Climate change gains more from nuclear substitution than from conservation

We show the massive reduction achievable, in both emissions and climate change impact, from enhanced nuclear energy use on the forecasts of future world energy use and its associated environmental impacts. A range encompassing the major scenarios for the World's energy demand have been analyzed using the latest version of the climate-modeling MAGICC/SCENGEN software (Version 4.1). We have updated and predicted the impacts of 80% substitution with CO₂-free sources (likely predominantly nuclear) for coal-fired electricity (by 2030) and for transportation fuel (by 2040). For transportation, hydrogen produced by CO₂-free sources would replace gasoline and diesel fuels. In this paper, to bracket the range of futures, we simply focus on two scenarios from the Intergovernmental Panel on Climate Change's (IPCC), one (A1FI) that is energy-profligate and one (B2) that is energy-conserving.The results show that, interestingly, projected average global temperatures for all scenarios are fairly similar until about 2035 (a further rise beyond the 1990 average temperature of +0.75 ± 0.1 K) regardless of energy usage and its sources. However, by 2050, the different IPCC scenarios diverge markedly. Understandably, A1FI is projected to have noticeably stronger effects than B2 on average global temperatures (about 0.3 K more in 2050) but the effect is much stronger over land at mid and high latitudes (up to almost 1 K more). What is most striking is that the substitution of CO₂-free sources gives projected average temperature rises in 2050 over key land areas (North America and China) that are very similar for the two energy-use scenarios—typically 1–1.5 K because A1FI's additional energy is predominantly supplied by nuclear. In contrast, projected rises with the unaltered cases are markedly different being about 2.5 K for A1FI and 1.5–2 K for B2. The projected changes in rainfall distribution show similar patterns, especially for the expected increases in higher latitudes.With the assumption of no additional policies for substitution of energy sources beyond 2040, temperature divergence between the two scenarios of relative energy profligacy or conservation grows in the latter half of the 21st century, even with substitution. However, the early substitution of nuclear energy and hydrogen appears to buy time and is not crucially dependent on severe, near-term curtailment of energy use. Near-term curtailment is too difficult to implement at a time of rapid industrialization of major emerging economies. Of course, proportionately larger deployments of CO₂-free energy sources are needed for more energy-intensive scenarios.Nuclear power must dominate as the source of CO₂-free energy since it is proven, dependable, available on a large scale, and economic. Social objections to nuclear energy in some countries and quarters are seen as well-meaning but misguided distractions from solving the energy and environmental crises that are now facing world sustainability. The time for real technical, social and political action is now.     

Effect of antioxidant oxidation potential in the oxygen radical absorption capacity (ORAC) assay

The “oxygen radical absorption capacity” (ORAC) assay (Ou, B., Hampsch-Woodill, M., Prior, R.L. (2001). Development and validation of an improved oxygen radical absorbance capacity assay using fluorescein as the fluorescent probe. Journal of Agricultural and Food Chemistry 49, 4619–4626) is widely employed to determine antioxidant content of foods and uses fluorescein as a probe for oxidation by peroxyl radicals. Kinetic modeling of the ORAC assay suggests that the lag phase for loss of fluorescence results from equilibrium between antioxidant and fluorescein radicals and the value of the equilibrium constant determines the shape of the lag phase. For an efficient antioxidant this constitutes a “repair” reaction for fluoresceinyl radicals and produces a well defined lag phase. The lag phase becomes less marked with increasing oxidation potential of the antioxidant. Pulse radiolysis confirms that fluoresceinyl radicals are rapidly (k ∼ 10⁹ dm³ mol⁻¹ s⁻¹) reduced by Trolox C, a water soluble vitamin E analogue. ORAC assays of phenols with varying oxidation potentials suggest that it might be employed to obtain an estimate of the redox potential of antioxidants within food materials.     

Canada’s program on nuclear hydrogen production and the thermochemical Cu–Cl cycle

This paper presents an overview of the status of Canada’s program on nuclear hydrogen production and the thermochemical copper–chlorine (Cu–Cl) cycle. Enabling technologies for the Cu–Cl cycle are being developed by a Canadian consortium, as part of the Generation IV International Forum (GIF) for hydrogen production with the next generation of nuclear reactors. Particular emphasis in this paper is given to hydrogen production with Canada’s Super-Critical Water Reactor, SCWR. Recent advances towards an integrated lab-scale Cu–Cl cycle are discussed, including experimentation, modeling, simulation, advanced materials, thermochemistry, safety, reliability and economics. In addition, electrolysis during off-peak hours, and the processes of integrating hydrogen plants with Canada’s nuclear plants are presented.     

Hydrogen sulphide oxidation over teflon treated activated alumina and titanium dioxide catalysts

Commercial activated alumina and titanium dioxide catalysts were treated with Teflon to reduce the negative effects of water vapour on the oxidation of hydrogen sulphide by sulphur dioxide (Claus Reaction) near the sulphur dew point. The tests were conducted at 200°C and 130°C (108 kPa), with and without 30% water vapour in the feed gas. An alumina/Teflon composite catalyst was found to be superior to both untreated commercial catalysts at 130°C. This improvement was probably due to an increase in macroporosity rather than to a wetproofing effect. At 200°C, the performance of the composite was similar to that of the untreated titanium dioxide which in turn was superior to the untreated activated alumina.     

A recycle reactor for measuring hydrogen isotope exchange kinetics under vapour phase and trickle bed conditions

A recycle reactor system has been developed to measure the activities of catalysts for isotope exchange between hydrogen gas and water vapour. To allow testing of reasonably large quantities of catalysts, the reactor was operated with a high recirculating flow of hydrogen gas passing through a saturator to provide the water vapour required for the reaction. In this mode of operation, only a small spiking gas flow was required as feed compared to the very high feed flow that would be required for once-through operation. The reactor was also operated as a trickle bed by recirculating the saturator water. By testing catalysts under both vapour and trickle bed modes, it was possible to investigate the effect of trickling water over the catalyst on the catalytic activity. Kinetic exchange rates under vapour phase operation were calculated from both plug flow and well-mixed reactor models. The former model was found to be the appropriate one for the ranges of operating conditions investigated. However, for trickle bed operation, the well-mixed reactor model was found to be the suitable one. Vapour phase and trickle bed tests done with random bed and structured bed catalysts indicated that the gas phase isotope exchange reaction was not impaired by the presence of liquid water in the reactor.     

Diffusional effects in wetproofed catalysts for isotopic exchange between hydrogen gas and water vapour

Deuterium transfer rates between water vapour and hydrogen gas have been obtained for platinized carbon powder (Pt-C) and Teflon wetproofed platinized carbon films. The pore diffusional resistance in the catalyst films was assessed by calculating the effectiveness factor, ?, from a mathematical model for simultaneous diffusion and first order reversible reaction kinetics. Wetproofing the Pt-C catalyst with Teflon increased the intrinsic rate of reaction, but the effectiveness factor decreased with increasing catalyst layer thickness. Pore size and surface area distributions and water vapour adsorption isotherms of the Pt-C/Teflon catalyst films were similar to those of the Pt-C itself. Since Teflon had negligibly small surface area and very large pores compared to the carbon support, wetproofing did not cause significant changes to the physical characteristics of the platinized carbon.     

Advances in unit operations and materials for the CuCl cycle of hydrogen production

This paper presents recent advances by an international team of five countries – Canada, U.S., China, Slovenia and Romania – on the development and scale-up of the copper–chlorine (CuCl) cycle for thermochemical hydrogen production using nuclear or solar energy. Electrochemical cell analysis and membrane characterization for the CuCl/HCl electrolysis process are presented. Constituent solubility in the ternary CuCl/HCl/H₂O system and XRD measurements are reported in regards to the CuCl₂ crystallization process. Materials corrosion in high temperature copper chloride salts and performance of coatings of reactor surface alloys are examined. Finally, system integration is examined, with respect to scale-up of unit operations, cascaded heat pumps for heat upgrading, and linkage of heat exchangers with solar and nuclear plants.     

Nuclear‐based hydrogen production with a thermochemical copper–chlorine cycle and supercritical water reactor: equipment scale‐up and process simulation

Issues related to equipment scale‐up and process simulation are described for a thermochemical cycle driven by nuclear heat from Canada's proposed Generation IV reactor (Super‐Critical Water‐Cooled Reactor; SCWR), which is a CANDU derivative using supercritical water cooling. The copper–chlorine (Cu‐Cl) cycle has been identified by Atomic Energy of Canada Limited as the most promising cycle for thermochemical hydrogen production with SCWR. Water is decomposed into hydrogen and oxygen through intermediate Cu‐Cl compounds. This article outlines the challenges and design issues of hydrogen production with a Cu‐Cl cycle coupled to Canada's nuclear reactors. The processes are simulated using the Aspen Plus process simulation code, allowing the cycle efficiency and possible efficiency improvements to be examined. The results are useful to assist the development of a lab‐scale cycle demonstration, which is currently being undertaken at the University of Ontario Institute of Technology in collaboration with numerous partners. Copyright © 2010 John Wiley & Sons, Ltd.     

Dissolved oxygen removal by combination with hydrogen using wetproofed catalysts

Dissolved oxygen in water at parts per million levels could be reduced to a few parts per billion by reaction with hydrogen using Pt catalysts supported on carbon and stainless steel in random and structured bed configurations. The carbon supported catalyst was Teflon coated to wetproof it. Both gas phase and liquid phase reactions occurred simultaneously under trickle bed operation, resulting in higher oxygen removal efficiency for this mode of operation than for the liquid-filled condition. The structured catalyst bed yielded greater hydraulic capacity than the random bed, and with wetproofed catalyst it gave the best oxygen removal efficiency. Since the gas phase reaction rate could be increased by reducing the wetted fraction of the catalyst through wetproofing, wetproofed catalysts offer a unique advantage over conventional hydrophilic catalysts.     

Recent Canadian advances in nuclear-based hydrogen production and the thermochemical Cu–Cl cycle

This paper presents recent Canadian advances in nuclear-based production of hydrogen by electrolysis and the thermochemical copper–chlorine (Cu–Cl) cycle. This includes individual process and reactor developments within the Cu–Cl cycle, thermochemical properties, advanced materials, controls, safety, reliability, economic analysis of electrolysis at off-peak hours, and integrating hydrogen plants with Canada's nuclear power plants. These enabling technologies are being developed by a Canadian consortium, as part of the Generation IV International Forum (GIF) for hydrogen production from the next generation of nuclear reactors.