Sustainability by combining nuclear,fossil, and renewable energy sources

The energy industries face two sustainability challenges: the need to avoid climate change and the need to replace traditional crude oil as the basis of our transport system. Radical changes in our energy system will be required to meet these challenges. These challenges may require tight coupling of different energy sources (nuclear, fossil, and renewable) to produce liquid fuels for transportation, match electricity production to electricity demand, and meet other energy needs. This implies a paradigm shift in which different energy sources are integrated together, rather than being considered separate entities that compete. Several examples of combined-energy systems are described. High-temperature nuclear heat may increase worldwide light crude oil resources by an order of magnitude while reducing greenhouse gas releases from the production of liquid fossil fuels. Nuclear–biomass liquid-fuels production systems could potentially meet world needs for liquid transport fuels. Nuclear–hydrogen peak power systems may enable renewable electricity sources to meet much of the world's electric demand by providing electricity when the wind does not blow and the sun does not shine.     

Electric Power from Renewable Energy: Realities for Policy-Makers

Current wind and photovoltaic technologies are incapable of providing the all-renewable electric power future that many have envisioned, because of the inherent mismatch between their unpredictable, intermittent nature and society's demands for electric power on demand. Paths for using these technologies are in combination with electric power storage or as fuel-savers with fossil-fueled power plants. In a cloudless world, photovoltaic costs double if power is needed at night, and when there are clouds, costs escalate dramatically. Electric power from wind turbines varies as the cube of the wind velocity, which can fluctuate from zero to high values over short periods. To make competent national energy policy, the public and policymakers need an unbiased, authoritative analysis of the maximum possible, long-term contributions of renewables to U.S. electric power needs.     

The case for the fusion hybrid

The use of nuclear fusion to produce fuel for nuclear fission power stations is discussed in the context of a crucial need for future energy options. The fusion hybrid is first considered as an element in the future of nuclear fission power to provide long term assurance of adequate fuel supplies for both breeder and convertor reactors. Generic differences in neutronic characteristics lead to a fuel production potential of fusion-fission hybrid systems which is significantly greater than that obtainable with fission systems alone. Furthermore, cost benefit studies show a variety of scenarios in which the hybrid offers sufficient potential to justify development costs ranging in the tens of billions of dollars. The hybrid is then considered as an element in the ultimate development of fusion electric power. The hybrid offers a near term application of fusion where experience with the requisite technologies can be derived as a vital step in mapping a credible route to eventual commercial feasibility of pure fusion systems. Finally, the criteria for assessment of future energy options are discussed with prime emphasis on the need for rational comparison of alternatives. This approach is contrasted with the dual standard too often used in judging the risks and benefits of nuclear power where, for example, rather minor radiological effects are highlighted while much larger exposures to radiation from medical x-rays, airplane travel, color television sets, etc., are ignored. It is concluded that the fusion hybrid deserves a prominent place among new energy resources but that early attention to insure an adequately informed public is a vital ingredient in assuring reasonable prospects of success.     

The advanced high-temperature reactor: High-temperature fuel, liquid salt coolant, liquid-metal-reactor plant

The Advanced High-Temperature Reactor is a new reactor concept that combines four existing technologies in a new way: (1) coated-particle graphite-matrix nuclear fuels (traditionally used for helium-cooled reactors), (2) Brayton power cycles, (3) passive safety systems and plant designs from liquid-metal-cooled fast reactors, and (4) low-pressure liquid-salt coolants with boiling points far above the maximum coolant temperature. The new combination of technologies enables the design of a large [2400- to 4000-MW(t)] high-temperature reactor, with reactor-coolant exit temperatures between 700 and 1000°C (depending upon goals) and passive safety systems for economic production of electricity or hydrogen. The AHTR [2400-MW(t)] capital costs have been estimated to be 49 to 61% per kilowatt (electric) relative to modular gas-cooled [600-MW(t)] and modular liquid-metal-cooled reactors [1000-MW(t)], assuming a single AHTR and multiple modular units with the same total electrical output. Because of the similar fuel, core design, and power cycles, about 70% of the required research is shared with that for high-temperature gas-cooled reactors.     

South Africa's opportunity to maximise the role of nuclear power in a global hydrogen economy

Global concern for increased energy demand, increased cost of natural gas and petroleum, energy security and environmental degradation are leading to heightened interest in using nuclear energy and hydrogen to leverage existing hydrocarbon reserves. The wasteful use of hydrocarbons can be minimised by using nuclear as a source of energy and water as a source of hydrogen. Virtually all hydrogen today is produced from fossil fuels, which give rise to CO₂ emissions. Hydrogen can be cleanly produced from water (without CO₂ pollution) by using nuclear energy to generate the required electricity and/or process heat to split the water molecule. Once the clean hydrogen has been produced, it can be used as feedstock to fuel cell technologies, or in the nearer term as feedstock to a coal-to-liquids process to produce cleaner synthetic liquid fuels. Clean liquid fuels from coal - using hydrogen generated from nuclear energy - is an intermediate step for using hydrogen to reduce pollution in the transport sector; simultaneously addressing energy security concerns. Several promising water-splitting technologies have been identified. Thermo-chemical water-splitting and high-temperature steam electrolysis technologies require process temperatures in the range of 850 °C and higher for the efficient production of hydrogen. The pebble bed modular reactor (PBMR), under development in South Africa, is ideally suited to generate both high-temperature process heat and electricity for the production of hydrogen. This paper will discuss South Africa's opportunity to maximise the use of its nuclear technology and national resources in a global hydrogen economy.     

月球~3He资源开发的经济、技术可行性研究

从能量学的角度对开采月球３＿Ｈｅ资源作为Ｄ－３＿Ｈｅ聚变燃料的经济技术可行性进行了研究。拟分如下部分：太阳风的参数分析与月球表层土中的３＿Ｈｅ贮量估算；月球Ｈｅ的开采成本估算；月球白天就地真空加热抽取Ｈｅ的成本估算；月球夜晚就地低温分离同位素３＿Ｈｅ／４＿Ｈｅ的成本计算；液态３＿Ｈｅ从月球运回地球的成本估算；以月球运回的３＿Ｈｅ作为Ｄ－３＿Ｈｅ聚变燃料的能量偿还比计算。最后与地球上开采２３５＿Ｕ和煤发电的能量偿还比对照，给出Ｄ－３＿Ｈｅ与Ｄ－Ｔ燃料聚变能单位电价的比较。     

Fusion: Expensive and Taking Forever?

The road map of fusion power is compared to the development and deployment of other energy technologies. A generic deployment model is presented, which describes the fastest deployment (of any new technology) achievable with the constraint that the industrial capacity that needs to be built up must be continuous and should not overshoot the replacement market in the final, saturated state. It is shown that the development needs an ‘investment’ phase to build up industrial capacity which takes several decades, during which growth is typically exponential, but net energy production is negligible. During the exponential growth the cost is dominated by the capital investment, which allows for a simple comparison of different energy technologies. Fusion is at the start of the exponential growth phase, while still having significant uncertainties concerning its technical feasibility. In comparison to e.g. solar PV and wind, fusion is ‘late’, lagging by some 50 years. To follow the same rate of development that fission, wind and PV have shown, fusion will need to have 3 DEMO reactors operational in the early 2050s, followed by 10 generation one (GEN1) plants in the early 2060s and 100 GEN2 plants in the early 2070s. For the cost development to be comparable, an estimated allowable cost for one DEMO reactor is ~20 G$. While these indicative numbers for the pace and cost of development are very challenging but perhaps not unthinkable for fusion, this analysis does point towards an emphasis on ‘simpler and cheaper’ reactor designs.     

Nuclear heat for hydrogen production: Coupling a very high/high temperature reactor to a hydrogen production plant

Hydrogen has been dubbed the fuel of the future. As fossil fuel reserves become depleted and greenhouse gas emissions are reduced inline with the Kyoto protocol, alternative energy sources and vectors, such as hydrogen, must be developed. Hydrogen produced from water splitting, as opposed to from hydrocarbons, has the potential to be a carbon neutral energy solution. There are several methods to extract hydrogen from water, three leading candidates being high temperature electrolysis, the SI thermochemical cycle and the HyS hybrid thermochemical cycle. All three of these processes involve a section requiring very high temperatures. The Very High Temperature Reactor (VHTR), a gas cooled Generation IV reactor, is ideally suited for providing this high temperature heat. Nuclear hydrogen production is being investigated around the world. The four leading consortiums are the Japan Atomic Energy Agency (JAEA), PBMR/Westinghouse, GA, and AREVA NP/CEA/EDF. There are also many smaller R&D efforts focussing on the development of particular materials and components and on process flowsheeting.A nuclear hydrogen plant involves four key pieces of equipment: the VHTR, the hydrogen production plant (HPP), the intermediate heat exchanger (IHX) and the power conversion system (PCS). The choice of all four items varies dramatically between programmes. Both pebble bed and prismatic fuel block VHTRs are being developed, which can be directly or indirectly coupled to a HPP and PCS placed either in series or parallel. Either a Rankine steam cycle or a Brayton gas turbine cycle can be employed in the PCS. This report details the choices made and research being carried out around the world.Predicted process efficiencies and plant costs are currently at a preliminary stage and are very similar, regardless of the options chosen. The cost of hydrogen produced from water splitting using nuclear technologies is around $2/kg H₂. This is competitive with hydrogen produced by other methods, particularly if carbon emissions are regulated and costed. The technological feasibility and testing of key components will be one of the determining factors in plant viability.     

Synthetic fuels and fusion

The decreasing availability of fossil fuels emphasizes the need to develop systems which will produce synthetic fuel to substitute for and supplement the natural supply. An important first step in the synthesis of liquid and gaseous fuels is the production of hydrogen. Thermonuclear fusion offers an inexhaustible source of energy for the production of hydrogen from water. Depending on design, electric generation efficiencies of 40–60% and hydrogen production efficiencies by high temperature electrolysis of 50–70% are projected for fusion reactors using high temperature blankets. Fusion/coal symbiotic systems appear economically promising for the first generation of commercial fusion synfuels plants. Coal production requirements and the environmental effects of large-scale coal usage would be greatly reduced by a fusion/coal system. In the long-term, there could be a gradual transition to an inexhaustible energy system based solely on fusion.     

A two-step photon-intermediate technique for the production of electricity, chemicals or lasers in nuclear energy conversion

The authors have developed an energy conversion concept, called Photon-Intermediate Direct Energy Conversion (PIDEC), that makes possible a two-step conversion of high grade nuclear energy (fission or fusion) to electricity or other useful high grade energy forms without intermediate thermalization. In PIDEC the nuclear fuel has a low average density, with local scale lengths significantly shorter than the range of the energetic nuclear reaction products. In the first step of the process, the nuclear energetic reaction product energy is transported to a fluorescer gas which converts it into photons. Then, in the second step of the process, the photons are transported out of the nuclear reactor to a medium which converts the photon energy to the desired product high grade energy form, such as electricity. We calculate that electricity can be produced, non-thermally, with an efficiency of up to 30%. With the addition of intermediate and bottoming thermal cycles, efficiency for electricity production could be as high as 70%, double that of conventional nuclear power plants. In addition to electric power, photolysis makes other product forms possible. These products include useful feedstock, or combustion chemicals, such as hydrogen and carbon monoxide, and excited molecular and atomic states, used for laser amplifiers or oscillators.     

Utilization of solar and nuclear energy for hydrogen production

Although the world-wide energy supply situation appears to have eased at present, non-fossil primary energy sources and hydrogen as a secondary energy carrier will have to take over a long-term and increasing portion of the energy supply system. The only non-fossil energy sources which are available in relevant quantities, are nuclear energy, solar energy and hydropower. The potential of H₂ for the extensive utilization of solar energy is of particular importance. Status, progress and development potential of the electrolytic H₂ production with photovoltaic generators, solar-thermal power plants and nuclear power plants are studied and discussed. The joint German-Saudi Arabian Research, Development and Demonstration Program HYSOLAR for the solar hydrogen production and utilization is summarized.     

Economic competitiveness of the new generation of NPPs with NP-500 units in Russia

An economic analysis of NPPs with the new design of the average capacity unit (NP-500) developed in Russia is carried out. The design is characterized by the application of passive safety systems, and a double protective containment, that allows a decrease in the probability of a severe accident by 2 or 3 orders of magnitude in comparison with present VVER units, operated at modern NPPs. The NP-500 unit has a capacity of 635 MWe; it is more compact, and therefore it has a smaller specific consumption of materials and a smaller number of regular staff. Licensing of the design on the basis of international practice is now nearing completion. The published data on costs by the Joint Parallel Nuclear Alternatives Study (JPNAS), executed for the US-Russia Joint Commission on Economic and Technological Cooperation, as well as recent forecasts by different authors for the period 1995–2010 on power consumption, specific investments in thermal power plants and the costs of organic fuels for different regions of Russia are used. An original methodology for analysis of equilibrium prices of energy (marginal costs), competition for developing power technologies and accounting for a factor of inertia in power systems is described. The total self-sufficiency of Russia with nuclear fuel for the forecasting period and the necessity of adequate development of the organic power infrastructure are taken into account. The individual rates of development of the different competitive energy technologies and appropriate returns on capital are determined. The competitiveness of NPPs with NP-500 units in different regions of Russia is analyzed. The attractiveness of investment in this objective is emphasized.     

Futures for hydrogen produced using nuclear energy

What is the future of hydrogen (H₂) produced from nuclear energy? Assuming that economically competitive nuclear H₂ can be produced, production of H₂ may become the primary use of nuclear energy and the basis for both a nuclear-H₂ renewable (solar, wind, etc.) energy economy and a nuclear-H₂ transport system. The technical and economic bases for these conclusions are described. In a nuclear-H₂ renewable energy economy, nuclear energy is used to produce H₂ that is stored and becomes the energy-storage component of the electrical generating system. The stored H₂ replaces piles of coal and tanks of liquid fuel. Capital-intensive renewable energy sources and nuclear reactors produce electricity at their full capacity. The stored H₂ is used in fuel cells to produce the highly variable quantities of electricity needed to fill the gap between the electricity demand by the customer and the electricity generated by the rest of the electrical generating system. Hydrogen is also used to produce the liquid or gaseous transport fuels. This energy-system architecture is a consequence of the fundamental differences between the characteristics of electricity (movement of electrons) and those of H₂ (movement of atoms). Electricity can be generated, transformed, and used economically on either a small or a large scale. However, it is difficult to generate, store, and transform H₂ economically on a small scale. This distinction favors the use of large-scale nuclear systems for H₂ production.     

核电工程经济数据库

核电工程经济数据库由核电厂经济数据库、核燃料循环经济数据库和核电规划与环境经济数据库三部分组成，用ＯＲＡＣＬＥ Ｖ６．０实现。核电厂经济数据库包括公共经济数据、电厂技术参数、工程投资数据、经济效益数据等内容。核燃料循环经济数据库燃料技术参数和价格数据。核电规划与环境经济数据库由历史经济、预测经济、能源平衡、电力、能源设施等数据组成。     

Roles of nuclear energy in Japan''s future energy systems

The roles of nuclear energy in Japan's future energy systems were analyzed from the viewpoint of securing stable energy supply and reducing carbon dioxide (CO₂) emissions. The MARKAL model, developed in the Energy Technology Systems Analysis Programme (ETSAP) of the IEA, was used for establishing several energy scenarios with different assumptions on the availability of nuclear energy, natural gas, and a CO₂ disposal option. Nuclear energy was assumed to apply for synthetic fuel production as well as for conventional electric power generation. By comparing the CO₂ emission and system costs between these energy scenarios, following results were obtained. Without nuclear energy, the CO₂ emissions will hardly be reduced because of substantial increases in coal utilization. CO₂ disposal will be effective in reducing the emissions, however at much higher costs than the case with nuclear energy. The expansion of natural gas imports, if alone, will not reduce the emissions at enough low levels.     

Requirements for alternate end uses of fusion energy

End uses of fusion energy other than the production of electricity have been receiving increasing attention over the past several years. Potential alternate end uses include: fissile fuel production, combustible fuel production, district heating, process steam generation, and fission product and actinide transmutation. Each of these uses will require energy conversion technologies different from those used for power generation and each will have to meet a different set of institutional requirements.This paper contains brief discussions of the energy conversion technologies which may be applicable for these alternate uses and assessments of the institutional requirements they will have to meet. Institutional requirements for the alternate end use plants are expected to depend on factors including how many plants are to be built, who will own and operate them, where they must be located, and whether or not the end product can be stored. A set of institutional requirements developed for EPRI as part of study of what the electric utility industry would require of fusion electric power generating plants was used as a basis. This set of requirements included considerations of finance and planning; safety, siting, and licensing; operations and maintenance; and resources and manufacturing. They were modified by the factors listed above for each end use and the resultant requirements were compared with the projected characteristics of the alternate use plants. The resulting assessments are, of course, very preliminary in nature but should provide guidance for further studies of alternate end use fusion plants.     

The effect of a micro bubble dispersed gas phase on hydrogen isotope transport in liquid metals under nuclear irradiation

The present work intend to be a first step towards the understanding and quantification of the hydrogen isotope complex phenomena in liquid metals for nuclear technology. Liquid metals under nuclear irradiation in, e.g., breeding blankets of a nuclear fusion reactor would generate tritium which is to be extracted and recirculated as fuel. At the same time that tritium is bred, helium is also generated and may precipitate in the form of nano bubbles. Other liquid metal systems of a nuclear reactor involve hydrogen isotope absorption processes, e.g., tritium extraction system. Hence, hydrogen isotope absorption into gas bubbles modelling and control may have a capital importance regarding design, operation and safety.Here general models for hydrogen isotopes transport in liquid metal and absorption into gas phase, that do not depend on the mass transfer limiting regime, are exposed and implemented in OpenFOAM® CFD tool for 0D–3D simulations. Results for a 0D case show the impact of a He dispersed phase of nano bubbles on hydrogen isotopes inventory at different temperatures as well as the inventory evolution during a He nucleation event. In addition, 1D and 2D axisymmetric cases are exposed showing the effect of a He dispersed gas phase on hydrogen isotope permeation through a lithium lead eutectic alloy and the effect of vortical structures on hydrogen isotope transport at a backward facing step.Exposed results give a valuable insight on current nuclear technology regarding the importance of controlling hydrogen isotope transport and its interactions with nucleation event through gas absorption processes.     

Update of the French R&D strategy on gas-cooled reactors

Gas-cooled reactors take up a strong second role in France's R&D strategy on future nuclear energy systems as priority was given in 2005 to fast neutron reactors with multiple-recycle for their potential to optimally use uranium resource and minimize the long term burden of radioactive waste. Owing to the European past experience on sodium-cooled fast reactors (SFRs), this reactor type was logically selected as reference for a new generation fast neutron reactor intended to be tested as a prototype in the 2020s and be ready for industrial deployment around 2040. At the same time, the potential merits of a gas fast reactor (GFR) with ceramic clad fuel for a safe management of cooling accident are acknowledged for the potential of this reactor type to resolve critical issues of liquid fast reactors (safety, operability and reparability). A pre-feasibility report on a first concept of GFR was issued in 2007 that summed-up results of a 5-year international R&D effort on GFR fuel technology, reactor design and operating transient analyses. This report established a global confidence in the feasibility of this concept and its potential for attractive performances. Furthermore, it suggested directions of R&D to generate by 2012 an updated concept with improved performances and taking better benefit from GFR specific technologies.A second activity on gas-cooled reactors originates from the current interest of CEA's industrial partner AREVA in high or very high temperature reactors (V/HTR) for supplying hydrogen, synthetic hydrocarbon fuels and process heat for the industry. This activity currently encompasses R&D on V/HTR key technologies such as particle fuel fabrication, high temperature compact heat exchangers and coupling technologies to various power conversion systems. R&D on V/HTR and GFR are synergistic in various respects. The GFR can be viewed as a more sustainable version of the VHTR and synergies exist in research on heat resisting materials, helium system technology and power conversion systems. Both reactors require active research in materials and spur developments of new metallic alloys and ceramics applicable to other advanced nuclear systems.     

Nuclear fusion and renewable energy forms: Are they compatible?

Nuclear fusion can be considered as a base-load power plant technology: High investment costs and limited operational flexibility require continuous operation. Wind and solar, on the other hand, as the putative main pillars of a future renewable energy system, are intermittent power sources. The resulting variations that occur on many different time scales require at first sight a rather flexible back-up system to balance this stochastic behavior. Fusion would appear not to be well suited for this task. The situation changes, however, if a large-scale renewable energy system is envisaged based on a transnational, or even transcontinental power grid. The present paper discusses a possible European power system in the year 2050 and beyond. A high percentage share of renewable energies and a strong power grid spanning the whole of Europe and involving neighboring countries, in particular those in North Africa, are assumed. The linear programming model URBS is used to describe the power system. The model optimizes the overall system costs and simulates power plant operation with an hourly resolution for one whole year. The geographical resolution is at least at the country level. The renewable technologies are modeled first on a more local level and then summed together at the country or regional level. The results indicate that the smoothing effects of the large-scale power grid transform the intermittent renewable supply, which is then more compatible with base-load power plants such as fusion reactors.     

Economic viability of small to medium-sized reactors deployed in future European energy markets

Future plans for energy production in the European Union as well as other locations call for a high penetration of renewable technologies (20% by 2020, and higher after 2020). The remaining energy requirements will be met by fossil fuels and nuclear energy. Smaller, less-capital intensive nuclear reactors are emerging as an alternative to fossil fuel and large nuclear systems. Approximately 50 small (<300 MWe) to medium-sized (<700 MWe) reactors (SMRs) concepts are being pursued for use in electricity and cogeneration (combined heat and power) markets. However, many of the SMRs are at the early design stage and full data needed for economic analysis or market assessment is not yet available. Therefore, the purpose of this study is to develop “target cost” estimates for reactors deployed in a range of competitive market situations (electricity prices ranging from 45-150 €/MWh). Parametric analysis was used to develop a cost breakdown for reactors that can compete against future natural gas and coal (with/without carbon capture) and large nuclear systems. Sensitivity analysis was performed to understand the impacts on competitiveness from key cost variables. This study suggests that SMRs may effectively compete in future electricity markets if their capital costs are controlled, favorable financing is obtained, and reactor capacity factors match those of current light water reactors. This methodology can be extended to cogeneration markets supporting a range of process heat applications.