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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 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Bare mass effects on the reheating process after inflation

We consider the effects of a bare mass term for the inflaton, when the inflationary potential takes the form V(Φ)=λΦ k about its minimum with k ≥ 4. We concentrate on k =4, but discuss general cases as well. Further, we assume $λΦ$$^{2}_{end}$ >> $m$$^{2}_{Φ}$, where Φ end is the inflaton field value when the inflationary expansion ends. We show that the presence of a mass term (which may be present due to radiative corrections or supersymmetry breaking) can significantly alter the reheating process, as the equation of state of the inflaton condensate changes from w Φ = $\frac{1}{3}$ to w Φ = 0 when λ⁢Φ 2 drops below $m$$^{2}_{Φ}$. We show that, for a mass mΦ ≳ 3⁢λ $\frac{1}{4}$ T RH , the mass term will dominate at reheating. The value of λ is relatively model independent as it is normalized by the cosmic microwave background perturbation spectrum. For T models of inflation, this leads to m Φ ≳ T RH /250. We compute the effects on the reheating temperature for cases where reheating is due to inflaton decay (to fermions, scalars, or vectors) or to inflaton scattering (to scalars or vectors). For scattering to scalars and in the absence of a decay, there is always a residual inflaton background that acts as cold dark matter. In this case, we derive a strong upper limit to the inflaton bare mass which for T models is m Φ < 350 MeV⁢(T RH /10 10 GeV) 3/5 . We also consider the effect of the bare mass term on the fragmentation of the inflaton condensate.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

BICEP/ Keck XVIII: Measurement of BICEP3 polarization angles and consequences for constraining cosmic birefringence and inflation

We use a custom-made calibrator to measure individual detectors’ polarization angles of BICEP3, a small aperture telescope observing the cosmic microwave background (CMB) at 95 GHz from the South Pole. We describe our calibration strategy and the statistical and systematic uncertainties associated with the measurement. We reach an unprecedented precision for such measurement on a CMB experiment, with a repeatability for each detector pair of 0.02°. Here, we show that the relative angles measured using this method are in excellent agreement with those extracted from CMB data. Because the absolute measurement is currently limited by a systematic uncertainty, we do not derive cosmic birefringence constraints from BICEP3 data in this work. Rather, we forecast the sensitivity of BICEP3 sky maps for such analysis. We investigate the relative contributions of instrument noise, lensing, and dust, as well as astrophysical and instrumental systematics. We also explore the constraining power of different angle estimators, depending on analysis choices. We establish that the BICEP3 2-year dataset (2017–2018) has an on-sky sensitivity to the cosmic birefringence angle of 𝜎 𝛼 = 0.07⁢8°, which could be improved to 𝜎 𝛼 = 0.05⁢5° by adding all of the existing BICEP3 data (through 2023). Furthermore, we emphasize the possibility of using the BICEP3 sky patch as a polarization calibration source for CMB experiments, which with the present data could reach a precision of 0.035°. Finally, in the context of inflation searches, we investigate the impact of detector-to-detector variations in polarization angles as they may bias the tensor-to-scalar ratio 𝑟. We show that while the effect is expected to remain subdominant to other sources of systematic uncertainty, it can be reliably calibrated using polarization angle measurements such as the ones we present in this paper.

Cosmic microwave background↗
DOE OSTI2021

A Bayesian nonparametric analysis for zero-inflated multivariate count data with application to microbiome study

High-throughput sequencing technology has enabled researchers to profile microbial communities from a variety of environments, but analysis of multivariate taxon count data remains challenging. Here, we develop a Bayesian nonparametric (BNP) regression model with zero inflation to analyse multivariate count data from microbiome studies. A BNP approach flexibly models microbial associations with covariates, such as environmental factors and clinical characteristics. The model produces estimates for probability distributions which relate microbial diversity and differential abundance to covariates, and facilitates community comparisons beyond those provided by simple statistical tests. We compare the model to simpler models and popular alternatives in simulation studies, showing, in addition to these additional community-level insights, it yields superior parameter estimates and model fit in various settings. The model's utility is demonstrated by applying it to a chronic wound microbiome data set and a Human Microbiome Project data set, where it is used to compare microbial communities present in different environments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Evaluating Impacts of the Inflation Reduction Act and Bipartisan Infrastructure Law on the U.S. Power System

The Inflation Reduction Act of 2022 (IRA) and the Infrastructure Investment and Jobs Act of 2021, commonly referred to as the 'Bipartisan Infrastructure Law (BIL),' collectively represent the largest commitment of the U.S. Federal Government to invest in the modernization and decarbonization of the U.S. energy system. The Congressional Budget Office (CBO) estimates that total support for the broad range of climate and clean energy programs, tax credits, and other incentives authorized through the two laws will exceed $430 billion from 2022 through 2031 (CRS 2022; CBO 2021, 2022). While the climate and clean energy provisions are numerous and have the potential to impact all aspects of the U.S. energy system from fuel and electricity production to final consumption in industry, transportation, and buildings, the provisions relevant to the electricity sector - in particular the suite of tax credits for clean generation, storage, and carbon dioxide ( CO 2 ) capture and storage - are expected to be some of the most consequential in terms of emissions reduction and clean energy deployment (Larsen et al. 2022; Jenkins, Mayfield, et al. 2022; Mahajan et al. 2022; Zhao et al. 2022). In this report, we detail the methods and results of a study estimating the potential impacts of key provisions of IRA and BIL on the contiguous U.S. power sector from present day through 2030. The analysis employs an advanced power system planning model, the Regional Energy Deployment System (ReEDS), to evaluate how major provisions from both laws impact investment in and operation of utility-scale generation, storage, and transmission, and, in turn, how those changes impact power system costs, emissions, and climate and health damages. While not exhaustive in capturing every provision, the analysis estimates the possible scale of power-sector impacts that could result from the modeled provisions in IRA and BIL. The study is structured around two scenarios to evaluate the potential impacts of both laws on the power sector: 1) No New Policy: A counter-factual scenario that reflects all Federal and state policies enacted as of September 2022, with exception to IRA and BIL, and assumes load growth consistent with the Energy Information Administration's Annual Energy Outlook 2022 (AEO22) Reference case (EIA 2022a); 2) IRA-BIL: A scenario reflecting all Federal and state policies enacted as of September 2022, including key IRA and BIL provisions, most notably the investment and production tax credits for zero-carbon emitting electricity generation and storage (ITC and PTC), the tax credit for CO 2 capture and storage (45Q), and the tax credit for existing nuclear plants (described further in Section 2.3). To account for the impacts of IRA and BIL on electrification, assumes increased load growth consistent with a scaled version of the Medium Electrification scenario from the Electrification Futures Study (Mai et al. 2018). These scenarios are simulated across seven sets of assumptions with varying projected future electricity market conditions, including technology costs and performance, natural gas prices, and the degree of availability, feasibility, and cost of development of renewable resources, electricity transmission, and CO 2 pipeline, injection, and storage infrastructure. In addition, we simulate two sensitivities on the 'policy' treatment in which we vary key assumptions pertaining to the realized value of the clean electricity ITC and PTC: 1) the cost of monetization of tax credits, and 2) the level of bonus crediting realized by project developers. We demonstrate that IRA and BIL have the collective potential to drive substantial growth in clean electricity by 2030, while reducing costs for consumers, mitigating climate change, and decreasing the human health impacts of power sector emissions. However, we also demonstrate that if expected cost improvements of clean technologies are not realized and/or constraints on deployment driven by factors such as supply-chain challenges, regulatory hurdles, and the social acceptability of energy infrastructure development limit the rate of clean energy and associated infrastructure deployment (such as transmission), then the share of clean generation achieved and the associated emissions benefits realized may be substantively reduced.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2023

Overview of the Inflation Reduction Act of 2022 (IRA) Home Energy Rebate Tool

The IRA Home Energy Rebate Tool (Tool) provides if/then analysis on the impact of two provisions of the Inflation Reduction Act (IRA); 50121 - Home Energy Performance-Based Whole-House Rebates (Home Efficiency Rebates or HOMES Program) and 50122 - High-Efficiency Electric Home Rebate Program (Home Electrification and Appliance Rebates or High-Efficiency Electric Appliances Rebates Program). The Tool can generate realistic scenarios based on the legislative text. The results of the Tool should not be interpreted as forecasts or predictions of what will happen for individual households, States or the nation. This overview provides a high level summary of the data inputs and methods.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2023

Assessing the Impact of the Inflation Reduction Act on Nuclear Plant Power Uprate and Hydrogen Cogeneration

On August 16, 2022, Congress passed the Inflation Reduction Act (IRA) to promote investment in new, carbon-free power generation and sustainable operation of existing carbon-free assets. Specifically, the IRA includes both a production tax credit (PTC – Section 45Y of the IRA) and an investment tax credit (ITC – Section 48E) which utilities may leverage to offset the costs of power uprate. Further, the IRA includes a provision (Section 45V) for a PTC associated with carbon-free hydrogen cogeneration. These tax credits, along with recent legislation efforts to decarbonize the country, have re-emphasized the importance of maintaining and optimizing the existing nuclear plant operating fleet. As a result, utilities are reexamining the possibility of uprating their existing nuclear assets to further maximize carbon-free electricity generation.

08 HYDROGEN↗
DOE OSTI2024

Potential Impacts of the Inflation Reduction Act on Domestic Manufacturing and Deployment for Land-Based Wind Turbines

The land-based wind energy industry in the United States has matured over the past several decades, representing 10% of the country's total electricity generation in 2022. It has experienced periods of rapid growth and decline in recent years, in large part because of supply chain disruptions at a global and domestic level. With the recent passing of the 2022 Inflation Reduction Act, the industry faces unprecedented opportunities to strengthen domestic manufacturing and enable greater deployment over the next decade. To better understand the opportunities and challenges, the authors explore the value of relevant IRA provisions and provide a set of scenarios evaluating impacts on domestic component demand and manufacturing.

17 WIND ENERGY↗
DOE OSTI2024

Driving Investment in Wind Energy: An Introduction to Incentives and the Inflation Reduction Act [Slides]

In a webinar hosted by the U.S. Department of Energy's WINDExchange initiative, experts from the North Carolina Clean Energy Technology Center and the National Renewable Energy Laboratory introduce attendees to the key incentives supporting investment in wind energy deployment and manufacturing in the United States, as well as the role that the Inflation Reduction Act (IRA) plays in shaping those investments. Over the past few decades, incentives like the production tax credit and investment tax credit have supported the growth of wind energy deployment, while manufacturing-related incentives have helped scale up domestic manufacturing of wind energy components. With its passage in 2022, the IRA ushered in a new wave of investment in wind energy and other renewable technologies, as well as introducing new workforce requirements and equity provisions. This presentation explores the history and impact of major incentives, unpacks some of the complex provisions of the IRA, and highlights the ways federal incentives and policies will continue to shape the wind energy industry.

17 WIND ENERGY↗
DOE OSTI2025

Final Technical Report: Testing the robustness of CMB-S4 inflation measurements to foreground models

This report summarizes the research activities for DOE award SC0024462, which focused on enhancing the robustness of CMB-S4 inflation measurements by characterizing and mitigating Galactic foreground interference. The project grounded foreground models in the physical processes of the Interstellar Medium with MHD and semi-analytic filament models, and developed analysis pipelines, such as Needlet Internal Linear Combination (NILC) techniques, to isolate faint cosmological signals.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗