SEARCH · Engineering Papers
Results for “clean”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Clean quartz matters for cosmogenic nuclide analyses: An exploration of the importance of sample purity using the CRONUS-N reference material
We report reference materials are key for assessing inter-laboratory variability and measurement quality, and for placing analytical uncertainty bounds on sample analyses. Here, we investigate four years of data resulting from repeated processing of the CRONUS-N reference material for cosmogenic 10 Be and 26 Al analyses. At University of Vermont, we prepared a CRONUS-N aliquot with most of our sample batches from 2013 to 2017; these reference material samples were then distributed to four different accelerator mass spectrometry facilities, yielding 73 10 Be analyses and 58 26 Al analyses. We determine CRONUS-N 10 Be concentrations of (2.26 ± 0.14) x 10 5 atoms g -1 (n = 73, mean, 1 SD) and 26 Al concentrations of (1.00 ± 0.08) x 10 6 atoms g -1 (n = 58, mean, 1 SD). We find a reproducibility of 6.3% for 10 Be and 7.7% for 26 Al (relative standard deviations). We also document highly variable 27 Al and Mg concentrations and a 10 Be dispersion twice as large as the mean AMS analytic uncertainty. Analyses of the CRONUS-N material with and without density separation demonstrate that non-quartz minerals are present in the material and have a large impact on measured concentrations of 27 Al, 10 Be, and impurities; these non-quartz minerals represent only a very small portion of the total mass (0.6–0.8%) but have a disproportionally large effect on the resulting data. Our results highlight the importance of completely removing all non-quartz mineral phases from samples prior to Be/Al extraction for the determination of in situ cosmogenic 10 Be and 26 Al concentrations.
System Dynamics Modeling of Indium Material Flows under Wide Deployment of Clean Energy Technologies
Not Available
High temporal resolution generation expansion planning for the clean energy transition
As power systems integrate increasing quantities of wind, solar and energy storage resources, it is important to revisit power system capacity expansion modeling methods and assumptions that have been utilized in thermal- dominated systems. We conduct a series of case study analyses using a simplified representation of the Electric Reliability Council of Texas (ERCOT) system to demonstrate how least-cost capacity expansion outcomes are impacted by changes in model resolution across two temporal dimensions: 1) the number of considered representative periods, and 2) the system dispatch interval. First, we find that the least-cost generation portfolio can differ significantly for small changes in the number of representative days, but largely converges to the 365-day result once 104 representative days are considered. Furthermore, systems with wind, solar and storage resources were more sensitive to changes in the number of representative days than a thermal-dominated system. Second, we find that considering five-minute dispatch resolution consistently results in least-cost generation portfolios with less solar capacity and more energy storage capacity than corresponding scenarios with hourly dispatch intervals. This suggests that hourly dispatch representation fails to capture the intra-hour volatility of solar generation, and therefore also overlooks opportunities for storage resources to provide system value by balancing this volatility. Collectively these results indicate that capacity expansion modelers should revisit conventional approaches to temporal representation when conducting analyses of deeply decarbonized power systems to ensure that such analyses are robust and actionable. To our knowledge, this is the first study to analyze capacity expansion outcomes with five-minute dispatch resolution in this manner.
Economic assessment of clean hydrogen production from fossil fuels in the intermountain-west region, USA
Not Available
A comparison of Clean Power Plan forecasts for Wyoming: The importance of implementation and modeling assumptions
Not Available
The potential impact of rate-based or mass-based rules on coal-producing states under the Clean Power Plan
Not Available
Integrated gasification and plasma cleaning for waste treatment: A life cycle perspective
Highlights: • A life cycle assessment of an advanced two-stage process is undertaken. • A comparison of the impacts of the process when fed with 7 feedstock is presented. • Sensitivity analysis on the system is performed. • The treatment of RDF shows the lowest impact in terms of both GWP and AP. • The plasma shows a small contribution to the overall impact of the plant. - Abstract: In the past, almost all residual municipal waste in the UK was landfilled without treatment. Recent European waste management directives have promoted the uptake of more sustainable treatment technologies, especially for biodegradable waste. Local authorities have started considering other options for dealing with residual waste. In this study, a life cycle assessment of a future 20 MWe plant using an advanced two-stage gasification and plasma technology is undertaken. This plant can thermally treat waste feedstocks with different composition and heating value to produce electricity, steam and a vitrified product. The objective of the study is to analyse the environmental impacts of the process when fed with seven different feedstocks (including municipal solid waste, solid refuse fuel, reuse-derived fuel, wood biomass and commercial & industrial waste) and identify the process steps which contribute more to the environmental burden. A scenario analysis on key processes, such as oxygen production technology, metal recovery and the appropriate choice for the secondary market aggregate material, is performed. The influence of accounting for the biogenic carbon content in the waste from the calculations of the global warming potential is also shown. Results show that the treatment of the refuse-derived fuel has the lowest impact in terms of both global warming potential and acidification potential because of its high heating value. For all the other impact categories analysed, the two-stage gasification and plasma process shows a negative impact for all the waste streams considered, mainly due to the avoided burdens associated with the production of electricity from the plant. The plasma convertor, key characteristic of the thermal process investigated, although utilising electricity shows a relatively small contribution to the overall environmental impact of the plant. The results do not significantly vary in the scenario analysis. Accounting for biogenic carbon enhanced the performance of biomass and refuse-derived fuel in terms of global warming potential. The main analysis of this study has been performed from a waste management perspective, using 1 ton of waste as functional unit. A comparison of the results when 1 kWhe of electricity produced is used as functional unit shows similar trends for the environmental impact categories considered.
A Differentially Pumped Dual Linear Quadrupole Ion Trap (DLQIT) Mass Spectrometer: A Mass Spectrometer Capable of Clean MSn Experiments
Explore the source record for details and available documents.
Extraction Chromatographic Materials for Clean Hydrometallurgical Separation of Rare-Earth Elements Using Diglycolamide Extractants
The uncertain supply of the rare-earth elements (REE) from conventional sources such as bastnaesite and monazite demands the search for alternative sources. Unconventional sources such as phosphate rock and mine tailings have REE contents at the level of only hundreds to a thousand parts per million, which challenges the conventional REE separation methods such as solvent extraction (SX) and ion exchange (IX). Alternatively, the potential of extraction chromatography (EXC) has been explored, as it combines the selectivity of SX and the convenience of column techniques of IX. Herein, we report a novel EXC material incorporating N , N '-dimethyl- N , N '-dioctyl-3-oxa-diglycolamide (DMDODGA) into a porous solid support because DMDODGA exhibits higher extraction efficiency for REE in SX than does conventional N , N , N ', N '-tetraoctyl-3-oxa-diglycolamide (TODGA) and as also compared with similarly made conventional TODGA-based EXC material. The extraction of mixed REE by DMDODGA and TODGA resins was evaluated in H 2 SO 4 , HCl, and HNO 3 media as a function of acid concentration. The REE feed concentrations were adjusted to achieve stoichiometric REE concentration and excess REE concentration, conditions that reflect near or complete saturation of resin capacity. In general, extraction at the same acid concentration followed the order HNO 3 > HCl > H 2 SO 4 . The extraction strength of the DMDODGA resin is significantly higher than that of the TODGA resin in all three examined mineral acids, especially at lower H 2 SO 4 and HCl concentrations (0.01 and 0.1 M), making it a promising EXC material for hydrometallurgical extraction of REE.