A huge challenge facing scientists is the development of adsorbent materials that exhibit ultrahigh porosity but maintain balance between gravimetric and volumetric surface areas for the onboard ...storage of hydrogen and methane gas-alternatives to conventional fossil fuels. Here we report the simulation-motivated synthesis of ultraporous metal-organic frameworks (MOFs) based on metal trinuclear clusters, namely, NU-1501-M (M = Al or Fe). Relative to other ultraporous MOFs, NU-1501-Al exhibits concurrently a high gravimetric Brunauer-Emmett-Teller (BET) area of 7310 m
g
and a volumetric BET area of 2060 m
cm
while satisfying the four BET consistency criteria. The high porosity and surface area of this MOF yielded impressive gravimetric and volumetric storage performances for hydrogen and methane: NU-1501-Al surpasses the gravimetric methane storage U.S. Department of Energy target (0.5 g g
) with an uptake of 0.66 g g
262 cm
(standard temperature and pressure, STP) cm
at 100 bar/270 K and a 5- to 100-bar working capacity of 0.60 g g
238 cm
(STP) cm
at 270 K; it also shows one of the best deliverable hydrogen capacities (14.0 weight %, 46.2 g liter
) under a combined temperature and pressure swing (77 K/100 bar → 160 K/5 bar).
Liquids and gases produced through biomass pyrolysis have potential as renewable fuels to replace fossil fuels in conventional internal combustion engines. This review compares the properties of ...pyrolysis fuels, produced from a variety of feedstocks and using different pyrolysis techniques, against those of fossil fuels. High acidity, the presence of solid particles, high water content, high viscosity, storage and thermal instability, and low energy content are typical characteristics of pyrolysis liquids. A survey of combustion, performance and exhaust emission results from the use of pyrolysis liquids (both crude and up-graded) in compression ignition engines is presented. With only a few exceptions, most authors have reported difficulties associated with the adverse properties of pyrolysis liquids, including: corrosion and clogging of the injectors, long ignition delay and short combustion duration, difficulty in engine start-up, unstable operation, coking of the piston and cylinders and subsequent engine seizure. Pyrolysis gas can be used more readily, either in spark ignition or compression ignition engines; however, NOx reduction techniques are desirable. Various approaches to improve the properties of pyrolysis liquids are discussed and a comparison of the properties of up-graded vs. crude pyrolysis liquid is included. Further developments in up-gradation techniques, such as hydrocracking and bio-refinery approaches, could lead to the production of green diesel and green gasoline. Modifications required to engines for use with pyrolysis liquids, for example in the fuel supply and injection systems, are discussed. Storage stability and economic issues are also reviewed. Our study presents recent progress and important R&D areas for successful future use of pyrolysis fuels in internal combustion engines.
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Lignocellulosic biomass is an abundant organic material that can be used for sustainable production of bioenergy and biofuels such as biogas (about 50–75% CH4 and 25–50% CO2). Out of all ...bioconversion technologies for biofuel and bioenergy production, anaerobic digestion (AD) is a most cost-effective bioconversion technology that has been implemented worldwide for commercial production of electricity, heat, and compressed natural gas (CNG) from organic materials. However, the utilization of lignocellulosic biomass for biogas production via anaerobic digestion has not been widely adopted because the complicated structure of the plant cell wall makes it resistant to microbial attack. Pretreatment of recalcitrant lignocellulosic biomass is essential to achieve high biogas yield in the AD process. A number of different pretreatment techniques involving physical, chemical, and biological approaches have been investigated over the past few decades, but there is no report that systematically compares the performance of these pretreatment methods for application on lignocellulosic biomass for biogas production. This paper reviews the methods that have been studied for pretreatment of lignocellulosic biomass for conversion to biogas. It describes the AD process, structural and compositional properties of lignocellulosic biomass, and various pretreatment techniques, including the pretreatment process, parameters, performance, and advantages vs. drawbacks. This paper concludes with the current status and future research perspectives of pretreatment.
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The clean and sustainable CO
2
reutilization toward products of higher value is of great interest in a background of established environmental concerns and reducing the use of fossil fuels. As ...promising alternative fuels, hydrocarbons are more valuable than CO, alcohols or formate and can be directly used in existing infrastructures with high energy densities. The prominent development of catalysts capable of selectively converting CO
2
into hydrocarbons, from methane to short olefins and long carbon-chains, has been reflected in an expanding volume of exploratory works, which suitably demand interpretive and continuous revision. In the past decades, conventional studies on the thermochemical conversion of CO
2
have consistently unlocked meaningful pathways toward the synthesis of hydrocarbons covering a fairly wide range of molecular weights. Conversely, both electrochemically and photochemically driven reactions have only now started to unveil encouraging results, with an extensive number of critical citations outlining the continuous emergence of very recently published reports. In a field in need of urgent development, the authors provide, in a clear form, a detailed retrospective on benchmark catalysts, pioneering approaches and competitive developments in this subject, mechanistic difficulties, emerging stability issues, and reactor design, while highlighting the latest noteworthy reports. Most importantly, this review highlights the advances toward an increase in the hydrocarbon chain-length in the synthesis of highly competitive alternative fuels. Comparisons of valuable thermochemical, electrochemical and photochemically driven strategies in the conversion of CO
2
to hydrocarbons are expected to serve as guidelines to disclose promising pathways in a field where mechanistic uncertainties remain a bottleneck for determining the product selectivity. The authors summarize leading and inquisitive perspectives with a focus on the viability and practicability of each approach at a larger scale, while tentatively paving the way to stimulate progress in this field.
Comprehensive insight into the thermochemical, photochemical and electrochemical reduction of CO
2
to methane and long-chain hydrocarbons as alternative fuels.
Biodiesel, derived from the transesterification of vegetable oils or animal fats, is composed of saturated and unsaturated long-chain fatty acid alkyl esters. In spite of having some application ...problems, recently it is being considered as one of the most promising alternative fuels in internal combustion engine. From scientific literatures, this paper has collected and analyzed the data on both advantages and disadvantages of biodiesel over conventional diesel. Since the aim of this study is to evaluate the biodiesel feasibility in automobiles, the first section is dedicated to materials compatibility in biodiesel as compared to that in diesel. The highest consensus is related to enhanced corrosion of automotive parts due to its compositional differences. In the subsequent sections, data on performance, emission and engine durability have been analyzed and compared. In this case, the highest consensus is found in reducing emissions as well as in increasing moving parts sticking, injector coking and filter plugging. This paper has also summarized the factors of biodiesel in contributing these technical performances.
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37.
Technical review on jet fuel production Liu, Guangrui; Yan, Beibei; Chen, Guanyi
Renewable & sustainable energy reviews,
09/2013, Volume:
25
Journal Article
Peer reviewed
Open access
In present study, we investigated jet fuel production process, including the crude oil-based conventional process, unconventional oil sources-based process, Fischer–Tropsch synthesis (F–T) process ...and renewable jet fuel process and analyzed the details of each jet fuel production process. Among these jet fuel production technologies, the F–T synthesis and renewable jet fuel process supply alternative fuels with potential environmental benefit of reduced life cycle greenhouse gas (GHG) emissions and the economic benefits associated with increased fuel availability and lower fuel costs. The F–T synthesis has a major advantage with the possibility of accepting any carbon-based input, which makes it suitable for using a variety of sources such as coal, natural gas and 2nd generation biomass as feedstocks. The renewable jet fuel process such as Bio-Synfining™ (Syntroleum) and Ecofining™ (UOP) as well as C-L™ (Tianjin University) is a low capital cost process of producing high quality synthetic paraffinic kerosene (SPK) from bio-renewable feeds like vegetable oils/fats and waste cooking oils/fats, greases, energy plants of jatropha and algal. The SPK has superior fuel properties to other options available today, with higher cetane number, lower cloud point and lower emissions
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Water electrolysis derived by renewable energy such as solar energy and wind energy is a sustainable method for hydrogen production due to high purity, simple and green process. One of the challenges ...is to reduce energy consumption of water electrolysis for large-scale application in future. Cell voltage, an important criterion of energy consumption, consists of theoretical decomposition voltage (Uθ), ohmic voltage drop (i⁎∑R) and reaction overpotential (η). The kinetic and thermodynamic roots of high cell voltage are analyzed systemically in this review. During water electrolysis, bubble coverage on electrode surface and bubble dispersion in electrolyte, namely bubble effect, result in high ohmic voltage drop and large reaction overpotential. Bubble effect is one of the most key factors for high energy consumption. Based on the theoretical analysis, we summarize and divide recent intensification technologies of water electrolysis into three categories: external field, new electrolyte composition and new thermodynamic reaction system. The fundamentals and development of these intensification technologies are discussed and reviewed. Reaction overpotential and ohmic voltage drop are improved kinetically by external field or new electrolyte composition. The thermodynamic decomposition voltage of water is also reduced by new reaction systems such as solid oxide electrolysis cell (SOEC) and carbon assisted water electrolysis (CAWE).
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This paper reviews the literature available concerning the energy balance of internal combustion engines operating on alternative fuels. Global warming and energy crisis are among the most important ...issues that threaten the peaceful existence of the man-kind. More usage of alternative fuels and energy loss minimization from automotive engines can be an effective solution to this issue. The energy balance analysis gives useful information on the distribution of supplied fuel energy in the engine systems and identifies the avoidable losses of the real engine process with respect to ideal process. It is a very widely used tool, mostly used for the layout of the engine components. The basic energy balance theory has been discussed in details along with the variations in energy balance approaches and terms. The wall energy loss may vary to a great extent depending on the selection of heat transfer correlations. The theoretical energy balance also explored in this paper with help of thermodynamic models. There are some significant variations observed in energy balance when the engine operating fuel is changed and devices like turbocharger, supercharger etc. are used to boost the intake air pressure. The review extends to the energy balance study of low heat rejection engines (LHR) as well as the effects of engine variables and design factors on energy balance.
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Energy technologies have attracted great attention due to the fast development of sustainable energy. Biodiesel technologies have been identified as the sustainable route through which overdependence ...on fossil fuels can be reduced. Biodiesel has played a key role in handling the growing challenge of a global climate change policy. Biodiesel is defined as the monoalkyl esters of vegetable oils or animal fats. Biodiesel is a cost-effective, renewable, and sustainable fuel that can be made from vegetable oils and animal fats. Compared to petroleum-based diesel, biodiesel would offer a non-toxicity, biodegradability, improved air quality and positive impact on the environment, energy security, safe-to-handle, store and transport and so on. Biodiesels have been used as a replacement of petroleum diesel in transport vehicles, heavy-duty trucks, locomotives, heat oils, hydrogen production, electricity generators, agriculture, mining, construction, and forestry equipment. This book describes a comprehensive overview, covering a broad range of topics on biodiesel technologies and allied applications. Chapters cover history, properties, resources, fabrication methods, parameters, formulations, reactors, catalysis, transformations, analysis, in situ spectroscopies, key issues and applications of biodiesel technology. It also includes biodiesel methods, extraction strategies, biowaste utilization, oleochemical resources, non-edible feedstocks, heterogeneous catalysts, patents, and case-studies. Progress, challenges, future directions, and state-of-the-art biodiesel commercial technologies are discussed in detail. This book is an invaluable resource guide for professionals, faculty, students, chemical engineers, biotechnologists, and environmentalists in these research and development areas.
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