• Energy Research
• nano-technology close
• 7. Clean energy close
• 13. Climate action close
• US close

Co-deposition of carbon atoms with hydrogen isotopes and hydrogenated carbon radicals and molecules is recognized as the main mechanism for tritium retention in the graphite walls of the previous tokamak fusion devices. Significant tritium retention would be a serious concern for safe and economic long-term operation of future fusion test reactors and fusion energy systems. Similar deposits are observed on the surface of the engineered components in a tritium-producing assembly, known as a Tritium-Producing Burnable Absorber Rod (TPBAR). Characterization of the deposits can help understand the tritium transport, accumulation history and distribution in TPBARs. This study reports our recent results from the carbonaceous deposits formed on an aluminide-coated cladding in the lower plenum of a TPBAR following thermal neutron irradiation. The observed deposits are amorphous in nature, consisting of flakes of interconnected nanoscale features. They contain primarily double-bonded carbon (e.g., alkene) and carbonyl carbon, as well as a minor fraction of aliphatic carbon, all of which are likely tritiated. A similar co-deposition process that occurred in previous fusion devices is responsible for the formation and growth of the carbonaceous deposits.

Developing high capacity yet stable cathodes is key to advancing Li-ion battery technologies. Now, a new metal oxide cathode that is rich in Li with a gradient in Li concentration is shown to be stable to O2 release leading to long cycle life and high capacity.

Abstract A numerical simulation program, based upon a finite difference nodal network, was used to simulate two Los Alamos test cells (one single and one multi-room cell) and a typical residence — all of which were exposed to intense insolation and large changes in ambient weather conditions. For the test cells, the predicted surface and globe temperatures are in good agreement with the measured values and indicate the acceptability of thermal modeling. The program was used to predict the behavior of a residential structure. The process of refining these predictions, guided by observations, led to the development of a stepwise simulation methodology. The insights gained as a result of this interdisciplinary involvement have been stimulating and instructive. The importance of recognizing the differences in the thought processes and the work styles of the several professions has been demonstrated. The most effective simulation methodology was that based upon human comfort, which appeared to be a common perception amongst all the program users.

Owing to its amorphous structure, a chalcogenide glass exhibits a thermal conductivity k approaching the theoretical minimum of its composition, called the Einstein’s limit. In this work, this limit is beaten in an amorphous solid consisting of glassy particles joined by nanosized contacts. When amorphous particles are sintered below the glass transition temperature under a high pressure, these particles can be mechanically bonded with a minimized interfacial thermal conductance. This reduces the effective k below the Einstein’s limit while providing superior mechanical strength under a high pressure for thermal insulation applications under harsh environments. The lowest room temperature k for the solid counterpart can be as low as 0.10 W/m·K, which is significantly lower than k≈0.2 W/m·K for the bulk glass.

Abstract Research on biofuels has been focused on improving yield of the conversion process while reducing the capital cost. Currently, 88% of the US ethanol production capacity and 96% of the planned expansion of capacity utilizes a dry milling process, which has a higher ethanol yield and a lower capital cost per gallon capacity than a wet milling process. However, the fact that all the corn ethanol plants that were bankrupted or idled during the 2008 economy recession used dry milling processes while all the plants that used wet milling processes had survived suggests that the efficiency driven approach may be flawed. This paper compares the economic performances of a typical dry milling plant with those of a typical wet milling plant under scenarios when market conditions are favorable or unfavorable to the corn ethanol production. The results show that the wet milling plant exhibits better performance under both scenarios due to its operational flexibility (e.g. having starch, high fructose corn syrup, gluten meal, gluten feed, and corn oil in its product portfolio). It is argued that the development of biofuel technologies should take operational flexibility into consideration in order to absorb disruptions from unexpected feedstock supply and volatile market conditions.

Abstract This paper presents a comparison of commercially used German and Russian reactor pressure vessel steels from the positron annihilation spectroscopy (PAS) point of view, having in mind knowledge obtained also from other techniques from the last decades. The second generations of Russian RPV steels seems to be fully comparable with German steels and their quality enables prolongation of NPP operating lifetime over projected 40 years. The embrittlement of CrMoV steel is very low due to the dynamic recovery of radiation-induced defects at reactor operating temperatures.

Abstract In this work, we propose an acoustic energy harvesting metamaterial consisting of an array of silicone rubber pillars and a PZT patch deposited on an ultrathin aluminum plate with several holes based on locally resonant mechanism. The resonance is formed by removing four pillars, drilling a few of holes and attaching the PZT patch on the aluminum plate. The strain energy originating from an incident acoustic wave is centralized in the resonant region, and the PZT patch is used to convert the elastic strain energy into electrical power. Numerical analysis and experimental results show that the proposed millimeter-scale harvester with holes obviously improves the effect of acoustic energy harvesting while performing at the subwavelength scale for sonic low-frequency environment (less than 1150 Hz). In addition, the experimental results demonstrate that the maximum output voltage and power of the proposed acoustic energy harvesting system with 16 holes of 2 mm radius are 3 and 10 times higher than those without holes at the resonant mode for 2 Pa of incident acoustic pressure. Both the number and size of holes have a significant effect on the performance of acoustic energy harvesting. The advantages of the proposed structure are easy-to-machine and full of practicality, and it can be used in broad applications for low-frequency acoustic energy harvesting.

A colloidal quantum dot solar cell is fabricated by spray-coating under ambient conditions. By developing a room-temperature spray-coating technique and implementing a fully automated process with near monolayer control-an approach termed as sprayLD-an electronic defect is eliminated resulting in solar cell performance and statistical distribution superior to prior batch-processed methods along with a hero performance of 8.1%.