A radical adjustment to current energy systems will be imperative in achieving the Paris Agreement. This paper analyses the holistic 2050 Danish energy system and particularly its future transport ...sector, which aims to be fossil fuel independent. Using a linear optimisation tool (Balmorel-OptiFlow), the role of electrofuels is analysed at a high temporal and geographic resolution for the Nordic + German region. Electrofuel technologies have been investigated and incorporated into the energy model creating a comprehensive catalogue of alternative fuel pathways. Results reveal an energy system with a high reliance on variable energy sources. Electrofuels that utilise biomass have been found to be more economically attractive compared to electrofuels using carbon capture. Biomass costs, fuel demands, and electricity prices drive the competition between the evaluated alternative fuel pathways. Carbon capture technologies are found to not play a role in the production of transport fuels unless future biomass resources are more limited or costly than expected. Additionally, it has been found that temporal resolution can greatly affect results when modelling alternative fuel pathways. The study concludes that electrofuels - particularly those using biomass - can play a prominent role in future transport sectors.
•Electrofuels have high use potential in future transport systems.•Fuels using hydrogen can be more economically attractive compared to biofuels.•Modelling of electrofuels in holistic energy systems enables sector coupling.•Novel modelling of electrofuels with high temporal and spatial resolution.•Linkage of power market model and detailed spatiotemporal network model.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The increase of energy demand coped with utilization of fossil resources have engendered serious environmental impact. The progressively stringent worldwide emission legislation and increasing ...greenhouse gas emission require significant research effort on alternative fuels. Therefore, biodiesels are becoming important increasingly due to its ease in adaptation, environmental benefits and prospect in energy security. Biodiesel derived from vegetable oils, waste cooking oils and animal fats are long chain fatty acid alkyl esters, which contains unsaturated portions that are susceptible to oxidation. Biodiesel oxidation is a complex process having a number of mechanisms involved. Autoxidation radical chain reactions are the primary cause of biodiesel degradation that leads to formation of hydroperoxide, which, after that decompose to form an array of secondary oxidation products like aldehydes, ketones, carboxylic acids, oligomers, gum, sediment etc. Antioxidants are often used to inhibit biodiesel oxidative degradation. The present review attempts to cover the inhibition action of natural and synthetic antioxidants, methods used to analyze biodiesel oxidation and their effect on biodiesel derived from various feedstocks. Phenolic antioxidants are more effective compared to amine antioxidants. Pyrogallol is found to be the most effective antioxidant to improve the oxidation stability in case of almost all biodiesels reviewed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The integration of energy, water and environment systems represents important opportunities for addressing the urgent imperative of climate neutrality. The 29 original papers in the virtual special ...issue of the 14th Conference on Sustainable Development of Energy, Water and Environment Systems exemplify multiple advances in integrated approaches. This editorial provides a review of recent scientific contributions in energy system integration, urban synergies in the energy transition, integration of energy and water systems as well as valorization of waste heat. Advances that relate to sustainable combustion, biomass, and managing emissions provide further perspectives. All seven themes contain new research directions in such areas as solar energy technologies, thermal energy storage, power-to-X technologies, district heating and cooling networks, wastewater treatment plants, water desalination, and salinity gradient technologies. Advanced optimization approaches, big data analytics for cogeneration, thermal management applications, pollution minimization, lignocellulosic biomass, catalysts for alternative fuels as well as carbon capture, storage and utilization are described among other scientific contributions. Across the world, the focus on integration is gaining prominence, especially with the European Union Strategy on Energy System Integration that recognizes the role of a coordinated approach for planning and operating the energy system as a whole. The research advances that are contained in this editorial will support the realization of a coherent approach on the path towards sustaining the life-support systems of the planet and thereby support sustainable development.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•A range of potential aviation biofuels were tested for their compatibility with Jet A-1.•Esters are more compatible with aviation kerosene than alcohols.•Biodiesel is suitable for aviation if ...composed soley of short chain saturates.•None of the fuels, except the hydrocarbons, matched the range vs. payload of Jet-A1.•Of the potential fuels studied, only limonene was found to fall within the required specification.
Environmental concerns and the rising cost of crude oil have incentivized the search for alternative aviation fuels. However, any potential alternatives must be thoroughly characterized and tested. In this investigation nine potential biofuels derived from sustainable sources were tested for their compatibility with Jet A-1 aviation kerosene. The fuels chosen were n-butanol, n-hexanol, butyl levulinate, butyl butyrate, ethyl octanoate, methyl linolenate, farnesene, ethyl cyclohexane and limonene. Viscosities were determined between −30 and 40°C and were observed to increase with decreasing temperature roughly in accordance with ideal fluid behavior. Cloud point temperatures of all samples were tested and all fuels except n-butanol and methyl linolenate were found to be below the specification maximum. Flash points of all fuels apart from pure and blends of ethyl cyclohexane and n-butanol were found to be greater than 38°C, the minimum threshold specified in the standard. Of all the samples only the hydrocarbon fuels met the required energy content minimum with energy content decreasing with increasing oxygen content. The effect of each fuel on the range vs. the payload, relative to Jet A-1 was determined using a simplified model in order to ascertain likely impact of adoption upon airline operations. Only limonene fulfilled all the requirements of an alternative aviation fuel, though butyl butyrate and ethyl octanoate were acceptable except for the reduced energy density.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The use of hydrogen as fuel represents a possible solution to reduce greenhouse gas emission from vehicles. Although proper engine running with hydrogen has been widely demonstrated, hydrogen storage ...onboard of the vehicle is a major problem.
A promising solution is storing hydrogen in the form of ammonia that is liquid at roughly 9 bar at environmental temperature and therefore involves relatively small volumes and requires light and low-cost tanks.
Ammonia can be burned directly in IC engines, however a combustion promoter is necessary to support combustion. As a matter of fact, the best (and carbon-free) promoter is hydrogen, which has very high combustion velocity and wide flammability range, whereas ammonia combustion is characterised by low flame speed and temperature, narrow flammability range and high ignition energy.
The experimental activity shown in this paper is focused on analysing the behaviour of a 4-stroke twin-cylinder SI engine of 505 cm3 fuelled ammonia-plus-hydrogen. This engine was expressly chosen and modified to be placed in a range extended vehicle where hydrogen is obtained from ammonia by means of on-board catalytic reforming. The experimental results confirm that it is necessary to add hydrogen to air-ammonia mixture to improve ignition and to increase combustion velocity, with ratios that depend mainly on load and less on engine speed. Owing to intake air dilution and to lower flame speed of the ammonia-hydrogen-air mixture, a general decrement in engine performances has been detected in respect to the original gasoline version.
► A 4-stroke S.I. engine has been modified to be fuelled with ammonia and hydrogen. ► Hydrogen to ammonia energy ratio mainly depends on load and less on engine speed. ► The efficiency of the engine fuelled with NH3–H2 is lower than with gasoline. ► Engine cyclic stability increases increasing the hydrogen to ammonia energy ratio. ► Hydrogen can be obtained from ammonia by on-board catalytic reforming.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Biogas from anaerobic digestion of biological wastes is a renewable energy resource. It has been used to provide heat, shaft power and electricity. Typical biogas contains 50–65% methane (CH4), ...30–45% carbon dioxide (CO2), moisture and traces of hydrogen sulphide (H2S). Presence of CO2 and H2S in biogas affects engine performance adversely. Reducing CO2 and H2S content will significantly improve quality of biogas. In this work, a method for biogas scrubbing and CH4 enrichment is presented. Chemical absorption of CO2 and H2S by aqueous solutions in a packed column was experimentally investigated. The aqueous solutions employed were sodium hydroxide (NaOH), calcium hydroxide (Ca(OH)2) and mono-ethanolamine (MEA). Liquid solvents were circulated through the column, contacting the biogas in countercurrent flow. Absorption characteristics were examined. Test results revealed that the aqueous solutions used were effective in reacting with CO2 in biogas (over 90% removal efficiency), creating CH4 enriched fuel. H2S was removed to below the detection limit. Absorption capability was transient in nature. Saturation was reached in about 50min for Ca(OH)2, and 100min for NaOH and MEA, respectively. With regular replacement or regeneration of used solutions, upgraded biogas can be maintained. This technique proved to be promising in upgrading biogas quality.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Graphene, as an ideal two-dimensional material and single-atom layer of graphite, has attracted exploding interests in multidisciplinary research because of its unique structure and exceptional ...physicochemical properties. Especially, graphene-based materials offer a wide range of potentialities for environmental remediation and energy applications. This review shows an extensive overview of the main principles and the recent synthetic technologies about designing and fabricating various innovative graphene-based materials. Furthermore, an extensive list of graphene-based sorbents and catalysts from vast literature has been compiled. The adsorptive and catalytic properties of graphene-based materials for the removal of various pollutants and hydrogen storage/production as available in the literature are presented. Tremendous adsorption capacity, excellent catalytic performance and abundant availability are the significant factors making these materials suitable alternatives for environmental pollutant control and energy-related system, especially in terms of the removal of pollutants in water, gas cleanup and purification, and hydrogen generation and storage. Meanwhile, a brief discussion is also included on the influence of graphene materials on the environment, and its toxicological effects. Lastly, some unsolved subjects together with major challenges in this germinating area of research are highlighted and discussed. Conclusively, the expanding of graphene-based materials in the field of adsorption and catalysis science represents a viable and powerful tool, resulting in the superior improvement of environmental pollution control and energy development.
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•Recent studies on synthetic pathways of graphene-based materials are reviewed.•Applications of graphene-based sorbents and catalysts are discussed and summarized.•Opportunities and outlook about graphene-based materials are presented.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Vertically aligned graphene nanosheets have been synthesized by radio-frequency plasma-enhanced chemical vapor deposition on nickel-foam current collectors and that have been used as substrates for ...cathodic electrodeposition of cobalt hydroxide nanosheets in Co(NO3)2 aqueous solution. Raman spectrum exhibits that high-quality graphene nanosheets have been synthesized. The composites have been characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, cyclic voltammetry and galvanostatic charge/discharge. It indicates that hexagonal Co(OH)2 has a network microstructure, consisting of interlaced sheets with the thickness of 12 nm coated on the graphene nanosheets. The binder-free nano-electrode exhibits excellent pseudocapacitive behavior with pseudocapacitances of 693.8 and 506.2 Fg−1 at current density of 2 and 32 Ag−1, respectively, in a potential range of −0.1–0.45 V. The capacitance can retain about 91.9% after 3000 charge–discharge cycles at 40 Ag−1, which is higher than that of Co(OH)2/Ni foam (after 2000 cycles, 75.5% of initial capacitance remains). The introduction of graphene between Co(OH)2 and Ni foam demonstrates an enhancement of electrochemical stability of the nano-electrodes.
► We report a novel route for preparation of Co(OH)2/graphene/Ni foam nano-electrode. ► The material has a specific capacitance of 693.8 Fg−1 at 2 Ag−1 in KOH solution. ► After 3000 cycles at 40 Ag−1, 91.9% specific capacitance could be retained. ► The good performance is related to covalent binding of C–O–Co.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
500.
Use of algae as biofuel sources Demirbas, Ayhan
Energy conversion and management,
12/2010, Volume:
51, Issue:
12
Journal Article
Peer reviewed
The aim of this study is to investigate the algae production technologies such as open, closed and hybrid systems, production costs, and algal energy conversions. Liquid biofuels are alternative ...fuels promoted with potential to reduce dependence on fossil fuel imports. Biofuels production costs can vary widely by feedstock, conversion process, scale of production and region. Algae will become the most important biofuel source in the near future. Microalgae appear to be the only source of renewable biodiesel that is capable of meeting the global demand for transport fuels. Microalgae can be converted to bio-oil, bioethanol, bio-hydrogen and bimethane via thermochemical and biochemical methods. Microalgae are theoretically very promising source of biodiesel.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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