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Proper pretreatment of organic residues prior to anaerobic digestion (AD) can maximize global biogas production from varying sources without increasing the amount of digestate, contributing to global decarbonization goals. However, the efficiency of pretreatments applied on varying organic streams is poorly assessed. Thus, we performed a meta-analysis on AD studies to evaluate the efficiencies of pretreatments with respect to biogas production measured as methane yield. Based on 1374 observations our analysis shows that pretreatment efficiency is dependent on substrate chemical dominance. Grouping substrates by chemical composition e.g., lignocellulosic-, protein- and lipid-rich dominance helps to highlight the appropriate choice of pretreatment that supports maximum substrate degradation and more efficient conversion to biogas. Methane yield can undergo an impactful increase compared to untreated controls if proper pretreatment of substrates of a given chemical dominance is applied. Non-significant or even adverse effects on AD are, however, observed when the substrate chemical dominance is disregarded., Funding Agencies|Linkoeping University

Enzymatic saccharification is used to convert polysaccharides in lignocellulosic biomass to sugars which are then converted to ethanol or other bio-based fermentation products. The efficacy of commercial cellulase preparations can potentially increase if lytic polysaccharide monooxygenase (LPMO) is included. However, as LPMO requires both a reductant and an oxidant, such as molecular oxygen, a reevaluation of process configurations and conditions is warranted. Saccharification and fermentation of pretreated softwood was investigated in demonstration-scale experiments with 10 m3 bioreactors using an LPMO-containing cellulase preparation, a xylose-utilizing yeast, and either simultaneous saccharification and fermentation (SSF) or hybrid hydrolysis and fermentation (HHF) with a 24-hour or 48-hour initial phase and with 0.15 vvm aeration before addition of the yeast. The conditions used for HHF, especially with 48 h initial phase, resulted in better glucan conversion, but in poorer ethanol productivity and in poorer initial ethanol yield on consumed sugars than the SSF. In the SSF, hexose sugars such as glucose and mannose were consumed faster than xylose, but, in the end of the fermentation >90% of the xylose had been consumed. Chemical analysis of inhibitory pretreatment by-products indicated that the concentrations of heteroaromatic aldehydes (such as furfural), aromatic aldehydes, and an aromatic ketone decreased as a consequence of the aeration. This was attributed mainly to evaporation caused by the gas flow. The results indicate that further research is needed to fully exploit the advantages of LPMO without compromising fermentation conditions.

Utilization of biomass and reuse of industrial by-products and their sustainable and resource-efficient development into products that are inherently non-toxic is important to reduce the use of hazardous substances in the design, manufacture and application of biomaterials. The hypothesis in this study is that spent mushroom substrate (SMS), a by-product from mushroom production, has already undergone a biological pretreatment and thus, can be used directly as a starting material for fibrillation into value-added and functional biomaterial, without the use of toxic substances. The study show that SMS can be effectively fibrillated at a very high concentration of 6.5 wt % into fibrils using an energy demand of only 1.7 kWh kg−1, compared to commercial and chemically pretreated wood pulp at 8 kWh kg−1, under same processing conditions. SMS is a promising resource for fibrillation with natural antioxidant activity and network formation ability, which are of interest to explore further in applications such as packaging. The study shows that biological pretreatment can offer lower environmental impact related to toxic substances emitted to the environment and thus contribute to reduced impacts on categories such as water organisms, human health, terrestrial organisms, and terrestrial plants compared to chemical pretreatments.

Three tubular bioreactors with a varied substrate flow rate of (2 mL/min, 5 mL/min, and 8 mL/min) were examined for 75 days. At 8 mL/min flow rate, the biohydrogen evolution was higher (3.88 mL H2/h), while its conversion efficiency was lower compared to 5 and 2 mL/min flow rate. The formation of volatile fatty acids and ammonium was also influenced by substrate flow rates. The volatile fatty acids production was slightly higher at 2 mL/min (12.74 ± 2.42 gCOD/L) and 5 mL/min (18.09 ± 2.01 gCOD/L) while, decreasing at 8 mL/min (11.85 ± 0.78 gCOD/L). Substrate flow rate significantly affected the pattern and composition of volatile fatty acids showing higher acetic acid, butyric and propionic acid production of 4.72 ± 1.46 gCOD/L (2 mL/min) 10.41 ± 0.91 gCOD/L (5 mL/min) and 1.78 ± 0.13 gCOD/L (5 mL/min). Continuous substrate input maintained the pH in the reactor due to replacement with fresh substrate, thereby controlling feedback inhibition and boosting metabolite production. Hydrogen-producing Firmicutes on the biofilm confirmed the pivotal role of the microbial community's significant contribution to converting waste to bioenergy. Overall, the present results support the use of a continuous operation mode for large-scale biohydrogen production. However, to ensure the efficacy of the system using waste or wastewater, low substrate flow rates are recommended., Validerad;2024;Nivå 2;2024-04-05 (marisr);Full text license: CC BY

Large quantities of polyvinyl chloride (PVC) and waste tires generated daily have the disadvantage of high content of harmful elements. They cannot be directly applied to blast furnace ironmaking. In this study, Cl in PVC and Zn in pyrolysis products of waste tires (pyrolysis carbon black, CB) were effectively removed by co-hydrothermal carbonization (co-HTC). The results indicated the dechlorination and dezincification efficiencies of co-HTC were improved by 2.78 % and 64.69 %, respectively, compared to HTC. Compositional analysis shows that the ash content of co-HTC is reduced by at least 7.67 % compared to conventional HTC. The hydrochar produced by co-HTC has an higher heating value (HHV) ranging from 30.67 to 34.13 MJ/kg. Results of physical and chemical characteristics analysis showed increasing the proportion of CB can reduce the C–H and -CHCl- functional groups and improve the carbon orderliness of the hydrochar. Combustion characteristics and kinetic analyses show that the combustibility of hydrochar increases with an increase in the proportion of PVC added to the co-HTC. The thermal stability and activation energy of the hydrochar increase with the addition of CB. Overall, this study has removed major harmful elements from PVC and CB through co-HTC, converting both into high-quality solid fuels that can be utilised in blast furnace ironmaking., QC 20240108

First experiments with biogenic residues and a plastic-rich rejects and woody biomass blend were conducted in an advanced 1 MW dual fluidized bed steam gasification demonstration plant at the Syngas Platform Vienna. Wood chips, bark, forest residues, and the plastic-rich rejects and woody biomass blend were tested and the tar composition was analyzed upstream and downstream of the upper gasification reactor, which is designed as a high-temperature column with countercurrent flow of catalytic material. Each feedstock was gasified with olivine as bed material in demonstration scale and is compared to the gasification of softwood pellets with olivine and limestone in pilot scale. A reduction in tar content was observed after countercurrent column for all feedstocks. However, a shift in tar species occurred. While styrene, phenol, and 1H-indene were predominant upstream, naphthalene and polycyclic aromatic hydrocarbons (PAHs) were the prevailing tar species downstream the countercurrent column. Hence, an increase of i.e. anthracene, fluoranthene, and pyrene from the upstream concentration was observed. For pyrene, up to twice the initial concentration was measured. This recombination to PAHs was observed for all feedstocks in demonstration- and pilot-scale. The only exception occurred with limestone as bed material, characterized by a higher catalytic activity in comparison to the typically used olivine. In the perspective of the integrated product gas cleaning, tar with higher temperature of condensation are separated more efficiently in the installed scrubbing unit. Hence, the recombination facilitates an overall decline of tar content after the gas cleaning.

This study aimed to investigate the potential of converting bio-based residues from industrial production of mushrooms and tomatoes into more valuable chemicals with antifungal properties using hydrothermal liquefaction (HTL). Liquid fractions were obtained from HTL of spent substrate of Agaricus bisporus (Lange) Imbach and Pleurotus ostreatus (jacq.) P. kumm., recomposted Agaricus bisporus spent substrate, and tomato residues. The quantitative 1H NMR spectroscopy analysis revealed that the HTL liquids of all residues contained antifungal constituents like phenols and organic acids. The HTL liquids at dilutions of 10 % were able to inhibit the fungi by over 80 %. Interestingly, the fungus P. ostreatus showed tolerance to these constituents as its growth was promoted at the lowest concentration of all the HTL liquids. The HTL liquids had lower ecotoxicity than the commercial wood preservative. These results suggest that the tested residues could be a promising source of preservative chemical constituents for the wood industry.

Bioenergy with carbon capture and storage (BECCS) can be a useful and cost-effective climate change mitigation tool but it is reliant on economic incentives. With this policy perspective article we question the ongoing discussion about the use of biomass for BECCS with basis in three points: (1) under the enhanced transparency framework under the Paris agreement, all parties to the agreement will use the same guidelines to estimate emissions by sources and removals by sinks, in which the emissions and removals in connection to cultivation of biomass are accounted for in the land-use, land-use change and forestry (LULUCF) sector, (2) adding carbon capture to existing processes may lead to a shift in products from that process rather than an increase in biomass use, and (3) BECCS requires substantial financial incentives. With basis in these points, we argue that a certification framework for BECCS that contradicts the guidelines of the Intergovernmental Panel on Climate Change (IPCC) risks unnecessarily hindering deployment of a potentially cost-effective climate change mitigation tool., QC 20231215

Achieving optimal nutrient composition in locally sourced ruminant feeds is important, but can be challenging in resource-limited production systems. For example, improving the composition of available local feed resources is a key obstacle to efficiently mitigating enteric methane (CH4) emissions in ruminants. This study characterized the nutritional content and in vitro methane (CH4) yield of ruminant feedstuffs accessible in Ethiopia. A survey of 60 experienced farmers in two representative districts in Amhara region, Ethiopia, provided 33 feed samples, which were classified into four ruminant feed categories: Grasses (n=10); indigenous plants (trees, shrubs, herbaceous plants) (n=13); crop residues (n=5); and agro-industrial by-products (n=5). Nutritional composition was assessed by proximate and detergent methods. Methane yield (g CH4/kg feed dry matter (DM)) and total gas yield (L/kg DM) were evaluated using a fully automated in vitro gas production system. A colorimetric assay was conducted to measure condensed tannin content (CT, mg/g) in relevant feeds. Lower crude protein (CP) values were observed for the grass (mean 65.2 g/kg DM) and crop residues (mean 54.5 g/kg DM) categories. Agro-industrial by-products had the highest CP (mean 260 g/kg DM), while indigenous plants exhibited intermediate levels (163 g/kg DM). There was significant variation in CH4 yield (P<0.01) between grasses (12.4–24.7 g/kg DM) indigenous plants (1.8–19.3 g/kg DM), and agro-industrial by-products (8.1–26.9 g/kg DM). The indigenous plant Trifolium acaule gave the lowest in vitro CH4 yield (1.8 g/kg DM). A positive relationship was observed between in vitro dry matter digestibility (IVDMD), CH4, and total gas yield. Percentage of CH4 in total gas production varied with feed category (grasses 14.5–19.6%; indigenous plants 3.1–16.9%; crop residues 15.8–20.6%; agro-industrial by-products 12.8–18.7%), and within category, e.g., Trifolium acaule (3.1%), Acacia nilotica L. (7.1%), Ziziph

Microbial inhibition by high ammonia concentrations is a recurring problem that significantly restricts methane formation from intermediate acids, i.e., propionate and acetate, during anaerobic digestion of protein-rich waste material. Studying the syntrophic communities that perform acid conversion is challenging, due to their relatively low abundance within the microbial communities typically found in biogas processes and disruption of their cooperative behavior in pure cultures. To overcome these limitations, this study examined growth parameters and microbial community dynamics of highly enriched mesophilic and ammonia-tolerant syntrophic propionate and acetate-oxidizing communities and analyzed their metabolic activity and cooperative behavior using metagenomic and metatranscriptomic approaches. Cultivation in batch set-up demonstrated biphasic utilization of propionate, wherein acetate accumulated and underwent oxidation before complete degradation of propionate. Three key species for syntrophic acid degradation were inferred from genomic sequence information and gene expression: a syntrophic propionate-oxidizing bacterium (SPOB) "Candidatus Syntrophopropionicum ammoniitolerans", a syntrophic acetate-oxidizing bacterium (SAOB) Syntrophaceticus schinkii and a novel hydrogenotrophic methanogen, for which we propose the provisional name "Candidatus Methanoculleus ammoniitolerans". The results revealed consistent transcriptional profiles of the SAOB and the methanogen both during propionate and acetate oxidation, regardless of the presence of an active propionate oxidizer. Gene expression indicated versatile capabilities of the two syntrophic bacteria, utilizing both molecular hydrogen and formate as an outlet for reducing equivalents formed during acid oxidation, while conserving energy through build-up of sodium/proton motive force. The methanogen used hydrogen and formate as electron sources. Furthermore, results of the present study provided a framework for fu

The use of green heterogeneous catalysts that are obtained from waste agricultural biomass can make the production of biodiesel more economical. In this research, three solid base heterogeneous catalysts (Catalyst A, B, and C) were synthesized from kola nut pod husks, and the synergistic effects of the elemental composition on catalytic activities for biodiesel production were studied. The results revealed a high surface area of Catalysts A, B, and C at 419.90 m2/g, 430.54 m2/g, and 432.57 m2/g, respectively. Their corresponding pore diameters are 3.53 nm, 3.48 nm, and 3.32 nm, showing that the catalysts are mesoporous in nature. The X-ray Fluorescence (XRF) results revealed the presence of a variety of alkaline earth metals and their corresponding metal oxides in substantial amounts. Catalyst A was produced with the highest concentration of calcium at 40.84 wt.% and calcium oxide at 68.02 mole%. The substantial concentration of other elements, such as potassium, magnesium, and aluminum, and their corresponding metal oxides are the proof of high catalytic activity of the produced green catalysts. The high CaO contents of all three produced catalysts and their high surface areas indicate their strong potential for good catalytic activities applied to the synthesis of biodiesel.

Samhället har ökade energibehov och krav på minskad miljöpåverkan, vilket gör biobränsle viktigt för hållbar energi. Biovärmeverks anläggningarna måste utvecklas för att bli mer miljövänliga och kunna ersätta fossila bränslen. De utsätts för höga termiska, kemiska och mekaniska påfrestningar, vilket innebär säkerhetsrisker. Således finns det lagar på trycksatta anordningar att fungera utan el genom att säkerhetsställa att överhettning undviks. Därför har biobränslepannor nödkylningssystem som förhindrar överhettning genom att hålla rörtemperaturen under den temperatur som pannan byggs för att klara, i denna studie är pannan dimensionerad för 140–150°C. Systemet, som består av stålrör med kallt vatten, aktiveras vid elavbrott eller temperaturökning, och luftflödet samt bränsletillförseln stoppas. Eftersom det är svårt att fastställa nödkylningseffekten överdimensioneras nödkylaren. Det är vanligt att nödkylaren tillverkas i diskreta storlekar och inte skräddarsys för varje panna. Vilket kan leda till onödig materialanvändning, kostnader och utsläpp. Studien, i samarbete med AKJ Energiteknik AB, syftar till att ge underlag för dimensionering av nödkylningssystemet för att minska kostnader och utsläpp. Målet är att skapa en dynamisk modell i Simulink och MATLAB och verifiera den med mätdata. Studien undersöker nödkylningssystemets funktion, kylbehov samt vatten- och materialåtgång, och utvärderar påverkan på kostnad och miljö genom CO2-ekvivalenter med förslag på åtgärder för systemets dimensioner. Den dynamiska modellen byggdes upp i Simulink och MATLAB Pannan konstruerades i zoner utifrån dimensionsförändringar i pannans rörkanaler där rökgasen flödade igenom samt förenklad beräkning för ugnens temperatur och rökgasflöde. Modellen verifierades mot mätdata från kapaciteter, temperaturer på rökgasen och vattnet samt granskades från företaget. Modellen kontrollerades utifrån känslighetsanalys, litteratur och värmeövergångstal och således skapades en trovärdig modell, Society has increasing energy demands and requirements for reduced environmental impact, making biofuel essential for sustainable energy. Facilities must be developed to become more environmentally friendly and capable of replacing fossil fuels. These facilities are subjected to high thermal, chemical, and mechanical stresses, which pose safety risks. Consequently, regulations exist for pressurized devices that operate without power by ensuring overheating is avoided. Therefore, biofuel boilers are equipped with emergency cooling systems to prevent overheating by maintaining the tube temperature below the design threshold, which in this study is 140–150°C. The system, composed of steel tubes containing cold water, activates in the event of a power outage or temperature increase, and airflow and fuel supply are halted. Since determining the emergency cooling effect is challenging, the emergency cooler is often oversized. It is common for emergency coolers to be manufactured in discrete sizes rather than customized for each boiler, which can lead to unnecessary material usage, costs, and emissions. This study, conducted in collaboration with AKJ Energiteknik AB, aims to provide insights for sizing emergency cooling systems to reduce costs and emissions. The objective is to develop a dynamic model in Simulink and MATLAB, validated with measurement data. The study investigates the emergency cooling system's function, cooling requirements, water and material consumption, and evaluates their impact on costs and the environment through CO2- equivalents, proposing dimensioning measures for the system. The dynamic model was constructed in Simulink and MATLAB. The boiler was segmented into zones based on changes in the boiler's pipe channels where flue gas flows, alongside simplified calculations for furnace temperature and flue gas flow. The model was validated against measurement data for capacities, flue gas and water temperatures, and reviewed by the company. Sensitiv

Bioenergi med avskiljning och lagring av koldioxid (BECCS) håller på att utvecklas till en viktig teknik för negativa utsläpp och planeras spela en avgörande roll för Sveriges mål om noll nettoutsläpp av koldioxid till 2045. Stora BECCS-anläggningar förväntas, till exempel den som planeras i Värtahamnen av Stockholm Exergi. Mindre punktkällor för koldioxidutsläpp, som avloppsreningsverket i Käppala, en biogasproducent, skulle också kunna bidra till negativa utsläpp genom BECCS, dvs. genom att fånga upp biogen koldioxid från anaerob jäsning. Ekonomiska faktorer begränsar dock implementeringen av hela BECCS-värdekedjan i mindre skala. Genom att använda en närliggande större BECCS-anläggning kan dessa kostnadsbarriärer övervinnas genom att skapa nav för BECCS och utnyttja synergier. I detta arbete undersöks de tekniska och ekonomiska utmaningarna med att integrera en CO2-ström från Käppala WWTP med Stockholm Exergis anläggning. Olika scenarier för CO2-integrering identifierades, med beaktande av flera faktorer, inklusive CO2-koncentration och renhetsbegränsningar för kondensering, kortdistanstransport och affärsmodell bakom biogasproducenten. Käppala reningsverk släpper för närvarande ut biogen CO2 i form av en CO2/luftblandning till atmosfären. Detta arbete visade att CO2 kan tas emot av Stockholm Exergi i form av en CO2/luftblandning, CO2-gas eller kondenserad CO2. Käppala reningsverk skulle antingen kunna behålla sin nuvarande vattenreningsprocess, som ger CO2/luftblandningen, eller modernisera sin biogasuppgraderingsprocess för att producera koncentrerad CO2. Vidare konstaterades att en rörledning är det mest ekonomiska alternativet för kortdistanstransport av CO2, antingen i en blandning eller i koncentrerad form, men långa ledtider kräver långsiktig planering. Om transporten istället sker med lastbilar krävs en ombyggnad och ett förvätskningssteg vid Käppalaverket. En litteraturgenomgång av tillgängliga tekniker för Käppala reningsverk identifierade en membran, Bio-energy with carbon capture and storage (BECCS) is emerging as a major negative emission technology and is scheduled to play a crucial role to Sweden’s net-zero goal by 2045. Large BECCS facilities are anticipated, such as the one planned in Värtahamnen by Stockholm Exergi. Smaller CO2 point sources like Käppala wastewater treatment plant (WWTP), a biogas producer, could also contribute to negative emissions through BECCS, i.e., by capturing the biogenic CO2 from anaerobic fermentation. However, economic constraints limit the implementation of the entire BECCS value chain on a smaller scale. Utilizing a nearby larger BECCS facility can help overcome these cost barriers by creating hubs for BECCS, leveraging synergies. This work explores the technical and economic challenges of integrating a CO2 stream from Käppala WWTP with Stockholm Exergi’s facility. Various scenarios for CO2 integration were identified, considering multiple factors, including CO2 concentration and purity constraints for liquefaction, short-distance transport, and business model behind the biogas producer. Käppala WWTP currently releases biogenic CO2 in the form of a CO2/air mixture to the atmosphere. This work found that CO2 can be received by Stockholm Exergi in the form of a CO2/air mixture, CO2 gas, or liquefied CO2. Whereas Käppala WWTP could either keep their current water scrubbing process, yielding the CO2/air mixture, or perform a revamp of their biogas upgrading process to produce concentrated CO2. Moreover, it was found that a pipeline is the most economical option for short-distance transport of CO2, either in a mixture or concentrated form, but long lead times make necessary long-term planning. If instead transport is carried out by trucks, a revamp and a liquefaction stage at Käppala WWTP are necessary. A literature review on the available technologies targeted at Käppala WWTP identified a membrane process as the most appropriate technology for a revamp of the biogas upgrading

The growing need for climate mitigation solutions has contributed so thatbiochar has gained significant interest. Primary for its ability as a carbon sinkbut there is also a growing interest due to several other aspects within industriese.g. substitution effects, increased resource efficiency, an enabler forindustrial symbiosis, and its beneficial properties when put in soil that can increasegrowth. Previous studies of biochar have been dominant within the environmentalperspective of biochar, analyzing detailed characteristics of its propertiesand carbon sink potential. Some studies have a holistic perspective reflectingon countries specific energy mix and the different benefits of producingbiochar. However, previous studies are far too few to determine the value-chainof biochar. Hence previous studies have knowledge gaps within the holistic lifecycle approach from a provider or customer perspective of biochar, not reflectingon demand for quality requirements in different utilization areas and markets.The need for validation of the environmental and the economic performanceof biochar has to be established, and the economic perspective of biochar hasmajor knowledge gaps since previous studies are scarce. The study aims to establish the value-chain of biochar by evaluating theenvironmental, economic, and social perspectives through life cycle thinking.The core of the study is to distinguish value, which first has to reflect thebiochar quality requirements from providers and customers, captured throughinterviews and literature research. The quality requirements enable a goal forproducing biochar and determine what processes and biomass are needed fordifferent markets. This is evaluated through a case development which considersthe different quality requirements. Life cycle assessment (LCA) with acradle-to-grave perspective and life cycle costing (LCC) with a cradle-to-gatewere then used to distinguish biochar´s environmental and economic performance. The interviews and

Anaerobic digestion (AD) technology can potentially address the gap between energy demand and supply playing a crucial role in the production of sustainable energy from utilization of biogenic waste materials as feedstock. The biogas production from anaerobic digestion is primarily influenced by the chemical compositions and biodegradability of the feedstock. Organosolv-steam explosion offers a constructive approach as a promising pretreatment method for the fractionation of lignocellulosic biomasses delivering high cellulose content.This study showed how synergetic co-digestion serves to overcome the challenges of mono-digestion's low efficiency. Particularly, the study evaluated the digestibility of organosolv-steam pretreated wheat straw (WSOSOL) in mono as well as co-digesting substrate with cheese whey (CW) and brewery spent grains (BSG). The highest methane yield was attained with co-digestion of WSOSOL + CW (338 mL/gVS) representing an enhanced biogas output of 1–1.15 times greater than its mono digestion. An ammonium production was favored under co-digestion strategy accounting for 921 mg/L from WSOSOL + BSG. Metagenomic study was conducted to determine the predominant bacteria and archaea, as well as its variations in their populations and their functional contributions during the AD process. The Firmicutes have been identified as playing a significant role in the hydrolysis process and the initial stages of AD. An enrichment of the most prevalent archaea genera enriched were Methanobacterium, Methanothrix, and Methanosarsina. Reactors digesting simpler substrate CW followed the acetoclastic, while digesting more complex substrates like BSG and WSOSOL followed the hydrogenotrophic pathway for biomethane production. To regulate the process for an enhanced AD process to maximize CH4, a comprehensive understanding of microbial communities is beneficial., Full text license: CC BY 4.0

Biogas has long been used as a household cooking fuel in many tropical counties, and it has the potential to be a significant energy source beyond household cooking fuel. In this study, we describe the use of low electrical energy input in an anaerobic digestion process using a microbial electrochemical cell (MEC) to promote methane content in biogas at 18, 28, and 37 °C. Although the maximum amount of biogas production was at 37 °C (25 cm3), biogas could be effectively produced at lower temperatures, i.e., 18 (13 cm3) and 28 °C (19 cm3), with an external 2 V power input. The biogas production of 13 cm3 obtained at 18 °C was ~65-fold higher than the biogas produced without an external power supply (0.2 cm3). This was further enhanced by 23% using carbon-nanotubes-treated (CNT) graphite electrodes. This suggests that the MEC can be operated at as low as 18 °C and still produce significant amounts of biogas. The share of CH4 in biogas produced in the controls was 30%, whereas the biogas produced in an MEC had 80% CH4. The MEC effectively reduced COD to 42%, whereas it consumed 98% of reducing sugars. Accordingly, it is a suitable method for waste/manure treatment. Molecular characterization using 16s rRNA sequencing confirmed the presence of methanogenic bacteria, viz., Serratia liquefaciens and Zoballella taiwanensis, in the inoculum used for the fermentation. Consistent with recent studies, we believe that electromethanogenesis will play a significant role in the production of value-added products and improve the management of waste by converting it to energy., Godkänd;2024;Nivå 0;2024-06-14 (joosat);Funder: Tribhuvan University under National Priority Area Research Project (TU-NPAR-077/78-ERG-07);Full text license: CC BY

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., Funding: Kamprad Family Foundation [20200041], Värdeskapande av koldioxid från biogasproduktion

Waste management in the northern latitudes is often more challenging than in the more central regions. Under the Arctic climate conditions with large distances between settlements and to the recycling facilities, and relatively smaller markets and volume of produced waste, there are special needs for developing new innovative solutions for waste management. WANO focuses on cross-border business and innovation cooperation in the field of waste management, including municipal and industrial waste, in the regions of Troms, Finnmark and Nordland (Norway), Lapland and North Ostrobothnia (Finland) and Norrbotten (Sweden). The project identifies key actors, technologies, innovation trends, and cross-border collaboration possibilities in the Arctic waste sector. Among the lessons learned so far which are highlighted in this policy brief are that waste management in Norway has already taken important steps to promote innovation and cooperation but that there is a demand for additional knowledge-based expertise among the waste management actors in north Norway. Cross-border initiatives are welcomed in north Norway by the actors. The big hindrance seems to be “know-who”: the Norwegian actors need more information about the actors across the border in north Finland and north Sweden.

The depletion of finite fossil fuel reserves and the severe environmental degradation resulting from human activities have compelled the expeditious development and application of sustainable waste to energy technologies. To encapsulate energy and environment in sustainability paradigm, bio waste based energy production is need to be forged in organic bio refinery setup. According to world bioenergy association, biomass can cover 50 % of the primary energy demand of the world. Therefore, the present study focuses on reforming the energy mix for a clean energy generation, where, sample composition of cotton stalk was acidified in dilute (5% wt.) hydrochloric acid (HCL) for analyzing material burnout patterns in biomass conversion systems utilized in organic bio refinery sector. Advanced thermochemical burning technique, which includes pyrolysis and combustion was applied at four different leaching times from 0 to 180 min under nitrogen environment from 0 degrees C to 500 degrees C and air from 500 degrees C to 900 degrees C, respectively. Different analyses including proximate, ultimate, gross calorific value (GCV), thermos-gravimetric, kinetic, XRD, FTIR, SEM-EDS were used for analyzing the degradation of demineralized cotton stalk at different treatment rates. Proximate study demonstrated that cotton stalk leaching for 180 min has efficiently infused HCL, leading in a significant increase in fixed carbon and higher heating value of 20.23 % and 12.48%, respectively, as well as a reduction in carbon footprint of around 54.80%. The findings of proximate was validated by GCV analysis and CHNS analysis as value of carbon and hydrogen has shown increasing behavior with the time delay in demineralization Thermo-gravimetric and derivative thermo-gravimetric data analyses shows an increasing trend of conversion efficiency, with the maximum increase of 98 % reported for sample 3H. TT.DEM. XRD characterization has reported 23 degrees to 25 degrees angle for all the observed p

The study evaluated removal of industrial CO2 from cement flue gas using algal cultivation. Local polycultures were grown in an up-scaled outdoor photobioreactor over 5 years in northern Europe. Algal biomass was harvested 2–3 times per week and the closed panel system was re-filled with seawater amended with nutrients. Flue gas was fed to the photobioreactor circulatory system in one direction or re-circulated. Removal efficiency of CO2 averaged 9 % in non-recirculation and 17 % in re-circulation modes and reached 20–60 % under best cultivation conditions. Recovery of carbon into algal biomass reached up to 10 g m2d−1 in non-recirculation mode. Biomass performance was explained by circulation mode and shift of polyculture traits. Stability of biomass quality was shown over seasons, with higher relative content of protein in autumn. Toxic elements in biomass were below legal thresholds for upcycling. The study shows feasibility of algal solutions for conversion of waste, applied in temperate climate. © 2023 The Authors

Scarcity in fossil fuel reserves and their environmental impacts has forced the world towards the production of clean and environment-friendly fuels called biofuels. This review focuses on the importance of different machine learning models and optimization techniques to simulate and optimize process conditions, yield and parameters in the fermentation of cellulosic biomass from fifty recent studies. The superiority of ML models, especially ANN dominance in 70 % of studies with highest coefficient of regression over conventional techniques in the production of bioethanol and biohydrogen is comprehensively reviewed. Research gaps and studies directed toward the usage of most optimum ML models in future are directed after the sensitivity analysis with 5 % variation that suggest the stability of ML models. It is intended to spur further investigation into the development and use of ML models combined with optimization methods and CFD in the fermentation process to produce bioethanol and biohydrogen.

In the Part I of this two-part series, the potential of hydrochar of two different provenances to augment biogas production in a batch process, was evaluated, using the Automatic Methane Potential Testing System (AMPTS II) in the lab at Karlstad University. In Part 2 of the two-part series, this part, single-stage anaerobic co-digestion in two continuously-fed reactors, replaced the batch process of Part 1. A The possibility of connecting an existing digester with a hydrothermal carbonization (HTC) reactor was investigated, and a life-cycle costing analysis was carried out to determine if, in addition to the environmental benefits written about in Part I, investing in an HTC system to produce hydrochar in-plant to augment biogas production will be economically feasible. Hydrochar addition resulted in a 59% rise in biogas yield (and 53.5% in methane yield). The pH remained stable around 7.6 throughout the digestion process. The study confirmed It will be the techno-economic feasibility for coupling an ally practical and feasible to interconnect an HTC plant with a digester supplying 25% of the digestate it produces, to the former, as the raw material for hydrochar production. The rest of the digestate (rich in carbon, nitrogen and phosphorus) can find use as fertiliser. Investing in an The LCC analysis showed that investing in an HTC plant contributing to a rise in methane production of 17% (or 53%), will result in a net profit of 363 million SEK (or 1237 million SEK) over a 20-year period. If the Karlskoga biogas plant decides to rely on purchasing hydrochar from the external market instead, the corresponding net profit will be 177 million SEK (or 1052 million SEK) over the same 20-year period, implying that a decision to integrate and interconnect is likely to be economically more feasible, in a circular bioeconomy in the future., Baserad på Annette Kariis: examensarbete fullført i 2023

At Biogasbolaget AB in Karlskoga in south-central Sweden, organic wastes like food waste, manure, and silage are digested anaerobically to yield biogas, which subsequently can be upgraded to biomethane, and used as a replacement for fossil-diesel in public transport. The digesters at the firm are currently operating below their maximum capacity. This chapter deals with the evaluation of the potential of hydrochar to augment biogas production in a batch process. Hydrochar produced from two sources – forestry sector and municipal organic wastes – were compared, and using the Automatic Methane Potential Testing System (AMPTS II) in the lab at Karlstad University, the optimal dosage was determined. Experiments were also conducted with hydrochar alone, to verify if the hydrochar was being anaerobically digested to yield biogas. The hydrochar sourced from municipal waste, when dosed at 8 g/l, produced 841 Nml of biogas /gram of VS (volatile solids) in the substrate, 93% greater than the reference case of no addition of hydrochar. The forestry-sector-sourced hydrochar on the other hand, at the same dosage, registered an increase of just 16.6%. A streamlined environmental life-cycle analysis showed that significant climate-benefits can be availed of, implying environmental sustainability, when the additional biogas is refined and used to replace fossil-diesel in public bus transport. Hydrochar-assisted anaerobic digestion of organic wastes may be posited as a technology which may entrench itself in the circular bio-economies of tomorrow, around the world, and bywhile doing so, contribute to a set of sustainable development goals. While these were batch-digestion experiments, this part of the two-part series recommends more-realistic continuous-digestion experiments which incidentally form the focus of Part 2., Baserad på Maria K:s examensarbete fulført i 2023.

Digestate processing is a strategy to improve the management of digestate from biogas plants. Solid-liquid separation is usually the primary step and can be followed by advanced treatments of the fractions. The knowledge about the performance of the separators and the quality of the fractions is scattered because of many available techniques and large variability in digestate characteristics. We performed a systematic review and found 175 observations of full-scale solid-liquid separation of digestate. We identified 4 separator groups, 4 digestate classes based on substrate, and distinguished whether chemical conditioners were used. We confirmed the hypothesis that the dominant substrate can affect the efficiency of the digestate separation. Furthermore, the results showed that centrifuges separated significantly more dry matter and total P than screw presses. Use of chemical conditioners in combination with a centrifuge lowered the dry matter concentration in the liquid fraction by 30%. Screw presses consumed 4.5 times less energy than centrifuges and delivered 3.3 tonne ammonium N in the liquid fraction and 0.3 tonne total P in the solid fraction using 1 MWh. The results can provide data for systems analyses of biogas solutions and can support practitioners when choosing among full-scale separator techniques depending on the digestate type. In a broader perspective, this work contributes to the continuous improvement of biogas plants operations and to their role as nutrients recovery sites., Funding Agencies|Biogas Research Center (BRC); Swedish Energy Agency [35624-2, 35624-3, P2023-00827]; Link oping University; Swedish University of Agricultural Sciences; Formas [2021-02429]

Open storages of organic material represent potentially large sources of the greenhouse gas methane (CH4), an emissions source that will likely become more common as a part of societal efforts toward sustainability. Hence, monitoring and minimizing CH4 emissions from such facilities are key, but effective assessment of emissions without disturbing the flux is challenging. We demonstrate the capacity of using a novel high-resolution hyperspectral camera to perform sensitive CH4 flux assessments at such facilities, using as a test case a biofertilizer storage tank for residual material from a biogas plant. The camera and simultaneous conventional flux chamber measurements showed emissions of 6.0 +/- 1.3 and 13 +/- 5.7 kg of CH4 h-1, respectively. The camera measurements covered the whole tank surface of 1104 m2, and the chamber results were extrapolated from measurements over 5 m2. This corresponds to 0.7-1.4% of the total CH4 production at the biogas plant (1330 N m3 h-1 corresponding to 950 kg h(-1)). The camera could assess the entire tank emission in minutes without disturbing normal operations at the plant and revealed additional unknown emissions from the inlet to the tank (17 g of CH4 h(-1)) and during the loading of the biofertilizer into trucks (3.1 kg of CH4 h(-1) during loading events). This study illustrates the importance of adequate measurement capacity to map methane fluxes and to verify that methane emission mitigation efforts are effective. Given the high methane emissions observed, it is important to reduce methane emissions from open storage of organic material, for example by improved digestion in the biogas reactor, precooling of sludge before storage, or building gastight storage tanks with sealed covers. We conclude that hyperspectral, ground-based remote sensing is a promising approach for greenhouse gas monitoring and mitigation., Funding Agencies|H2020 European Research Council [725546]; European Research Council (ERC) under the European Union [101015825]; European Union [VR 2016-04829]; Swedish Research Council VR [2018-01794]; FORMAS; Avfall Sverige (Project U 1000)

The distribution of inorganic elements between solid and liquid phases during biomass hydrothermal carbonization (HTC) is a poorly investigated topic despite its importance for process optimization. To fill in this gap, the distribution of inorganic elements and their forms were determined for three agro-food waste feedstocks converted at HTC temperatures of 180, 220, and 260 °C in 12 h. Satisfactory balances were achieved, with values between 80 and 92% for C and N, and 80 and 110% for most inorganic elements. At 180 °C, over 90% of P, Mg, Ca, K, Na, and Mn were removed from hydrochars whatever feedstock. At higher temperatures, P, Mg, Ca, and Mn were partly reincorporated into hydrochars (between 7 and 53%), possibly due to the formation of insoluble precipitates, while K and Na remained in the liquid. On the opposite, some minor elements, Cu and Al, remained in the hydrochars, whatever temperature. Si showed different removal behaviors according to feedstock and temperature. These results show the possibility of optimizing the removal of inorganic elements from hydrochars using different temperatures.

One of the key elements in this transition is the securing of a large supply of sustainable biomass. In this study, the feedstock potential of long rotation poplar plantations (12–30 years with diameter of 15 of 30 cm) was determined and the properties of poplar biomass fuel were analyzed with the aim of using thermochemical conversion methods to produce biofuel. Our results demonstrate that Sweden has great potential for producing biofuels from long rotation poplar plantations, with a total of 1.8 million hectares (ha) consisting of arable (0.5 million ha) and forested arable land (1.3 million ha). Based on available land and biomass production potential, our results indicate that 10 million Mg DW could be produced annually. Regions in mid/southern Sweden have the largest potential (larger areas and higher biomass production. Our results further suggest that poplar biomass from these plantations has fuel characteristics similar to forest fuels from other conifer tree species, making the biomass suitable as feedstock for biofuel production based on thermochemical conversion methods. If 25% of the available land were used, 7.6 TWh methanol biofuels could be produced annually from 16 biofuel plants, using 160,000 Mg DW yr−1, primarily located in the southern part of Sweden. Two counties (Skåne and Västra Götaland) would be able to support their biofuel plants using poplar plantations as feedstock. Stable biofuel production in the other counties would depend on collaborating with neighboring counties., Validerad;2023;Nivå 2;2023-11-08 (marisr);License full text: CC BY

Global uppvärmning på̊ grund av utsläpp av växthusgaser är ett globalt problem, med en förutspådd ökning av den globala medeltemperaturen med 2°C inom 30 år. En teknik för att hantera det är koldioxidavskiljning och förvaring med hjälp av bioenergi (BECCS). BECCS involverar absorption genom lösningsmedel som nyckelsteget för avlägsnande av CO2 från förbränningsrökgas. Ett framträdande lösningsmedel för BECCS är vattenlöslig kaliumkarbonat (K2CO3). Drift av en BECCS fabrik kräver analys av lösningsmedlet för att avgöra mängden CO2 som tagits upp av lösningsmedlet. Idag förlitar man sig till mätningar gjorda offline, vilka är dyra och långsamma. I det här arbetet utforskar vi FTIR i kombination med mätningar av fysikalisk-kemiska egenskaper för lösningsmedelsanalys av K2CO3-lösningar. FTIR och fysikalisk- kemiska egenskaper kan mätas på plats, vilket gör de lämpliga för online-analys. Det här arbetet utvecklar modeller för analys av datan från sensorerna som i en framtida uppsättning fås från sådana online-mätningar. Ett träningsset av efterliknade prover med olika lösnings- styrka och laddning skapades och mättes i labbet. Uppsättningen av data användes för att träna modeller baserat på principalkomponentanalys (PCA), partiell minsta kvadratregression (PLS) och feed-forward neuralt nätverk (FFNN). De tränade modellerna användes för att analysera prover av lösningsmedel erhållna från en faktisk BECCS fabrik i pilotskala. Resultaten visade att FTIR är ett kraftfullt verktyg för att analysera absorptionslösningsmedel. Medan PCA visade bra exakthet men dålig robusthet, visade PLS motsatsen med bättre robusthet men sämre exakthet. Att inkorporera FTIR och fysikalisk-kemiska egenskaper in i en FFNN-modell ledde till detekterbara förbättringar av modellens styrka att förutspå resultat. Dock, på grund av den relativt lilla uppsättningen av data som användes för att träna FFNN är dess förmåga a, Global warming due to emissions of greenhouse gasses is a global problem, with a predicted global average temperature increase of 2°C within 30 years. A technique for tackling this is bioenergy carbon capture and storage (BECCS). BECCS involves solvent absorption as the key step for removal of CO2 from combustion flue gases. A prominent solvent for BECCS is aqueous potassium carbonate (K2CO3). Operating a BECCS plant requires solvent analysis to determine the amount of CO2 taken up by the solvent. Today, it relies on off-line measurements, which are expensive and slow. In this work, we explore FTIR in combination with measurements of physico-chemical properties for solvent analysis of K2CO3 solutions. FTIR and physico-chemical properties can be measured in-situ, which makes them suitable for on-line analysis. This work deals with the development of models for the analysis of the sensor data that, in a future setup, would be obtained from such online measurements. A training set of mimicked samples with different solvent strength and loading was created and measured in the laboratory. The data set was used for training models based on principal component analysis (PCA), partial least-square regression (PLS) and feed- forward neural network (FFNN). The trained models were used to analyse solvent samples obtained from an actual BECCS pilot plant. The results showed that FTIR is a powerful tool for analysis of absorption solvents. While PCA showed good accuracy but poor robustness, PLS performed oppositely by showing better robustness but lower accuracy. Incorporating FTIR and physico- chemical properties into an FFNN model led to detectable improvements of the predictive power of the model. However due to the relatively small data set used to train the FFNN its accuracy to predict the actual field samples is relatively low.

Mellan 1960 och idag har världspopulationen dubblerats medan matproduktionen tredubblats. Det har möjliggjorts av kemiskt framställda gödsel som introducerades på mitten av 1900-talet. Sedan 1965 har användandet av kvävegödsel ökat sexdubblet. Kvävegödsel ökar lönsamheten och avkastningen men har stora koldioxdutsläpp och orsaker övergödning. Därför finns det en efterfrågan på andra alternativ. Ett alternativ skulle kunna vara en syntetsik föränding av rhizosfären. För att undersöka om det är möjligt kommer ett modellsystem för insulerat metaboliskt utbyte att skapas. Modellsystemet kommer att ha en kvävefixarande bakterie som fixerar kväve från atmosfären och producerar en kvävekälla till en kolfixerande bakterie, som kommer modellera en växt i system. Den kolfixerande bakterien kommer att fixera koldioxid from atmosfären och producera en kolkälla för den kvävefixerande bakterien att använda. I den här studien har olika produktioner av olika kvävekällor i Escherichia coli och Anabaena sp. undersökts. Fyra olika plasmider har skapats för produktionen av alanin, guanin och allantoin. Alla odlingar med plasmiderna växte bättre än kontrollodlingarna, men de har inte blivit analyserade för produktion av metaboliterna på grund av tidsbrist. Tilläggningsvis, två av tre replikat av Anabaena sp. med en plasmid för allantoin produktion i media med urinsyra verkar ha varit stressade för okända anledningar, Between 1960 and today, the world population has doubled while food production has tripled. This has been made through chemical fertilisers being introduced in the middle of the 20th century. From 1965, the usage of nitrogen fertilisers has increased by sixfold. Nitrogen fertilisers improve crop profitability and yield but have large carbon dioxide emissions as well as cause eutrophication. Thus, there is a demand for an alternative. One alternative would be to engineer the rhizosphere. To investigate whether this is possible, a model system for insulated metabolic exchange will be created. The model system will have a nitrogen-fixating bacteria that will fixate atmospheric nitrogen and produce a nitrogen compound to a carbon-fixating bacteria, that will act as a plant in the model system. The carbon-fixating bacteria will fixate carbon dioxide from the atmosphere and produce a carbon source for the nitrogen-fixating bacteria to utilise. In this study, different productions of different nitrogen compounds in Escherichia coli and Anabaena sp. have been investigated. Four different plasmids have been constructed for the production of alanine, guanine and allantoin, respectively. The strains containing the plasmids all grew better than the control cultures, however, they have not been analysed for producing the metabolites due to time constraints.

Detta självständiga arbete utfördes på kraftvärmeanläggningen Affärsverken AB i Karlskrona med syfte att minska stadens vattenförbrukning, minimera utsläpp i naturen och bidra till globala miljömål. Se bilagor (7–10) för mer information.Projektet omfattade flera perspektiv, inklusive tekniker för att rena rökgaskondensat och de ekonomiska aspekterna av ett sådant projekt. Sammanfattningsvis syftar projektet till att förbättra effektiviteten och hållbarheten i kraftvärmeverket. Studiebesöket på kraftvärmeverket i Karlskrona har gett information om flödet av kommunalt vatten och rökgaskondensat mängden som används för att bestämma återvinningen av vatten och mängden rökgaskondensat som behövs. Detta kommer att användas för att utvärdera teknikerna för att rena rökgaskondensatet och de ekonomiska aspekterna av projektet.Målet med projektet var att minska stadens vattenkonsumtion på kraftvärmeverket genom att använda rökgaskondensat istället för stadsvatten. Detta minskar kostnaden för råvatten och bidrar till att uppnå globala miljömål. Konstruktion och installation kan kombineras med befintliga anläggningar, utrustning och ekonomiska faktorer som tas i beaktning vid valet av lösning. En hållbar och kostnadseffektiv lösning bör väljas för att minska stadens vattenkonsumtion utan att påverka produktiviteten., This independent project was conducted at the combined heat and powerplant (Affärsverken AB) in Karlskrona with the aim of reducing city waterconsumption, minimizing emissions into the environment, and contributingto global environmental goals, see appendix (7-10). The project included several perspectives, including technologies for cleaning flue gas condensateand the economic aspects of such a project. In summary, the project aimed toimprove the efficiency and sustainability of the combined heat and powerplant.The study visit to the combined heat and power plant in Karlskrona has provided information on the flow of municipal water and the amount of flue gascondensate used to determine the recovery of water and the amount of fluegas condensate needed. This will be used to evaluate the technologies forcleaning the flue gas condensate and the economic aspects of the project.The conclusion of the project was to be able to reduce city water consumption at cogeneration plants by using flue gas condensate instead of city water.This reduces the cost of city water and contributes to achieving environmental global goals. Construction and installation can be combined with existingfacilities and equipment, and economic factors should be taken into accountwhen choosing a solution. Sustainable and cost-effective solution should bechosen to reduce city water consumption without affecting productivity.

Hydrothermal carbonization (HTC) technology upgrades combustible waste (CW) to high-quality fuel known as hydrochar. However, there is a research gap regarding the application limit of hydrochar instead of fossil fuels in blast furnaces. In this study, the physical, chemical, and metallurgical properties of hydrochar were thoroughly analyzed. The results showed that gross calorific value, grindability, ignition temperature, explosivity, combustion and gasification all improved by HTC process compared with the waste feedstocks. Moreover, the HTC process can effectively remove harmful elements (K, Na, Cl, and S) from feedstocks into liquid and gas phase without adding other reagents, reducing harmful effects in the blast furnace. Removal rates by HTC were >80% for alkali metals and >73.9% for Cl (reaching 98.18% for polyvinyl chloride hydrochar). The environmental benefit calculation shows that the CO2 emission reduction of replacing bituminous coal with 40% HTC-treated maize straw can reach 94.7 kg/tHM. The annual CO2 reduction can reach 1.7 x 107 kg and the annual coal reduction is 1.5 x 107 kg of a blast furnace. The results showed that hydrochar is a clean energy source compared with fossil fuel alternatives and meets the blast furnace injection requirements., QC 20230117

Olivine and alkali-feldspar were utilized in separate campaigns in an indirect dual fluidized bed gasification campaign with woody biomass as fuel. After three days, both bed materials were reported to be active towards tar removal and exhibited oxygen-carrying abilities and had formed an ash layer consisting of an outer ash deposition layer and an inner interaction layer. X-ray microtomography analysis concluded that a preferred deposition of ash happens onto convex regions of the bed particles, which results in an increase in thickness of the ash layer over convex regions. This effect is most pronounced for the outer layer which is a product of ash deposition. The inner layer exhibits a homogeneous thickness and is probably formed by interaction of Ca from the outer layer with the particles. Transmission electron microscopy revealed the presence of Fe and Mn on the surface of the particles in a solid solution with Mg. The oxygen-carrying effect which is found for aged particles is therefore attributed to the presence of Fe and Mn on the surface of aged particles. Alkali were found on the surface of both particles which are likely contributing to the catalytic activity of the material towards tar removal., Validerad;2022;Nivå 2;2022-11-02 (sofila);This article has previously appeared as a manuscript in a thesis

Följande rapport återspeglar ett examensarbete utfört hos Solör Bioenergi, examensarbetet har syftat till att utvärdera den höga andelen oförbränt som uppstår vid deras förbränning. Solör äger anläggningen i Nora och förser orten med fjärrvärme. Detta sker genom förbränning av biomassa och bränslet utgörs av sågspån och stamvedsflis. Under en stor del av eldningssäsongen blandas dessa bränslen med varandra men under säsongens varma perioder eldas enbart sågspån. För utvärderingen har information från kurslitteratur inhämtats, dessutom har studerande av forskningsrapporter hjälpt till att samla in kunskap för projektet och vilka faktorer som kan påverka en förbränning. Resultatet av litteraturstudien har jämförts med en utförd nulägesanalys tillsammans med flertalet intervjuer med drifttekniker, anläggningsansvarig och externa entreprenörer. Denna arbetsmetodik har skapat en samlad bild över förbränningen i pannan och har möjliggjort utformningen av en lista över åtgärdsförslag. Listan återfinns i ett, tillsammans med en ekonomisk kalkyl, eget avsnitt. Pålitligheten hos de rekommenderade åtgärderna har också kunnat bekräftats med en provkörning, där tillämpad teori har förbättrat förbränningen. En generell slutsats som kan dras efter arbetet visar hur viktig en bra processtyrning är för ett ökat bränsleutnyttjande, detta kan förenklat sammanfattas med grundregeln för utformning av styrsystem: -Det som kan automatiseras, bör automatiseras., The following report reflects a degree project carried out at Solör Bioenergi, the project has aimed to evaluate the high proportion of unburned that occurs during their combustion. Solör owns the plant in Nora and supplies the town with district heating. This is done by burning biomass and the fuel consists of sawdust and stemwood chips. During a large part of the heating season, these fuels are mixed with each other. But during the warm season, only sawdust is burned. For the evaluation, information from course literature has been collected. Together with studying of research reports, they have helped to gather knowledge for the project and what factors can affect an combustion. The results of the literature study have been compared with a performed current situation analysis together with several interviews with operating technicians, plant managers and external contractors. This working methodology has created an overall picture of combustion in the boiler and has enabled the design of a list of proposed measures. The list can be found in a separate section, together with a financial calculation. The reliability of the recommended measures has also been confirmed with a test run, where applied theory has improved combustion. A general conclusion that can be drawn after the work shows how important a good process control is for increased fuel utilization, this can be summarized with the basic rule for the design of control systems: -What can be automated, should be automated.

Koldioxid (CO₂) har en negativ påverkan på klimatet, men har även många praktiska användningsområden. Många industriella processer släpper ut CO₂ i höga koncentrationer som skulle kunna fångas in för att begränsa emissioner och samtidigt skapa värdefulla produkter. Ett exempel på en sådan process är biogasuppgradering – en separationsprocess av förnybara gaser, där metan tas till vara för användning som fordonsbränsle eller energibärare inom industri, medan CO₂ släpps ut i atmosfären. Syftet med detta projekt har varit att kartlägga möjligheter och tekniker för att tillvarata grön CO₂ från biogasproduktion, så kallad carbon capture and utilization (CCU), samt att utreda förutsättningar för att tillämpa dessa i en svensk kontext. Arbetet har vägletts av följande frågeställningar: Hur stor är den nuvarande och framtida potentialen för CCU från biogasproduktion? Vilka möjliga användningsområden finns det för CO₂ från biogasproduktion? Vilka faktorer påverkar valet av användningsområde för CO₂ från biogasproduktion? Hur stor är den miljömässiga nyttan av CCU från biogasproduktion? För att besvara dessa frågeställningar genomfördes potentialberäkningar, multikriterieanalys och livscykelanalys, med utgångspunkt i svensk biogasproduktion. En referensgrupp bestående av representanter för stora svenska företag inom biogasproduktion och teknik för biogasuppgradering användes för att möjliggöra samproduktion och nätverkande mellan forskargruppen och branschen. Produktionen av CO₂ från biogas uppskattades till 160 000 ton/år 2020, med potential att öka till 540 000 – 840 000 ton/år på medellång sikt och 790 000 – 1 230 000 ton/år på lång sikt, som en följd av en förmodad ökning av biogasproduktionen i Sverige. En stor del av koldioxiden produceras dock vid relativt små uppgraderingsanläggningar, vilket kan begränsa möjligheten att tillämpa CCU på grund av höga investerings- och driftskostnader. Att tillföra vätgas för att omvandla all CO₂ till metan skulle potentiellt kunna öka, Carbon dioxide (CO₂) has a negative impact on the climate, but it also has several practical areas of use. Many industrial processes emit CO₂ in high concentrations, which could be captured to mitigate emissions while also creating valuable products. One example of such a process is biogas upgrading – a process separating renewable gases, where methane is taken care of for use as vehicle fuel or industrial energy carrier, while CO₂ is released into the atmosphere. The aim of this project has been to chart alternatives and technologies for taking care of green CO₂ from biogas upgrading, so-called carbon capture and utilization (CCU), and to investigate the conditions for applying these in a Swedish context. The work has been guided by the following research questions: How large is the current and future potential for CCU from biogas production? What are the possible areas of use for CO₂ from biogas production? What factors influence the choice of areas of use for CO₂ from biogas production? How large is the environmental benefit of CCU from biogas production? To answer these questions, calculations of potentials, a multi-criteria assessment and a life cycle assessment were carried out, based on the Swedish biogas production. A reference group comprising representatives for large Swedish companies within biogas production and biogas upgrading technology was used to enable coproduction and networking between the research group and the business sector. The production of CO₂ from biogas was estimated to 160,000 ton/year in 2020, with potential to increase to 540,000 – 840,000 ton/year in a few years and 790,000 – 1,230,000 ton/year in a longer perspective, as a consequence of an expected increase in the Swedish biogas production. A large share of the CO₂ is however produced at relatively small upgrading facilities, which could limit the feasibility for CCU due to high costs for investment and operation. Adding hydrogen to transform all the CO₂ into methane could potentia, Värdeskapande av koldioxid från biogasproduktion

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.

Renewable fuels for transport are needed to reach future climate targets. However, the potential future role of different biofuels, hydrogen, and electrofuels (produced by electricity, water, and CO2) in different transportation sectors remains uncertain. Increased knowledge about the preconditions for different renewable fuels for road and air transport to contribute to the transformation of the transport sector is needed to ensure the transformation is done in a climate- and cost-effective way. The CO2 abatement cost, i.e., the cost of reducing a certain amount of greenhouse gas (GHG) emissions is central from both a societal and business perspective, the latter partly due to the design of the Swedish reduction obligation system. The abatement cost of a specific fuel value chain depends on the fuel production cost and the GHG reduction provided by the fuel. This report provides an updated summary of the CO2 abatement costs for various types of biofuels and electrofuels for road transport and aviation, relevant in a Swedish context. Fuel production costs and GHG performance (well to wheel) for the selected renewable fuel pathways are mapped based on published data. The estimated CO2 abatement cost ranges from -0.37 to 4.03 SEK/kg CO2-equivalent. Methane from anaerobic digestion of sewage sludge and ethanol from fermentation of sugarcane and maize end up with negative CO2 abatement cost given the assumptions made, meaning it is more economically beneficial to use than its fossil counterpart. Electrofuels pathways (particularly diesel and aviation fuels) have, on the other hand, relatively high CO2 abatement costs. Also, so-called bio-electrofuels produced from biogenic excess CO2 from biofuel production and electricity linked to biofuel production generally have higher CO2 abatement costs than the corresponding forest biomass-based biofuel pathway. For forest biomass-based biofuels, bio-electrofuels and electrofuels, methanol, and methane pathways in general have so, Commissioned by: Statens Energimyndighet

Bed materials provide efficient heat transfer and catalytic function in the thermochemical conversion of biomass, but their interactions with the fuel remain incompletely understood. In this study, the effects of bed materials on alkali release and fuel conversion during wood pyrolysis and CO2 gasification are investigated by online alkali detection combined with thermogravimetric analysis. The investigated bed materials include silica, sea sand, alumina and the natural ores olivine, ilmenite and dolomite. Only dolomite has a significant effect on fuel mass loss and alkali release during wood pyrolysis, while all bed materials influence char reactivity and alkali release during gasification. Sea sand, alumina and dolomite enhance the char gasification during the whole or most of the gasification process, which is related to alkali migration from the bed materials. All bed materials affect char reactivity and alkali release when the conversion approaches completion, and small amounts of some bed materials reduce the alkali release by an order of magnitude. The findings can be understood based on the chemical composition of the different materials. Silicon-rich materials reduce the levels of catalytically active alkali by formation of stable alkali silicates, and a similar explanation applies for ilmenite that captures alkali efficiently. Magnesium and calcium in contrast promote alkali release through their influence on alkali silicate chemistry. Analysis of char surfaces using scanning electron microscopy with energy dispersive spectroscopy indicates that low amounts of several elements are transferred from the bed material to the char where they may be directly involved in the char conversion process. The transferred elements are specific for each bed material and relates to their chemical composition. Mechanisms for material exchange between bed material and char are discussed., QC 20230821

Hydrothermal carbonization (HTC) technology was used to carbonize and improve biomass raw material to obtain hydrochar. The effects of HTC temperature and holding time on the yield, composition, structure, combustion behavior, and safety of hydrochar were studied systematically. In addition, the results show that with the increase in HTC temperature and the prolongation of holding time, the yield of hydrochar gradually reduces, the fixed carbon content of hydrochar increases, the volatile content decreases, and a large number of ash and alkali metals enter the liquid phase and are removed. Further, the analysis of the combustion properties and the structure of hydrochar can be observed in that, as the HTC process promotes the occurrence of polymerization reactions, the specific surface area gradually reduces, the degree of carbon ordering increases, and the combustion curve moves toward the high-temperature zone and gradually approaches bituminous coal. Since biomass hydrochar has the characteristic of being carbon neutral, blast furnace injection hydrochar can reduce CO2 emissions, and every 1 kg/tHM of biomass hydrochar can reduce CO2 emissions by 1.95 kg/tHM., QC 20230321

The search for new energy sources together with the need to control greenhouse gas emissions has led to continued interest in low-emitting renewable energy technologies. In this context, water splitting for hydrogen production is a reasonable alternative to replace fossil fuels due to its high energy density producing only water during combustion. Cellulose is abundant in nature and as residuals from human activity, and therefore a natural, ecological, and carbon-neutral source for hydrogen production. In the present work, we propose a sustainable method for hydrogen production using sunlight and cellulose as sacrificial agents during the photocatalytic water splitting process. Platinum (Pt) catalyst activates hydrogen production, and parameters such as pH of the system, cellulose concentration, and Pt loading were studied. Using different biomasses, we found that the presence of hemicellulose and xyloglucan as part of the molecular composition considerably increased the H-2 production rate from 36 mu mol L-1 in one hour for rapeseed cellulose to 167.44 mu mol L-1 for acid-treated cellulose isolated from Ulva fenestrata algae. Carboxymethylation and TEMPO-oxidation of cellulosic biomass both led to more stable suspensions with higher rates of H-2 production close to 225 mu mol L-1, which was associated with their water solubility properties. The results suggest that cellulosic biomass can be an attractive alternative as a sacrificial agent for the photocatalytic splitting of water for H-2 production., QC 20230503

Syntrophic relationships between fatty acid degrading bacteria and hydrogenotrophic methanogens are important for a well-functioning anaerobic degradation process during biogas production from organic waste material. This is particularly important in biogas processes fed protein-rich material as their degradation gives rise to high levels of ammonia, which inhibits many microorganisms. A common problem arising in the high-ammonia biogas process is the accumulation of volatile fatty acids, such as acetate, propionate or butyrate, which negatively affects the methane production. The aim of this study was to isolate and identify the syntrophic butyrate-oxidizing bacteria present in the enriched syntrophic communities originating from thermophilic continuously fed laboratory-scale reactors. Butyrate was added to batch assays containing the enrichment cultures. Sequencing of a 464 bp region within the 16S rRNA gene was conducted to study the change in microbial community structure over time during the butyrate degradation. The enrichment culture was also used as an inoculum source during the isolation attempts using agar cultivation, colony transfer and 16S rRNA gene sequencing of the obtained isolates. From the Illumina sequencing data, it could be concluded that the novel species of interest belonged to the genus Syntrophothermus. Two species were isolated, however neither appeared to be the butyrate-degrading bacterium. One of the species was Defluviitoga tunisiensis and the other was a novel species related to the mesophilic bacterium Schnuerera ultunensis.

This study has been carried out within the framework of the Minor Field Studies ScholarshipProgramme (MFS), which is funded by the Swedish International Development Cooperation Agency,Sida. The field study was conducted in Grenada in the spring of 2023. Grenada, along with severalcountries in the Caribbean, has under the last couple of years experienced an increasing influx ofSargassum seaweed. The seaweed accumulates on beaches and causes complications relating tohealth, recreation, economy and the ecosystems by the coast. Moreover, Grenada is dependent onimported fossil fuels which causes the country to have a relatively high ecological footprint as well asmaking the country sensitive to volatile oil prices. To produce biogas with Sargassum, and morespecifically for generating electricity, is one possible solution to the aforementioned issues. However,there is a need to investigate the prerequisites for such a solution. This was done by conducting anexperiment and a market analysis. The experiment aimed to investigate how the methane content inthe biogas is affected by mechanical pretreatment of the seaweed. The market analysis delved into thepossibilities of using biogas to generate electricity in Grenada. For the experiment, a small-scale biogas digester was used, which was located at the True Blue BayBoutique Resort. Feeding of the digester was divided into three batches with two differentcompositions of food waste and Sargassum; untreated and mechanically pretreated Sargassum. Thedigester was fed for 42 days in total while the measurements were conducted for 28 days. In terms ofthe market analysis, a literature study and 4 interviews with relevant actors were conducted. Theinterviewees were approached based on local suggestions. For the analysis, four different areas ofinterest were selected: Electricity system in Grenada, Policy and regulation, Infrastructure andAvailability of organic waste for co-digestion. The experiment revealed a weak yet positive trend, Denna studie är genomförd inom ramen för stipendieprogrammet Minor Field Studies (MFS) somfinansieras av Sida och fältstudien genomfördes i Grenada våren 2023. Grenada, tillsammans medflera länder i Karibien, har under de senaste åren upplevt ett ökande inflöde av Sargassotång. Tångensamlas på stränderna och skapar problem kopplade till hälsa, rekreation, ekonomi och ekosystemenvid kusten. Vidare är Grenada beroende av importerade fossila bränslen, vilket gör att landet har ettrelativt högt ekologiskt fotavtryck, samtidigt som det är känsligt för volatila oljepriser. Att producerabiogas med sargassotång, och mer specifikt för att generera el, är en möjlig lösning till de ovannämnda problemen. Emellertid finns det ett behov att undersöka förutsättningarna för en sådanlösning. Detta gjordes genom att genomföra ett experiment och en marknadsanalys. Experimentetsyftade till att undersöka hur metaninnehållet påverkas av att mekaniskt förbehandla sargassotången.Marknadsanalysen undersökte förutsättningarna för att använda biogasen för att generera el påGrenada. För experimenten användes en småskalig biogasanläggning på True Blue Bay Boutique Resort påGrenada. Matningen delades upp i tre delar med två olika sammansättningar av matavfall ochsargassotång; obehandlade och mekaniskt förbehandlade alger. Totalt matades anläggningen i 42dagar medan experimentet med vattenkokning genomfördes 28 dagar. För marknadsanalysengenomfördes en litteraturstudie och 4 intervjuer med relevanta aktörer. Intervjupersonerna valdesutifrån lokala förslag. För analysen valdes sedan fyra områden: Elsystemet på Grenada, Policy ochreglering, Infrastruktur och Tillgänglighet av biologiskt nedbrytbart avfall. Experimentet visade en svag men positiv trend i metanhalten under den uppmätta perioden, vilkettyder på att mekanisk förbehandling av Sargassum potentiellt kan öka metanhalten. Mer specifikt varden genomsnittliga koncentrationen av metan per volym 57% för den obehandlade delen och 63% förden meka

Som följd av klimatförändringar ställs nya krav på producenter och konsumenter. För att tillmötesgå dessa krav behöver framtida omställningar vara ekonomiskt och ekologiskt hållbara. Tidigare forskning visar att biokol, skapat via pyrolys, kan binda koldioxid från atmosfären. Denna rapport undersöker de ekonomiska och miljömässiga konsekvenserna vid omställning från värmeproduktion via förbränning, till värmeproduktion via pyrolys. I rapporten presenteras värmeproduktion genom pyrolys som samproduktion av biokol och bioolja från ett fjärrvärmeverk med kapacitet på 3 MW. Rapporten undersöker den teoretiska mängden alstrade pyrolysprodukter, värme, biokol och bioolja och den potentiella koldioxidssänkan som kan uppnås från biokol från tre olika scenarier. En tekno-ekonomisk analys har gjorts för undersökning avbetalningstid, avkastning på investering och en känslighetsanalys har utförts för att illustrera hur återbetalningstiden påverkas när faktorerna: försäljningspris för samtliga pyrolysprodukter och investerings- samt underhållskostnader förändrades. Resultatet visar att vid räntorna 0-, 5- och 10 % blir avbetalningstiden mindre än 4 år samt med en potentiell avkastning på minst 600% efter 25 år. De faktorer som hade störst påverkan på återbetalningstiden var grundinvesteringen vars förändring direkt påverkade återbetalningstiden. Ifall grundinvesteringen ökade med 40% - förlängdes återbetalningstiden med 40%. Den andra faktorn som påverkade mest priset för fjärrvärme. Ifall priset minskade med 40% så förlängdes återbetalningstiden med minst 63%. Resultatet visar också att det finns potential att binda mellan 3560 och 8400 ton koldioxid per år. Denna rapport utgår från data och för framtida undersökningar vore nästa mål att uppnå en mer realistisk uppfattning om kostnader och verkningsgrader som mer exakt speglar verkligheten., nej.

I denna studie har kartlagts hur mycket av de biogena utsläppen i Sveriges inventering av växthusgasutsläpp, som rapporteras till EU och UNFCCC, som härrör från inhemsk produktion av biomassa och hur mycket som är importerad råvara. Ett viktigt syfte har varit att belysa i vad mån storleken på de biogena utsläppen från förbränning av biomassa inom energisektorn som redovisas under ’memo items’ CO2 emissions from biomass överensstämmer med storleken på den del av de rapporterade balanserna för förändringar i kolförråden levande och död biomassa som redovisas i sektorn markanvändning och skogsbruk, LULUCF, som kan förknippas med de biogena utsläppen. Rapporten innehåller en djupgående beskrivning av de metoder som idagsläget används för beräkningar av CO2 emissions from biomass, redovisade under ’memo items’ och de metoder som används i beräkningarna av nettoupptag i LULUCF-sektorn där de biogena utsläppen ingår. Den officiella redovisningen av LULUCF-sektorn är en nettoberäkning av kolförrådsförändringar inom Sverige som inkluderar (men inte särredovisar) upptag och avgång av koldioxid. Därför har en kartläggning gjorts av biomassaflöden i Sverige, inklusive export och import, för att möjliggöra en skattning av utsläppen av biogen koldioxid i LULUCF-sektorn och i vilken utsträckning dessa kan förknippas med utsläpp från energiproduktion från biogent bränsle i Sverige. Tillförseln av skogsråvaror från import och från inhemskt skogsbruk till industrin, inklusive rundved, avverkningsrester samt brännved och annat som används direkt av hushållen, motsvarade nästan 70 miljoner ton koldioxid varav ca 6 miljoner ton härrör från import. Ungefär hälften av rundvirket som tas ut från skogen blir pappersmassa och träprodukter. Resten (brännved, flis, spån, bark, svartlut) används främst till energiframställning och motsvarar ca 32 miljoner ton koldioxid. Utöver rundvirket tas avverkningsrester (grenar och toppar från skogsbruket) tillvara för energiproduktion motsvarande ca 3,5

The intensified burning of fossil fuels and the discharging of industrial wastes are severe threats to the environment. The released CO2 and organic fractions of industrial and municipal wastes exacerbate global warming. Converting the released CO2 and organic wastes into beneficial electricity and biofuel-chemicals is deemed an environmental necessity. Microbial electrosynthesis (MES) presents a promising technology for bio-electrochemical conversion of released CO2 and organic wastes into electricity and biofuel-chemicals using external-powered and/or self-powered microbial oxidation/reduction processes. The MES system consists of anodic and cathodic processes. The technology mostly relies on the capacity of electron transfer from electroactive biofilm to the electrode for reducing organics into value-added chemicals and sustaining their respiration and growth. The current review aims to summarize and explore the diversified application of electrogenic microbes and their metabolic pathways of electron transfer. It also summarizes the MES reactor design and operational parameters that influence the catalysis of biofilm and hence, the system performance. The review concludes with a critical evaluation of technical challenges that should be overcome before large-scale implementation. Furthermore, various recommendations on technical perspectives for successful implementation and application, including future research directions, are presented in this study.

Different biomaterials have different chemical compositions and since the densification properties are strongly related to feedstock, it is important to increase knowledge about biomass relationship to densification properties. The purpose of this chapter is to give a brief introduction to the development of the plant kingdom, the chemical composition of biomasses, and how different components can affect the densification characteristics. A study where 11 different pure substances (cellulose, hemicelluloses, lignin, etc.), added to pine and beech, are pelletized in a single pellet press and results are presented showing that polysaccharides can play an important role when biomasses are densified as single sources or blends solutions in a densification process.

Future pellet plants will need to be more flexible regarding the need to vary the feedstock species and increase the areas for biomass. By blending biomass species, pellets can be a solution that meets new desirable specifications for different conversion pathways, such as biochemical, thermochemical, and biopower. In this chapter, the authors address opportunities for blending and densification to homogenize the chemical composition of biomaterials and improve the potential for other processing and transformation methods. The advantages of blending biomasses are many: increasing the potential supply of biomass, creating new markets, reducing raw material costs, and improving biomass flow and pelletizing properties. Important densification parameters to keep in mind are highlighted, and five different studies are summarized; these include investigations from a single pellet press study to briquette applications. Some conclusions are that blending woody and herbaceous biomasses yields products with uniform product quality in terms of physical properties and chemical composition. Furthermore, blending pine and switchgrass yields a compressed product with higher density and durability while reducing energy consumption.