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NASA NTRS1981

A potential enstrophy and energy conserving scheme for the shallow water equations

To improve the simulation of nonlinear aspects of the flow over steep topography, a potential enstrophy and energy conserving scheme for the shallow water equations is derived. It is pointed out that a family of schemes can conserve total energy for general flow and potential enstrophy for flow with no mass flux divergence. The newly derived scheme is a unique member of this family, that conserves both potential enstrophy and energy for general flow. Comparison by means of numerical experiment with a scheme that conserves (potential) enstrophy for purely horizontal nondivergent flow demonstrated the considerable superiority of the newly derived potential enstrophy and energy conserving scheme, not only in suppressing a spurious energy cascade but also in determining the overall flow regime. The potential enstrophy and energy conserving scheme for a spherical grid is also presented.

Arakawa, A.↗

DOE OSTI2016

Heterologous production of an energy-conserving carbon monoxide dehydrogenase complex in the hyperthermophile Pyrococcus furiosus

In this study, carbon monoxide (CO) is an important intermediate in anaerobic carbon fixation pathways in acetogenesis and methanogenesis. In addition, some anaerobes can utilize CO as an energy source. In the hyperthermophilic archaeon Thermococcus onnurineus , which grows optimally at 80°C, CO oxidation and energy conservation is accomplished by a respiratory complex encoded by a 16-gene cluster containing a CO dehydrogenase, a membrane-bound [NiFe]-hydrogenase and a Na + /H + antiporter module. This complex oxidizes CO, evolves CO 2 and H 2 , and generates a Na+ motive force that is used to conserve energy by a Na+-dependent ATP synthase. Herein we used a bacterial artificial chromosome to insert the 13.2 kb gene cluster encoding the CO-oxidizing respiratory complex of T. onnurineus into the genome of the heterotrophic archaeon, Pyrococcus furiosus , which grows optimally at 100° C. P. furiosus is normally unable to utilize CO, however, the recombinant strain readily oxidized CO and generated H 2 at 80° C. Moreover, CO also served as an energy source and allowed the P. furiosus strain to grow with a limiting concentration of sugar or with peptides as the carbon source. Moreover, CO oxidation by P. furiosus was also coupled to the re-utilization, presumably for biosynthesis, of acetate generated by fermentation. The functional transfer of CO utilization between Thermococcus and Pyrococcus species demonstrated herein is representative of the horizontal gene transfer of an environmentally relevant metabolic capability. The transfer of CO utilizing, hydrogen-producing genetic modules also has applications for biohydrogen production and a CO-based industrial platform for various thermophilic organisms.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2017

Compatible, energy conserving, bounds preserving remap of hydrodynamic fields for an extended ALE scheme

From the very origins of numerical hydrodynamics in the Lagrangian work of von Neumann and Richtmyer [83], the issue of total energy conservation as well as entropy production has been problematic. Because of well known problems with mesh deformation, Lagrangian schemes have evolved into Arbitrary Lagrangian–Eulerian (ALE) methods [39] that combine the best properties of Lagrangian and Eulerian methods. Energy issues have persisted for this class of methods. We believe that fundamental issues of energy conservation and entropy production in ALE require further examination. The context of the paper is an ALE scheme that is extended in the sense that it permits cyclic or periodic remap of data between grids of the same or differing connectivity. The principal design goals for a remap method then consist of total energy conservation, bounded internal energy, and compatibility of kinetic energy and momentum. We also have secondary objectives of limiting velocity and stress in a non-directional manner, keeping primitive variables monotone, and providing a higher than second order reconstruction of remapped variables. Particularly, the new contributions fall into three categories associated with: energy conservation and entropy production, reconstruction and bounds preservation of scalar and tensor fields, and conservative remap of nonlinear fields. Our paper presents a derivation of the methods, details of implementation, and numerical results for a number of test problems. The methods requires volume integration of polynomial functions in polytopal cells with planar facets, and the requisite expressions are derived for arbitrary order.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2022

Energy conserving and well-balanced discontinuous Galerkin methods for the Euler–Poisson equations in spherical symmetry

ABSTRACT This paper presents high-order Runge–Kutta (RK) discontinuous Galerkin methods for the Euler–Poisson equations in spherical symmetry. The scheme can preserve a general polytropic equilibrium state and achieve total energy conservation up to machine precision with carefully designed spatial and temporal discretizations. To achieve the well-balanced property, the numerical solutions are decomposed into equilibrium and fluctuation components that are treated differently in the source term approximation. One non-trivial challenge encountered in the procedure is the complexity of the equilibrium state, which is governed by the Lane–Emden equation. For total energy conservation, we present second- and third-order RK time discretization, where different source term approximations are introduced in each stage of the RK method to ensure the conservation of total energy. A carefully designed slope limiter for spherical symmetry is also introduced to eliminate oscillations near discontinuities while maintaining the well-balanced and total-energy-conserving properties. Extensive numerical examples – including a toy model of stellar core collapse with a phenomenological equation of state that results in core bounce and shock formation – are provided to demonstrate the desired properties of the proposed methods, including the well-balanced property, high-order accuracy, shock-capturing capability, and total energy conservation.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS1982

Retrofit energy conservation in residential buildings in southern California

The common energy conservation techniques (ECTs) that can be retrofit-installed into residential buildings are surveyed. The quantity of saved energy for heating and cooling attributable to each ECT is evaluated for three common modes of heating: natural gas heating at 60/therm; heating via heat pump at $1.20/therm; and electric resistance heating at $2.40/therm. In every case, a life cycle cost comparison is made between the long term revenue due to energy conservation and a safe and conventional alternative investment that might be available to the prudent homeowner. The comparison between investment in an ECT and the alternative investment is brought into perspective using the life cycle payback period and an economic Figure of Merit (FOM). The FOM allows for relative ranking between candidate ECTs. Because the entire spectrum of winter heating climates in California is surveyed, the decision maker can determine whether or not a considered ECT is recommended in a given climate, and under what conditions an ECT investment becomes attractive.

Turner, R. H.↗

DOE OSTI2011

Analysis of 2009 International Energy Conservation Code Requirements for Residential Buildings in Mesa, Arizona

The 2009 International Energy Conservation Code (IECC) contains several major improvements in energy efficiency over the 2006 IECC and the 2003 IECC. The notable changes are: (1) Improved duct sealing verified by testing the duct system; (2) Increased duct insulation; (3) Improvement of window U-factors from 0.40 to 0.35; and (4) Efficient lighting requirements. An analysis of these changes resulted in estimated annual energy cost savings of $145 a year for an average new house compared to the 2003 IECC. This energy cost saving decreases to $125 a year for the 2009 IECC compared to the 2006 IECC. Construction cost increases (per home) for complying with the 2009 IECC are estimated at $1256 relative to the 2003 IECC and $800 for 2006 IECC. Home owners will experience an annual cost savings of about $80 a year by complying with the 2009 IECC because reduction to energy bills will more than compensate for increased mortgage payments and other costs.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2022

Resolution requirements for energy conservation in kinetic plasma simulations

The kinetic codes used to model the coupled dynamics of electromagnetic fields and charged particle transport have requirements for spatial, temporal, and charge resolution. These requirements may vary by the solution technique and scope of the problem. In this report, we investigate the resolution limits in the energy-conserving implicit particle-in-cell code CHICAGO. This report has the narrow aim of determining the maximum acceptable grid spacing for the dense plasmas generated in models of z-pinch target gases and power-flow electrode plasmas. In the 2D sample problem, the plasma drifts without external forces with velocity of 10 cm/µs. Simulations are scaled by plasma density to maintain uniform strides across the plasma and from the plasma to the boundaries. Additionally, the cloud-in-cell technique is used with 400 particles per cell and Δ t = 0.85× the Courant limit. For the linear cloud distribution, the criterion for conserving energy is Δ E/E tot < 0.01 for 50,000 time steps. The grid resolution is determined to crudely be Δx ≲ 3 l s , where l s is the electron collisionless skin depth. For the second-order cloud distribution the criterion is Δ E/E tot < 0.005 yielding Δx ≤ 15 l s . These scalings are functions of the chosen v d , Δ t , particles-per-cell, and number of steps.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2013

Assessing Foundation Insulation Strategies for the 2012 International Energy Conservation Code in Cold Climate New Home Construction

Even though the International Energy Conservation Code 2012 (International Code Council 2012) is a model code now available for adoption by individual states, only two cold-climate states have adopted it as their new home energy code. Understanding the resistance to adoption is important in assisting more states to accept the code and engage in deep energy strategies nationwide. This three-part assessment by the NorthernSTAR Building America Partnership was focused on foundation insulation R-values for cold climates and the design, construction, and performance implications. In Section 1, a literature review and attendance at stakeholder meetings held in Minnesota were used to assess general stakeholder interest and concerns about proposed code changes. Section 2 includes drawings of robust foundation insulation systems that were presented at one Minnesota stakeholder meeting to address critical issues and concerns for adopting best practice strategies. In Section 3, a sampling of builders participated in a telephone interview to gain baseline knowledge on insulation systems used to meet the current energy code and how the same builders intend to meet the new proposed code. In general, most builders expressed interest in being able to deliver greater energy efficiency to their customers. Concerns were voiced, however, about the costs compared to the energy savings, constructability, and durability risk resulting from increased foundation insulation R-values. When solutions for building robust foundation wall systems were presented to stakeholders, they did express interest in learning the details of the strategies. There was, however, continued interest in proof of cost, payback, and hygrothermal performance. Builders who participated in the interview were more confident in being able to meet the new requirements. This might have been a result of these respondents already using more advanced techniques for foundation insulation. This insight gives Building America an opportunity to engage the industry with existing research and practice measures that can address constructability and durability concerns at the proposed code levels. It also indicates that builders are interested in more specific information on cost, energy savings, and overall hygrothermal performance. Filling these voids could yield the supportive data needed to enhance building industry confidence and engage more states in the adoption of 2012 International Energy Conservation Code for new homes.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2011

Analysis of 2009 International Energy Conservation Code Requirements for Residential Buildings in Kansas City, Missouri

The 2009 International Energy Conservation Code (IECC) contains several major improvements in energy efficiency over the 2006 IECC. The notable changes are: (1) Improved duct sealing verified by testing the duct system; (2) Increased duct insulation; (3) Improvement of window U-factors from 0.40 to 0.35; and (4) Efficient lighting requirements. An analysis of these changes resulted in estimated annual energy cost savings of about $145 a year for an average new house. Construction cost increases are estimated at $655. Home owners will experience an annual cost savings of close to $100 a year because reduction to energy bills will more than compensate for increased mortgage payments and other costs.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2019

Energy-conserving perfect-conductor boundary conditions for an implicit, curvilinear Darwin particle-in-cell algorithm

We propose here a conservative prescription for perfect-conductor boundary conditions for a Darwin particle-in-cell (PIC) model on curvilinear meshes and arbitrarily shaped boundaries. The Darwin model is a subset of Maxwell's equation in which the electromagnetic mode (light wave) has been analytically removed. This renders the Darwin formulation elliptic, instead of hyperbolic. Historically, Darwin-PIC practitioners have had difficulty implementing a well-posed set of boundary conditions for realistic applications. In this study, we demonstrate the well-posedness and effectiveness of a simple boundary-condition prescription for perfect conductors of specified potential and of arbitrary shape in multiple dimensions, using a recently developed conservative, implicit Darwin-PIC algorithm. The boundary conditions conserve the electromagnetic energy, and preserve the Coulomb gauge of the vector potential, ∇ · A = 0 exactly. We demonstrate that global energy is exactly conserved in curvilinear, simply-connected domains in the specific case of particles reflecting off perfect conductors.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2018

ECsim-CYL: Energy Conserving Semi-Implicit particle in cell simulation in axially symmetric cylindrical coordinates

Based on the previously developed Energy Conserving Semi Implicit Method (ECsim) code, we present its cylindrical implementation, called ECsim-CYL, to be used for axially symmetric problems. The main motivation for the development of the cylindrical version is to greatly improve the computational speed by utilizing cylindrical symmetry. The ECsim-CYL discretizes the field equations in two-dimensional cylindrical coordinates using the finite volume method. For the particle mover, it uses a modification of ECsim’s mover for cylindrical coordinates by keeping track of all three components of velocity vectors, while only keeping radial and axial coordinates of particle positions. In this paper, we describe the details of the algorithm used in the ECsim-CYL and present a series of tests to validate the accuracy of the code including a wave spectrum in a homogeneous plasma inside a cylindrical waveguide and free expansion of a spherical plasma ball in vacuum. Finally, the ECsim-CYL retains the stability properties of ECsim and conserves the energy within machine precision, while accurately describing the plasma behavior in the test cases.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2019

Potential benefits of cool walls on residential and commercial buildings across California and the United States: Conserving energy, saving money, and reducing emission of greenhouse gases and air pollutants

Solar-reflective “cool” walls reduce absorption of sunlight by the building envelope, which may decrease cooling load in warm weather and increase heating load in cool weather. Changes to annual heating, ventilation, and air conditioning (HVAC) energy use depend on climate, wall construction, wall orientation, building geometry, HVAC efficiency, and operating schedule. Changes to annual energy cost and energy-related emissions further vary with local energy prices and emission factors. In this work, we used EnergyPlus to perform over 100,000 whole-building energy simulations, spanning 10 different building categories, three building vintages, 16 California climate zones, and 15 United States (U.S.) climate zones. We find that cool walls yielded annual source energy, energy cost, and emission savings in all California climate zones and in warm U.S. (ASHRAE) climate zones. In California, annual whole-building HVAC energy cost savings were 4.0–27% in single-family homes, 0.5–3.8% in medium office buildings, and 0.0–8.5% in stand-alone retail stores. In warm U.S. climates—zones 1A (Miami, FL) through 4B (Albuquerque, NM)—annual HVAC energy cost savings were 1.8–8.3% in single-family homes, 0.3–4.6% in medium office buildings, and 0.5–11% in stand-alone retail stores. California and U.S. fractional source energy and emission savings were comparable to fractional energy cost savings. Per unit surface area modified, cool-wall savings often exceeded cool-roof savings because building codes typically prescribe much less wall insulation than roof insulation.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2025

Energy conservation in real-time nuclear–electronic orbital Ehrenfest dynamics

Real-time nuclear–electronic orbital Ehrenfest (RT-NEO-Ehrenfest) dynamics methods provide a first-principles approach for describing nonadiabatic molecular processes with nuclear quantum effects. For an efficient description of proton transfer within RT-NEO-Ehrenfest dynamics, the basis function center associated with the quantum proton can be allowed to move classically. Here, this traveling proton basis (TPB) approach effectively captures proton quantum dynamics, although its energy conservation behavior is not yet fully satisfactory. Two recently proposed TPB approaches, in principle, conserve the extended energy, which includes both the system energy and the kinetic energy associated with the proton basis function center. Herein, a thermostatted TPB approach is proposed to improve the conservation of the system energy, excluding the kinetic energy associated with the proton basis function center. In this approach, the quantum proton dynamics are modulated by dynamically rescaling the proton momentum operator to maintain the system energy conservation. With the excited-state intramolecular proton transfer of o-hydroxybenzaldehyde as an example, this approach is shown to significantly improve the system energy conservation while preserving the accuracy of the quantum proton dynamics as achieved in the original TPB approach.

Ehrenfest dynamics↗

NASA NTRS1975

ECASTAR: Energy conservation. An assessment of systems, technologies and requirements

A methodology was presented for a systems approach to energy conservation actions and their potentials and impacts in the United States. Constraints affecting the approach were ranked, and the most important ones are the present economic and technical conditions. The following unresolved issues were identified: consumptive lifestyles vs. conservation ethic, environmental standards vs. energy conservation, capital availability, decentralization and vertical integration vs. centralization, fuel rich regions vs. fuel poor regions, supply vs. end use conservation, life cycle costing vs. initial cost, mandatory savings vs. voluntary savings, labor intensive vs. capital intensive, price control vs. free market. The following recommendations were made: provide action/impact assessment, establish regional energy centers, improve technology articulation with government, design total energy systems, utilize existing systems approach expertise.

Source record↗

DOE OSTI2011

Higher-order energy-conserving gyrokinetic theory

A higher-order self-consistent energy-conserving gyrokinetic system of equations is derived. It is shown that additional terms appear in the quasineutrality condition. These terms are nonlinear in the electric field. The derivation includes higher-order terms in the gyrokinetic Hamiltonian (needed for the energy conservation) and employs a variational principle that automatically provides all the conservation laws through the Noether theorem. The equations derived here can be applied in certain transition layers such as the stellarator transport barriers caused by the transition between the electron and ion root regimes. The theory may also be of interest for the edge plasma, where the nonlinear terms in the quasineutrality equation could be relevant. The equations derived are simple enough and can readily be used in gyrokinetic codes.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2012

Guide to the Changes between the 2009 and 2012 International Energy Conservation Code

The International Code Council (ICC) published the 2012 International Energy Conservation Code® (IECC) in early 2012. The 2012 IECC is based on revisions, additions, and deletions to the 2009 IECC that were considered during the ICC code development process conducted in 2011. Solid vertical lines, arrows, or asterisks printed in the 2012 IECC indicate where revisions, deletions, or relocations of text respectively were made to 2009 IECC. Although these marginal markings indicate where changes have been made to the code, they do not provide any further guidance, leaving the reader to consult and compare the 2009 and 2012 IECC for more detail.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

DOE OSTI2025

A dynamic protein interactome drives energy conservation and electron flux in Thermococcus kodakarensis

ABSTRACT Life is supported by energy gains fueled by catabolism of a wide range of substrates, each reliant on the selective partitioning of electrons through redox ( red uction and ox idation) reactions. Electron flux through tunable and regulated protein interactions provides dynamic routes for energy conservation, but how electron flux is regulated in vivo , particularly for archaeal metabolisms that support rapid growth at the thermodynamic limits of life, is poorly understood. Identification of bona fide in vivo protein assemblies and how such assemblies dictate the totality of electron flux is critical to our understanding of the regulation imposed on metabolism, energy production, and energy conservation. Here, 25 key proteins in central metabolic redox pathways in the model, genetically accessible, hyperthermophilic archaeon Thermococcus kodakarensis , were purified to reveal an extensive, dynamic, and tightly interconnected network of protein interactions that responds to environmental cues (such as the availability of various reductive sinks) to direct electron flux to maximize energetic gains. Interactions connecting disparate functions suggest many catabolic and anabolic activities occur in spatial proximity in vivo , and while protein complexes have been historically defined under optimal conditions, many of these complexes appear to maintain alternative partnerships in changing conditions. The totality of the results obtained redefines our understanding of in vivo assemblies driving ancient metabolic strategies supporting the growth of modern Archaea. IMPORTANCE Given the potential for rational genetic manipulations of biofuel- and biotech-promising archaea to yield transformative results for major markets, it is a priority to define how the metabolisms of such species are controlled, at least in part, by in vivo protein assemblies, and from such, define routes of energy flux that can be most efficiently altered toward biofuel or biotechnological gains. Proteinaceous electron carriers (PECs, such as ferredoxins) offer the potential for specific protein–protein interactions to coordinate selective reductive flow. Employing the model, genetically accessible, hyperthermophilic archaeon, Thermococcus kodakarensis , we establish the metabolic protein interactome of 25 key redox proteins, revealing that each redox active protein has a dynamic partnership profile, suggesting catabolic and anabolic activities may occur in concert and in temporal and spatial proximity in vivo . These results reveal critical importance in evaluating the newly identified partnerships and their role and utility in providing regulated redox flux in T. kodakarensis .

Williams, Sere A. (ORCID:0000000235509590)↗

NASA NTRS1979

Energy conserving norms for the solution of hyperbolic systems of partial differential equations

The hyperbolic system of partial differential equations with a real constant square coefficient matrix A is considered. The problem of finding an energy conserving norm for the solution of the system is reduced to the problem of characterizing those matrices appearing in the boundary conditions which satisfy two specific matrix equations. Necessary and sufficient conditions on the coefficient matrix A and the matrices appearing in boundary conditions are derived for an energy conserving norm. The conditions serve as criteria on a given system which determine whether or not the solution will have its energy conserved in some norm. Examples of specific systems and boundary conditions are also provided.

Gunzburger, M. D.↗