| 1. |
- Arfan, Muhammad, et al.
(author)
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Biogas as a transport fuel—a system analysis of value chain development in a Swedish context
- 2021
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In: Sustainability. - : MDPI. - 2071-1050. ; 13:8
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Journal article (peer-reviewed)abstract
- Biofuels policy instruments are important in the development and diffusion of biogas as a transport fuel in Sweden. Their effectiveness with links to geodemographic conditions has not been analysed systematically in studying biogas development in a less urbanised regions, with high potential and primitive gas infrastructure. One such region identified is Gävleborg in Sweden. By using value chain statistics, interviews with related actors, and studying biofuels policy instruments and implications for biogas development, it is found that the policy measures have not been as effective in the region as in the rest of Sweden due to different geodemographic characteristics of the region, which has resulted in impeded biogas development. In addition to factors found in previous studies, the less-developed biogas value chain in this region can be attributed particularly to undefined rules of the game, which is lack of consensus on trade-off of resources and services, unnecessary competition among several fuel alternatives, as well as the ambiguity of municipalities’ prioritization, and regional cultural differences. To strengthen the regional biogas sector, system actors need a strategy to eliminate blocking effects of identified local factors, and national policy instruments should provide mechanisms to process geographical conditions in regulatory, economic support, and market formation.
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| 2. |
- Arfan, Muhammad, et al.
(author)
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Life cycle assessment and life cycle costing of hydrogen production from biowaste and biomass in Sweden
- 2023
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In: Energy Conversion and Management. - : Elsevier. - 0196-8904 .- 1879-2227. ; 291
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Journal article (peer-reviewed)abstract
- In this study, an environmental and economic assessment of hydrogen production from biowaste and biomass is performed from a life cycle perspective, with a high degree of primary life cycle inventory data on materials, energy, and investment flows. Using SimaPro LCA software and CML-IA, 2001 impact assessment method, ten environmental impact categories are analyzed for environmental analysis. Economic analysis includes capital and operational expenditures and monetization cost of life cycle environmental impacts. The hydrogen production from biowaste has a high climate impact, photochemical oxidant, and freshwater eutrophication than biomass while it performs far better in ozone depletion, terrestrial ecotoxicity, abiotic depletion-fossil, abiotic depletion, human toxicity, and freshwater ecotoxicity. The sensitivity analysis of LCA results indicates that feedstock to biogas/pyrolysis-oil yields ratio and the type of energy source for the reforming process can significantly influence the results, particularly climate change, abiotic depletion, and human toxicity. The life cycle cost (LCC) of 1 kg hydrogen production has been accounted as 0.45–2.76 € with biowaste and 0.54–3.31 € with biomass over the plant's lifetime of 20 years. From the environmental impacts of climate change, photochemical oxidant, and freshwater eutrophication hydrogen production from biomass is a better option than biowaste while from other included impact categories and LCC perspectives it’s biowaste. This research contributes to bioresources to hydrogen literature with some new findings that can be generalized in Europe and even globally as it is in line with and endorse existing theoretical and simulation software-based studies.
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| 3. |
- Carlos-Pinedo, Sandra
(author)
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Renewable Energy and Nutrient Valorization from Anaerobic Digestion : Resource-Efficient Solutions
- 2023
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Doctoral thesis (other academic/artistic)abstract
- This thesis presents a comprehensive analysis aimed at understanding process performance, methane yield, and key influencing factors within the context of solid-state anaerobic digestion (SS-AD). SS-AD is used to treat organic material with high solids content, which can be challenging to address by alternative methods. The investigation involves modelling and simulation exploring mass and energy balances and the associated environmental implications. To achieve this, a waste management tool, ORganic WAste REsearch (ORWARE) was adapted and validated to suit the unique parameters of SS-AD operating under a plug-flow reactor configuration, representing a specific case study. The search of an optimal feedstock mix that enhances the digestion process and energy performance is highlighted. Findings suggest that feedstock selection significantly affects methane yield in SS-AD systems, and optimizing substrate mixtures can enhance process efficiency. Key considerations include biodegradability and lignocellulosic content. Operational parameters, such as temperature variations, impact the results from the model, while responsiveness of hydraulic retention time and organic loading rate remains limited. A further comparison between a liquid anaerobic digestion (L-AD) vs SS-AD is made, despite similar methane yields, SS-AD outperforms due to higher energy turnover. Additionally, effective management of digestate nutrients is crucial for its biofertilizer use. Beyond the biogas system, the thesis explores interconnected relationships between SS-AD inputs and outputs and their subsequent use as resources for a hydroponic greenhouse production system. The examination of system interconnections and their broader implications emphasizes the importance of comprehensive assessments when integrating biogas systems beyond their conventional applications.
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| 4. |
- Carlos-Pinedo, Sandra, et al.
(author)
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Study of the digestion process at a full-scale solid-state biogas plant by using ORWARE : Model modification and implementation
- 2020
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In: Waste Management. - : Elsevier. - 0956-053X .- 1879-2456. ; 107, s. 133-142
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Journal article (peer-reviewed)abstract
- The configuration of the reactor influences the digestion process and thus the product yields; other factors such as the rate of biogas production or biogas loss also affect the process specifically with high solid configuration. With these in mind, the ORganic WAste REsearch (ORWARE) anaerobic digestion sub-model was modified to be able to study solid-state anaerobic digestion (SS-AD) (using plug-flow reactor). The simulation results from the updated model agreed with the operational data with respect to methane yield, digestate yield and energy turnover. The model was found to be sensitive to changes in feedstock composition but to a lesser extent to changes in process temperature and retention time. By applying the model on several cases of liquid anaerobic digestion (L-AD), it was noticed that L-AD at mesophilic condition with 25 retention days seemed to be superior to other cases of L-AD with regard to energy turnover. However, even if similar methane production were observed for L-AD and SS-AD, the model suggested higher energy turnover for the case of SS-AD at thermophilic condition, being 10% more in average in comparison with cases of L-AD.
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| 5. |
- Kapoor, Manali, et al.
(author)
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Impact of Conditioning Prior to Dilute Acid Deconstruction of Biomass for the Production of Fermentable Sugars
- 2017
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In: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 5:5, s. 4285-4292
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Journal article (peer-reviewed)abstract
- Cost of cellulases is a major impediment in commercialization of cellulosic ethanol. To reduce the enzyme doses for the production of fermentable sugars from rice straw (RS), a series of alkali conditioning experiments were conducted prior to dilute acid (DA) pretreatment. This approach resulted in removal of a majority of extractives, ash, acetic acid, and part lignin, and thus resulted in lowering pseudolignin formation thereby increasing enzymatic hydrolysis yields. Glucan hydrolysis of 69.8%, 74.0%, and 83.5% was obtained at 10 wt % water insoluble solid (WIS) using 8 FPU enzyme/g WIS of biomass conditioned using 0.2, 0.4, and 0.5 wt % alkali prior to pretreatment, which is 14–37% higher than the control (61.0%). The overall sugar recovery in these experiments were 69.2%, 70.2%, and 68.5% at 15 wt % WIS resulting in a sugar concentration greater than 120 g/L, which in turn can produce approximately 5–6% w/v ethanol concentration in fermentation broth. It was found that this approach resulted in a decrease of the enzyme consumption vis-a-vis the conventional process by 46.4% to recover the same amount of sugars. This lowering of enzyme consumption has resulted in net savings, after taking into account the cost of alkali used in the conditioning steps.
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| 6. |
- Kapoor, M., et al.
(author)
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Pilot scale dilute acid pretreatment of rice straw and fermentable sugar recovery at high solid loadings
- 2017
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In: Bioresource Technology. - : Elsevier. - 0960-8524 .- 1873-2976. ; 224, s. 688-693
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Journal article (peer-reviewed)abstract
- The aim of this work was to study the dilute acid pretreatment of rice straw (RS) and fermentable sugar recovery at high solid loadings at pilot scale. A series of pretreatment experiments were performed on RS resulting in >25 wt% solids followed by enzymatic hydrolysis without solid-liquid separation at 20 and 25 wt% using 10 FPU/g of the pretreated residue. The overall sugar recovery including the sugars released in pretreatment and enzymatic hydrolysis was calculated along with a mass balance. Accordingly, the optimized conditions, i.e. 0.35 wt% acid, 162 °C and 10 min were identified. The final glucose and xylose concentrations obtained were 83.3 and 31.9 g/L respectively resulting in total concentration of 115.2 g/L, with a potential to produce >50 g/L of ethanol. This is the first report on pilot scale study on acid pretreatment of RS in a screw feeder horizontal reactor followed by enzymatic hydrolysis at high solid loadings.
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| 7. |
- Raj, Tirath, et al.
(author)
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Microalgae biomass deconstruction using green solvents: Challenges and future opportunities
- 2023
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In: Bioresource Technology. - : Elsevier. - 0960-8524 .- 1873-2976. ; 369
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Journal article (peer-reviewed)abstract
- Microalgae enable fixation of CO2 into carbohydrates, lipids, and proteins through inter and intracellularly biochemical pathways. These cellular components can be extracted and transformed into renewable energy, chemicals, and materials through biochemical and thermochemical transformation processes. However, recalcitrant cell wall and lack of environmentally benign efficient pretreatment processes are key obstacles in the commercialization of microalgal biorefineries. Thus, current article describes the microalgal chemical structure, type, and structural rigidity and summarizes the traditional pretreatment methods to extract cell wall constituents. Green solvents such as ionic liquid (ILs), deep eutectic solvents (DES), and natural deep eutectic (NDESs) have shown interesting solvent characteristics to pretreat biomass with selective biocomponent extraction from microalgae. Further research is needed in task-specific IL/DES design, cation-anion organization, structural activity understanding of ILs-biocomponents, environmental toxicity, biodegradability, and recyclability for deployment of carbon-neutral technologies. Additionally, coupling the microalgal industry with biorefineries may facilitate waste management, sustainability, and gross revenue.
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| 8. |
- Rani Singhania, Reeta, et al.
(author)
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Consolidated Bioprocessing of Lignocellulosic Biomass: Technological Advances and Challenges
- 2022
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In: Bioresource Technology. - : Elsevier. - 0960-8524 .- 1873-2976. ; 354
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Journal article (peer-reviewed)abstract
- Consolidated bioprocessing (CBP) is characterized by a single-step production of value-added compounds directly from biomass in a single vessel. This strategy has the capacity to revolutionize the whole biorefinery concept as it can significantly reduce the infrastructure input and use of chemicals for various processing steps which can make it economically and environmentally benign. Although the proof of concept has been firmly established in the past, commercialization has been limited due to the low conversion efficiency of the technology. Either a native single microbe, genetically modified microbe or a consortium can be employed. The major challenge in developing a cost-effective and feasible CBP process is the recognition of bifunctional catalysts combining the capability to use the substrates and transform them into value-added products with high efficiency. This article presents an in-depth analysis of the current developments in CBP around the globe and the possibilities of advancements in the future.
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| 9. |
- Ruchi, Gaur, et al.
(author)
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Bench scale dilute acid pretreatment optimization for producing fermentable sugars from cotton stalk and physicochemical characterization
- 2016
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In: Industrial crops and products (Print). - : Elsevier BV. - 0926-6690 .- 1872-633X. ; 83, s. 104-112
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Journal article (peer-reviewed)abstract
- Cotton stalk is a holocellulose rich, inexpensive agricultural residue available in surplus without any competitive uses neither as food nor as animal fodder. These aspectshold high potential for cotton stalk as a biomass to be suitable for ethanol production. Dilute acid pretreatment conditions on bench scale have been optimized for cotton stalk by Response Surface Methodology (RSM) using Central Composite Design (CCD). Effect of four pretreatment process variables viz. temperature, acid concentration, time of reaction and stirring speed has been optimized for maximum enzymatic sugar release during the subsequent enzymatic saccharification. Under the optimized pretreatment conditions, i.e., temperature: 157. °C, acid concentration: 1.07% (w/w),and time: 20 min, enzymatic sugar releasewas found to be 684 mg/g of dry pretreated biomass. A correlation of hemicellulose removal and inhibitor formation with combined severity factor (CSF) was drawn. Mass balance carried out for the pretreatment step under optimized conditions resulted in 68.35 and 8.31% of xylose and glucose saccharificationyieldsrespectively. Subsequent enzymatic saccharification yieldsofglucose and xylose were 93.56 and 19.93% respectively. The overall saccharification yield integrating pretreatment and enzymatic hydrolysis of cotton stalk was 91.06%. Physicochemical characterization of native and pretreated biomass was carried out by compositional analysis, FT-IR and XRD revealing significant changes in biomassproperties responsible for improved saccharification efficiency.
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| 10. |
- Silvestro, Daniele, et al.
(author)
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The role of hydrogen in mitigating global climate change
- 2023
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In: Handbook on Climate Change and Technology. - : Elgar. - 9781800882102 - 9781800882119 ; , s. 134-162
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Book chapter (peer-reviewed)abstract
- Climate change is challenging human life and infrastructures by modifying the environment in which we live at a difficult-to-adapt rate. The transition to a low carbon and sustainable society is key to avoid a further decline of the climate and the environment and can be achieved by adopting renewable energy sources. The necessary increase in renewable energy production faces challenges like identifying cost effective power storage solutions and adapting to inadequate electricity grid infrastructures. Renewable energy, however, cannot be the only solution for sectors that are hard to electrify. Green hydrogen from renewable-based electricity can represent a solution for decarbonization. Hydrogen, produced from renewable resources, storable, and with a high potential to replace fossil fuels in the most energy intensive, hard-to-decarbonize and polluting applications, can play a pivotal role in climate change mitigation.
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