Synfuel development impacts— econometric modelling and policy analysis

The prospects for rapid near-term development of a synfuel industry in the USA have decreased, due to depressed world oil prices, synfuel project cost overruns, and the lukewarm support of the Reagan administration. Nonetheless, socioeconomic and environmental impact analysis studies can provide valuable information for determining the regional welfare effects of proposed projects. The author discusses the results of a regional econometric analysis of the synfuel projects planned for Western Kentucky, which focuses on environmental impacts, and reveals the inevitable trade-offs that would accompany synfuel development. Some policy issues are briefly reviewed, especially that of efficient energy pricing.     

Stresses and their impacts on proton exchange membrane fuel cells: A review

The Proton Exchange Membrane (PEM) fuel cell is a promising substitute for combustion engines owing to its low level of output pollutants and high efficiency. Great efforts have been done toward the commercialization of PEM fuel cell. A number of review papers that investigate the electrochemical aspects of the fuel cell have already been published. However, the literature on the mechanical aspects is relatively limited. The durability of a PEM fuel cell is one of the significant factors that influence the industrialization of this technology. The PEM fuel cell is subjected to several mechanical stresses due to the different assembly procedures, operational and environmental aggressive conditions. Avoiding the high stress points is necessary for long term PEM fuel cell durability. The behavior of these generated stresses and how they affect each other is not well understood, including the compressive clamping stress, hygrothermal stress, freeze-thaw stress, and the stress due to vibration conditions. This paper reviews the developed stresses within the PEM fuel cell under different conditions. In addition, the various failure and damage mechanisms in the MEA, GDL, gas flow channel and bipolar plate due to these stresses are reviewed. The aforementioned stresses are discussed separately in the literature. The review shows that the combination of these stresses could be a key reason for the performance degradation and structural damage. This review suggests an effective tool to explore the correlation between the addressed stresses and to find out how they contribute to mechanical damage of PEM fuel cell systems and recommendations that can be implemented for improving the cell durability.     

The analysis on energy and environmental impacts of microalgae-based fuel methanol in China

The whole life of methanol fuel, produced by microalgae biomass which is a kind of renewable energy, is evaluated by using a method of life cycle assessment (LCA). LCA has been used to identify and quantify the environment emissions and energy efficiency of the system throughout the whole life cycle, including microalgae cultivation, methanol conversion, transport, and end-use. Energy efficiency, defined as the ratio of the energy of methanol produced to the total required energy, is 1.24, the results indicate that it is plausible as an energy producing process. The environmental impact loading of microalgae-based fuel methanol is 0.187mPET₂₀₀₀ in contrast to 0.828mPET₂₀₀₀ for gasoline. The effect of photochemical ozone formation is the highest of all the calculated categorization impacts of the two fuels. Utilization of microalgae an raw material of producing methanol fuel is beneficial to both production of renewable fuels and improvement of the ecological environment. This Fuel methanol is friendly to the environment, which should take an important role in automobile industry development and gasoline fuel substitute.     

Thermal impact performance study for the thermal management of ammonia-fueled single tubular solid oxide fuel cell

With the substantial improvement of the direct ammonia fuel cells performance, it has become the key to the further development of ammonia fuel cells to deeply understand the heat and mass transfer process inside the cell and to study the thermal impacts generation mechanism during cell operation. In this paper, a whole-cell model of single tubular direct ammonia cracking solid oxide fuel cell (SOFC) is established, and the generation mechanism of thermal impacts inside the cell is analysed in a data-driven method. The model includes the coupling of chemical-electrochemical reactions, local current, local temperature, mass flow and energy transfer inside the cell. It's identified from model simulations that the key to the thermal impact optimization of direct ammonia cracking SOFCs is to reduce the effect of the excessively fast and unbalanced ammonia cracking reaction on the cell. Both introducing the ammonia pre-reforming reaction and improving the activation energy of the ammonia cracking reaction can increase the overall average temperature of the cell and improve the temperature distribution. The 96% ammonia pre-reforming SOFCs can improve the extreme temperature difference in the anode from 37.71 K to 0.52 K at the operating temperature of 800 °C. Increasing activation energy of ammonia cracking reaction by 1.5 times can also make the ammonia cracking reaction rate distribution more uniform at the fuel channel, it can improve the extreme temperature difference in the anode to 4.49 K. This study can enrich the basic theory and research methods of thermal management of direct ammonia cracking SOFCs, and provide theoretical support for further improving cell performance.     

Life cycle simulation-based economic and risk assessment of biomass-based fuel ethanol (BFE) projects in different feedstock planting areas

Increasing attention is being paid to biomass-based fuel ethanol (BFE) for its contributions to moderating oil crisis, reducing environmental impact, and promoting local economy. This paper aims to assess and compare the economic viabilities and investment risks of three BFE projects in different feedstock planting areas in China. Internal cost models of wheat-based fuel ethanol (WFE) in Central China, corn-based fuel ethanol (CFE) in Northeast China, and cassava-based fuel ethanol (KFE) in Southwest China are developed. The projects’ net cash flow (NCF) and net present values (NPV) are pursued by internal cost model simulation with the Monte Carlo method. According to the simulation results, KFE project is economically viable for its positive expected NPV and its expected internal rate of return (IRR) (12%), while CFE and WFE are not economically viable for their negative expected NPVs. Sensitivity analysis is performed to find out the key determinants of the projects’ expected NPVs and to evaluate their future economic viabilities. The analysis results indicate that CFE has better potential to become economically viable comparing to WFE project. Possible measures to improve the expected NPV of CFE are then proposed.     

Thermodynamic analysis of synthetic hydrocarbon fuel production in pressurized solid oxide electrolysis cells

A promising way to store wind and solar electricity is by electrolysis of H₂O and CO₂ using solid oxide electrolysis cells (SOECs) to produce synthetic hydrocarbon fuels that can be used in existing fuel infrastructure. Pressurized operation decreases the cell internal resistance and enables improved system efficiency, potentially lowering the fuel production cost significantly. In this paper, we present a thermodynamic analysis of synthetic methane and dimethyl ether (DME) production using pressurized SOECs, in order to determine feasible operating conditions for producing the desired hydrocarbon fuel and avoiding damage to the cells. The main parameters of cell operating temperature, pressure, inlet gas composition and reactant utilization are varied to examine how they influence cell thermoneutral and reversible potentials, in situ formation of methane and carbon at the Ni–YSZ electrode, and outlet gas composition. For methane production, low temperature and high pressure operation could improve the system efficiency, but might lead to a higher capital cost. For DME production, high pressure SOEC operation necessitates higher operating temperature in order to avoid carbon formation at higher reactant utilization. Optimal operating conditions are dependent on the total system design.     

Modeling and simulation of a single direct carbon fuel cell

A mathematical model was developed to simulate the performance of a direct carbon fuel cell. The model takes account of the electrochemical reaction dynamics, mass-transfer and the electrode processes. An improved packed bed anode was adopted. Polarization losses for the cell components were examined supposing graphite as the fuel and molten carbonate as the electrolyte. The results indicated that the anode activation polarization was the major potential loss in 923–1023 K. The effects of temperature, anode dimension, and carbon particle size on the cell performance were investigated. The model predicted that the power density can be as high as 200–500 W m⁻², with carbon particle size in the range 1.0 × 10⁻⁷ to 1.0 × 10⁻⁴ m and in 923–1023 K and that the overall efficiency of the cell is higher than 55% for low current density and is 45–50% for high current density.     

关于降低内燃机车燃油消耗和维修费用加速代用燃料发动机开发的探讨和建议

从发展内燃机车燃油替代品、降低现有内燃机车的维修费用两个方面进行了探讨,并提出了建议。     

An analysis of development and research on spent nuclear fuel reprocessing

Nuclear energy comes back to the discussions on the world stage as an energy source that does not contribute to global warming during production process. It can be chosen as the main source of power generation in some countries or complement the energy matrix in others. In this context, there is the need to develop new technologies for the management of radioactive waste generated by the production process. Final repositories for spent fuel are not yet in commercial operation, and techniques for fuel reprocessing have been developed, because after use, the fuel still has materials that produce energy. Some countries already use reprocessing, and develop research to make it more secure and more competitive, while others prefer to adopt policies to prevent developments in this area due to the problem of nuclear proliferation. In another line of research, new reactors are being developed in order to reduce the amount of waste in energy production and some will be designed to work in closed loop, recycling the materials generated.     

Conversion of greenhouse gases to synthetic fuel using a sustainable cyclic plasma process

In the present article, a new thermodynamic process is proposed in which a thermal plasma reactor is utilised to dissociate carbon dioxide/steam blend into synthetic fuel using chemical looping technology. Chrome/chrome oxide (Cr/Cr₂O₃) pair was used as the oxygen carrier and also the thermal transport medium between the thermal plasma reactor and a synthetic fuel fluidized bed reactor. The proposed process was hybridised with renewable energy resources including solar photovoltaic and wind to account for the energy demand of the thermal plasma reactor. Results showed that at a molar ratio of CO₂/Cr = 1.12 and steam/Cr ratio = 2.8, the syngas quality referred to as H₂: CO > 2.05, which is suitable for liquid fuel production and Fischer-Tropsch applications. Also, the thermal plasma reactor reached chemical conversion >0.99 at 5273 K, while SFR represented the conversion extent >0.95 at 1473 K. The highest thermodynamic efficiency of the proposed process was 0.43 with a 3 MW electricity production capacity that could be utilised by thermal plasma aiming at improving self-sustaining factor of the system. The integration of the system with solar photovoltaic and wind in Whyalla, South Australia, showed that the renewable energy penetration in the proposed system can be as high as 68.4% with battery storage of 30 MWh together with an installed capacity of 50 MW and 37.5 MW for photovoltaic panels and wind turbines, respectively. Larger battery storage did not affect the renewable energy fraction as solar irradiance and wind velocity were not sufficient to complete the charging cycle of the battery.     

二甲醚发动机燃料喷射系统研究现状及发展

介绍了近几年国内外在二甲醚(DME)柴油机代用燃料方面的研究进程,并重点介绍了现阶段一种较适合DME燃料的低压共轨喷射系统。     

车用柴油机燃用生物柴油的研究进展和发展前景

简要介绍了生物柴油的主要制备方法和燃料特性,综述了生物柴油对车用柴油机的低温起动性能、动力性、经济性,排放特性以及燃烧特性影响的研究进展,阐述了近期针对生物柴油研究的新对象和新方法,并探讨了生物柴油的应用前景。     

Direct alkaline fuel cell for multiple liquid fuels: Anode electrode studies

A direct alkaline fuel cell with a liquid potassium hydroxide solution as an electrolyte is developed for the direct use of methanol, ethanol or sodium borohydride as fuel. Three different catalysts, e.g., Pt-black or Pt/Ru (40 wt.%:20 wt.%)/C or Pt/C (40 wt.%), with varying loads at the anode against a MnO₂ cathode are studied. The electrodes are prepared by spreading the catalyst slurry on a carbon paper substrate. Nickel mesh is used as a current-collector. The Pt–Ru/C produces the best cell performance for methanol, ethanol and sodium borohydride fuels. The performance improves with increase in anode catalyst loading, but beyond 1 mg cm⁻² does not change appreciably except in case of ethanol for which there is a slight improvement when using Pt–Ru/C at 1.5 mA cm⁻². The power density achieved with the Pt–Ru catalyst at 1 mg cm⁻² is 15.8 mW cm⁻² at 26.5 mA cm⁻² for methanol and 16 mW cm⁻² at 26 mA cm⁻² for ethanol. The power density achieved for NaBH₄ is 20 mW cm⁻² at 30 mA cm⁻² using Pt-black.     

The importance and the policy impacts of post-contractual opportunism and competition in the English and Welsh non-fossil fuel obligation

The non-fossil fuel obligation (NFFO), which consisted in a competitive auction for the deployment of renewable electricity, was the main policy for almost a decade in England and Wales. Once also used in Ireland and France, it has recently been abandoned in all countries. Many critics of the NFFO have focused on its inability to develop a national industry and promote a climate of stability among investors. This paper focuses on the incentives faced by developers bidding for a NFFO contract and shows that the low deployment rate under this scheme is likely to have been a predictable outcome of how the policy was structured and implemented rather than an unfortunate accident. The importance of the NFFO goes beyond the lack of an intense deployment of renewable electricity generation observed in the years in which the policy was on place. In fact, the NFFO has contributed to: promoting hostility against wind farms; creating false expectations of a price competitive renewable electricity sector; creating a playing field giving advantages to big players; preventing the creation of a wide renewable lobby coalition and the effective solution of planning constraints encountered by several renewable developers.     

Potential of hydrolyzed oxymethylene dimethyl ether for the suppression of fuel crossover in polymer electrolyte fuel cells

Fuel crossover is a crucial issue for polymer electrolyte fuel cells (PEFCs) supplied directly with liquid fuels. Therefore, finding a type of fuel with a low fuel crossover rate is required. In this study, we investigated fuel crossover characteristics for oxymethylene dimethyl ether (OME), which has attracted attention for use in engines, and compared it with methanol. Cell performance tests and exhaust gas analyses showed that fully hydrolyzed OME (h-OME), which consisted of methanol and formaldehyde, yields high cell performance at high fuel concentrations, due to the low fuel crossover rate, compared with a direct methanol fuel cell (DMFC). To clarify a factor suppressing fuel crossover, h-OME's effective diffusion coefficient in the membrane was measured. Although an effective diffusion coefficient for fuels like methanol commonly increases with increased fuel's concentration, h-OME's effective diffusion coefficient decreased with increased fuel concentration, leading to a low fuel crossover rate at high h-OME concentrations.     

Direct liquid-feed fuel cells: Thermodynamic and environmental concerns

The present paper briefly reviews the different direct liquid-feed fuel cells that have been regarded through the open literature. It especially focuses on thermodynamic-energetic data and toxicological–ecological hazards of the chemicals used as liquid fuels. The analysis of those two databases shows that borohydride, ethanol and 2-propanol would be the most adequate liquid fuels for the polymer electrolyte membrane fuel cell-type systems, even if they are inferior to hydrogen. All the fuels and also all the by-products stem from their decomposition are more or less harmful towards health and environment. More particularly, hydrazine should be avoided because it and its by-product are very dangerous. It is to note that the present paper does not intend to review and to compare the performances of those fuel cells because of great differences in the efforts devoted to each of them.     

Potential benefits of solar reflective car shells: Cooler cabins,fuel savings and emission reductions

Vehicle thermal loads and air conditioning ancillary loads are strongly influenced by the absorption of solar energy. The adoption of solar reflective coatings for opaque surfaces of the vehicle shell can decrease the “soak” temperature of the air in the cabin of a vehicle parked in the sun, potentially reducing the vehicle’s ancillary load and improving its fuel economy by permitting the use of a smaller air conditioner. An experimental comparison of otherwise identical black and silver compact sedans indicated that increasing the solar reflectance (ρ) of the car’s shell by about 0.5 lowered the soak temperature of breath-level air by about 5–6 °C. Thermal analysis predicts that the air conditioning capacity required to cool the cabin air in the silver car to 25 °C within 30 min is 13% less than that required in the black car. Assuming that potential reductions in AC capacity and engine ancillary load scale linearly with increase in shell solar reflectance, ADVISOR simulations of the SC03 driving cycle indicate that substituting a typical cool-colored shell (ρ = 0.35) for a black shell (ρ = 0.05) would reduce fuel consumption by 0.12 L per 100 km (1.1%), increasing fuel economy by 0.10 km L⁻¹ [0.24 mpg] (1.1%). It would also decrease carbon dioxide (CO₂) emissions by 2.7 g km⁻¹ (1.1%), nitrogen oxide (NO_x) emissions by 5.4 mg km⁻¹ (0.44%), carbon monoxide (CO) emissions by 17 mg km⁻¹ (0.43%), and hydrocarbon (HC) emissions by 4.1 mg km⁻¹ (0.37%). Selecting a typical white or silver shell (ρ = 0.60) instead of a black shell would lower fuel consumption by 0.21 L per 100 km (1.9%), raising fuel economy by 0.19 km L⁻¹ [0.44 mpg] (2.0%). It would also decrease CO₂ emissions by 4.9 g km⁻¹ (1.9%), NO_x emissions by 9.9 mg km⁻¹ (0.80%), CO emissions by 31 mg km⁻¹ (0.79%), and HC emissions by 7.4 mg km⁻¹ (0.67%). Our simulations may underestimate emission reductions because emissions in standardized driving cycles are typically lower than those in real-world driving.     

Clean fuel options with hydrogen for sea transportation: A life cycle approach

In this study, two potential fuels, namely hydrogen and ammonia, are alternatively proposed to replace heavy fuel oils in the engines of sea transportation vehicles. A comparative life cycle assessments of different types of sea transportation vehicles are performed to investigate the impacts of fuel switching on the environment. The entire transport life cycle is considered in the life cycle analyses consisting of production of freight ship and tanker; operation of freight ship and tanker; construction and land use of port; operation, maintenance and disposal of port; production and transportation of these clean fuels. Various environmental impact categories, such as global warming, marine sediment ecotoxicity, marine aquatic ecotoxicity, acidification and ozone layer depletion are selected in order to examine the diverse effects of switching to clean fuels in maritime transportation. As a carbon-free fuel for marine vehicle engines, ammonia and hydrogen, yield considerably lower global warming impact during the operation. Furthermore, numerous production methods of alternative fuels are evaluated to comparatively show environmentally benign options. The results of this study demonstrate that if ammonia is even partially utilized in the engines of ocean tankers as dual fuel (with heavy fuel oils), overall life cycle greenhouse gas emissions per tonne-kilometer can be decreased about 27% whereas it can be decreased by about 40% when hydrogen is used as dual fuel.