Potential importance of hydrogen as a future solution to environmental and transportation problems

Air pollution is a serious public health problem throughout the world, especially in industrialized and developing countries. In industrialized and developing countries, motor vehicle emissions are major contributors to urban air quality. Hydrogen is one of the clean fuel options for reducing motor vehicle emissions. Hydrogen is not an energy source. It is not a primary energy existing freely in nature. Hydrogen is a secondary form of energy that has to be manufactured like electricity. It is an energy carrier. Hydrogen has a strategic importance in the pursuit of a low-emission, environment-benign, cleaner and more sustainable energy system. Combustion product of hydrogen is clean, which consists of water and a little amount of nitrogen oxides. Hydrogen has very special properties as a transportation fuel, including a rapid burning speed, a high effective octane number, and no toxicity or ozone-forming potential. It has much wider limits of flammability in air than methane and gasoline. Hydrogen has become the dominant transport fuel, and is produced centrally from a mixture of clean coal and fossil fuels (with C-sequestration), nuclear power, and large-scale renewables. Large-scale hydrogen production is probable on the longer time scale. In the current and medium term the production options for hydrogen are first based on distributed hydrogen production from electrolysis of water and reforming of natural gas and coal. Each of centralized hydrogen production methods scenarios could produce 40 million tons per year of hydrogen. Hydrogen production using steam reforming of methane is the most economical method among the current commercial processes. In this method, natural gas feedstock costs generally contribute approximately 52–68% to the final hydrogen price for larger plants, and 40% for smaller plants, with remaining expenses composed of capital charges. The hydrogen production cost from natural gas via steam reforming of methane varies from about 1.25 US$/kg for large systems to about 3.50 US$/kg for small systems with a natural gas price of 6 US$/GJ. Hydrogen is cheap by using solar energy or by water electrolysis where electricity is cheap, etc.     

化学催化生物质基化合物制备运输燃料

石油资源的日益减少和世界对全球气候的关注,使发展可再生能源迫在眉睫。生物质资源是一种新型、清洁的可再生能源。文章着重介绍了近些年来一些重要生物质基化合物经一系列化学催化,制备C6以上运输燃料的最新进展。其中包括C-C扩链和C-O断裂所涉及的催化剂、反应温度、反应压力等工艺条件,以及加氢、脱水、脱氧、羟醛缩合、诺文葛耳反应、酮基化反应等反应机理。     

The water needs for LDV transportation in the United States

Concern over increased demand for petroleum, reliable fuel supply, and global climate change has resulted in the US government passing new Corporate Average Fuel Economy standards and a Renewable Fuels Standard. Consequently, the fuel mix for light duty vehicle (LDV) travel in the United States will change over the coming years. This paper explores the embodied water consumption and withdrawal associated with two projections for future fuel use in the US LDV sector. This analysis encompasses conventional and unconventional fossil fuels, corn ethanol, cellulosic ethanol, soy biodiesel, electricity, and hydrogen. The existing mandate in the US to blend ethanol into gasoline had effectively committed 3300 billion liters of irrigation water in 2005 (approximately 2.4% of US 2005 fresh water consumption) for producing fuel for LDVs. With current irrigation practices, fuel processing, and electricity generation, it is estimated that by 2030, approximately 14,000 billion liters of water per year will be consumed and 23,000–27,000 billion liters withdrawn to produce fuels used in LDVs. Irrigation for biofuels dominates projected water usage for LDV travel, but other fuels (coal to liquids, oil shale, and electricity via plug-in hybrid vehicles) will also contribute appreciably to future water consumption and withdrawal, especially on a regional basis.     

Leveling the playing field of transportation fuels: Accounting for indirect emissions of natural gas

Natural gas transportation fuels are credited in prior studies with greenhouse gas emissions savings relative to petroleum-based fuels and relative to the total emissions of biofuels. These analyses, however, overlook a source of potentially large indirect emissions from natural gas transportation fuels, namely the emissions from incremental coal-fired generation caused by price-induced substitutions away from natural-gas-fired electricity generation. Because coal-fired generation emits substantially more greenhouse gases and criteria air pollutants than natural-gas-fired generation, this indirect coal-use change effect diminishes potential emissions savings from natural gas transportation fuels. Estimates from a parameterized multi-market model suggest the indirect coal-use change effect rivals in magnitude the indirect land-use change effect of biofuels and renders natural gas fuels as carbon intensive as petroleum fuels.     

An integrated impact assessment of hydrogen as a future energy carrier in Nigeria's transportation,energy and power sectors

A hydrogen economy, the long-term goal of visionary nations, has the potential to provide energy security, along with environmental and economic benefits. The concept of a hydrogen energy economy was first conceived at The Hydrogen Economy Miami Energy (THEME) Conference, held in March 1974 in Miami, Florida, where the International Association for Hydrogen Energy was established. Forty years later, advances in hydrogen technologies have led the world's most developed countries to invest extensively in preparation for a future hydrogen-based economy. However, the transition from a conventional petroleum-based energy economy to a hydrogen economy involves many uncertainties regarding concerns such as the development of efficient fuel cell technologies, problems in hydrogen production and distribution infrastructure, hydrogen safety issues, and the response of carbon-based fuel markets. This paper presents an assessment of the economic impact of hydrogen energy on the transportation and energy use sectors of Nigeria, along with implications for Greenhouse Gas (GHG) emissions. The analysis uses the Long range Energy Alternatives Planning (LEAP) technology database and model to simultaneously consider the impact of alternative and conventional technologies and fuels on these sectors.     

The role of hydrogen in the road transportation sector for a sustainable energy system: A case study of Korea

This study analyzes the impact of the introduction of hydrogen as fuel in the road transportation sector of Korea. Since this sector is completely dependent on petroleum and alternative technologies such as fuel cell vehicles, hydrogen is one alternative fuel that could meet the challenges that Korea is facing due to rising oil prices. This study uses a scenarios-based energy economic model including the hydrogen path way as a sub-energy system to explore the energy system of Korea through 2044. This study also constructs six scenarios consisting of three government policies concerning carbon dioxide reduction and two oil price scenarios in order to assess the impact on hydrogen as fuel in the road transportation sector. The results of this study show that in a particular case (high Btu tax and oil prices) the share of hydrogen would reach 76% of the road transportation sector, and hydrogen would be produced mainly from renewable and nuclear resources via electrolysis facilities. It is also revealed that hydrogen is effective at reducing carbon dioxide, improving energy efficiency and contributing to the energy security of Korea.     

Autothermal chemical looping reforming process of different fossil liquid fuels

The autothermal Chemical-Looping Reforming (a-CLR) is a process where syngas is produced with two main advantages; there are captured CO₂ emissions and the heat required for the syngas production is generated by the process itself. A Ni-based material is used as oxygen carrier circulating between two fluidized bed reactors: the fuel and air reactors. In this work, the auto-thermal conditions in a global H₂ production process, integrated by the a-CLR process and a Water Gas Shift reactor, using different liquid fossil fuels were theoretically determined. The hydrogen production per mol of carbon in the fuel was similar for all fossil fuels, taking a value of 2.2 at the optimal operating temperature (700 °C). In addition, the possibility of working at low temperature for a maximum H₂ production was experimentally demonstrated in a continuous 1 kW_th a-CLR unit.     

Hydrogen quality from decarbonized fossil fuels to fuel cells

Increased focus on curbing carbon dioxide (CO₂) emissions and a limited and unstable supply of fossil fuel resources make diversification of energy resources a priority. Hydrogen has emerged as a promising energy vector for solving these issues. However, there are numerous challenges related to production, distribution and end use of hydrogen. Of particular importance is the link between hydrogen purity requirements for use in fuel cells and the capabilities of production. Impurities can adversely affect fuel cell performance and durability, and the fuel composition must therefore be carefully controlled. However, impurity specifications should be balanced against production and purification costs. This paper examines the effects of impurities on fuel cell performance and assesses the capabilities of hydrogen production from decarbonized fossil fuels to meet the purity requirements dictated by use in fuel cells. While carbon monoxide, hydrogen sulfide and ammonia impurities are shown to most negatively affect fuel cell performance, these species are also the most easily removed during purification. In hydrogen production from decarbonized fossil fuels, inert gases are the most limiting species in the separation. If inert gas specifications were relaxed, then carbon monoxide would become the most limiting factor.     

Development of a multi-criteria assessment model for ranking of renewable and non-renewable transportation fuel vehicles

Several factors, including economical, environmental, and social factors, are involved in selection of the best fuel-based vehicles for road transportation. This leads to a multi-criteria selection problem for multi-alternatives. In this study, a multi-criteria assessment model was developed to rank different road transportation fuel-based vehicles (both renewable and non-renewable) using a method called Preference Ranking Organization Method for Enrichment and Evaluations (PROMETHEE). This method combines qualitative and quantitative criteria to rank various alternatives. In this study, vehicles based on gasoline, gasoline–electric (hybrid), E85 ethanol, diesel, B100 biodiesel, and compressed natural gas (CNG) were considered as alternatives. These alternatives were ranked based on five criteria: vehicle cost, fuel cost, distance between refueling stations, number of vehicle options available to the consumer, and greenhouse gas (GHG) emissions per unit distance traveled. In addition, sensitivity analyses were performed to study the impact of changes in various parameters on final ranking. Two base cases and several alternative scenarios were evaluated. In the base case scenario with higher weight on economical parameters, gasoline-based vehicle was ranked higher than other vehicles. In the base case scenario with higher weight on environmental parameters, hybrid vehicle was ranked first followed by biodiesel-based vehicle.     

Nanometallic fuels for transportation: a well‐to‐wheels analysis

Nanometallic iron and aluminium, along with hydrogen and electricity, are among the proposed alternatives to the petroleum‐based fuels for future transportation. The advantages of the metallic fuels appear to be high volumetric energy densities and zero greenhouse gas emissions during the operation of the vehicle. However, nanometallic fuels do not exist in nature, and a well‐to‐wheel analysis of the fuel manufacture‐utilization system is required to quantify the energy consumption and assess the true environmental impact of the proposed alternative. The three‐component nanometallic fuel system consisting of a metal production process, a nanoparticle formulation process and the metal combustion process is analysed in this paper. The energy balance and the environmental impact are estimated for nanometallic iron and aluminium based systems. The sustainability of once‐through systems that do not involve recycle of combustion products is questionable because of resource limitations. A viable system for satisfying the transportation fuel demands will involve the reduction and recycle of the combustion products. A comparison of these nanometallic fuels with gasoline and hydrogen indicates that nanometallic fuels are the least efficient, with primary energy consumption greater than 11 MJ km^?1 compared to 0.625 MJ km^?1 for gasoline and 8.6 MJ km^?1 for hydrogen. The nanometallic fuels will also have the most severe impact of the three, with CO₂‐equivalent emissions of 13.44 billion tons year^?1 for iron and 21.1 billion tons year^?1 for aluminium as compared to approximately 0.8 billion tons year^?1 for gasoline. These emissions from nanometallic fuels are at least an order‐of‐magnitude higher than those for gasoline and hydrogen. The results of the analysis emphasize the need for well‐to‐wheel assessment for determining the true impact of technologies proposed as replacements for the current technologies. Copyright © 2006 John Wiley & Sons, Ltd.     

Application of advanced correlative approaches to modeling hydrogen solubility in hydrocarbon fuels

In petroleum and petrochemical refineries, having precise knowledge regarding H₂ solubility in hydrocarbon fuels and feedstocks is critical. In this study, the hydrogen solubility in hydrocarbon fuels was estimated using genetic programming (GP) and group method of data handling (GMDH), two exemplary robust advanced models for generating correlation. To do this, 445 observations derived from labratory findings on hydrogen solubility in 17 different hydrocarbon fuels such as bitumen, atmospheric residue, heavy coking gas oil, heavy virgin gas oil, light virgin gas oil, straight run gas oil, shale fuel oil, dephenolated shale fuel oil, diesel, hydrogenated coal liquid, coal liquid, and coal oil, over a large interval of P- operating pressures and T-temperatures were collected. Temperature, pressure, as well as density at 20 °C, molecular weight, and weight percentage of carbon (C) and hydrogen (H) in hydrocarbon fuels, were used as input parameters in developing robust correlations. The outcomes showed the GMDH approach is more precise compared to the GP, with a root mean square error (RMSE) of 0.053302 and a determination coefficient (R²) of 0.9641. Additionally, sensitivity analysis showed that pressure, followed by temperature and H (wt%) of hydrocarbon fuels, has the greatest impact on hydrogen solubility in hydrocarbon fuels. Ultimately, the Leverage method's results suggested that the GMDH model could be relied on to predict hydrogen solubility in hydrocarbon fuels.     

Hydrogen utilization in various transportation modes with emissions comparisons for Ontario, Canada

The paper compares the atmospheric emissions of different hydrogen production scenarios for various transportation modes in a case study for Ontario, Canada. Hydrogen demand scenarios are based on historical data of the various transportation modes. Predicting the CO₂ emissions for a market with hydrogen vehicles against a purely fossil fuel market outlines the benefits of utilizing hydrogen. For road vehicles less than 4,500 kg in weight, emissions from a thermochemical production fraction of 20% produced a 9.8% decrease in CO₂ emissions (or over 3,000 kilotonnes), compared to a 100% fossil fuel market. When these studies are applied to other transportation modes such as rail, air and marine, similar trends are observed. The largest benefits occur from automobiles and rail, where increasing carbon emission trends were reversed due to the increasing hydrogen propulsion base. Further decreases in carbon dioxide emissions could be realized by lower emitting production sources such as nuclear thermochemical production and electrolysis from wind, solar, and hydro.     

Transition to hydrogen-based transportation in China: Lessons learned from alternative fuel vehicle programs in the United States and China

This paper examines the experience of existing alternative fuel vehicle (AFV) programs in the US and China to provide insights into appropriate strategies for developing hydrogen vehicles and infrastructure in China. Although an increasing number of AFVs have been deployed in recent years, various factors have limited this progress, such as large sunk investments in conventional technologies, limited networks of refueling stations, the typically higher cost of AFVs, and the relatively low price of oil. Given these barriers, and additional barriers specific to hydrogen, a transition to hydrogen will be a slow process, and must be supported by both near- and long-term policies that have clear and measurable goals that take hydrogen beyond fleet applications into broader vehicle markets. Because a transition to hydrogen vehicles will not occur quickly, it is necessary for the government to have consistent and integrated transportation policies combining short- and long-term goals. These policies should draw upon resources from both governments and multinational companies to provide incentives for vehicle purchases, promote investment in infrastructure, and disseminate information to raise public awareness. Multinationals may find China to be an ideal testing ground for innovative hydrogen vehicles with appropriate incentive policies and programs.     

The dimensions of the policy debate over transportation energy: The case of hydrogen in the United States

Environmental and politico-strategic concerns have driven the increase in policy activity related to energy that the United States witnessed in the last few years. The nature of the issues at stake and the level of stakeholder involvement result in a highly complex policy debate. The broad concern of this paper is the study of this energy-policy process and the identification of the main policy issues. Specifically, multivariate analysis is applied to data on a wide variety of stakeholders’ policy beliefs and policy preferences to identify the policy dimensions that characterize the debate over energy policy in the United States. The focus is on the policy debate over hydrogen as a transportation fuel, although many results are applicable to the debate over transportation energy at large. The analysis uses a dataset of 502 individuals from 323 different stakeholder organizations obtained via a web-based survey specifically designed for this study.     

Hydrogen and ethanol: Production,storage, and transportation

The present paper provides insights into the feasibility of using hydrogen and bioethanol blends as energy carriers in the foreseeable future upon discussions on the advantages and the disadvantages. The comprehensive overviews on the production, storage, and transportation of hydrogen and bioethanol have been made; and the current problems and potential solutions for the three stages have been summarized. Finally, the prospections on hydrogen and bioethanol could be expect optimistically.     

Economics of producing hydrogen as transportation fuel using offshore wind energy systems

Over the past few years, hydrogen has been recognized as a suitable substitute for present vehicular fuels. This paper covers the economic analysis of one of the most promising hydrogen production methods—using wind energy for producing hydrogen through electrolysis of seawater—with a concentration on the Indian transport sector. The analysis provides insights about several questions such as the advantages of offshore plants over coastal installations, economics of large wind-machine clusters, and comparison of cost of producing hydrogen with competing gasoline. Robustness of results has been checked by developing several scenarios such as fast/slow learning rates for wind systems for determining future trends. Results of this analysis show that use of hydrogen for transportation is not likely to be attractive before 2012, and that too with considerable learning in wind, electrolyzer and hydrogen storage technology.     

A transportation model approach for constructing the cost effective central hydrogen supply system in Korea

One of the major tasks in transition to a hydrogen economy is to build a cost-effective infrastructure of hydrogen supply. Building an infrastructure of hydrogen supply includes a series of logistical steps from production through delivery and storage to utilization of the hydrogen. This paper attempts to build the cost-effective central hydrogen supply system using a transportation model. As a case study, a hydrogen delivery plan for 2040 was established by dividing the Korean peninsula into two regions, northern and southern regions. Average hydrogen delivery distances for 2040 in the northern and the southern regions are estimated as 69.8 km and 85.2 km. The subsequently derived hydrogen supply network of centrally produced hydrogen in 2040 is expected to be similar to the liquefied natural gas pipeline network in 2005. The derived hydrogen supply network, delivery distances, and delivery costs are expected to provide a set of basic and indispensable information in building a cost-effective infrastructure of hydrogen supply in the Korean peninsula.     

A computational study on the combustion of hydrogen/methane blended fuels for a micro gas turbines

To understand the combustion performance of using hydrogen/methane blended fuels for a micro gas turbine that was originally designed as a natural gas fueled engine, the combustion characteristics of a can combustor has been modeled and the effects of hydrogen addition were investigated. The simulations were performed with three-dimensional compressible k-ε turbulent flow model and presumed probability density function for chemical reaction. The combustion and emission characteristics with a variable volumetric fraction of hydrogen from 0% to 90% were studied. As hydrogen is substituted for methane at a fixed fuel injection velocity, the flame temperatures become higher, but lower fuel flow rate and heat input at higher hydrogen substitution percentages cause a power shortage. To apply the blended fuels at a constant fuel flow rate, the flame temperatures are increased with increasing hydrogen percentages. This will benefit the performance of gas turbine, but the cooling and the NO_x emissions are the primary concerns. While fixing a certain heat input to the engine with blended fuels, wider but shorter flames at higher hydrogen percentages are found, but the substantial increase of CO emission indicates a decrease in combustion efficiency. Further modifications including fuel injection and cooling strategies are needed for the micro gas turbine engine with hydrogen/methane blended fuel as an alternative.     

About the process improvement of adsorptive desulphurisation by adding hydrogen donators as additives in liquid fuels

For the use in fuel cell system commercial fuels, like diesel or domestic heating oil, have to be desulphurised to ultra deep sulphur levels of below 1 mg kg⁻¹. To reach this goal the adsorptive desulphurisation using a nickel-based sorbent has been identified. The evaluation of the reaction mechanism reveals in principle the same route as that of the hydrodesulphurisation (HDS) whereas the sulphur is adsorbed by the sorbent instead of being converted to hydrogen sulphide. The required hydrogen for the process is provided out of the fuel itself and not by an external supply of hydrogen. This analysis leads to an easy applicable enhancement of the process by adding a hydrogen donator as an additive to the liquid fuel. In correlation to the mass fraction of the donator the reaction rates and sorbent capacities are improved significantly.Furthermore the influence of aromatic compounds has been investigated, which exhibit similar molecular structures and chemical properties than comparable high refractory sulphur species. This leads to side reactions especially of di- and tri-aromatics which influence the sulphur adsorption. A shift of the aromatic fraction from mono- to di- and tri-aromatic compounds has been observed as well as the alkylation of di- and tri-aromatics.     

A hydrogen energy system and prospects for reducing emissions of fossil fuels pollutants in the Ceará state—Brazil

A model of a solar–wind hydrogen energy system was applied to the Ceará state—Brazil and the prospects for reducing emissions of fossil fuels pollutants in such federal state were studied. This long-term study simulates three scenarios of fast, slow and no introduction of hydrogen in the energy balance of the Ceará state. Not including nitrogen oxides, if fuel burning continues, results indicate that hydrogen energy eventually will reduce to zero all emissions of fossil fuels pollutants in the Ceará state by the year 2060 in both scenarios of hydrogen introduction.