time of sea-based cultivated U. fenestrata depends on the downstream application of the biomass and must be carefully selected to balance yield, quality, and desired biochemical contents to maximize the output of future sea-based algal cultivations in the European Northern Hemisphere.
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| 2. |
- Amiandamhen, Stephen, 1983-, et al.
(författare)
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Bioenergy production and utilization in different sectors in Sweden: A state of the art review
- 2020
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Ingår i: BioResources. - : University of North Carolina Press. - 1930-2126. ; 15:4, s. 9834-9857
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Forskningsöversikt (refereegranskat)abstract
- In the continual desire to reduce the environmental footprints of human activities, research efforts to provide cleaner energy is increasingly becoming vital. The effect of climate change on present and future existence, sustainable processes, and utilizations of renewable resources have been active topics within international discourse. In order to reduce the greenhouse gases emissions from traditional materials and processes, there has been a shift to more environmental friendly alternatives. The conversion of biomass to bioenergy, including biofuels has been considered to contribute to the future of climate change mitigation, although there are concerns about carbon balance from forest utilization. Bioenergy accounts for more than one-third of all energy used in Sweden and biomass has provided about 60% of the fuel for district heating. Apart from heat and electricity supply, the transport sector, with about 30% of global energy use, has a significant role in a sustainable bioenergy system. This review presents the state of the art in the Swedish bioenergy sector based on literature and Swedish Energy Agency’s current statistics. The review also discusses the overall bioenergy production and utilization in different sectors in Sweden. The current potential, challenges, and environmental considerations of bioenergy production are also discussed.
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| 3. |
- Cowie, A. L., et al.
(författare)
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Applying a science-based systems perspective to dispel misconceptions about climate effects of forest bioenergy
- 2021
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Ingår i: Global Change Biology Bioenergy. - : John Wiley and Sons Inc. - 1757-1693 .- 1757-1707. ; 13:8, s. 1210-1231
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Tidskriftsartikel (refereegranskat)abstract
- The scientific literature contains contrasting findings about the climate effects of forest bioenergy, partly due to the wide diversity of bioenergy systems and associated contexts, but also due to differences in assessment methods. The climate effects of bioenergy must be accurately assessed to inform policy-making, but the complexity of bioenergy systems and associated land, industry and energy systems raises challenges for assessment. We examine misconceptions about climate effects of forest bioenergy and discuss important considerations in assessing these effects and devising measures to incentivize sustainable bioenergy as a component of climate policy. The temporal and spatial system boundary and the reference (counterfactual) scenarios are key methodology choices that strongly influence results. Focussing on carbon balances of individual forest stands and comparing emissions at the point of combustion neglect system-level interactions that influence the climate effects of forest bioenergy. We highlight the need for a systems approach, in assessing options and developing policy for forest bioenergy that: (1) considers the whole life cycle of bioenergy systems, including effects of the associated forest management and harvesting on landscape carbon balances; (2) identifies how forest bioenergy can best be deployed to support energy system transformation required to achieve climate goals; and (3) incentivizes those forest bioenergy systems that augment the mitigation value of the forest sector as a whole. Emphasis on short-term emissions reduction targets can lead to decisions that make medium- to long-term climate goals more difficult to achieve. The most important climate change mitigation measure is the transformation of energy, industry and transport systems so that fossil carbon remains underground. Narrow perspectives obscure the significant role that bioenergy can play by displacing fossil fuels now, and supporting energy system transition. Greater transparency and consistency is needed in greenhouse gas reporting and accounting related to bioenergy.
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| 4. |
- Nickel, David, 1990
(författare)
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Process development for platform chemical production from agricultural and forestry residues
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- As part of a bio-based economy, biorefineries are envisaged to sustainably produce platform chemicals via biochemical conversion of agricultural and forestry residues. However, supply risks, the recalcitrance of lignocellulosic biomass, and inhibitor formation during pretreatment impair the economic feasibility of such biorefineries. In this thesis, process design and assessment were developed with the aim of addressing these hurdles and improving the cost-effectiveness of lignocellulose-derived platform chemicals. To expand the feedstock base and reduce operational costs, logging residues served as underutilised and inexpensive raw material. The major impediment in converting logging residues was their high recalcitrance and low cellulose content, which resulted in low attainable ethanol titres during simultaneous saccharification and co-fermentation (SSCF). Pretreatment optimisation reduced inhibitor formation and recalcitrance, and led to enzymatic hydrolysis yields at par with those obtained for stem wood, despite the less favourable chemical composition. Upgrading logging residues with carbohydrate-rich oat hulls increased ethanol titres to >50 g/L using batch SSCF at 20% WIS loadings, demonstrating the potential to further decrease downstream processing costs. To alleviate the toxicity of inhibitors generated during pretreatment, preadaptation was applied to Saccharomyces cerevisiae . Exposure to the inhibitors in the pretreated liquid fraction improved ethanol production during subsequent fermentation. Transferring the concept of preadaptation to lactic acid production by Bacillus coagulans cut the process times by half and more than doubled the average specific lactic acid productivity, showcasing how preadaptation could decrease operational costs. To assess the performance and robustness of process designs against process input variations, a multi-scale variability analysis framework was developed. The framework included models for bioprocess, flowsheet, techno-economic, and life cycle assessment. In a case study, multi-feed processes, in which solids and cells are fed to the process using model-based predictions, were more robust against variable cellulolytic activities than batch SSCFs in a wheat straw-based ethanol biorefinery. The developed framework can be used to identify robust biorefinery process designs, which simultaneously meet technological, economic, and environmental goals.
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| 5. |
- Spetea, Cornelia, 1968
(författare)
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Energy-efficient cultivation of marine microalgae for biomass production : Final rapport: Energimyndigheten P45907-1
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This project has demonstrated the principle of rotational cultivation of marine microalgae and that species adapted to cold climates can provide higher productivity during cold periods. By using marine species, and thus seawater instead of freshwater in cultivation, the environmental impact is reduced. Society faces major challenges to produce sufficient amounts of biomass for energy and material, and microalgae have a great potential to complement sources from forestry and agriculture. At Nordic latitudes year-round microalgae cultivation is debatable due to seasonal variations in productivity. Shall the same species be used throughout the year or shall seasonal-adapted species be used? The aims of the project were to identify suitable algal strains for a potential annual rotation model, where different strains are rotated during three cultivation seasons, and to further develop and optimize an energy-efficient cultivation process for the marine environment. To achieve these aims, a laboratory study was performed where two marine microalgal strains out of 167 were selected for intended cultivation at the west coast of Sweden. One strain belongs to the species Nannochloropsis granulata and the other to Skeletonema marinoi. The strains were cultivated in three simulated growth seasons: summer, winter and spring, and thereafter compared. We show that Nannochloropsis produced more biomass with more incorporated energy in lipids during summer and spring (25 MJ kg-1 compared to about 45 MJ kg-1 for diesel), whereas Skeletonema produced more biomass rich in carbohydrates and proteins during winter. Skeletonema was in general more efficient in taking up phosphate. Based on our results, biomass production as energy feedstock would be energy efficient only during the summer on the Swedish west coast. Nevertheless, species could be rotated for different purposes during the year. Biomass production could be combined with nutrient recycling of wastewater, for example, from fish industry. Our project faces a challenge in boosting the biomass produced in winter, but this could be solved, for example, by optimization of the cultivation medium and temperature increase with heat wastewater or other heat waste. The summer species Nannochloropsis proved to withstand winter by activating different lipid metabolic pathways than the cold-adapted species Skeletonema uses. Enhanced synthesis of proteins, such as enzymes, in Skeletonema during winter may compensate for their reduced activities, promoting growth and biomass production even at low temperatures. More species need to be studied to find those with higher productivity under winter conditions. In practice, the work-related consequences of a rotational cultivation should be weighed against its benefits, relative to a shorter cultivation season in each application. Potential applications mainly include cleaning of air and seawater, production of energy, biomass and biomaterials for the industry.
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| 6. |
- Andersson, Viktor, 1983, et al.
(författare)
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Alkali interactions with a calcium manganite oxygen carrier used in chemical looping combustion
- 2022
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Ingår i: Fuel Processing Technology. - : Elsevier BV. - 0378-3820 .- 1873-7188. ; 227
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Tidskriftsartikel (refereegranskat)abstract
- Chemical-Looping Combustion (CLC) of biofuels is a promising technology for cost-efficient CO2 separation and can lead to negative CO2 emissions when combined with carbon capture and storage. A potential challenge in developing CLC technology is the effects of alkali metal-containing compounds released during fuel conversion. This study investigates the interactions between alkali and an oxygen carrier (OC), CaMn0.775Ti0.125Mg0.1O3-δ, to better understand the fate of alkali in CLC. A laboratory-scale fluidized bed reactor is operated at 800–900 °C in oxidizing, reducing and inert atmospheres to mimic CLC conditions. Alkali is fed to the reactor as aerosol KCl particles, and alkali in the exhaust is measured online with a surface ionization detector. The alkali concentration changes with gas environment, temperature, and alkali loading, and the concentration profile has excellent reproducibility over repeated redox cycles. Alkali-OC interactions are dominated by alkali uptake under most conditions, except for a release during OC reduction. Uptake is significant during stable reducing conditions, and is limited under oxidizing conditions. The total uptake during a redox cycle is favored by a high alkali loading, while the influence of temperature is weak. The implications for the understanding of alkali behavior in CLC and further development are discussed.
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| 7. |
- Cao, Wenhan, et al.
(författare)
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Release of potassium in association with structural evolution during biomass combustion
- 2021
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Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 287, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- A mechanistic understanding of potassium release is essential to mitigate the potassium-induced ash problems during biomass combustion. This work studies the effects of operational condition on the potassium release and transition during the combustion of wheat straw, and elucidate the release potential of potassium associated with the structural change of biomass particles. The combustion tests were carried out in a laboratory-scale reactor, working in a wide range of temperatures and heating rates. It was found that the combustion of biomass sample at a temperature up to 1000 °C results in a release of over 60% of its initial potassium content. Raising the heating rate from 8 °C/min to 25 °C/min could lead to an additional release of up to 20% of the initial amount of potassium. A three-stage potassium release mechanism has been concluded from this work: the initial-step release stage (below 400 °C), the holding stage (400–700 °C) and the second-step release stage (above 700 °C). Comprehensive morphology analysis with elemental (i.e. K, S, O, Si) distribution was carried out; the results further confirmed that potassium is likely to exist inside the stem-like tunnel of biomass particles, mainly in forms of inorganic salts. During the heating-up process, the breakdown and collapse of biomass particle structure could expose the internally located potassium and thus accelerate the release of potassium and the transform of its existing forms. Lastly, a detailed temperature-dependent release mechanism of potassium was proposed, which could be used as the guidance to mitigate the release of detrimental potassium compounds by optimising the combustion process.
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| 8. |
- Cintas Sanchez, Olivia, 1982, et al.
(författare)
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Geospatial supply-demand modeling of lignocellulosic biomass for electricity and biofuels in the European Union
- 2021
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 144
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Tidskriftsartikel (refereegranskat)abstract
- Bioenergy can contribute to achieving European Union (EU) climate targets while mitigating impacts from current agricultural land use. A GIS-based modeling framework (1000 m resolution) is employed to match biomass supply (forest and agricultural residues, complemented by lignocellulosic energy crops where needed) with biomass demand for either electricity or bio-oil production on sites currently used for coal power in the EU-28, Norway, and Switzerland. The framework matches supply and demand based on minimizing the field-to-gate costs and is used to provide geographically explicit information on (i) plant-gate supply cost; (ii) CO2 savings; and (iii) potential mitigation opportunities for soil erosion, flooding, and eutrophication resulting from the introduction of energy crops on cropland. Converting all suitable coal power plants to biomass and assuming that biomass is sourced within a transport distance of 300 km, would produce an estimated 150 TW h biomass-derived electricity, using 1365 PJ biomass, including biomass from energy crops grown on 6 Mha. Using all existing coal power sites for bio-oil production in 100-MW pyrolysis units could produce 820 PJ of bio-oil, using 1260 PJ biomass, including biomass from energy crops grown on 1.8 Mha. Using biomass to generate electricity would correspond to an emissions reduction of 135 MtCO2, while using biomass to produce bio-oil to substitute for crude oil would correspond to a reduction of 59 MtCO2. In addition, energy crops can have a positive effect on soil organic carbon in most of the analyzed countries. The mitigation opportunities investigated range from marginal to high depending on location.
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| 9. |
- Englund, Oskar, et al.
(författare)
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Multifunctional perennial production systems for bioenergy: performance and progress
- 2020
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Ingår i: Wiley Interdisciplinary Reviews. - : Wiley. - 2041-8396 .- 2041-840X.
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Tidskriftsartikel (refereegranskat)abstract
- As the global population increases and becomes more affluent, biomass demands for food and biomaterials will increase. Demand growth is further accelerated by the implementation of climate policies and strategies to replace fossil resources with biomass. There are, however, concerns about the size of the prospective biomass demand and the environmental and social consequences of the corresponding resource mobilization, especially concerning impacts from the associated land-use change. Strategically integrating perennials into landscapes dominated by intensive agriculture can, for example, improve biodiversity, reduce soil erosion and nutrient emissions to water, increase soil carbon, enhance pollination, and avoid or mitigate flooding events. Such ?multifunctional perennial production systems? can thus contribute to improving overall land-use sustainability, while maintaining or increasing overall biomass productivity in the landscape. Seven different cases in different world regions are here reviewed to exemplify and evaluate (a) multifunctional production systems that have been established to meet emerging bioenergy demands, and (b) efforts to identify locations where the establishment of perennial crops will be particularly beneficial. An important barrier towards wider implementation of multifunctional systems is the lack of markets, or policies, compensating producers for enhanced ecosystem services and other environmental benefits. This deficiency is particularly important since prices for fossil-based fuels are low relative to bioenergy production costs. Without such compensation, multifunctional perennial production systems will be unlikely to contribute to the development of a sustainable bioeconomy.
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| 10. |
- Perruca Foncillas, Raquel
(författare)
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Evaluation of biosensors and flow cytometry as monitoring tools in lignocellulosic bioethanol production
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The significant environmental impact of the current fossil fuel-based industry is a major concern for society. Consequently, various initiatives are being undertaken to establish a more sustainable industrial model. One example is via the transition from conventional fossil fuel refineries to biorefineries, where renewable raw materials are utilised. Amongst these raw materials, the use of lignocellulosic biomass from agricultural residues or wood has been favoured, as it does not compete with food or land resources. In particular, extensive research has been conducted to produce biofuels such as bioethanol from lignocellulosic biomass, referred to as second-generation (2G) bioethanol.In this thesis work, the goal was to develop and apply new tools to address challenges encountered in 2G bioethanol production. Specifically, the work focused on monitoring the impact of inhibitory compounds and mixed sugars on the fermentation performance of the yeast Saccharomyces cerevisiae.Inhibitory compounds are released during the pretreatment of the lignocellulosic biomass, a crucial step necessary to break down its complex structure and to enhance sugar accessibility This thesis work specifically focused on the redox imbalance induced in cells exposed to furaldehydes such as furfural or HMF. To study this effect, a biosensor for redox imbalance, TRX2p-yEGFP, was introduced into the cells and its fluorescence signal was monitored in real-time using flow cytometry. One potential strategy for enhancing the cells' tolerance to these inhibitors is to prepare them by introducing lignocellulosic hydrolysate in the feed during cell propagation. During this pre-exposure phase, a transient induction of the TRX2p-yEGFP biosensor signal for redox imbalance was observed, which gradually diminished. This indicated that, by the time of cell collection, the cells had adapted to the inhibitor concentration within the culture. To examine whether an increased induction level of the biosensor at the time of cell collection influenced the fermentation performance, an automated control system was devised. This system utilised data from the flow cytometry analysis to control the level of inhibitors in the cultivation feed. Consequently, when the biosensor signal began to decline, higher amounts of inhibitors were added, as long as the addition did not lead to an increase in the number of damaged cells.A second biosensor was used in this thesis work to investigate the sugar signalling response of S. cerevisiae to the presence of xylose. Xylose is the second most abundant sugar in lignocellulosic biomass; however, naturally, S. cerevisiae cannot metabolise it. Genetically modified S. cerevisiae strains have been generated by introducing heterologous pathways such as the XR/XDH or XI pathways to enable xylose consumption. Nevertheless, xylose consumption rates remain lower compared to glucose. Sugar signalling emerged as a potential bottleneck in the efficient utilisation of xylose. In the present work, the response of the SUC2p-yEGFP biosensor for sugar signalling was found to vary significantly depending on the pathway employed. A higher induction for the strains carrying the XI pathway was associated with poorer growth on xylose. Lastly, the effect of introducing a xylose epimerase capable of catalysing the conversion between the two anomers, α-D-xylopyranose and β-D-xylopyranose, as a strategy to improve xylose consumption was studied. The effect was enzyme-specific and proved to be particularly beneficial in strains utilising the xylose isomerase from Lachnoclostridium phytofermentans.In conclusion, the results presented in this thesis demonstrate how biosensors can facilitate the understanding and monitoring of intracellular processes that occur within the cell under stress conditions and be a key tool for improving production processes.
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| 11. |
- Zetterholm, Jonas, 1989-, et al.
(författare)
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Large-scale introduction of forest-based biorefineries : Actor perspectives and the impacts of a dynamic biomass market
- 2020
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Ingår i: Biomass and Bioenergy. - : Elsevier. - 0961-9534 .- 1873-2909. ; 142
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Tidskriftsartikel (refereegranskat)abstract
- Large-scale implementation of forest-based biofuel production will have an impact on biomass prices, something which in turn will affect biofuel production costs. The profitability of emerging biofuel production technologies is usually assessed using techno-economic or market approaches. While techno-economic approaches have a detailed description of technologies within plant-level or supply chain system boundaries, they build on exogenously given static biomass prices. Conversely, market approaches have a consistent description of the economic system including market interactions for prices within local or national boundaries, but they generally lack technological depth. This paper combines these two approaches using an iterative framework for a case study optimising the production cost of liquefied biomethane (LBG) using different configurations of sawmill-integrated biomass gasification.Cost estimates are developed using system boundaries surrounding a LBG production plant, and the Swedish national borders, reflecting the plant-owner and policymaker perspectives, respectively. The results show that different plant configurations are favoured depending on the choice between minimising the biofuel production cost for the plant-owner or for the policymaker. Market dynamics simulated by the iterative procedure show that a direct policy support of 36–56 EUR/MWh would be needed to sustain large-scale LBG production, which is 12–31% higher than the necessary policy support estimated based on static biomass prices.
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| 12. |
- Fagerström, Anton, et al.
(författare)
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Economic and Environmental Potential of Large‐Scale Renewable Synthetic Jet Fuel Production through Integration into a Biomass CHP Plant in Sweden
- 2022
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Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 15:3
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Tidskriftsartikel (refereegranskat)abstract
- The potential of bio‐electro‐jet fuel (BEJF) production with integration into an existing biomass‐based combined heat and power (CHP) facility was investigated. The BEJF is produced via Fischer–Tropsch (F–T) synthesis from biogenic CO2 and H2 obtained by water electrolysis. Techno-economic (TEA)‐ and life. cycle (LCA)‐ assessments were performed to evaluate the production cost and environmental impact of the BEJF production route. The BEJF mass fraction reached 40% of the total F–T crude produced. A reduction of 78% in heating demands was achieved through energy integration, leading to an increase in the thermal efficiency by up to 39%, based on the F–T crude. The total production cost of BEJF was in the range of EUR 1.6–2.5/liter (EUR 169–250/MWh). The GWP of the BEJF was estimated to be 19 g CO2‐eq per MJ BEJF. The reduction potential in GWP in contrast to the fossil jet baseline fuel varied from 44% to more than 86%. The findings of this study underline the potential of BEJF as a resource‐efficient, cost‐effective, and environmentally benign alternative for the aviation sector. The outcome is expected to be applicable to different geograph-ical locations or industrial networks when the identified influencing factors are met.
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| 13. |
- Cañete Vela, Isabel, 1992, et al.
(författare)
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Feedstock recycling of cable plastic residue via steam cracking on an industrial-scale fluidized bed
- 2024
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Ingår i: Fuel. - 0016-2361. ; 355
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Tidskriftsartikel (refereegranskat)abstract
- The use of plastic materials in a circular way requires a technology that can treat any plastic waste and produce the same quality of product as the original. Cable plastic residue from metal recycling of electric wires is composed of cross-linked polyethene (XLPE) and PVC, which is a mixture that cannot be mechanically recycled today. Through thermochemical processes, polymer chains are broken into syngas and monomers, which can be further used in the chemical industry. However, feedstock recycling of such a mixture (XLPE, PVC) has been scarcely studied on an industrial scale. Here, the steam cracking of cable plastic was studied in an industrial fluidised bed, aiming to convert cable plastics into valuable products. Two process temperatures were tested: 730 °C and 800 °C. The results show that the products consist of 27–31 wt% ethylene and propylene, 5–16% wt.% other linear hydrocarbons, and more than 10 wt% benzene. Therefore, 40%–60% of the products are high-value chemicals that could be recovered via steam cracking of cable plastic.
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| 14. |
- Ma, Chunyan, et al.
(författare)
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Towards negative carbon emissions : Carbon capture in bio-syngas from gasification by aqueous pentaethylenehexamine
- 2020
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Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 279
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Tidskriftsartikel (refereegranskat)abstract
- In this work, an aqueous pentaethylenehexamine (PEHA) solution was studied for CO2 removal from bio-syngas for the first time. Firstly, pure CO2 absorption in aqueous PEHA solution under different conditions was conducted, and 20 wt% PEHA solution was identified as the best option. Secondly, the capture of CO2 was tested with synthetic syngas from a gas cylinder, and the species other than CO2 showed a negligible impact on CO2 removal. Finally, to evaluate the practical feasibility of using aqueous PEHA solution on the downstream CO2 capture, the pilot experiments of gasification with boreal forest-based biomasses were designed to provide real syngas with a realistic distribution in composition for further testing. The results showed that the operating conditions and the type of feedstocks affected the distribution in the bio-syngas composition. Among these feedstocks, at the optimal oxygen supply, using spruce needles generated the highest yields of CO and H2 and, meanwhile, gave rise to similar yields of other gases such as CO2, CH4, etc. The influence of the species other than CO2 for CO2 removal was negligible. Additionally, aqueous PEHA solution was tested as a biomass pretreatment agent, showing that no significant changes could be identified by the ultimate analysis (except for increased nitrogen content), but the yields of CO were affected negatively. On the other hand, when using the pretreated biomass by the aqueous PEHA solution, the NH3 concentration in bio-syngas reached to the highest (4000 parts per million), which slightly affected the CO2 absorption capacity and initial absorption rate of 20 wt% PEHA solution in a positive way.
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| 15. |
- Ahmad, Waqar, et al.
(författare)
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Coke-free conversion of benzene at high temperatures
- 2023
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Ingår i: Journal of the Energy Institute. - : Elsevier. - 1743-9671 .- 1746-0220. ; 109
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the conversion of benzene in a novel highly non-porous ɣ-Al2O3 packed bed reactor at 1000–1100 °C. The influences of packed bed presence, reforming medium (steam and CO2), gas flow rate and benzene concentration on steady state benzene conversion are examined. In presence of packed bed, benzene conversions of 52, 75, and 84% were achieved with combined steam and CO2 reforming at 1000, 1050, and 1100 °C, respectively. Whereas, benzene conversion of 65% without the packed bed at 1000 °C experienced a continuous increase in differential upstream pressure (DUP) of high temperature (HT) filter at reactor downstream due to deposition of in situ generated coke. High concentrations of generated CO and H2 of 2.3 and 6 vol% with packed bed than 1.4 and 4.7 vol% without the packed respectively, were achieved. CO2 reforming achieved high benzene conversions of 68–98% than 42–80% achieved with stream reforming at packed bed reactor temperatures of 1000–1100 °C. The results indicated that presence of ɣ-Al2O3 packed bed with possible surface reactions directed the conversion of benzene to combustible gases instead of coke. Hence, ɣ-Al2O3 packed bed reactor could be a suitable choice for coke-free conversion of tar of gasifier producer gas.
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| 16. |
- Mei, Daofeng, 1986, et al.
(författare)
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Investigation of LD-slag as oxygen carrier for CLC in a 10 kW unit using high-volatile biomasses
- 2023
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier Ltd. - 1750-5836 .- 1878-0148. ; 127
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Tidskriftsartikel (refereegranskat)abstract
- A steel slag from the Linz-Donawitz process, called LD-slag, having significant calcium and iron-fractions, was investigated as an oxygen carrier in a recently developed 10 kWth chemical-looping combustor with three high-volatile biomass fuels. In order to improve operability, the LD-slag was found to require heat-treatment at high temperatures before being used in the unit. In total, operation with the biomasses was conducted for more than 26 h at temperatures of 870–980 °C. The fuel thermal power was in the range of 3.4–10 kWth. The operation involved chemical looping combustion (CLC), chemical looping gasification (CLG) and oxygen carrier aided combustion (OCAC). Around 12 h was in CLC operation, 13.3 h was conducted in CLG-conditions, while the remaining 0.7 h was OCAC. Here, the results obtained during the CLC part of the campaign is reported. Increased temperature in the fuel reactor and higher airflows to the air reactor both lead to better combustion performance. Steam concentration in the fuel reactor has little effect on the performance. The LD-slag showed higher oxygen demand (31.0%) than that with ilmenite (21.5%) and a manganese ore (19.5%) with the same fuel and normal solids circulation. However, with the LD-slag, there is possibility to achieve a lower oxygen demand (15.2%) with high solids circulation. © 2023 The Author(s)
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| 17. |
- Toktarova, Alla, 1992, et al.
(författare)
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Pathways for Low-Carbon Transition of the Steel Industry-A Swedish Case Study
- 2020
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Ingår i: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 13:15
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Tidskriftsartikel (refereegranskat)abstract
- The concept of techno-economic pathways is used to investigate the potential implementation of CO(2)abatement measures over time towards zero-emission steelmaking in Sweden. The following mitigation measures are investigated and combined in three pathways: top gas recycling blast furnace (TGRBF); carbon capture and storage (CCS); substitution of pulverized coal injection (PCI) with biomass; hydrogen direct reduction of iron ore (H-DR); and electric arc furnace (EAF), where fossil fuels are replaced with biomass. The results show that CCS in combination with biomass substitution in the blast furnace and a replacement primary steel production plant with EAF with biomass (Pathway 1) yield CO(2)emission reductions of 83% in 2045 compared to CO(2)emissions with current steel process configurations. Electrification of the primary steel production in terms of H-DR/EAF process (Pathway 2), could result in almost fossil-free steel production, and Sweden could achieve a 10% reduction in total CO(2)emissions. Finally, (Pathway 3) we show that increased production of hot briquetted iron pellets (HBI), could lead to decarbonization of the steel industry outside Sweden, assuming that the exported HBI will be converted via EAF and the receiving country has a decarbonized power sector.
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| 18. |
- Awais, Fawad, et al.
(författare)
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Logistic characteristics and requirements of Swedish wood biofuel heating plants
- 2021
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Ingår i: Renewable & sustainable energy reviews. - : Elsevier Ltd. - 1364-0321 .- 1879-0690. ; 138
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Tidskriftsartikel (refereegranskat)abstract
- The demand for wood biofuel for district heating plants and combined heat and power plants (CHPs) has increased, caused by an increase in both the number and size of CHPs. This places large demands on the logistics system supplying these plants with fuel, with a particular interest in the use of alternative modes of transport such as rail and sea. The aim of this paper is to identify the industry actors’ requirements, constraints, and preferences regarding the wood-biofuel supply chain and to identify the logistical challenges this entails, as well as how this impacts the opportunity for an increased use of alternative transport solutions. A survey was sent to all Swedish CHPs, combined with six interviews with transport companies, terminal operators, and forest companies. The study shows that the industry has a local focus that limits potential logistics and sourcing solutions. It is also challenged by urban sprawl, with expanding residential areas close to the CHPs putting further constraints on the operations. Significant variations in fuel demand, depending on unpredictable outside temperature and seasonal variation, is a further challenge. The low density of the fuel has a negative impact on transport costs and introduces a trade-off between chipping close to the forest to increase density versus more efficient chipping at the CHP. Intermodal transport only used by large plants, driven by a shortage of local fuel. © 2020 The Authors
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| 19. |
- Etikyala, Sreelekha, 1991, et al.
(författare)
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Effect of Renewable Fuel Blends on PN and SPN Emissions in a GDI Engine
- 2020
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627.
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Tidskriftsartikel (refereegranskat)abstract
- To characterize the effects of renewable fuels on particulate emissions from GDI engines, engine experiments were conducted using EN228-compliant gasoline fuel blends containing no oxygenates, 10% ethanol (EtOH), or 22% ethyl tert-butyl ether (ETBE). The experiments were conducted in a single cylinder GDI engine using a 6-hole fuel injector operated at 200 bar injection pressure. Both PN in raw exhaust and solid PN (SPN) were measured at two load points and various start of injection (SOI) timings. Raw PN and SPN results were classified into various size ranges, corresponding to current and future legislations. At early SOI timings, where particulate formation is dominated by diffusion flames on the piston due to liquid film, the oxygenated blends yielded dramatically higher PN and SPN emissions than reference gasoline because of fuel effects. For particulates >23 nm and with optimized SOI timing, the use of oxygenated blends significantly increases SPN and conversely decreases raw PN emissions at low load (4.5 bar IMEP). At high load (9 bar IMEP), overall SPN emissions were significantly higher and there were no clear differences between the blends. Additionally, SPN measurements showed that soot formation and emissions of volatile organic compounds (VOC) depended strongly on blend composition. Finally, adding oxygenates (up to 22%) to gasoline did not reduce emissions of SPN in the size ranges addressed by current regulations.
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| 20. |
- Mukesh Kumar, Awasthi, et al.
(författare)
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Bacterial dynamics during the anaerobic digestion of toxic citrus fruit waste and semi-continues volatile fatty acids production in membrane bioreactors
- 2022
-
Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 319
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Tidskriftsartikel (refereegranskat)abstract
- Citrus wastes (CW) are normally toxic to anaerobic digestion (AD) because of flavors such as D-limonene. In this study, bacterial community was evaluated during volatile fatty acids (VFAs) production from CW inoculated by sludge in a membrane bioreactor (MBR) using semi-continuous AD with different organic loading rates (OLR). Four treatments including untreated CW filled with 4 and 8 g center dot VS center dot L(-1)d(-1) OLR (UOLR4 and UOLR8), pretreated Dlimonene-free CW filled with 4 and 8 g center dot VS center dot L(-1)d(-1) OLR (POLR4 and POLR8). The initial inoculum and the CW mixture (DAY0) was used as control for comparison. There was an obviously higher bacterial diversity in raw material (66848 sequences in DAY0), while decreased after AD and higher in POLR4 and POLR8 (65239 and 63916) than UOLR4 and UOLR8 (49158 and 51936). The key bacterial associated with VFAs production mainly affiliated to Firmicutes (37.35-84.73%), Bacteroidetes (0.48-36.87%), and Actinobacteria (0.35-29.38%), and the key genus composed of Lactobacillus, Prevotella, Bacillus, Bacteroides and Olsenella which contributed in VFA generation by degradable complex organic compounds. Noticeably, methanogen completely suppressed after MBR-AD and UOLR4 has greater acid utilizing bacteria (70.09%).
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| 21. |
- Guldris Leon, Lorena, 1983, et al.
(författare)
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Selective Comminution Applied to Mineral Processing of a Tantalum Ore: A Technical, Economic Analysis
- 2022
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Ingår i: Minerals. - Basel : MDPI AG. - 2075-163X. ; 12:8
-
Tidskriftsartikel (refereegranskat)abstract
- There is an increasing demand to simulate and optimize the performance and profit of comminution circuits, especially in low-grade ore processing, as is the case with critical metals minerals. Recent research has shown that the optimization result is greatly influenced by quality aspects of the products, such as cost, profit, and capacity. This paper presents a novel approach to performing a multi-objective technical and economic analysis of tantalum ore processing to increase the production of critical metals minerals. The article starts with mineral composition analysis to highlight the potential of strategies for balancing the process layout for maximized production. The introduction of a combined technical and economic analysis presents the possibility of improving the profit by rearranging the mass flow given the rock's mineral composition. Results show that selective comminution can improve process capacity by 23% and decrease production cost by 10% for the presented case.
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| 22. |
- Ahlström, Johan, 1990
(författare)
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Shaping Future Opportunities for Biomass Gasification - The Role of Integration
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A considerable number of studies indicate that biofuels produced from lignocellulosic biomass will most probably play a significant role in achieving the climate goals stated in the Paris agreement. Several candidate technologies could be implemented to produce these fuels, and one of the most promising is thermal gasification. Gasification is a robust technology that has been demonstrated successfully at industrial scale and shown to be able to achieve high conversion efficiencies and relatively low production costs. However, there are currently no large-scale plants in operation or under construction, since such plants are unable to compete with their fossil counterparts under current conditions. This thesis explores how different forms and levels of integration could facilitate deployment of large-scale biomass gasification for future production of biofuels. Three levels of integration are considered, a technological level, a process level and a value-chain level. Different integration concepts are then assessed with respect to these levels. From a technology perspective, the implications of switching feedstock are studied. At the process level, heat integration with existing sawmill plants as well as integration of an electrolyser unit with a gasification plant are investigated. From a value chain perspective, integration with the value chain for producing fuels for use the Swedish iron and steel industry is considered, as well as integration with the electricity system. The results presented in this thesis indicate that the different integration options investigated can contribute to making biofuel production through biomass gasification more cost-efficient. Switching gasifier feedstock can lower biofuel production costs by up to 42%. Efficient heat integration with sawmills is the most attractive option to decrease production costs from a plant-owner perspective. Integration of a flexible gasification unit equipped with CO2 capture capacity for either long-term storage or re-use as feedstock for biomethane production through the Sabatier reaction with hydrogen produced through electrolysis increases the economic competitiveness of the gasification unit, while stimulating increased construction of renewable electricity generation capacity. The thesis thus demonstrates that well-planned integration of biomass gasification plants can contribute significantly to making the technology more competitive
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| 23. |
- Stovicek, Vratislav, et al.
(författare)
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Rational and evolutionary engineering of Saccharomyces cerevisiae for production of dicarboxylic acids from lignocellulosic biomass and exploring genetic mechanisms of the yeast tolerance to the biomass hydrolysate
- 2022
-
Ingår i: Biotechnology for Biofuels and Bioproducts. - : Springer Science and Business Media LLC. - 2731-3654. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Lignosulfonates are significant wood chemicals with a $700 million market, produced by sulfite pulping of wood. During the pulping process, spent sulfite liquor (SSL) is generated, which in addition to lignosulfonates contains hemicellulose-derived sugars—in case of hardwoods primarily the pentose sugar xylose. The pentoses are currently underutilized. If they could be converted into value-added chemicals, overall economic profitability of the process would increase. SSLs are typically very inhibitory to microorganisms, which presents a challenge for a biotechnological process. The aim of the present work was to develop a robust yeast strain able to convert xylose in SSL to carboxylic acids. Results: The industrial strain Ethanol Red of the yeast Saccharomyces cerevisiae was engineered for efficient utilization of xylose in a Eucalyptus globulus lignosulfonate stream at low pH using CRISPR/Cas genome editing and adaptive laboratory evolution. The engineered strain grew in synthetic medium with xylose as sole carbon source with maximum specific growth rate (µmax) of 0.28 1/h. Selected evolved strains utilized all carbon sources in the SSL at pH 3.5 and grew with µmax between 0.05 and 0.1 1/h depending on a nitrogen source supplement. Putative genetic determinants of the increased tolerance to the SSL were revealed by whole genome sequencing of the evolved strains. In particular, four top-candidate genes (SNG1, FIT3, FZF1 and CBP3) were identified along with other gene candidates with predicted important roles, based on the type and distribution of the mutations across different strains and especially the best performing ones. The developed strains were further engineered for production of dicarboxylic acids (succinic and malic acid) via overexpression of the reductive branch of the tricarboxylic acid cycle (TCA). The production strain produced 0.2 mol and 0.12 mol of malic acid and succinic acid, respectively, per mol of xylose present in the SSL. Conclusions: The combined metabolic engineering and adaptive evolution approach provided a robust SSL-tolerant industrial strain that converts fermentable carbon content of the SSL feedstock into malic and succinic acids at low pH.in production yields reaching 0.1 mol and 0.065 mol per mol of total consumed carbon sources. Moreover, our work suggests potential genetic background of the tolerance to the SSL stream pointing out potential gene targets for improving the tolerance to inhibitory industrial feedstocks.
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| 24. |
- Andersson, Viktor, 1983, et al.
(författare)
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Design and first application of a novel laboratory reactor for alkali studies in chemical looping applications
- 2023
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Ingår i: Fuel Processing Technology. - 0378-3820. ; 252
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Tidskriftsartikel (refereegranskat)abstract
- Alkali compounds are readily released during biomass conversion and their complex interactions with reactor walls and sampling equipment makes detailed investigations challenging. This study evaluates a novel laboratory-scale fluidized bed reactor for chemical looping combustion (CLC) studies. The reactor design is based on detailed consideration of the behavior of alkali-containing molecules and aerosol particles and is guided by computational fluid dynamic simulations. The design allows for interactions between gaseous alkali and a fluidized bed, while minimizing alkali interactions with walls before and after the fluidized bed. The function of the laboratory reactor is demonstrated in experiments using online gas and alkali analysis. Alkali is continuously fed to the reactor as KOH or KCl aerosol with and without a fluidized bed of the oxygen carrier CaMn0.775Ti0.125Mg0.1O3-δ present in inert, reducing and oxidizing conditions at temperatures up to 900 °C. Alkali uptake by the OC is characterized in all conditions, and observed to sensitively depend on gas composition, reactor temperature and type of alkali compound. The experimental setup is concluded to have a significantly improved functionality compared to a previously used reactor, which opens up for detailed studies of interactions between alkali compounds and oxygen carriers used in CLC.
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| 25. |
- Ramirez Camargo, Luis, et al.
(författare)
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Pathway to a land-neutral expansion of Brazilian renewable fuel production
- 2022
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 13:1
-
Tidskriftsartikel (refereegranskat)abstract
- Biofuels are currently the only available bulk renewable fuel. They have, however, limited expansion potential due to high land requirements and associated risks for biodiversity, food security, and land conflicts. We therefore propose to increase output from ethanol refineries in a land-neutral methanol pathway: surplus CO2-streams from fermentation are combined with H2 from renewably powered electrolysis to synthesize methanol. We illustrate this pathway with the Brazilian sugarcane ethanol industry using a spatio-temporal model. The fuel output of existing ethanol generation facilities can be increased by 43%–49% or ~100 TWh without using additional land. This amount is sufficient to cover projected growth in Brazilian biofuel demand in 2030. We identify a trade-off between renewable energy generation technologies: wind power requires the least amount of land whereas a mix of wind and solar costs the least. In the cheapest scenario, green methanol is competitive to fossil methanol at an average carbon price of 95€ tCO2−1.
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| 26. |
- Persson, Michael
(författare)
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Integrated starch and lignocellulose based biorefineries : Synergies and opportunities
- 2021
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The transition from a reliance on fossil resources to the use of renewables for the production of energy, fuels and chemicals is essential for ensuring the sustainability of continued human development. Plant-based biomass is a renewable resource which can be transformed into all of these products. However, biomass is a heterogeneous material composed of several fractions with different chemical properties. Furthermore, the composition varies between species. In order to maximize the environmental and economic sustainability of biomass-based production, production systems that utilize all fractions of biomass to their fullest potential have to be developed. This is the goal of a biorefinery.The work presented in this thesis mainly revolves around biorefineries that utilize feedstocks rich in starch and lignocellulose together to produce ethanol in an integrated process. The work is focused on comparing the performance of stand-alone and integrated biorefineries by investigating the impact that feedstock blending has on parameters important for the process economy, identifying potential synergies from integration and opportunities for improved material utilization.It was found in this work, that the integration of starch- and lignocellulose-based feedstocks could result in improved ethanol productivity and yield during hydrolysis and fermentation compared to a stand-alone lignocellulose process without losing performance compared to a stand-alone starch-based process.The prospects of introducing a sequential fractionation of the lignocellulosic biomass prior to integration was investigated. It was shown that this method could be used to produce separate fractions enriched in cellulose and lignin as well as improving the hydrolyzabilty of the cellulose fraction. This kind of fractionation could facility the utilization of all biomass fractions in both feedstocks by creating new byproduct streams as well as decreasing negative impacts on existing byproduct streams.
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| 27. |
- Vincevica-Gaile, Zane, et al.
(författare)
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Applying Macroalgal Biomass as an Energy Source : Utility of the Baltic Sea Beach Wrack for Thermochemical Conversion
- 2022
-
Ingår i: Sustainability. - : MDPI. - 2071-1050. ; 14:21
-
Tidskriftsartikel (refereegranskat)abstract
- Global resource limits and increasing demand for non-fossil energy sources have expanded the research on alternative fuels. Among them, algal biomass is designated as a third-generation feedstock with promising opportunities and the capability to be utilized for energy production in the long term. The paper presents the potential for converting beach wrack containing macroalgal biomass into gaseous fuel as a sustainable option for energy production, simultaneously improving the organic waste management that the coastline is facing. Beach wrack collected in the northern Baltic Sea region was converted by gasification technology applicable for carbon-based feedstock thermal recovery, resulting in syngas production as the main product and by-product biochar. Proximate and ultimate analysis, trace and major element quantification, detection of calorific values for macroalgal biomass, and derived biochar and syngas analysis were carried out. A higher heating value for beach wrack was estimated to be relatively low, 5.38 MJ/kg as received (or 14.70 MJ/kg on dry basis), but produced syngas that contained enough high content of CH4 (42%). Due to macroalgal biomass specifics (e.g., high moisture content and sand admixture), an adjusted gasification process, i.e., the combination of thermochemical procedures, such as mild combustion and pyrolytic biomass conversion, might be a better choice for the greater economic value of biowaste valorization.
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| 28. |
- Ge, Yaxin, 1992, et al.
(författare)
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Real-time monitoring of alkali release during CO2 gasification of different types of biochar
- 2022
-
Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 327
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Tidskriftsartikel (refereegranskat)abstract
- Potassium and sodium compounds play both positive and negative roles during biomass gasification, but the detailed behavior of alkali metal compounds remain incompletely understood. In this study, alkali release during CO2 gasification of biochar is characterized online with a surface ionization method in combination with thermogravimetric analysis of the char samples undergoing gasification. For wood chars, the alkali release rate follows a slowly decreasing trend as the char conversion proceeds, but increases by up to two orders of magnitude when the conversion approaches completion. In contrast, the alkali release from straw char is 40-50 times higher than observed for wood char and decreases continuously during the whole gasification process. A high temperature and a high CO2 concentration enhance both alkali release and char reactivity. The char preparation method also influences the alkali release from pine char, while the char reactivity is less affected. Alkali release and char reactivity are linked, but other factors including mineral content, surface area and char structure may play important roles for the observed reactivity. The results provide a basis for understanding of alkali behavior during gasification and may help optimize catalytic effects and reduce detrimental issues in biomass gasification.
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| 29. |
- Svensson, Elin, 1980, et al.
(författare)
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Potential for Negative Emissions by Carbon Capture and Storage From a Novel Electric Plasma Calcination Process for Pulp and Paper Mills
- 2021
-
Ingår i: Frontiers in Climate. - : Frontiers Media SA. - 2624-9553. ; 3
-
Tidskriftsartikel (refereegranskat)abstract
- The pulp and paper industry has a high potential to contribute to negative emissions through carbon capture and storage (CCS) applied to existing processes. However, there is a need to investigate how CCS solutions also can be combined with implementation of other emerging technologies in pulp and paper mills. This paper investigates the integration of a novel calcination process in two kraft mills and evaluates its potential combination with capture and storage of CO2 from the calcination plant. The alternative calcination process uses electric gas-plasma technology combined with steam slaking and allows replacing the conventional fuel-driven lime kilns with a process driven by electricity. The novel calcination process generates a pure, biogenic, CO2 stream, which provides an opportunity to achieve negative emissions at relatively lower costs. The potential reduction of greenhouse gas emissions when replacing the lime kiln with the plasma calcination concept depends strongly on the emissions intensity of grid electricity, and on whether fossil fuel or biomass was used as a fuel in the lime kiln. If fossil fuel is replaced and electricity is associated with very low emissions, avoided CO2 emissions reach ~50 kt/a for the smaller mill investigated in the paper (ca 400 kt pulp per year) and almost 100 kt/a for the larger mill (ca 700 kt pulp per year). Further emission reductions could then be achieved through CCS from the electrified calcination process, with capture potentials for the two mills of 95 and 164 kt/a, respectively, and capture and storage costs estimated to 36–60 EUR/tCO2.
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| 30. |
- Johnsson, Filip, 1960, et al.
(författare)
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Marginal Abatement Cost Curve of Industrial CO 2 Capture and Storage – A Swedish Case Study
- 2020
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Ingår i: Frontiers in Energy Research. - : Frontiers Media SA. - 2296-598X. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- Carbon capture and storage (CCS) is expected to play a key role to achieve deep emission cuts in the energy intensive industry sector. The implementation of carbon capture comes with a considerable investment cost and a significant effect on the plants operating cost, which both depend on site conditions, mainly due to differences in flue gas flow and composition and depending on the availability of excess heat that can be utilized to power the capture unit. In this study we map the costs required to install and operate amine-based post-combustion CO2 capture at all manufacturing plants in Sweden with annual emissions of 500 kt CO2 or more, of both fossil and of biogenic origin, of which there are 28 plants (including a petrochemical site, refineries, iron and steel plants, cement plants and pulp and paper mills). The work considers differences in the investment required as well as differences in potential for using excess heat to cover the steam demand of the capture process. We present the resulting total CO2 capture costs in the form of a marginal abatement cost curve (MACC) for the emission sources investigated. Cost estimations for a transport and storage system are also indicated. The MACC shows that CO2 capture applied to 28 industrial units capture CO2 emissions corresponding to more than 50% of Swedish total CO2 emissions (from all sectors) at a cost ranging from around 40 €/t CO2 to 110 €/t CO2, depending on emission source. Partial capture from the most suited sites may reduce capture cost and, thus, may serve as a low-cost option for introducing CCS. The cost for transport and storage will add some 25 to 40 €/t CO2, depending on location and type of transportation infrastructure.
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| 31. |
- Karlsson, Sebastian, 1994, et al.
(författare)
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Large-Scale Implementation of Bioenergy With Carbon Capture and Storage in the Swedish Pulp and Paper Industry Involving Biomass Supply at the Regional Level
- 2021
-
Ingår i: Frontiers in Energy Research. - : Frontiers Media SA. - 2296-598X. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Bioenergy with carbon capture and storage (BECCS) has been identified as a possible major contributor to efforts to reach ambitious climate targets through the provision of negative emissions–offsetting residual fossil emissions in “hard-to-abate” sectors and accomplishing net-negative emissions. The pulp and paper industry is the single largest consumer of biomass in Sweden, with many large point sources of biogenic CO2 emissions that could be captured. This work investigates the biomass supply required for large-scale implementation of BECCS in the pulp and paper industry. Logging residues are considered as a fuel to supply the additional energy demand imposed by the capture plant, and the potential of these residues is evaluated in a case study that includes four pulp and paper mills located in regions of Sweden with different conditions for biomass supply. Two of the mills are located in southern Sweden, where there is strong competition for logging residues from the heating sector, and two of the mills are located in northern Sweden, where the competition is weaker. We show that implementing carbon capture at the four pulp and paper mills using regional logging residues to supply the additional heat demand required by the capture process (the reboiler heat demand) has the potential to capture around 4.6 Mt CO2/year. The results also show that the fuel share of the capture cost, i.e., the cost to supply the reboiler heat demand with regional logging residues, is 22–30 €/tCO2 captured, where the lower value corresponds to regions with weaker competition for logging residues (in this study, northern Sweden). In regions that have competition for logging residues, the possibility to increase the regional supply of logging residues to fuel the capture process while maintaining mill production output is limited, which in turn limits the possibilities to generate negative emissions via BECCS. In contrast, in regions with a low level of competition and strong availability of logging residues, there is an additional potential for logging residues to cover the additional heat demand required for CCS implementation.
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| 32. |
- Kmezik, Cathleen, 1991, et al.
(författare)
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Characterization of a novel multidomain CE15-GH8 enzyme encoded by a polysaccharide utilization locus in the human gut bacterium Bacteroides eggerthii
- 2021
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- Bacteroidetes are efficient degraders of complex carbohydrates, much thanks to their use of polysaccharide utilization loci (PULs). An integral part of PULs are highly specialized carbohydrate-active enzymes, sometimes composed of multiple linked domains with discrete functions—multicatalytic enzymes. We present the biochemical characterization of a multicatalytic enzyme from a large PUL encoded by the gut bacterium Bacteroides eggerthii . The enzyme, Be CE15A-Rex8A, has a rare and novel architecture, with an N-terminal carbohydrate esterase family 15 (CE15) domain and a C-terminal glycoside hydrolase family 8 (GH8) domain. The CE15 domain was identified as a glucuronoyl esterase (GE), though with relatively poor activity on GE model substrates, attributed to key amino acid substitutions in the active site compared to previously studied GEs. The GH8 domain was shown to be a reducing-end xylose-releasing exo-oligoxylanase (Rex), based on having activity on xylooligosaccharides but not on longer xylan chains. The full-length Be CE15A-Rex8A enzyme and the Rex domain were capable of boosting the activity of a commercially available GH11 xylanase on corn cob biomass. Our research adds to the understanding of multicatalytic enzyme architectures and showcases the potential of discovering novel and atypical carbohydrate-active enzymes from mining PULs.
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| 33. |
- Gogolev, Ivan, 1984, et al.
(författare)
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Commissioning, performance benchmarking, and investigation of alkali emissions in a 10 kWth solid fuel chemical looping combustion pilot
- 2021
-
Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 287
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Tidskriftsartikel (refereegranskat)abstract
- Chemical looping combustion of biomass-sourced fuels (bio-CLC) is a novel bio-energy with carbon capture and storage (BECCS) technology for power and heat generation with net negative CO2 emissions. In this study, a new 10 kWth CLC pilot designed for high-volatiles biomass fuels was commissioned with ilmenite oxygen carrier and five different biomass fuels of varying volatile and alkali content fractions. The system was tested for its ability to convert high and low volatile content biomass, while achieving high carbon capture efficiency. The new pilot achieved carbon capture close to 100% for high-volatiles biomass, and >94% for low-volatiles biomass char fuels. Furthermore, due to the implementation of a volatiles distributor, the new pilot demonstrated an improvement of up to 10 percentage points of gas conversion efficiency for high-volatiles biomass vs. the previous generation reactor. Gaseous alkali emissions were measured with a surface ionization detection system. Flue gas alkali release levels were found to rise with higher fuel alkali content. Alkali emissions were found to be approximately similar in the AR and the FR for all but the straw pellet mixture fuel (highest alkali content fuel). For the straw pellet mixture, gaseous alkali release levels in the AR were up to seven times higher than those of the FR. In all cases, over 96% of the fuel's alkalis were absorbed by the ilmenite bed material. Ilmenite's strong alkali absorption characteristics were concluded to be the key determinant of gas-phase release of biomass alkali in the conducted experiments.
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| 34. |
- Ahlström, Johan, 1990, et al.
(författare)
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Economic potential for substitution of fossil fuels with liquefied biomethane in Swedish iron and steel industry – Synergy and competition with other sectors
- 2020
-
Ingår i: Energy Conversion and Management. - : Elsevier Ltd. - 0196-8904 .- 1879-2227. ; 209
-
Tidskriftsartikel (refereegranskat)abstract
- In Sweden, the iron and steel industry (ISI) is a major source of greenhouse gas (GHG) emissions. Most of the emissions result from the use of fossil reducing agents. Nevertheless, the use of fossil fuels for other purposes must also be eliminated in order to reach the Swedish emissions reduction targets. In this study, we investigate the possibility to replace fossil gaseous and liquid fuels used for heating in the ISI, with liquefied biomethane (LBG) produced through gasification of forest residues. We hypothesize that such utilization of fuels in the Swedish ISI is insufficient to independently drive the development of large-scale LBG production, and that other sectors demanding LBG, e.g., for transportation, can be expected to influence the economic potential for the ISI to switch to LBG. The paper investigates how demand for LBG from other sectors can contribute to, or prevent, a phase-out of fossil fuels used for heating purposes in the ISI under different future energy market scenarios, with additional analysis of the impact of a CO2 emissions charge. A geographically explicit cost-minimizing biofuel production localization model is combined with heat integration and energy market scenario analysis. The results show that from a set of possible future energy market scenarios, none yielded more than a 9% replacement of fossil fuels used for heating purposes in the ISI, and only when there was also a demand for LBG from other sectors. The scenarios corresponding to a more ambitious GHG mitigation policy did not achieve higher adoption of LBG, due to corresponding higher biomass prices. A CO2 charge exceeding 200 EUR/tonCO2 would be required to achieve a full phase-out of fossil fuels used for heating purposes in the ISI. We conclude that with the current policy situation, substitution of fossil fuels by LBG will not be economically feasible for the Swedish ISI.
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| 35. |
- Marhendraswari, M. B.D., et al.
(författare)
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Production of edible fungal (Rhizopus delemar CBS 145940) biomass from organosolv-pretreated oil palm empty fruit bunch (OPEFB) in submerged fermentation
- 2020
-
Ingår i: IOP Conference Series: Materials Science and Engineering. - : Institute of Physics (IOP). - 1757-8981 .- 1757-899X. ; 991:1
-
Konferensbidrag (refereegranskat)abstract
- Accumulation of oil palm empty fruit bunches (OPEFB) from palm oil industry poses challenges for the disposal process, which leads to environmental damage. For this reason, valorization of OPEFB fractions to produce edible fungal biomass was carried out in this research. The fungus was Rhizopus delemar CBS 145940, which is an edible fungus, Indonesian indigenous, and is favorable for the production of several end products. Organosolv pretreatment was first conducted on OPEFB using ethanol (50%) as the solvent. Enzymatic hydrolysis was then performed using Cellic® Ctec3 on the pretreated-OPEFB fractions. Hydrolyzates from cellulose-rich fraction, slurry (a mixture of cellulose-rich fraction and hemicellulose-rich fraction), and hemicellulose-rich fraction were used as the cultivation media for fungal growth. The corresponding yield of fungal biomass from each medium was 0.62 ± 0.07 g/g glucose; 0.41 ± 0.02; and 0.61 ± 0.13 g/g fermentable sugars, respectively. These results showed that Rhizopus delemar CBS 145940 could be grown in all the hydrolyzates from the OPEFB fractions. Nevertheless, in order to obtain higher fungal biomass, supplementation of nutrition was needed.
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| 36. |
- Gall, Dan, et al.
(författare)
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A new technique for real-time measurements of potassium and sodium aerosols based on field-reversal surface ionization
- 2021
-
Ingår i: Measurement Science and Technology. - : IOP Publishing. - 0957-0233 .- 1361-6501. ; 32:7
-
Tidskriftsartikel (refereegranskat)abstract
- A new method for real-time measurements of potassium and sodium containing aerosol particles is described and verified. The method is based on surface ionization technique and may be used to explore the alkali chemistry related to high temperature chemistry processes. The measurement device is a further development of the simple and cost-effective surface ionization detector previously used for online alkali measurements in combustion and gasification research. The discrimination between sodium and potassium is possible due to differences in their surface desorption kinetics and facilitated by rapidly reversing the field potential between the ion source and the nearby collector. The instrument is evaluated in a series of laboratory experiments using size-selected alkali salt particles containing KCl, NaCl, K2SO4, Na2SO4, KNO3 and NaNO3. The filament temperature was found to be a key influencing factor in order to optimize the strength and Na-K deviation of the observed ion current. The ability to simultaneously report absolute concentrations of Na and K makes the instrument attractive for solid fuel conversion of alkali-rich fuels such as low-grade biomass and to explore behavior deviations of Na and K in high temperature processes. © 2021 The Author(s). Published by IOP Publishing Ltd.
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| 37. |
- Stanicic, Ivana, 1994, et al.
(författare)
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Thermodynamic Analysis on the Fate of Ash Elements in Chemical Looping Combustion of Solid Fuels Iron-Based Oxygen Carriers
- 2022
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 36:17, s. 9648-9659
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Tidskriftsartikel (refereegranskat)abstract
- Chemical looping combustion (CLC) enables efficient combustion of hydrocarbon fuels while also producing a gas stream with high CO2 concentrations, suitable for carbon capture and storage (CCS). CLC of biomass in combination with CCS results in efficient removal of carbon dioxide from the atmosphere, i.e., negative emissions. However, biomass and waste-derived fuels can contain significant fractions of aggressive ash precursors, which can affect the operability and functionality of oxygen carriers. In this paper, the fate of common ash elements will be investigated thermodynamically in a system utilizing iron-based oxygen carriers: ilmenite and iron oxide. Multiphase, multicomponent equilibrium calculations were performed using databases from FACT and a user-defined database, with a specific focus on alkali (K and Na) and heavy metals (Cu, Zn, and Pb). A detailed and comprehensive comparison with available literature data from experimental investigations was performed, and compounds not available in the databases were identified. Due to a lack of thermodynamic data in the literature, thermodynamic properties for four compounds, K0.85Fe0.85Ti0.15O2, K0.4Fe0.4Ti0.6O2, KTi8O16, and KTi8O16.5, were obtained from first-principles calculations. The fate of ash elements is studied for CLC of three biomass and waste-derived solid fuels under relevant CLC conditions: 950 °C in the fuel reactor and 1050 °C in the air reactor. Results show that the choice of the oxygen carriers largely influences the behavior of the ash elements. Compared to CLC with iron oxide, ilmenite is more beneficial with respect to high-temperature corrosion since less potassium is released into the gas phase since the titanium content in ilmenite immobilizes both potassium and calcium. For both oxygen carriers, the most corrosive compounds are expected to leave with the gas in the fuel reactor, keeping the air reactor free from chlorides. It was found that the compound KTi8O16 is stable in reducing conditions and low potassium concentrations. This is in conformity with previous experimental data, where this phase has been identified in the interior of ilmenite particles used in oxygen carrier aided combustion of wood chips.
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| 38. |
- Brynolf, Selma, 1984, et al.
(författare)
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Review of electrofuel feasibility—prospects for road, ocean, and air transport
- 2022
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Ingår i: Progress in Energy. - : IOP Publishing. - 2516-1083. ; 4:4, s. 042007-042007
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Tidskriftsartikel (refereegranskat)abstract
- To meet climate targets the emissions of greenhouse gases from transport need to be reduced considerably.Electrofuels (e-fuels) produced from low-CO2 electricity, water, and carbon (or nitrogen) are potential low-climate-impact transportation fuels. The purpose of this review is to provide a technoeconomic assessment of the feasibility and potential of e-fuels for road, ocean, and air transport.The assessment is based on a review of publications discussing e-fuels for one or more transport modes. For each transport mode, (a) e-fuel options are mapped, (b) cost per transport unit (e.g. vehicle km) and carbon abatement costs are estimated and compared to conventional options, (c) prospects and challenges are highlighted, and (d) policy context is described.Carbon abatement costs for e-fuels (considering vehicle cost, fuel production and distribution cost) are estimated to be in the range 110–1250 € tonne−1 CO2 with e-gasoline and e-diesel at the high end of the range.The investigated combined biofuel and e-fuels production pathways (based on forest residues and waste) are more cost-competitive than the stand-alone e-fuel production pathways, but the global availability of sustainable biomass is limited making these pathways more constrained.While the potential for e-fuels to decarbonize the transport sector has been discussed extensively in the literature, many uncertainties in terms of production costs, vehicle costs and environmental performance remain. It is too early to rule out or strongly promote particular e-fuels for different transport modes. For e-fuels to play a significant role in transportation, their attractiveness relative to other transport options needs to be improved. Incentives will be needed for e-fuels to be cost-effective and increased clarity on how e-fuels are linked to existing policies is needed.
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| 39. |
- Juul, Louise, et al.
(författare)
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Combining pressing and alkaline extraction to increase protein yield from Ulva fenestrata biomass
- 2022
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Ingår i: Food and Bioproducts Processing: Transactions of the Institution of of Chemical Engineers, Part C. - : Elsevier BV. - 1744-3571 .- 0960-3085. ; 134, s. 80-85
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Tidskriftsartikel (refereegranskat)abstract
- Many seaweed species have a high production potential and attract interest as future protein sources. A high fiber and ash content, however, demand extraction of the protein to improve its digestibility and protein utilization in food or feed. This study explores three different approaches for protein extraction from Ulva fenestrata in order to maximize the protein extraction yield. Soluble protein was recovered either by mechanical pressing or by homogenization and osmotic shock of the biomass followed by alkaline extraction. The soluble protein was then concentrated by isoelectric precipitation. A combined procedure was carried out by pressing the biomass and following subjecting the residual pulp fraction to homogenization, osmotic shock and alkaline extraction. The three methods were ranked as follows with respect to protein extraction yield (as % of biomass protein); the combined method (23.9 ± 0.3%)> the alkaline extraction (6.8 ± 0.2%)> mechanical pressing (5.0 ± 0.2%). The significant increase when combining the methods was ascribed to a high precipitation yield after alkaline extraction of the pulp, hypothesized to be due to a reduced conductivity of the alkali-soluble protein fraction when derived from pulp rather than whole biomass.
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| 40. |
- Hildor, Fredrik, 1992, et al.
(författare)
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Tar characteristics generated from a 10 kW th chemical-looping biomass gasifier using steel converter slag as an oxygen carrier
- 2023
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 331
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Tidskriftsartikel (refereegranskat)abstract
- Tar management is one of the key components to achieve high energy efficiency and low operational costs connected to thermal gasification of biomass. Tars contain a significant amount of energy, and unconverted tars result in energy efficiency losses. Also, heavy tars can condense downstream processes, resulting in increased maintenance. Dual fluidized beds for indirect gasification operated with active bed material can be a way to better convert and control the tar generated in the process. Using an active material to transport oxygen in an indirect dual reactor gasification setup is referred to as chemical-looping gasification (CLG). A higher oxidative environment in the gas phase, in addition to possible catalytic sites, could mean lower yields in comparison to normal indirect gasification. This paper investigates the effect of using Steel converter slag (LD slag), a byproduct of steel manufacturing, as an oxygen-carrying bed material on tar species generated in a 10 kWth dual fluidized bed biomass gasifier. The results are compared to the benchmark oxygen carrier ilmenite and conventional silica sand. Three different solid biofuels were used in the reactor system: steam exploded pellets, pine forest residue and straw. Tar was absorbed from the raw syngas using a Solid Phase Adsorption (SPA) column and was analyzed using GC-FID. Bench-scale experiments were also performed to investigate benzene conversion of LD slag and ilmenite at different oxidation levels. The findings of this study suggest that oxygen carriers can be used to decrease the tars generated in a dual fluidized bed system during gasification. Phases in LD slag possess catalytic properties, resulting in a decreased ratio of heavy tar components compared to both ilmenite and sand. Temperature and fuel load showed a significant effect on the tar generation compared to the circulation and steam ratio in this reactor system. Increased temperature generated lower tar yields and lower ratios of heavy tar components for LD slag in contrast to sand.
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| 41. |
- Mei, Daofeng, 1986, et al.
(författare)
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Modelling of gas conversion with an analytical reactor model for biomass chemical looping combustion (bio-CLC) of solid fuels
- 2022
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 433
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Tidskriftsartikel (refereegranskat)abstract
- Manganese ores are promising oxygen carriers for chemical looping combustion (CLC), due to their high reactivity with combustible gases. In this work, a manganese ore called EB (Elwaleed B, originating from Egypt) is studied for its reaction rate with CH4, CO and H2 and the data are used in an analytically solved reactor model. The reactivity of fresh and three used EB samples from previous operation in a 10 kWth pilot was examined in a batch fluidized bed reactor with CH4 and syngas (50%CO + 50%H2). In comparison with other manganese ores, the EB ore has a lower rate of reaction with CH4, while showing a significantly higher reactivity with syngas. Nevertheless, this manganese ore always presents a better conversion of CH4 and syngas than the benchmark ilmenite. Mass-based reaction rate constants were obtained using a pseudo first-order reaction mechanism: 1.1·10-4 m3/(kg·s) for CH4, 6.6·10-3 m3/(kg·s) for CO and 7.5·10-3 m3/(kg·s) for H2. These rate constants were used in an analytical reactor model to further investigate results from previous operation in the 10 kWth unit. According to the analytical model, in the 10 kWth operation, 98% of the char in the biomass fuels was gasified before leaving the fuel reactor, while the char gasification products (CO and H2) have a 90% contact efficiency with the bed material. On the contrary, the volatiles have a much lower contact efficiency with the oxygen carrier bed, i.e. 20%, leading to low conversion of volatiles released. Thus, the results emphasize the importance of improving the contact between volatiles and bed material in order to promote combustion performance in the CLC process.
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| 42. |
- Saeed, Muhammad Nauman, 1995, et al.
(författare)
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Production of aviation fuel with negative emissions via chemical looping gasification of biogenic residues: Full chain process modelling and techno-economic analysis
- 2023
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Ingår i: Fuel Processing Technology. - : Elsevier BV. - 0378-3820 .- 1873-7188. ; 241
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Tidskriftsartikel (refereegranskat)abstract
- The second-generation bio aviation fuel production via Chemical Looping Gasification (CLG) of biomass combined with downstream Fischer-Tropsch (FT) synthesis is a possible way to decarbonize aviation sector. The CLG process has the advantage of producing undiluted syngas without the use of an air-separation unit (ASU) and improved syngas yield compared to the conventional gasification processes. This study is based on modelling the full chain process of biomass to liquid fuel (BtL) with LD-slag and Ilmenite as oxygen carriers using Aspen Plus software, validating the model results with experimental studies and carrying out a techno-economic analysis of the process. For the gasifier load of 80 MW based on LHV of fuel entering the gasifier, the optimal model predicts that the clean syngas has an energy content of 8.68 MJ/Nm3 with a cold-gas efficiency of 77.86%. The optimized model also estimates an aviation fuel production of around 340 bbl/day with 155 k-tonne of CO2 captured every year and conversion efficiency of biomass to FT-crude of 38.98%. The calculated Levelized Cost of Fuel (LCOF) is 35.19 $ per GJ of FT crude, with an annual plant profit (cash inflow) of 11.09 M$ and a payback period of 11.56 years for the initial investment.
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| 43. |
- Zetterholm, Jonas, 1989-, et al.
(författare)
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Economic Evaluation of Large-Scale Biorefinery Deployment : A Framework Integrating Dynamic Biomass Market and Techno-Economic Models
- 2020
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Ingår i: Sustainability. - : MDPI. - 2071-1050. ; 12:17
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Tidskriftsartikel (refereegranskat)abstract
- Biofuels and biochemicals play significant roles in the transition towards a fossil-free society. However, large-scale biorefineries are not yet cost-competitive with their fossil-fuel counterparts, and it is important to identify biorefinery concepts with high economic performance. For evaluating early-stage biorefinery concepts, one needs to consider not only the technical performance and process costs but also the economic performance of the full supply chain and the impacts on feedstock and product markets. This article presents and demonstrates a conceptual interdisciplinary framework that can constitute the basis for evaluations of the full supply-chain performance of biorefinery concepts. This framework considers the competition for biomass across sectors, assumes exogenous end-use product demand, and incorporates various geographical and technical constraints. The framework is demonstrated empirically through a case study of a sawmill-integrated biorefinery producing liquefied biomethane from forestry and forest industry residues. The case study results illustrate that acknowledging biomass market effects in the supply chain evaluation implies changes in both biomass prices and the allocation of biomass across sectors. The proposed framework should facilitate the identification of biorefinery concepts with a high economic performance which are robust to feedstock price changes caused by the increase in biomass demand.
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| 44. |
- Eliasson Störner, Felicia, 1994, et al.
(författare)
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Oxygen Carrier Aided Combustion in Fluidized Bed Boilers in Sweden - Review and Future Outlook with Respect to Affordable Bed Materials
- 2021
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Ingår i: Applied Sciences (Switzerland). - : MDPI AG. - 2076-3417. ; 11:17
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Forskningsöversikt (refereegranskat)abstract
- Oxygen carriers are metal oxide particles that could potentially enhance both fuel conversion and heat distribution in fluidized bed combustion, resulting in e.g., lowered emissions of unconverted species and better possibilities to utilize low‐grade fuels. A related technology based on fluidized beds with oxygen carriers can separate CO2 without large energy penalties. These technologies are called oxygen carrier aided combustion (OCAC) and chemical‐looping combustion (CLC), respectively. In the past few years, a large number of oxygen carriers have been suggested and evaluated for these purposes, many of which require complex production processes making them costly. Affordable metal oxide particles are, however, produced in large quantities as products and byproducts in the metallurgical industries. Some of these materials have properties making them potentially suitable to use as oxygen carriers. Uniquely for Sweden, the use of oxygen carriers in combustion have been subject to commercialization. This paper reviews results from utilizing low‐cost materials emerging from metallurgical industries for conversion of biomass and waste in semi‐commercial and commercial fluidized bed boilers in Sweden. The paper further goes on to discuss practical aspect of utilizing oxygen carriers, such as production and transport within the unique conditions in Sweden, where biomass and waste combustion as well as metallurgical industries are of large scale. This study concludes that utilizing metal oxides in this way could be technically feasible and beneficial to both the boiler owners and the metallurgical industries.
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| 45. |
- Gustafsson, Marcus, 1987-, et al.
(författare)
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Climate performance of liquefied biomethane with carbon dioxide utilization or storage
- 2024
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Ingår i: Renewable and sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 192
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Tidskriftsartikel (refereegranskat)abstract
- In the process of upgrading biogas to biomethane for gas grid injection or use as a vehicle fuel, biogenic carbon dioxide (CO₂) is separated and normally emitted to the atmosphere. Meanwhile, there are a number of ways of utilizing CO₂ to reduce the dependency on fossil carbon sources. This article assesses the climate performance of liquefied biomethane for road transport with different options for utilization or storage of CO₂. The analysis is done from a life cycle perspective, covering the required and avoided processes from biogas production to the end use of biomethane and CO₂. The results show that all of the studied options for CO₂ utilization can improve the climate performance of biomethane, in some cases contributing to negative CO₂ emissions. One of the best options, from a climate impact perspective, is to use the CO₂ internally to produce more methane, although continuous supply of hydrogen from renewable sources can be a challenge. Another option that stands out is concrete curing, where CO₂ can both replace conventional steam curing and be stored for a long time in mineral form. Storing CO₂ in geological formations can also lead to negative CO₂ emissions. However, with such long-term storage solutions, opportunities to recycle biogenic CO₂ are lost, together with the possibility of de-fossilizing processes that require carbon, such as chemical production and horticulture.
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| 46. |
- Martin, Michael, et al.
(författare)
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Assessing the aggregated environmental benefits from by-product and utility synergies in the Swedish biofuel industry
- 2020
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Ingår i: Biofuels. - : Taylor & Francis. - 1759-7269 .- 1759-7277. ; 11:6, s. 683-698
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Tidskriftsartikel (refereegranskat)abstract
- The production of biofuels in Sweden has increased significantly in the past years in order to reduce fossil fuel dependence and mitigate climate impacts. Nonetheless, current methodological guidelines for assessing the GHG savings from the use of biofuels do not fully account for benefits from by-products and other utilities (e.g. waste heat and electricity) from biofuel production. This study therefore reviews the aggregated environmental performance of these multi-functional biofuel systems by assessing impacts and benefits from relevant production processes in Sweden in order to improve the decision base for biofuel producers and policymakers in the transition to a bio-based and circular economy. This was done by (1) conducting a mapping of the Swedish biofuel production portfolio, (2) developing future production scenarios, and (3) application of life cycle assessment methodology to assess the environmental performance of the production processes. Special focus was provided to review the potential benefits from replacing conventional products and services with by-products and utilities. The results provide evidence that failure to account for non-fuel-related benefits from biofuel production leads to an underestimation of the contribution of biofuels to reduce greenhouse gas emissions and other environmental impacts when replacing fossil fuels, showing the importance of their multi-functionality.
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| 47. |
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| 48. |
- Hedayati, Ali, 1984, et al.
(författare)
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Experimental evaluation of manganese ores for chemical looping conversion of synthetic biomass volatiles in a 300 W reactor system
- 2021
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Ingår i: Journal of Environmental Chemical Engineering. - : Elsevier BV. - 2213-3437 .- 2213-2929. ; 9:2
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Tidskriftsartikel (refereegranskat)abstract
- Two manganese ores with different iron content were investigated as oxygen carriers for chemical looping conversion of simulated biomass volatiles. The aim was to study the performance of the oxygen carriers with regards to combustion and potential use for chemical-looping gasification of wood-based biomass. The oxygen carriers were studied in a 300 W chemical-looping reactor system with circulation of oxygen carriers between the fluidized air and fuel reactors. The temperature was 850-900 °C and the fuel flow rates were 0.6-3 Lmin-1. The Mn ore with higher iron content showed significant oxygen release at 900 °C under inert conditions, as well as full conversion of CO, H2 and methane at low fuel flow. The other Mn ore showed little methane conversion and poorer conversion of the other gases when compared at similar fuel flows. However, the gas composition attained was rather similar if compared for a similar overall gas conversion. Nonetheless, a slightly higher syngas fraction and H2 to CO ratio in the product stream was obtained with the Mn ore with lower iron content. In all cases the syngas fraction in the product gas increased with temperature and fuel flow. The formation of fines (attrition rate), particle size distribution, and the bulk density of the oxygen carriers were measured to evaluate their mechanical properties during chemical looping of biomass volatiles.
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| 49. |
- Mei, Daofeng, 1986, et al.
(författare)
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Reactivity and lifetime assessment of an oxygen releasable manganese ore with biomass fuels in a 10 kW th pilot rig for chemical looping combustion
- 2021
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Ingår i: Fuel Processing Technology. - : Elsevier BV. - 0378-3820 .- 1873-7188. ; 215
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Tidskriftsartikel (refereegranskat)abstract
- Finding a suitable oxygen carrier is crucial for the development of Chemical Looping Combustion (CLC). A new manganese ore was tested with different biomass fuels in a recently commissioned 10 kWth unit. The ore maintains the capability of generating O2 gas in N2 after continuous operations with the fuels, however, the concentration was relatively low within 0.45–1.0 vol% at 820 to 975 °C. Influence of temperature, solids circulation and fuel power was examined for different fuels. Temperature increase enhances the carbon capture and reduces the oxygen demand, while the solids circulation and fuel power should be carefully controlled. Using biomass char the oxygen demand can be lowered to 2.6% while the carbon capture was close to 99%. The manganese ore showed a higher reactivity than the often-used ilmenite. Thus, a decrease of 8–10% in oxygen demand was achieved by using the manganese ore in comparison to ilmenite. During the 42 h of hot operation, defluidisation was not observed. Based on the analysis of the 35 fine samples collected, the initial attrition after first hours of operation was high, but gradually decreased to a relatively stable value of 0.27 and 0.12 wt%/h for hot and fuel operations, respectively, corresponding a lifetime of 370–830 h.
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| 50. |
- Wang, Shule, 1994-
(författare)
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Pyrolysis of Biodegradable Waste for Negative Carbon Emissions
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Bioenergy with Carbon Capture and Storage represents a crucial technology that enables an energy production with negative carbon emissions, which is needed to achieve global climate goals. Appropriated management of biodegradable waste, including biodegradable lignocellulosic waste, sewage sludge, organic fraction of municipal solid waste, can make this contribution. The implementation of pyrolysis process is able to produce biochar, liquid and gas product from biodegradable waste. Based on the pyrolysis technology, a sustainable management of biodegradable waste for negative carbon emission is proposed in this work. The proposed novel process combines an anaerobic digestion, pyrolysis of the digestate following by catalytic reforming the pyrolytic vapor, then methanation of the reforming gas, separating the stream of CH4 and CO2. The storage of separated CO2 streams and biochar can be considered as negative emissions. Furthermore, the pyrolysis behaviors of the solid residue, which was produced from hydrothermal carbonization pretreatment of biodegradable wastes, are investigated. The pyrolytic liquid was further upgraded to a higher quality product with a less oxygen content, a higher calorific value by using ex-situ and in-situ hydrogen donors. Carbon stability of the pyrolytic biochar, which is one of key parameters to assess the biochar as carbon sink, was evaluated by using the accelerated oxidation method. Finally, energy and mass balance on the proposed process was obtained. The pyrolysis behavior of hydrothermal carbonization-treated sewage sludge digestate, and paper sludges were investigated. Thermogravimetric analysis, Py- Gas chromatography–Mass spectrometry and bench-scale experiments were employed to fulfil this objective. The thermal degradation behavior of these two feedstocks was investigated. Initially, the compounds in the pyrolytic vapor were identified. Thereafter, the pyrolytic product from the bench-scale experiment was characterized. It was found that the pyrolysis reaction of both feedstocks was a two-stage reaction. The organic fraction with a higher heating value around 28.47 to 38.46 MJ/kg was produced from the pyrolysis of hydrothermal carbonization-treated biodegradable waste. More organic fraction can be produced from the pyrolysis of the paper sludge than that from sewage sludge digestate. It was also found that the fixed carbon content in raw materials is difficult to be determined by using the standard method due to the ash oxidation behavior in such materials. Therefore, a method to determine the sample's fixed carbon content without affected by the ash oxidation behavior was developed. Introducing hydrogen donors to upgrade the pyrolytic liquid products for a higher quality product with a lower oxygen content and a higher calorific value is investigated. The H2 was used as an ex-situ hydrogen donor in the lignocellulosic waste pyrolysis in both non-catalytic and catalytic cases. The catalyst used in this study was a commercial HZSM-5, catalyst with a strong selectivity of aromatics. The hydrogen consumption during pyrolysis in the H2 atmosphere was indicated by experiments. The gas and liquid production were promoted while the biochar yield was suppressed in the presence of the H2 atmosphere. However, the presence of an H2 atmosphere was found to increase the acidity of the HZSM-5 and enhance the production of polyaromatics during the pyrolysis process. Further, the study using the sewage sludge digestate as an in-situ hydrogen donor to pyrolysis of lignocellulosic biomass obtained from the salix family was investigated. The sewage sludge digestate was premixed with salix in five blended ratios and pyrolyzed in a bench-scale reactor. The composite of 75% sludge digestate and 25% salix presented the highest mass and energy yields of the organic fraction in the liquid product. The yield of biochar was suppressed in this copyrolysis. The synergistic effect between the sludge digestate and salix was studied with respect to reaction mechanisms, carbon number distribution of the compounds in organic fraction, and biochar stability. The competition reaction between the short-chain carboxylic acid from salix pyrolysis and a long-chain carboxylic acid from digestate pyrolysis was one of the main reasons for the synergistic reaction regarding the composition of the organic fraction. This competition reaction results in a higher amount of long-chain carboxylic acid esters and N-heterocyclic compounds, a lower amount of the long-chain nitriles in the organic fraction produced from copyrolysis compared to it from individual pyrolysis. The stabilities of the biochar products from the copyrolysis of sewage sludge digestate and salix, were determined by using the accelerated oxidation method. It was found that the biochar stabilities are promoted by this copyrolysis. The nitrogen yield in the biochar product was also enhanced by the copyrolysis process. The proposed CO2 negative process was modelled using the process simulation software, and the modelling results were validated by using an experimental data. The pyrolysis temperature and dewatering technology were used for sensitivity analysis. In this process, methane was chosen as the final product. Pyrolytic biochar and compressed CO2 was captured and stored as the negative carbon emission. It was found that for 1000 kg of dry matter digestate, one can obtain 151.4 kg CH4 in a purity of 96 vol%, 304.5kg compressed CO2, and 80.8 kg biochar. The latter two are equal to 355.64 kg negative CO2 emission.
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