Secondary Energy Carrier Research Articles

Alternative World Energy Outlook (AWEO) and the role of hydrogen in a changing energy landscape

The global energy situation is about to change at an accelerating pace and society is largely unprepared. Common energy analyses, such as the International Energy Agency's “World Energy Outlook”, do not take into account foreseeable supply mismatches from conventional primary energy sources. It is thus the purpose of this paper to provide a progressive view based on an accelerated transition to renewable energies in the framework of LBST's “Alternative World Energy Outlook”. A transition to renewable energies appears feasible; however, with an intermediate period with limited supplies between 2015 and 2025. Furthermore, the potential role of hydrogen as a secondary energy carrier is reflected in this context. Hydrogen used for transportation can increase the penetration of intermittent renewable energy sources through offering the ability to convert electricity to fuel.

The potential role of hydrogen in energy systems with and without climate policy

Introduction of hydrogen in global energy system can lead to lower CO 2 emissions (high end-use efficiency; low-carbon production of hydrogen) but might also increase CO 2 emissions (producing hydrogen from coal). We used the long-term energy model TIMER 2.0, to study the use and production of hydrogen and its influence on global CO 2 emissions. This is done using a set of scenarios with assumptions on technology development, infrastructural barriers and climate policy (CP). We found that even under optimistic assumptions hydrogen plays a minor role in the global energy system until the mid-21st century due to the system inertia—but could become a dominant secondary energy carrier in the second half of the century. Hydrogen is mainly produced from coal and natural gas. Hence, hydrogen-rich scenarios without climate policy increase CO 2 emissions up to 15% by 2100 compared to the baseline. However, if climate policy is assumed, CO 2 from fossil feedstock-based hydrogen production is captured and sequestrated, which indicates that an energy system that includes hydrogen is much more flexible in responding to climate policy.

The hydrogen economy: technology, logistics and economics

AbstractThere is much current discussion on the contribution the 'hydrogen economy' can make to a 'sustainable energy system', centring around the environmental and supply advantages that may accrue from use of hydrogen as a secondary energy carrier. Whether generated by electrolysis or reforming, or even produced locally at filling stations, the hydrogen must be packaged by compression or liquefaction, transported by surface vehicles or pipelines, stored and transferred to the end user. Hydrogen may represent an option for clean energy use if produced using reduced carbon or carbon-free primary energy sources, e.g. renewable, biomass or nuclear energy. To date, hydrogen has competed with direct use of clean primary energy and/or electrical energy produced without CO2 emissions. However, to succeed as a secondary energy carrier, hydrogen must demonstrate advantages over established systems, especially electricity.

Technological Options for Producing Hydrogen from Renewable Resources

Hydrogen is gaining increasing attention as an encouraging future energy. Hydrogen as secondary energy carrier is produced from natural gas, biomass, and water by electrolysis, thermolysis, and biological process photolitically. Hydrogen has the potential to be a clean alternative to the fossil fuels currently used in the transportation sector. This is especially true if the hydrogen is manufactured from renewable resources. Hydrogen has the potential to solve two major energy problems: reducing dependence on petroleum and reducing pollution and greenhouse gas emissions. Biomass can be thermally processed through gasification or pyrolysis to produce hydrogen. Future energy technology will utilize hydrogen with an increasing trend in steady as well as unsteady combustion processes. Hydrogen could be advantageously used as a clean energy carrier for heat supply and transportation purposes.

Silicon as energy carrier—Facts and perspectives

Due to the diminishing reserves of carbon based primary energy carriers and the need to reduce carbon dioxide (CO 2) emissions worldwide, an alternative energy concept was developed using elemental silicon as secondary energy carrier. Starting from sand, silicon can be accessible on a carbon/carbon dioxide free route in a process cycle using cost-effective—at best renewable—energy anywhere in the world. The reduction process sand→silicon, just as the generation of every synthetic secondary energy carrier, requires a significant amount of energy, which then is partially stored in the metal. Using existing technology, silicon can be transported and stored without any risk. Reactions of silicon with oxygen or nitrogen are exothermic and result in the release of thermal energy as well as formation of economically valuable products—instead of CO 2. From silicon nitride, ammonia is obtained as a feed stock for the fertilizer industry as well as for hydrogen production. Alternatively, hydrogen is produced from silicon directly by simple reactions with water or alcohols, giving sand or silicon-based compounds as byproducts. These are available for a variety of different technical applications and, if required, can be recycled easily.

Development of European hydrogen infrastructure scenarios—CO 2 reduction potential and infrastructure investment

For the introduction of a hydrogen economy one of the most relevant questions is: what are the suitable feedstocks and production technologies for hydrogen, which is a secondary energy carrier, taking into account the manifold objectives of hydrogen introduction: the cost-effective substitution of oil, increasing the security of energy supply, and reducing CO 2 and other emissions? This study focuses on constructing a hydrogen infrastructure in Europe by 2030. Several hydrogen technologies and their integration into an infrastructure system, including the production, transport and distribution of hydrogen, are analysed on the basis of energy chain calculations and expert judgements and consistent scenarios are developed. It can be shown that under economic and CO 2-reduction objectives, the steam reforming of gas, followed by coal gasification and, to a limited extent, the electrolysis of electricity from renewable energy carriers are the most promising hydrogen production options in this first phase for developing a hydrogen infrastructure. These options result in a significant level of CO 2-reduction. However, the total cost of the infrastructure will account for 0.3% of EU-25 GDP in 2030. This shows the extent of the challenge involved in constructing a hydrogen infrastructure.

Prospects for hydrogen in the German energy system

The focus of the paper concerns the current discussion on the contribution of the hydrogen economy to a “sustainable energy system”. It considers whether advantages for the environmental situation and energy carrier supply can be expected from the already visible future characteristics of hydrogen as a new secondary energy carrier. Possible production paths for hydrogen from hydrocarbon-based, renewable or carbon-reduced/-free primary energy carriers are evaluated with respect to primary energy use and CO 2 emissions from the fuel cycle. Hydrogen has to be packaged by compression or liquefaction, transported by surface vehicles or pipelines, stored and transferred to the end user. Whether generated by electrolysis or by reforming, and even if produced locally at filling stations, the gaseous or liquid hydrogen has to undergo these market processes before it can be used by the customer. In order to provide an idea of possible markets with special emphasis on the German energy sector, a technical systems analysis of possible hydrogen applications is performed for the stationary, mobile and portable sector. Furthermore, different “business as usual” scenarios are analysed for Germany, Europe and the World concerning end energy use in different sectors. The very small assumed penetration of hydrogen in the analysed scenarios up to the year 2050 indicates that the hydrogen economy is a long-term option. With reference to the assumed supply paths and analysed application possibilities, hydrogen can be an option for clean energy use if hydrogen can be produced with carbon-reduced or -free primary energy carriers like renewable energy or biomass. However, the energetic use of hydrogen competes with the direct use of clean primary energy and/or with the use of electric energy based on renewable primary energy. As a substitution product for other secondary energy carriers hydrogen is therefore under pressure of costs and/or must have advantages in comparison to the use of traditional energy carriers.

Electricity, hydrogen—competitors, partners?

Electricity, hydrogen—What they have in common, where they are unique. Electricity and hydrogen have in common that they are secondary energies which can be generated from any primary energy (raw materials). Once generated they are environmentally and climatically clean along the entire length of their respective energy conversion chains. Both electricity and hydrogen are grid delivered (with exceptions); they are interchangeable via electrolysis and fuel cell. Both are operational worldwide, although in absolutely dissimilar capacities. And their peculiarities? Electricity stores and transports information, hydrogen does not. Hydrogen stores and transports energy, electricity transports energy but does not store it (in large quantities). For long (i.e., continental) transport routes, hydrogen has advantages. The electricity sector is part of the established energy economy. Hydrogen, on the other hand, takes two pathways: one where it has been in use materially in the hydrogen economy almost since its discovery in the later 18th century; today, it is traded worldwide as a commodity up to an amount of some 50 million tonnes p.a., e.g., in methanol or ammonia syntheses, for fat hardening in the food industry, as a cleansing agent in glass or electronics manufacturing, and the like. And along the other pathway it serves as an energy carrier in the up coming hydrogen energy economy which started with the advent of the space launching business after WW II. Essentially, the hydrogen energy economy deals with the introduction of the, after electricity, now second major secondary energy carrier, hydrogen, together with its conversion technologies, e.g., fuel cells, into portable electronic equipment such as television cameras, laptops, cellular phones, etc., into the distributed stationary electricity and heat supply in the capacity range of kilowatts to megawatts, and into transport vehicles on earth, at sea, in the air, or space-borne. It is never a question of the energy carrier alone, be it either hydrogen or hydrogen reformat. On the contrary, environmentally and climatically clean hydrogen energy technologies along the entire length of the energy conversion chain, from production via storage, transport and distribution to, finally, end use, are what is of overarching importance. Of course, technologies are not energies, but they are as good as energies. Efficient energy technologies provide more energy services from less primary energy (raw materials). Energy efficiency gains are energies! Especially for energy poor, but technology-rich countries, efficiency gains compare well to indigenous energy sources! The trend is clearly visible: increasingly, the world is moving from national fuels to global fuels, and energy technologies serve as their opening valves. CO 2 capture and sequestration technologies bring hydrogen-dependent clean fossil fuels to life, and hydrogen supported fuel cell technology activates dormant virtual distributed power. Both technologies are key for the hydrogen energy economy which, thus, becomes the linchpin of future world energy.

FLUIDIZATION BEHAVIOR OF WOOD/SAND MIXTURES

In conversion of biomass to secondary energy carriers, several routes are possible, such as gasification, combustion and pyrolysis. In many of these processes it is necessary or advantageous to dry the biomass before further processing. For wooden biomass, fluidized bed drying in superheated steam is a promising option. Given the difficulty to fluidize wood particles alone, it is very common to fluidize these kinds of particles with sand. This also gives better defined fluidization behavior. Especially when the wood particles come in various size and shape (i.e. from sawdust to chopped wood), this gives a more reliable scale-up. Also heat transfer to the wood particles may benefit from the use of sand. However, not much is known about fluidization behavior in pressurized steam of binary mixtures with large particle size ratio and large particle density ratio. Therefore minimum fluidization velocity and bed porosity of wood/sand mixtures in air have been experimentally determined and compared to correlations known from literature. The experimental values show a clear trend, but correlations from literature appear not to be very accurate. So more experiments have to be done to find a correlation that gives more accurate predictions in case of the specific particles used in this work. From segregation experiments could be found that, to keep the wood/sand bed well-mixed, finer sand (0.1-0.5 mm) with maximum 10 weight-% wood should be used, and the superficial gas velocity should be at least 3-4 times the minimum fluidization velocity.

Energy Issues for Vehicles: R&D, Carbon Sequestration, Fuel Conversion

Energy Issues for Vehicles: R&D, Carbon Sequestration, Fuel Conversion

Future implications of China's energy-technology choices: summary of a report to the Working Group on Energy Strategies and Technologies

This paper summarizes results of an assessment of future energy-technology strategies for China highlighting implications of different advanced energy-technology strategies that could allow China to continue its social and economic development while ensuring national energy-supply security and promoting environmental sustainability. The MARKAL energy-system modeling tool was used to build a model of China's energy system. Different scenarios for the evolution of energy supply and demand from 1995 to 2050 were explored, enabling insights to be gained into different energy development choices that China might make. The overall conclusion from the analysis is that there are plausible energy-technology strategies that would enable China to continue social and economic development through at least the next 50 years while ensuring security of energy supply and improved local and global environmental quality. Surprisingly, except for the case when very major reductions in carbon emissions are sought, the model predicts that such energy strategies would not involve significantly higher cumulative (1995–2050) discounted costs for the energy system than “business-as-usual” strategies. Furthermore, “business-as-usual” strategies, which were also modeled, will not enable China to meet all of its environmental and energy security goals. To meet these goals, an energy development strategy that relies on the introduction of advanced technologies is essential. To realize such strategies, policies are needed in China that will (1) encourage utilization of a wider variety of primary energy sources (especially biomass and wind) and clean secondary energy carriers (especially synthetic fluid fuels from coal and biomass), (2) support the development, demonstration and commercialization of radically new clean energy conversion technologies to ensure that they are commercially available beginning in the next 10 to 20 years, and (3) support aggressive end-use energy efficiency improvement measures.

Secondary Energy Carriers in Oil Refineries

The possibility of utilizing oil refining residues and wastes for developing energy carriers using modern energy technologies both in energetics and in oil refineries is demonstrated.

Global Link of Renewable Energy Sources: Technical, Economical, and Environmental Aspects of an Intercontinental Electricity Transmission and Distribution System

The present energy system mainly depends on worldwide transport of fossil primary energy carriers. One way to reduce fossil fuel consumption would be to substitute the worldwide transport of fossil primary energy carriers by transportable secondary energy carriers converted from renewable energy sources. This could also reduce global and local environmental effects resulting from the use of fossil fuels as energy. By means of a Global Link, regions with large supplies of renewable energy could be connected to regions where the energy demand is relatively high. In this context, it is the objective of this article to, first, give a general overview of the different possibilities. Then possible compensation and equalization effects of an intercontinental electricity transmission and distribution system are analyzed; environmental and economic aspects are also discussed. Some conclusions are drawn in the final section.

Hydrogen in a global long-term perspective

For many countries, the hydrogen economy offers an operational objective for their long-term energy structure. At the end of the next century, the world will depend on the predominant use of carbon-free and carbon-neutral sources of energy, such as flow energy, energy from modern biomass and safe nuclear energy. According to current expectations, traditional fossil fuels will either be practically exhausted or no longer useful as a result of the greenhouse effect. In both cases, a scarcity motive is at issue. This implies that the direct and indirect costs involved in the use of traditional energy supplies will increase sharply with the passage of time, so that the economic feasibility of the less intensive use of energy and the introduction of alternative energy supply systems will no longer be insurmountable problems. The supply and demand structures of energy will be optimally blended by the use of hydrogen and electricity, an almost ideal combination of secondary energy carriers. With these carriers, practically every centralized or decentralized, environmentally sound energy supply can be permanently maintained, both within and outside of industrialized, metropolitan areas. How the transition to a hydrogen economy will precisely take place is not clear. In general, it is assumed that for many decades to come, the economic development of developing countries will depend on the predominant use of relatively “cheap” fossil energy carriers (coal, petroleum and natural gas), as well as on the accompanying energy supply structures. However, those countries, similar to the wealthy industrial countries, will also have to start using highly capital-intensive and very energy-efficient energy supply systems and energy consumption technologies. This requires innovative strategies that are aimed at compensating developing countries (temporarily) for their lack of purchasing power and knowledge infrastructure. Presumably nowhere in the world will a substantial changeover to hydrogen as an energy carrier possibly be at issue in the first few decades. The costs involved in the hydrogen chain are still too high, and world energy prices are still to low for such a changeover to take place. Attention, however, will focus on drastic energy saving, decarbonization of fossil fuels, substitution to natural gas, the opening up of flow energy, biomass production and the development of inherently safe nuclear energy.

Utilization of methanol for polymer electrolyte fuel cells in mobile systems

The constantly growing volume of road traffic requires the introduction of new vehicle propulsion systems with higher efficiency and drastically reduced emission rates. As part of the fuel cell programme of the Research Centre Jülich a vehicle propulsion system with methanol as secondary energy carrier and a polymer electrolyte membrane fuel cell (PEMFC) as the main component for energy conversion is developed. The fuel gas is produced by a heterogeneously catalyzed steam reforming reaction in which methanol is converted to H 2, CO and CO 2. The required energy is provided by the catalytic conversion of methanol for both heating up the system and reforming methanol. The high CO content of the fuel gas requires further processing of the gas or the development of new electrocatalysts for the anode. Various PtRu alloys show promising behaviour as CO-tolerant anodes. The entire fuel cell system is discussed in terms of energy and emission balances. The development of important components is described and experimental results are discussed.

Safety concept of an engine test rig with liquid hydrogen supply

As a secondary energy carrier, hydrogen is considered to offer a potential answer to the question of how individual mobility can be preserved in the future. BMW began to examine the use of liquid hydrogen as a fuel for motor vehicles as long as 10 years ago. In addition to investigating the storage technology inside the vehicle, work focussed particularly on engine development. The conflicting interests which that engine design provoked with regard to engine output, NOx emissions, backfiring into the intake pipe and the costs of a mixture preparation system caused BMW to start planning a special test rig for hydrogen engines in 1987. The test rig was designed to operate a stationary hydrogen-driven engine in an enclosed room at fuel temperatures of between −240° and + 100°C and pressures of up to a maximum of 200 bar. Since there was no precedent for such a test rig system anywhere else in the world, it was necessary to develop an independent safety concept based on existing technical principles.

Energetics of solar methanol synthesis from atmospheric carbon dioxide compared to solar liquid hydrogen generation

The energetics of different synthesis methods for the secondary energy carriers hydrogen and methanol are compared. In the case of hydrogen generation by water electrolysis, followed by liquefaction, 602% of the electric energy is converted to chemical energy. With methanol production the energy consumption depends on the type of synthesis, the enrichment of CO 2 from the atmosphere and the distillation process used for product separation. The overall energy efficiencies for the chemical and electrochemical production are 49.5% and 49.0%, respectively. The calculated values of the energy efficiencies are compared with regard to technical and economical considerations.

41952 Nondestructive evaluation of adhesively bonded joints using acousto-ultrasonics : Tanary, S.; Fahr, A.; Haddad, Y. Journal of Acoustic Emission, Vol. 8, Nos. 1–2, pp. 5314–5316 (Jan. – Jun. 1989). Special Supplement - Extended Summaries of Papers to be presented at the World Meeting on Acoustic Emission, Charlotte, North Carolina, USA, 20–23 Mar. 1989

This paper describes a review of programmatic and experimental activities as well as study work of DFVLR-Deutsche Forschungs- und Versuchsanstalt für Luft- und Raumfahrt. Intending to achieve a consensus among those concerned with energy in the Federal Republic of Germany, a programmatic paper entitled “Hydrogen as a secondary energy carrier” was presented in 1981 by DFVLR as a proposal for a research and development programme. The programme outlines the objectives and indicates the technological problems of introducing hydrogen into the energy scenario of a national economy; it recommends appropriate research and development activities as well as study and demonstration work. The programme accepts the fact that non-fossil hydrogen, produced from water, will not be a competitive secondary energy carrier within the next few decades. It is, however, important to open up the secondary energy carrier options which are compatible with any of the development paths and thus to maximise maneuvrability in future energy policies. A review of this programme is given, including some results of DFVLR research activities and the more important promotional steps already taken. Finally, a suggestion is made for future research, development and demonstration activities in the international arena.

Hydrogen Fuel for Motorcars

AbstractHydrogen is a potential secondary energy carrier that meets the requirements for an energy source of the future. Its combustion does not produce carbon monoxide, carbon dioxide or hydrocarbons. The present review describes the most important technical questions relating to the mobile use of hydrogen. Besides the discussion of the three suitable technologies for storing hydrogen in a vehicle – gaseous hydrogen in pressure vessels, liquefied hydrogen in vacuum-insulated tanks, and chemically compounded hydrogen in metal hydride stores – the properties of a hydrogen engine with external and internal mixture formation are described and compared. Furthermore, the design of the hydrogen-powered vehicles as developed at Daimler-Benz is shown. The review closes with the discussion of basic conditions for a future introduction of hydrogen as a fuel.

Wasserstoff‐Technik

AbstractHydrogen technology. Hydrogen is used today on a large scale as raw material in chemical engineering and in the long term has tremendous potential as one of the most important secondary energy carriers. Hydrogen is produced with fossil and nonfossil primary energy sources from fossil and nonfossil primary raw materials. As an almost pollution‐free secondary energy carrier, which is storable and transportable on a large scale, hydrogen can be used with nearly all energy utilization techniques fueled at present by natural gas, and products of petroleum and coal. Decisive influence on the introduction of hydrogen as energy carrier is exerted by the status and further development potential of hydrogen energy technology, cost of hydrogen production, and safety of a widespread use of hydrogen in the energy economy.