High-energy Fuels Research Articles

Potential contribution of the wastewater sector to energy supply

The biological treatment of wastewater could yield high energy fuels such as methane and alcohols, however most conventional treatment systems do not recover this energy potential. with a simple model of the energy yields of various wastewater treatment technologies it is possible to demonstrate how minor shifts in technology selection can lead the industry from being identified as predominantly energy intensive, to being recognised as a source of energy resources. The future potential energy yield is estimated by applying energy yield factors to alternative use scenarios of the same wastewater loads. The method for identifying the energy potential of wastewater was demonstrated for the New Zealand wastewater sector, but can equally be applied to other countries or regions. The model suggests that by using technologies that maximise the recovery of energy from wastewater, the potential energy yield from this sector would be substantially increased (six fold for New Zealand).

Photosynthesis driven conversion of carbon dioxide to fatty alcohols and hydrocarbons in cyanobacteria

The production of high value biochemicals and high energy biofuels from sustainable resources through the use of microbial based, green conversion technologies could reduce the dependence on petrochemical resources. However, a sustainable source of carbon and a clean, cost effective method for its conversion to high quality biofuel products are obstacles that must be overcome. Here we describe the biosynthesis of fatty alcohols in a genetically engineered cyanobacterial system through heterologously expressing fatty acyl-CoA reductase and the effect of environmental stresses on the production of fatty alcohols in the mutant strains. Hydrocarbon production in three representative types of native cyanobacterial model strains and the mutant strain overexpressing acetyl-CoA carboxylase was evaluated. The results of this investigation demonstrate the potential for direct production of high value chemicals and high energy fuels in a single biological system that utilizes solar energy as the energy source and carbon dioxide as the carbon source.

ChemInform Abstract: Metallacarboranes of the Lanthanoid and Alkaline-Earth Metals: Potential High-Energy Fuel Additives

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Microbial production of fatty-acid-derived fuels and chemicals from plant biomass

Increasing energy costs and environmental concerns have emphasized the need to produce sustainable renewable fuels and chemicals. Major efforts to this end are focused on the microbial production of high-energy fuels by cost-effective 'consolidated bioprocesses'. Fatty acids are composed of long alkyl chains and represent nature's 'petroleum', being a primary metabolite used by cells for both chemical and energy storage functions. These energy-rich molecules are today isolated from plant and animal oils for a diverse set of products ranging from fuels to oleochemicals. A more scalable, controllable and economic route to this important class of chemicals would be through the microbial conversion of renewable feedstocks, such as biomass-derived carbohydrates. Here we demonstrate the engineering of Escherichia coli to produce structurally tailored fatty esters (biodiesel), fatty alcohols, and waxes directly from simple sugars. Furthermore, we show engineering of the biodiesel-producing cells to express hemicellulases, a step towards producing these compounds directly from hemicellulose, a major component of plant-derived biomass.

Turbo graphene

Future high-speed propulsion systems will require environmentally friendly high-energy fuels. One emerging approach to this challenge is not to develop new fuels but to improve existing fuels by adding nanostructured particles. Now Richard Yetter, Ilhan Aksay and co-workers at the Pennsylvania State University and Princeton University have shown that the combustion performance of nitromethane, a potential rocket propellant, can be greatly enhanced by adding functionalized graphene sheets to the fuel.

Borides and vitreous compounds sintered as high-energy fuels

Boron was chosen as fuel in view of its excellent thermodynamic values for combustion, as compared to traditional fuels. The problem of the boron in combustion is the formation of a surface layer of oxide, which delays the ignition process, reducing the performance of the rocket engine. This paper presents a high-energy fuel for rocket engines. It is composed of sintered boron (borides and carbides and vitreous compounds) with a reducing chemical agent. Borides and boron carbide were prepared since the combustion heat of the latter is similar to that of the amorphous boron (in: K.K. Kuo (Ed.), Boron-Based Solid Propellant and Solid Fuel, Vol. 427, CRC Press, Boca Raton, FL, 1993). Several chemical reducing elements were used, such as aluminum, magnesium, and coke. As the raw material for boron, different compounds were used: amorphous boron, boric acid and boron oxide.

Thermal Stability and Shelf-life of High Energy Fuel for Torpedoes (Short Communication)

1,2-Dinitroxy propane-based liquid fuel is an advanced high energy fuel for torpedoes. The high energy fuel is used with an oxidiser, viz., hydroxyl ammonium perchlorate as a bi-propellant system for torpedo propulsion. Thermal stability of high energy fuel has been arrived at by differential thermal analysis and also by following the depletion in stabiliser content as well as increase in acidity with ageing. Rate constant for decomposition, activation energy for depletion of 2-nitro diphenylamine (2-NDPA) and shelf-life of high energy fuel have been determined. Due to the high vapour pressure of high energy fuel (because of 1,2-dinitroxy propane ), usual experimental set up could not be used and the sample was conditioned in sealed tubes. The shelf-life of high energy fuel is arrived at using Woolwich, Berthelot and Arrhenius equations and the results obtained are 100 years, 125 years and 276 years, respectively. Considering the safety aspect, the lowest value, viz., 100 years is recommended as safe life of high energy fuel. This work confirms the reported estimates of the good storage stability of high energy fuel.

Theoretical characterization of oligocubanes

Cubanes are interesting molecules as structural units for a new class of materials, the polycubanes. It is believed that these materials can be used in the production of high-energy fuels as well as present remarkable properties. We report in this work a theoretical investigation on the electronic structure of oligocubanes using semiempirical and ab initio methods. Our geometrical data are in good agreement with the available experimental data. The possibility of using cubane derivatives to synthetize a new class of conducting polymer with small gap is also adressed.

Dynamics and Microexplosion of High Energy Fuels Injected into a Combustor

The effects of microexploding fuel droplets injected into the shear layer in an axisymmelric dump combustor are studied numerically. The fuel droplets considered are multicomponent consisting of a solid high-energy fuel core surrounded by a liquid carrier. When droplets microexplode, pressure waves are generated that reverberate through the system and in some cases couple with the characteristic frequencies of the system. In a particular case, the low frequency quarter wave acoustic mode of the inlet is amplified, resulting in the formation of a large vortex structure near the combustor step. Periodic energy release associated with this large vortex structure sustains the low frequency oscillations even though droplets are injected continuously at a constant rate. By phase-coupling droplet injection to an external acoustic forcing frequency, it is demonstrated that pressure fluctuations at the forced frequency may be amplified or attenuated by the microexplosion of the fuel droplets.

Physico-Chemical Properties and Combustion Characteristics of New High-Energy-Density Caged Hydrocarbon Compounds

A new class of pentacyclic hydrocarbon compounds with high-energy/high density have been synthesized to be used as fuels or fuel additives, with the expectation that their inclusion in the fuel mixture will result in a net increase in volumetric efficiency of the current generation of powerplants. These compounds exhibit high density and contain a moderate amount of strain energy which contributes to the energy output during combustion. Through direct measurements, melting and boiling points, specific heats and latent heats of fusion were determined. Droplet combustion experiments with binary solutions of solid high-energy fuels in kerosene indicated increased effervescence and higher heat output. The liquid high-energy-density formulations exhibited microexplosive combustion behavior.

Evaluation of energy conservation potential by exhaust air recirculation for a commercial-type heated-air batch hay dryer

Energy conservation in drying and processing operations is essential in order to improve the reliability of low and moderate temperature renewable energy systems, and to reduce operating costs and energy consumption in systems using high-energy content fossil fuels in farms and processing plants especially in industrialized economies. An experimental evaluation of energy conservation potential by recirculating exhaust air in a commercial heated-air batch hay dryer is presented. The design of the exhaust recirculation unit is such that only about 30% of the total exhaust air is recirculated through the heater inlet. Experimental tests were conducted on the dryer with and without exhaust air recirculation. Maximum energy savings of 27% and 17% were achieved with exhaust air recirculation during fall and summer dryer operation, respectively.

Alkylation of purine bases by carbon-centered radicals.

Mono- and di-substituted hydrazines are found ubiquitously (1, 2). They are present in the environment since they are used as herbicides, chemical intermediates, and as high energy fuels for rockets. They are found in plants such as tobacco and mushrooms. They are also present in medicine. All substituted hydrazines tested for carcinogenicity in long-term animal studies have been found to be positive (1). 1, 2-dimethylhydrazine (DMH) is a well known carcinogen that induces tumors specifically in the colon of rodents (3). Since DMH-induced lesions have characteristics that are remarkably similar to those of human colon cancer, this carcinogen is widely used as a model in the study of colon cancer. The ethyl derivative of DMH, 1, 2-diethylhydrazine (DEH), is also a carcinogen. DEH produces cancer in the thymus, liver, and brain (4). The mechanism(s) by which these di-alkyl hydrazines induce tumors is not known. Kang et al. (5) have shown that in rats the metabolism of DMH and DEH produces methyl radicals (·CH3) and ethyl radicals (·CH2CH3), respectively. Therefore, this investigation was conducted to explore the nature of the chemical interaction(s) between alkyl radicals and biomolecules using CH3 and RNA as models.KeywordsAlkyl RadicalEthyl RadicalPurine BaseChemical IntermediateChemical CarcinogenesisThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Studies of the Deposit Formation on Storage of a High Energy Fuel

AbstractStorage stabilities of a petroleum‐derived jet fuel (JP‐5), manufactured by the Chinese Petroleum Corporation in Taiwan, were studied. Fuel degradation was monitored in the presence of added specific heteroatomic (O, N, S) and unsaturated compounds, copper, iron and aluminum powders and mixtures of some of these at room temperature and 80°C. A mechanism is suggested for the sediment formation with the sulfur compounds. The extent of light scattering and of metal drawn into JP‐5 from added metal powder measured by ICP‐AES are correlated with the extent of deposit formation in degradation of the fuel. Metal promotes deterioration of JP‐5, because of metal complex formation.

High-energy fuels and materials from plants

Description of a number of plant families that produce harvestable amounts of terpenes that can be used as hydrocarbon fuel.

High Energy Fuels I: A Novel Preparation of Exo‐Tetrahydrodicyclopentadiene by Isomerization of Endo‐Tetrahydrodicyclopentadiene

AbstractEndo‐tetrahydrodicyclopentadiene (IV) is isomerized in the presence of trifluoromethanesulfonic acid (I) to give exo‐tetrahydrodicyclopentadiene (V). At higher acid concentrations, the isomerization occurs instantaneously. The preferred molar ratio of I to IV is in the range 0.05 to 4.0 and the preferred temperature is in the range 20°C to 100°C. Under these conditions, virtually no admantane is formed and undesirable C10H16 isomers can be reduced to a minimum. Besides the homogeneous system, the acid catalyst also works in a two‐phase heterogeneous system. The spent acid in the heterogeneous system can be reused without losing catalytic effectiveness.

High Energy Fuels II: Gas Chromatographic Separation of Energetic Compounds Derived from Dicyclopentadiene

AbstractAn effective gas‐liquid chromatographic separation of thirteen energetic dicyclopentadiene derivatives has been established using OV‐17 as the stationary phase. FID was chosen as the favorable detector after comparing its response factors with those of TCD. Using this method good repeatability, reproducibility and precision are obtained in both qualitative and quantitative analyses of compounds investigated.

Experimental investigation of fuel combustion in counterflowing high-temperature air flow

The possibility of using high-energy synthetic hydrocarbon fuels, borane fuels, as well as borohydrocarbon fuels are currently being studied for use by various kinds of aircraft with jet engines. The problem addressed in this work included experimental determination of the geometric characteristics of the vaporization and combustion zones of borohydrocarbon fuel sprayed in a counterflowing air flow and comparing them with the analogous characteristics of hydrocarbon fuel and gaseous hydrogen. A direct spray nozzle with the same construction was used in the experiments and the parameters of the counterflowing air remained approximately the same. The preliminary stage of the investigations, performed with fuel injected into the ocmoving, passing, and counterflowing air flow, showed that stable combustion of the liquid fuel was possible only in the case of counterflow fuel injection. It was demonstrated that the hitting distance and diameter of the jet of boron containing fuel turned out to be approximately two times shorter than that of the hydrocarbon fuel, and 1.5 times greater than that of hydrogen fuel. Therefore, the borohydrocarbon jet vaporized two times more rapidly in the counterflowing high-temperature air flow than a hydrocarbon jet. The results apparently indicate that the combustion mechanisms of these fuels aremore » different, which should be considered by researchers concerned with theoretical methods for calculating the working process in combustion chambers operating on borane fuels.« less

A New Prepolymer: Lactone-Terminated Polybutadiene (LTPB) for High-Energy Solid Propellants

N composite propellants, polybutadiene prepolymers are considered as high-energy fuels. Poly(butadiene-acrylic acid) (PBAA) is the earliest prepolymer in this category wherein the functional COOH groups are randomly distributed along the chain. The uneven spacing of the carboxyl groups, which gives rise to poor mechanical properties of the PBAA-based propellant, is improved by the interjection of acrylonitrile groups between the polybutadiene and acrylic acid molecules. The resulting terpolymer, viz. poly(butadiene-acrylic acid-acrylo-nitrile) (PBAN), has more reproducible mechanical characteristics and is widely used as a fuel prepolymer in high-energy solid propellants. However, for better low-temperature properties and for improved performance, carboxyl-terminated polybutadiene (CTPB) prepolymer made by various methods1;3 is preferred to PBAN. Hydroxyl-terminated polybutadiene (HTPB) is the most recent entrant; it permits solid loadings of up to 90% and still retains mechanical properties within acceptable limits. An extensive review of the work on polybutadiene based solid propellants is given by Mastrolia and Klager.4 In the present paper we report the synthesis of a new prepolymer, lactone-terminated polybutadiene (LTPB), which has terminal functional groups different from those in any of the polybutadiene prepolymers reported so far. The characteristics of the propellant based on the LTPB prepolymer are also presented here. The prepolymer is designated as HEF-20, short for high-energy fuel of series 20.

High-Energy Fuels for Cruise Missiles

The development and operational deployment of air-, sea-, and ground-launched cruise missiles may be the most significant advance in the U.S. strategic and tactical weapon systems in the next several years. Both the U.S. Air Force and U.S. Navy have developed specially synthesized liquid hydrocarbon fuels which are used in the air-launched cruise missile (ALCM) and the sea-launched cruise missile (SLCM). The preparation, properties, and performance of these and other high-energy fuels are described. These fuels have extended the range of cruise missiles approximately 15% over that which could be achieved with conventional fuels.

Fuels from biomass—energy outlay versus energy returns: A critical appraisal

The concept of fuel production by the microbial conversion of biomass is discussed with particular emphasis upon the energy implications involved. Both the energy requirements and energy returns for a number of selected systems are assessed in the light of current technology, while areas for future improvements are also mentioned. The general trend of such biological energy systems is that energy gains made via plant photosynthesis using intensive systems are subsequently more than lost in the conversion of biomass energy content into storable, high-energy fuels such as ethanol and methane. Of the operations under investigation, the growth of sugarcane and its fermentation to ethanol is considered to be the most favourable as a marginal net energy production process.