We’ll start by giving two answers to a single question, “Why hydrogen?” We’ll follow this with abrief discussion of the energy system architecture’s five-link chain, to emphasize the key role of the central link, energy currencies. Then, gluing these two concepts together – (a) systemic architecture and (b) the answer to why hydrogen – we can set out the rationale leading to the premise that our system will ultimately be dominated by the twin currencies, hydrogen and electricity. All this will serve as a foundation for considering the sources, infrastructures and service technologies likely to characterise the deeper future (2100 ~ 2200). Finally, based on this long view (and our sliver of time within it) we can use the perspective to suggest near-term strategies...

World petroleum production cannot be sustained, and will begin to decline during the next ten to fifteen years. Petroleum represents 39% of US primary energy and 97% of its transportation energy. Hundred year time profiles for per capita supply were calculated for 108 possible combinations of peak production rates, peak years, field depletion rates, and population growth. An optimistic subset of assumptions produced per capita supply reductions of 17% and 45% in 2025 and 2050, respectively; a median subset increased those reductions to 31% and 64%. The energy capacity required for replacement of petroleum-based transportation energy is 312 GWe. 515 GWe would be required for hydrogen production, distribution, storage, and transfer. It could be produced by 515 1 000-MW nuclear reactors or 1.72 million 1-MW wind turbines. Subsequent replacement of natural gas would increase total energy demand to 798 GWe. Hydrogen storage as either a pressurised gas, liquid at 20K, or metallic hydride is technically feasible; however, all three pose significant practical difficulties...

Sustainability on economical growth, energy supply and environment are major issues for the 21st century. Within this context, one of the promising concepts is the possibility of nuclear-produced hydrogen. In this study, the effect of nuclear-produced hydrogen on the environment is discussed, based on the output of the computer code “Grape”, which simulates the effects of the energy, environment and economy in 21st century...

Clean forms of energy are needed to support sustainable global economic growth while mitigating greenhouse gas emissions and impacts on air quality. To address these challenges, the U.S. President’s National Energy Policy and the U.S. Department of Energy’s (DOE’s) Strategic Plan call for expanding the development of diverse domestic energy supplies. Working with industry, the Department developed a national vision for moving toward a hydrogen economy – a solution that holds the potential to provide sustainable clean, safe, secure, affordable, and reliable energy. In February 2003, President George W. Bush announced a new Hydrogen Fuel Initiative to achieve this vision...

The potential of hydrogen as a transportation fuel and for stationary power applications has generated significant interest in the United States. President George W. Bush has set the transition to a “hydrogen economy” as one of the Administration’s highest priorities. A key element of an environmentally-conscious transition to hydrogen is the development of hydrogen production technologies that do not emit greenhouse gases or other air pollutants. The Administration is investing in the development of several technologies, including hydrogen production through the use of renewable fuels, fossil fuels with carbon sequestration, and nuclear energy. The US Department of Energy’s Office of Nuclear Energy, Science and Technology initiated the Nuclear Hydrogen Initiative to develop hydrogen production cycles that use nuclear energy...

Several theoretical papers deal with the efficiency of the thermochemical cycles. In 1966, Funk and Reinstrom established the conditions to fulfill in order that no work is required by the cycle. They investigated a cycle comprised of two reactions and concluded that it was not feasible. In 1974, Abraham and Schreiner found that a minimum of three reactions were required if the maximum temperature is lower than 1 000 °K, and proposed the entropy vs. temperature diagram analysis to evaluate the thermochemical cycles. Finally, in 1975 Estève, Lecoanet and Roncato presented a simplified method to estimate the efficiency of a cycle. Each endothermic reaction is assumed to be achieved at a constant temperature for which °°°°. This enables a calculation of the thermal irreversibility due to the exchanges of heat with the intermediate circuit of the reactor. Until now, none of these theories have been applied to the well known Iodine Sulphur (I-S) cycle. The objective of the paper is to put in evidence the conclusions that can be drawn from the application of these theoretical results to the I-S cycle, and in particular what efficiency bounds one can reasonably expect...

The French Commissariat à l’Énergie Atomique (CEA) has, since mid-2001, performed a preliminary evaluation of different methods to produce hydrogen from nuclear energy. The objective is to compare the hydrogen production costs via high temperature electrolysis or via thermochemical cycles, which are nowadays the two main routes for the long term production of hydrogen without greenhouse effect, both from the technical and economical points of view...

The Japan Atomic Energy Research Institute (JAERI) has conducted a study on the thermochemical water-splitting process of the iodine-sulfur family (IS process). In the IS process, water will react with iodine and sulfur dioxide to produce hydrogen iodide and sulfuric acid, which are then decomposed thermally to produce hydrogen and oxygen. High temperature nuclear heat, mainly supplied by a High Temperature Gas-cooled Reactor (HTGR), is used to drive the endothermic decomposition of sulfuric acid. JAERI has demonstrated the feasibility of the water-splitting hydrogen production process by carrying out laboratory-scale experiments in which combined operation of fundamental reactions and separations using the IS process was performed continuously. At present, the hydrogen production test is continuing, using a scaled-up glass apparatus. Corrosion-resistant materials for constructing a largescale plant and process improvements by introducing advanced separation techniques, such as membrane separation, are under study. Future R&D items are discussed based on the present activities...

The Secure Transportable Autonomous (STAR-H2) project is part of the US Department of Energy’s (DOE’s) Nuclear Energy Research Initiative (NERI) to develop Generation IV (Gen IV) nuclear reactors that will supply high-temperature (over 1 100K; 800°C) heat. The goal of NERI is to develop an economical, proliferation-resistant, sustainable, nuclear-based energy supply system based on a modular-sized fast reactor that is passively safe and cooled with heavy liquid metal. STAR-H2 consists of the following....

A new thermochemical and electrolytic hybrid hydrogen production process (thermochemical and electrolytic hybrid hydrogen process in lower temperature range: HHLT) is under investigation to realise the hydrogen production from water by using the heat generation of coolant in fast breeding reactor (FBR). HHLT is based on sulphuric acid (H2SO4) synthesis and the decomposition processes developed earlier (Westinghouse process), and sulphur trioxide (SO3) decomposition process at about 500°C is facilitated by electrolysis with ionic oxygen conductive solid electrolyte which is extensively utilised for high-temperature electrolysis of water...

A Department of Energy goal is to identify new technologies for producing hydrogen cost effectively without greenhouse gas emissions. Thermochemical cycles are one of the potential options under investigation. Thermochemical cycles consist of a series of reactions in which water is thermally decomposed and all other chemicals are recycled. Only heat and water are consumed. However, most thermochemical cycles require process heat at temperatures of 850-900°C. Argonne National Laboratory is developing low temperature cycles designed for lower temperature heat, 500-550°C, which is more readily available. For this temperature region, copper-chlorine (Cu-Cl) cycles are the most promising cycle. Several Cu-Cl cycles have been examined in the laboratory and the most promising cycle has been identified. Proof-of-principle experiments are nearly complete. A preliminary assessment of cycle efficiency is promising. Details of the experiments and efficiency calculations are discussed...

Thermochemical processes are the primary candidates to produce hydrogen (H2) using hightemperature heat from nuclear reactors. The leading thermochemical processes have the same hightemperature chemical reaction (dissociation of sulphuric acid into H2O, O2, and SO2) and thus all require heat inputs at temperatures of -850°C. The processes differ in that they have different lowertemperature chemical reactions. The high temperatures are at the upper limits of high-temperature nuclear reactor technology. If peak temperatures can be reduced by 100 to 150°C, existing reactor technology can be used to provide the necessary heat for H2 production and the H2 produced using nuclear reactors becomes a much more viable near-term industrial option. If process pressures can be increased, significant reductions in capital cost and improvements in efficiency may be possible....

Processes and technologies to produce hydrogen synergistically by the steam reforming reaction using fossil fuels and nuclear heat are reviewed. Formulas of chemical reactions, required heats for reactions, saving of fuel consumption or reduction of carbon dioxide emission, possible processes and other prospects are examined for such fossil fuels as natural gas, petroleum and coal...

An experimental research programme is being conducted by the INEEL and Ceramatec, Inc., to test the high-temperature, electrolytic production of hydrogen from steam using a solid oxide cell. The research team is designing and testing solid oxide cells for operation in the electrolysis mode, producing hydrogen using a high-temperature heat and electrical energy. The high-temperature heat and the electrical power would be supplied simultaneously by a high-temperature nuclear reactor. Operation at high temperature reduces the electrical energy requirement for electrolysis and also increases the thermal efficiency of the power-generating cycle. The high-temperature electrolysis process will utilise heat from a specialised secondary loop carrying a steam/hydrogen mixture...

Water dissociates into oxygen and hydrogen at high temperatures. The problem with exploiting this reaction is that very low concentrations of hydrogen and oxygen are generated even at relatively high temperatures (e.g., only 0.1 and 0.042% for hydrogen and oxygen, respectively, at 1 600°C), because the equilibrium constant for this reaction is small. However, significant amounts of hydrogen or oxygen can be generated at moderate temperatures if the equilibrium is shifted toward dissociation by either oxygen or hydrogen removal using a mixedconducting (both electrons and ions) membrane...

Steam reforming of natural gas (methane) currently produces the bulk of hydrogen gas used in the world today. Because this process depletes natural gas resources and generates the greenhouse gas carbon dioxide as a by-product, there is a growing interest in using process heat and/or electricity generated by nuclear reactors to generate hydrogen by splitting water. Process heat from a hightemperature nuclear reactor can be used directly to drive a set of chemical reactions, with the net result of splitting water into hydrogen and oxygen. For example, process heat at temperatures in the range 850°C to 950°C can drive the sulphur-iodine (S-I) thermochemical process to produce hydrogen with high efficiency. The S-I process produces highly pure hydrogen and oxygen, with formation, decomposition, regeneration, and recycle of the intermediate chemical reagents...

This paper presents results of a conceptual design study involving gas and vapour core reactors (G/VCR) with a combined scheme to generate hydrogen and power. The hydrogen production schemes include high temperature electrolysis as well as two dominant thermochemical hydrogen production processes. Thermochemical hydrogen production processes considered in this study included the calcium-bromine process and the sulphur-iodine processes. G/VCR systems are externally reflected and moderated nuclear energy systems fuelled by stable uranium compounds in gaseous or vapour phase that are usually operated at temperatures above 1 500K. A gas core reactor with a condensable fuel such as uranium tetrafluoride (UF4) or a mixture of UF4 and other metallic fluorides (BeF2, LiF, KF, etc.) is commonly known as a vapour core reactor (VCR)....

Hydrogen is becoming the reference fuel for future transportation and the timetable for its adoption is shortening. However, to deploy its full potential, hydrogen production either directly or indirectly needs to satisfy three criteria: no associated emissions, including CO2; wide availability; and affordability. This creates a window of great opportunity within the next 15 years for nuclear energy to provide the backbone of hydrogen-based energy systems. But nuclear must establish its hydrogengenerating role long before the widespread deployment of Gen IV high-temperature reactors, with their possibility of producing hydrogen directly by heat rather than electricity...

The HTTR project aims at demonstrating inherent safety features of High temperature gas-cooled reactors (HTGRs) by safety demonstration tests, and establishing nuclear heat utilisation technology by a hydrogen production demonstration test. The safety demonstration tests are divided to the first phase and second phase tests. In the first phase tests, simulation tests of anticipated operational occurrences and anticipated transients without scram are conducted. The second phase tests will simulate accidents such as a depressurisation accident (loss of coolant accident)...

A new plant concept of nuclear-produced hydrogen is being studied using a Fast Reactor-Membrane Reformer (FR-MR). The conventional steam methane reforming (SMR) system is a three-stage process. The first stage includes the reforming, the second contains a shift reaction and the third is the separation process. The reforming process requires high temperatures of 800~900 °C. The shift process generates heat and is performed at around 200°C...

The secure transportable autonomous reactor (STAR) hydrogen project is part of the US Department of Energy’s (DOE’s) Nuclear Energy Research Initiative (NERI) to develop Generation IV nuclear reactors that will supply high-temperature heat at over 800°C. The goal of NERI is to develop an economical, proliferation-resistant, sustainable, nuclear-based energy supply system based on a modular-sized fast reactor that is passively safe and cooled with heavy liquid metal. STAR-H2 consists of...

This paper discusses the use of liquid-silicon-impregnated (LSI) carbon-carbon composites for the development of compact and inexpensive heat exchangers, piping, vessels and pumps capable of operating in the temperature range of 800 to 1 100°C with high-pressure helium, molten fluoride salts, and process fluids for sulfur-iodine thermochemical hydrogen production. LSI composites have several potentially attractive features, including ability to maintain nearly full mechanical strength to temperatures approaching 1 400°C, inexpensive and commercially available fabrication materials, and the capability for simple forming, machining and joining of carbon-carbon performs, which permits the fabrication of highly complex component geometries. In the near term, these materials may prove to be attractive for use with a molten-salt intermediate loop for the demonstration of hydrogen production with a gas-cooled high temperature reactor. In the longer term, these materials could be attractive for use with the molten-salt cooled advanced high temperature reactor, molten salt reactors, and fusion power plants...