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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.

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At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

The cost savings potential of controlling solar thermal collectors with storage for time-of-use electricity rates

Homes and commercial buildings account for roughly 40% of U.S. energy consumption. A significant portion of this energy consumption, and therefore utility cost, comes from domestic hot-water use. Solar collectors such as flat plate collectors, evacuated tubes, and combined photovoltaic/thermal panels, are renewable options that collect thermal energy and could help reduce utility costs. Hot water is generated by pumping a working fluid through the solar collector, where the fluid captures thermal energy via absorbed solar radiation incident on the collector surface. The collection of heat coincides with the availability of solar radiation, but the best time to use this thermal energy depends on the utility rate at a given time, which often changes throughout the day. In this work, we implement and simulate a control strategy using Transient System Simulation Tool (TRNSYS) that reduces utility costs by controlling when the system stores and uses thermal energy based on solar availability and time-of-use electricity rates. Our modeled results show that the control strategy can reduce utility costs associated with using hot water between 3% and 30%. Here, we also show how the on-peak utility rates, the size and type of the solar collectors, and the location's climate impact the results.

14 SOLAR ENERGY↗
DOE OSTI2021

Build solar-energy systems to last — save billions

Here, to withstand extreme weather, rapid innovation and rock-bottom prices, solar installations need tighter quality control, standards and testing. Solar energy is being adopted the world over. Prices have plunged 100-fold since 1980. By 2023, the installed capacity of photovoltaics globally is expected to surpass 1 terawatt — 30–100 TW will be required by 2050. Yet colliding trends mean that many of the technologies being installed today might not last until then if quality is not assured.

14 SOLAR ENERGY↗
DOE OSTI2021

Early-Career Reflections: Curiosity Saves the Researcher

Defining your own research questions and working with a clear direction in mind is key to a successful career in academia. Evangelia Spyrou explains how following her thirst for knowledge in her specific area of interest prepared her for when research opportunities arose.

electricity↗
DOE OSTI2024

Molecular-level design of alternative media for energy-saving pilot-scale fibrillation of nanocellulose

The outstanding mechanical properties, light weight, and biodegradability of cellulose nanofibrils (CNFs) make them promising components of renewable and sustainable next-generation reinforced composite biomaterials and bioplastics. Manufacturing CNFs at a pilot scale requires disc-refining fibrillation of dilute cellulose fibers in aqueous pulp suspensions to shear the fibers apart into their nanodimensional forms, which is, however, an energy-intensive process. Here, in this study, we used atomistic molecular dynamics (MD) simulation to examine media that might facilitate the reduction of interactions between cellulose fibers, thereby reducing energy consumption in fibrillation. The most suitable medium found by the simulations was an aqueous solution with 0.007:0.012 wt.% NaOH:urea, and indeed this was found in pilot-scale experiments to reduce the fibrillation energy by ~21% on average relative to water alone. The NaOH:urea-mediated CNFs have similar crystallinity, morphology, and mechanical strength to those formed in water. The NaOH and urea act synergistically on CNFs to aid fibrillation but at different length scales. NaOH deprotonates hydroxyl groups leading to mesoscale electrostatic repulsion between fibrils, whereas urea forms hydrogen bonds with protonated hydroxyl groups thus disrupting interfibril hydrogen bonds. This suggests a general mechanism in which an aqueous medium that contains a strong base and a small organic molecule acting as a hydrogen-bond acceptor and/or donor may be effectively employed in materials processes where dispersion of deprotonable polymers is required. The study demonstrates how atomic-detail computer simulation can be integrated with pilot-scale experiments in the rational design of materials processes for the circular bioeconomy.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Inelastic dark matter scattering off Thallium cannot save DAMA

We study the compatibility of the observed DAMA modulation signal with inelastic scattering of dark matter (DM) off of the 0.1% Thallium (Tl) dopant in DAMA. In this work we test whether there exist regions of parameter space where the Tl interpretation gives a good fit to the most recent data from DAMA, and whether these regions are compatible with the latest constraints from other direct detection experiments. Previously, Chang et al. in 2010, had proposed the Tl interpretation of the DAMA data, and more recently (in 2019) the DAMA/LIBRA collaboration found regions in parameter space of Tl inelastic scattering that differ by more than 10σ from a no modulation hypothesis. We have expanded upon their work by testing whether the regions of parameter space where inelastic DM-Tl scattering gives a good fit to the most recent DAMA data survive the constraints placed by the lack of a DM signal in XENON1T and CRESST-II. In addition, we have tested how these regions change with the main sources of uncertainty: the Tl quenching factor, which has never been measured directly, and the astrophysical uncertainties in the DM distribution. We conclude that inelastic DM scattering off Tl cannot explain the DAMA data in light of null results from other experiments.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

Multiple axions save high-scale inflation

Many models of dark matter QCD axion require inflation at a scale H inf ≲ 10 6 GeV ,which precludes a detectable tensor mode fluctuation. This constraint arises because the domain wall problem forces the Peccei-Quinn symmetry to be broken during inflation and the axions to be produced by the misalignment mechanism. Here, we point out that theories with multiple axions can evade this constraint, thereby allowing high-scale inflation with detectable tensor mode. The only requirement is a condition on the anomaly coefficients that ensures a unique minimum of the axion potential without fine-tuning or the introduction of small parameters.

Kondo, Dan [University of Tokyo (Japan). Kavli Ins↗
DOE OSTI2024

Save or spend? Diverging water‐use strategies of grasses and encroaching clonal shrubs

Abstract Shrub encroachment is one of the primary threats to mesic grasslands around the world. This dramatic shift in plant cover has the potential to alter ecosystem‐scale water budgets and responses to novel rainfall regimes. Understanding divergent water‐use strategies among encroaching shrubs and the grasses they replace is critical for predicting shifts in ecosystem‐scale water dynamics as a result of shrub encroachment, particularly if drought events become more frequent and/or severe in the future. In this study, we assessed how water‐use traits of a rapidly encroaching clonal shrub (Cornus drummondii) and a dominant C 4 grass (Andropogon gerardii) impact responses to changes in water availability in tallgrass prairie. We assessed intra‐annual change in depth of water uptake, turgor loss point and stomatal regulation in each species. Sampling took place at Konza Prairie Biological Station (northeastern KS, USA) during the 2021 and 2022 growing seasons. Cornus drummondiishifted from shallow to deep soil water sources across the 2021 and 2022 growing seasons. This plasticity in depth of water uptake facilitated a ‘wasteful’ water‐use strategy inC. drummondii, where stomatal conductance and transpiration rates continued to increase even when no further gain in photosynthetic rate occurred.A. gerardiiphotosynthetic rates and stomatal conductance were more variable through time and were more responsive to changes in leaf water potential thanC. drummondii. However, intra‐annual adjustment of turgor loss point was more pronounced inC. drummondii(Δπ TLP = −0.48 MPa ± 0.15 SD) than inA. gerardii(Δπ TLP = −0.29 MPa ± 0.19 SD). Synthesis. These results suggest thatC. drummondiiis highly resilient to changes in water availability in surface soils and will likely remain unaffected by future droughts unless they are severe enough to reduce the availability of deep soil water. Given that clonal shrubs are key invaders of grasslands world‐wide, increased leaf‐level water loss is expected to accelerate ecosystem‐level drying as clonal shrub encroachment proceeds in mesic grasslands.

Environmental Sciences & Ecology↗
DOE OSTI2022

Save the Mekong Delta from drowning

Owing to only a few decades of human influence and unsustainable management of the Mekong River basin’s natural resources, the Mekong Delta is receding rapidly. Most of the delta landform, home to 17 million people and an economic powerhouse, could slip below sea level by 2100. Avoiding such a catastrophic impact will require concerted actions that acknowledge root causes for land loss and the global importance of the delta landform. Deltas persist and grow if sediment supply from an upstream river basin builds delta land at the same or greater rates than land is submerged by relative sea level rise and erosion. Further, with more rapid sea level rise, more sediment resources are needed to maintain the current extent of the delta. Only improved coordination of governance and investments, informed by science, will provide the delta with those critical resources.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

FEST: Facility Energy Saving and Securing Technology Using Multi-Source Data: (Milestone 2 Report)

This project aims to demonstrate three technologies developed in-house at LLNL and University of Michigan-Dearborn (UMD), at a military site, including i) Grid Data Crossing (called GriD-Xing) for increasing smart meter data usability, ii) Facility Energy Optimization (called Facility E-GO) for improving facility energy efficiency in both operation and planning perspectives, and iii) Co-simulation tool (called Co-Sim) for enhancing smart meter and energy facility networks resilience and security. In this report, Millstone 2 - Integration A: Integrate GriD-Xing and facility optimization tools is documented.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗