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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 1,351 records · Page 75
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

State-by-State comparison of combined heat and power to photovoltaic installations at manufacturing facilities with heat and power loads

Manufacturing facilities with large electricity and steam loads commonly meet those loads with a grid and boiler (GB) system configuration. In this study, two alternatives, a natural gas turbine cycle driven combined heat and power (CHP) system configuration and a grid boiler system augmented with photovoltaics (GB-PV), are investigated sustainable manufacturing in reference to the GB system configuration. For this purpose, their discounted payback period (DPP), carbon dioxide (CO 2 ) and nitrogen oxides (NO x ) emission reductions, and primary fossil energy impacts are calculated. The major contribution of this study is that it directly compares the application of both CHP and PV technologies at an assumed manufacturing facility in all 50 states of the United States. This highlights the location-specific impacts of the facility. The examined manufacturing facility utility requirements are 5 MW of power and over 12,000 kg/h of 250 kPa and 400 K saturated steam. A DPP of less than 25 years, the technology lifetime, is found in 44 states for the CHP system configuration and 6 states for the GB-PV system configuration. GB-PV and CHP cost-effectively reduce CO 2 in 44 and 38 states, respectively. CHP is better for NO x reduction, whereas GB-PV is better for primary fossil energy reduction.

14 SOLAR ENERGY↗
DOE OSTI2018

Olivine, dolomite and ceramic filters in one vessel to produce clean gas from biomass

Highlights: • Syngas free of particles and with very low amount of tar is produced from biomass gasification. • Combination is tested of primary catalyst in the gasifier fluidized bed with catalytic ceramic candles in its freeboard. • Remarkable process intensification and thermal integration is obtained. • The adoption of catalytic filter candles doesn’t increase the required standard filtration surface in practical applications. - Abstract: Heavy organic compounds produced during almond shells gasification in a steam and/or air atmosphere, usually called tar, are drastically reduced in the product gas by using simultaneously in one vessel a ceramic filter placed in the freeboard and a mixture of olivine and dolomite particles in the fluidized bed of the gasifier. The content of tar in the product gas during a reference gasification test with air, in presence of fresh olivine particles only, was 8600 mg/Nm{sup 3} of dry gas. By gasifying biomass with steam at the same temperature level of 820 °C in a bed of olivine and dolomite (20% by weight), and in the presence of a catalytic ceramic filter inserted in the freeboard of the fluidized bed gasifier, the level of tar was brought down to 57 mg/Nm{sup 3} of dry producct gas, with a decrease of more than two orders of magnitude.

09 BIOMASS FUELS↗
DOE OSTI2020

Favorable Redox Thermodynamics of SrTi 0.5 Mn 0.5 O 3–δ in Solar Thermochemical Water Splitting

Two-step, solar thermochemical splitting of water using nonstoichiometric redox-active metal oxides has emerged as an intriguing approach for large-scale hydrogen production. Perovskites have been proposed as alternatives to state-of-the-art fluorite CeO 2–δ because of their potential for lowering reduction temperature while maintaining high fuel productivity. Guided by computational insights, we explore the thermodynamic properties and water splitting efficacy of the cubic perovskite SrTi 0.5 Mn 0.5 O 3–δ (STM55). Thermogravimetric analysis is performed under controlled oxygen partial pressures (pO 2 ) and temperatures up to 1500 °C, from which both the enthalpy and entropy of reduction as a function of oxygen nonstoichiometry are determined. STM55 provides an attractive combination of moderate enthalpy, 200–250 kJ (mol-O) –1 , and high entropy, with unusual δ dependence. Using a water splitting cycle in which the material is thermally reduced at 1350 °C (pO 2 , ~10 –5 atm) and subsequently exposed to steam at 1100 °C (steam partial pressure of pH 2 O = 0.4 atm), we demonstrate a hydrogen yield of 7.4 mL g –1 . Through both half-cycles, the material remains largely in quasi-equilibrium with the gas phase, as reflected in the agreement of the measured data with predicted profiles based on the thermodynamic data. This behavior indicates rapid surface and bulk diffusion kinetics. Cyclic operation showed the material to be free of degradation and always resulted in a 2:1 yield of H 2 /O 2 . Altogether, STM55 provides outstanding performance characteristics for thermochemical hydrogen production.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Synthetic Graphene Oxide Leaf for Solar Desalination with Zero Liquid Discharge

Water vapor generation through sunlight harvesting and heat localization by carbon-based porous thin film materials holds great promise for sustainable, energy-efficient desalination and water treatment. However, the applicability of such materials in a high-salinity environment emphasizing zero-liquid-discharge brine disposal has not been studied. Here this paper reports the characterization and evaporation performance of a nature-inspired synthetic leaf made of graphene oxide (GO) thin film material, which exhibited broadband light absorption and excellent stability in high-salinity water. Under 0.82-sun illumination (825 W/m 2 ), a GO leaf floating on water generated steam at a rate of 1.1 L per m 2 per hour (LMH) with a light-to-vapor energy conversion efficiency of 54%, while a GO leaf lifted above water in a tree-like configuration generated steam at a rate of 2.0 LMH with an energy efficiency of 78%. The evaporation rate increased with increasing light intensity and decreased with increasing salinity. During a long-term evaporation experiment with a 15 wt % NaCl solution, the GO leaf demonstrated stable performance despite gradual and eventually severe accumulation of salt crystals on the leaf surface. Furthermore, the GO leaf can be easily restored to its pristine condition by simply scraping off salt crystals from its surface and rinsing with water. Therefore, the robust high performance and relatively low fabrication cost of the synthetic GO leaf could potentially unlock a new generation of desalination technology that can be entirely solar-powered and achieve zero liquid discharge.

42 ENGINEERING↗
DOE OSTI2021

Multiobjective Dynamic Optimization for Optimal Load-Following of Natural Gas Combined Cycle Power Plants under Stress Constraints

With the increasing penetration of intermittent renewable energy sources into the electric grid, there is an associated need for conventional thermal power plants that are designed to operate at base-load conditions to cycle their load rapidly and frequently and operate under low-load conditions. Fast load-following operations lead to plant efficiency loss and the reduction of equipment life. A high-fidelity dynamic model of a natural gas combined cycle power plant, with rigorous equipment level submodels, is developed to capture the plant transient performance and the thermomechanical stress evolution at the high-pressure drum is computed to assess the drum life consumption. Stress evolution is modeled for the location of the edge at the drum/downcomer junction that experiences high circumferential stress amplitude during the fast load-following operation, leading to higher fatigue damage than locations considered under existing design standards. A dynamic optimization problem is solved for optimal load-following operation. Depending on the value of the stress constraint and the desired ramp rate, satisfying the desired stress constraint may be infeasible without relaxing the ramp rate. A multiobjective dynamic optimization problem is solved using a lexicographic approach that minimizes ramp rate relaxation and maximizes efficiency while satisfying stress constraints, avoiding spraying to saturation, and maintaining main steam and reheat steam temperature within bounds. It was observed that the optimal ramp rate can be highly nonlinear as opposed to the industry-standard linear ramp rate. Nonlinear optimal ramp-rate profiles not only help to avoid stress constraints that may be unavoidable by using the linear profile but also result in higher efficiency than the linear profile. Furthermore, the study shows that there is a strong tradeoff between the relaxation in the plant ramp rate and the time-average thermal efficiency.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Water treatment capacity of forward osmosis systems utilizing power plant waste heat

Forward osmosis (FO) has the potential to improve the energy efficiency of membrane-based water treatment by leveraging waste heat from steam electric power generation as the primary driving force for separation. In this study, we develop a comprehensive FO process model, consisting of membrane separation, heat recovery, and draw solute regeneration (DSR) models. We quantitatively characterize three alternative processes for DSR: distillation, steam stripping, and air stripping. We then construct a mathematical model of the distillation process for DSR that incorporates hydrodynamics, mass and heat transport resistances, and reaction kinetics, and we integrate this into a model for the full FO process. Finally, we utilize this FO process model to derive a first-order approximation of the water production capacity given the rejected heat quantity and quality available at U.S. electric power facilities. We find that the upper bound of FO water treatment capacity using low-grade heat sources at electric power facilities exceeds process water treatment demand for boiler water make-up and flue gas desulfurization wastewater systems.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2025

Technoeconomic Analysis of Microwave-Assisted Dry Reforming Integrated with Chemical Looping for Production of Methanol

Methanol is a key component in producing formaldehyde, acetic acid, and methyl tert -butyl ether (MTBE) and supports a wide array of industries, including plastics, textiles, and automotive. It also plays a growing role in renewable energy solutions. However, the conventional production of methanol involves steam reforming of methane, which is very energy-intensive and produces significant quantities of the greenhouse gas carbon dioxide. In this research, a chemical looping scheme is combined with dry reforming of natural gas in a novel microwave reactor to produce an industrial quantity of methanol. A heat exchanger network is developed to substantially reduce hot and cold utility usage. The effect of the cost of purchasing carbon dioxide from an external source for dry reforming, the capital cost of the microwave reactor, and the cost of electricity on the net present value is analyzed. Technoeconomic comparison with the conventional industrial process that produces methanol via steam reforming of methane indicates that the chemical looping generates a significant positive net present value along with a substantial reduction in carbon dioxide emissions while producing methanol significantly below the U.S. Department of Energy’s goal of $800/ton.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Spectroscopic Investigation of the Mechanisms Responsible for the Superior Stability of Hybrid Class 1/Class 2 CO 2 Sorbents: A New Class 4 Category

Hybrid Class 1/Class 2 supported amine CO 2 sorbents demonstrate superior performance under practical steam conditions, yet their amine immobilization and stabilization mechanisms are unclear. Uncovering the interactions responsible for the sorbents’ robust features is critical for further improvements and can facilitate practical applications. We employ solid state 29 Si CP-MAS and 2-D FSLG 1 H– 13 C CP HETCOR NMR spectroscopies to probe the overall molecular interactions of aminosilane/silica, polyamine [poly(ethylenimine), PEI]/silica, and hybrid aminosilane/PEI/silica sorbents. A unique, sequential impregnation sorbent preparation method is executed in a diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) setup to decouple amine binding mechanisms at the amine–silica interface from those within bulk amine layers. These mechanisms are correlated with each sorbents’ resistance to accelerated liquid H 2 O and TGA steam treatments (H 2 O stability) and to oxidative degradation (thermal stability). High percentages of CO 2 capture retained (PCR) and organic content retained (OCR) values after H 2 O testing of N-(3-(trimethoxysilyl)propyl)ethylenediamine (TMPED)/PEI and (3-aminopropyl)trimethoxysilane (APTMS)/PEI hybrid sorbents are associated with a synergistic stabilizing effect of the amine species observed during oxidative degradation (thermal gravimetric analysis-differential scanning calorimetry, TGA-DSC). Solid state NMR spectroscopy reveals that the synergistic effect of the TMPED/PEI mixture is manifested by the formation of hydrogen-bonded PEI–NH 2 ···NH 2 –TMPED and PEI–NH 2 ···HO–Si/O–Si–O (TMPED, T 2 ) linkages within the sorbent. DRIFTS further determines that PEI enhances the grafting of TMPED to silica and that PEI is dispersed among a stable network of polymerized TMPED in the bulk, utilizing H-bonded linkages. These findings provide the scientific basis for establishing a Class 4 category for aminosilane/polyamine/silica hybrid sorbents.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2023

Ceria Incorporation in Sinter-Resistant Platinum-Based Catalysts

Platinum group metals (PGM) are widely used for exhaust emission abatement. Sintering during the high-temperature emission control conditions decreases noble metal utilization efficiency. Efficient use of scarce noble metals requires sinter-resistant catalysts. Here we extend an approach to synthesize catalysts consisting of platinum nanoparticles encapsulated in a mixture of cerium and aluminum oxides (Pt@Al 2 O 3 -CeO 2 ). We tested the activity of this catalyst toward carbon monoxide, propene, and propane oxidation chosen as model oxidation reactions for emission control catalysts. Pt@Al 2 O 3 -CeO 2 catalysts demonstrated similar activity and stability upon aging as the comparison system without ceria, Pt@Al 2 O 3 , while maintaining small Pt nanoparticles and ceria crystallites. Additionally, we studied the influence of various thermal treatments on CO oxidation activity and determined that a steam treatment can activate low temperature CO oxidation activity of Pt@Al 2 O 3 -CeO 2 . STEM-EDS analysis revealed that thermal treatments led to the co-location of Pt and CeO 2 and temperature programmed-reduction analysis revealed that the steam treatment specifically enhanced CO oxidation activity through surface reduction of the CeO 2 . As a result, we demonstrate the versatility of this encapsulation approach to generate mixed metal-oxide supports with improved metal-support interactions without hindering nanoparticle stability.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2017

Systematic Structure–Property Relationship Studies in Palladium-Catalyzed Methane Complete Combustion

To limit further rising levels in methane emissions from stationary and mobile sources and to enable promising technologies based on methane, the development of efficient combustion catalysts that completely oxidize CH 4 to CO 2 and H 2 O at low temperatures in the presence of high steam concentrations is required. Palladium is widely considered as one of the most promising materials for this reaction, and a better understanding of the factors affecting its activity and stability is crucial to design even more improved catalysts that efficiently utilize this precious metal. Here we report a study of the effect of three important variables (particle size, support, and reaction conditions including water) on the activity of supported Pd catalysts. We use uniform palladium nanocrystals as catalyst precursors to prepare a library of well-defined catalysts to systematically describe structure–property relationships with help from theory and in situ X-ray absorption spectroscopy. With this approach, we confirm that PdO is the most active phase and that small differences in reaction rates as a function of size are likely due to variations in the surface crystal structure. We further demonstrate that the support exerts a limited influence on the PdO activity, with inert (SiO 2 ), acidic (Al 2 O 3 ), and redox-active (Ce 0.8 Zr 0.2 O 2 ) supports providing similar rates, while basic (MgO) supports show remarkably lower activity. Finally, we show that the introduction of steam leads to a considerable decrease in rates that is due to coverage effects, rather than structural and/or phase changes. Altogether, the data suggest that to further increase the activity and stability of Pd-based catalysts for methane combustion, increasing the surface area of supported PdO phases while avoiding strong adsorption of water on the catalytic surfaces is required. Furthermore, this study clarifies contrasting reports in the literature about the active phase and stability of Pd-based materials for methane combustion.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Natural Ores as Oxygen Carriers in Chemical Looping Combustion

Chemical looping combustion (CLC) is a combustion technology that utilizes oxygen from oxygen carriers (OC), such as metal oxides, instead of air to combust fuels. The use of natural minerals as oxygen carriers has advantages, such as lower cost and availability. Eight materials, based on copper or iron oxides, were selected for screening tests of CLC processes using coal and methane as fuels. Thermogravimetric experiments and bench-scale fixed-bed reactor tests were conducted to investigate the oxygen transfer capacity, reaction kinetics, and stability during cyclic reduction/oxidation reaction. Most natural minerals showed lower combustion capacity than pure CuO/Fe{sub 2}O{sub 3} due to low-concentrations of active oxide species in minerals. In coal CLC, chryscolla (Cu-based), magnetite, and limonite (Fe-based) demonstrated better reaction performances than other materials. The addition of steam improved the coal CLC performance when using natural ores because of the steam gasification of coal and the subsequent reaction of gaseous fuels with active oxide species in the natural ores. In methane CLC, chryscolla, hematite, and limonite demonstrated excellent reactivity and stability in 50-cycle thermogravimetric analysis tests. Fe{sub 2}O{sub 3}-based ores possess greater oxygen utilization but require an activation period before achieving full performance in methane CLC. Particle agglomeration issues associated with the application of natural ores in CLC processes were also studied by scanning electron microscopy (SEM).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Determining the location and nearest neighbours of aluminium in zeolites with atom probe tomography

Zeolite catalysis is determined by a combination of pore architecture and Brønsted acidity. As Brønsted acid sites are formed by the substitution of AlO4 for SiO4 tetrahedra, it is of utmost importance to have information on the number as well as the location and neighbouring sites of framework aluminium. Unfortunately, such detailed information has not yet been obtained, mainly due to the lack of suitable characterization methods. Here we report, using the powerful atomic-scale analysis technique known as atom probe tomography, the quantitative spatial distribution of individual aluminium atoms, including their three-dimensional extent of segregation. Ultimately, using a nearest-neighbour statistical analysis, we precisely determine the short-range distribution of aluminium over the different T-sites and determine the most probable Al–Al neighbouring distance within parent and steamed ZSM-5 crystals, as well as assess the long-range redistribution of aluminium upon zeolite steaming.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

All-day fresh water harvesting by microstructured hydrogel membranes

Abstract Solar steam water purification and fog collection are two independent processes that could enable abundant fresh water generation. We developed a hydrogel membrane that contains hierarchical three-dimensional microstructures with high surface area that combines both functions and serves as an all-day fresh water harvester. At night, the hydrogel membrane efficiently captures fog droplets and directionally transports them to a storage vessel. During the daytime, it acts as an interfacial solar steam generator and achieves a high evaporation rate of 3.64 kg m −2 h −1 under 1 sun enabled by improved thermal/vapor flow management. With a homemade rooftop water harvesting system, this hydrogel membrane can produce fresh water with a daily yield of ~34 L m −2 in an outdoor test, which demonstrates its potential for global water scarcity relief.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Environmental degradation of high-temperature protective coatings for ceramic-matrix composites in gas-turbine engines

Abstract The need for higher efficiencies and performance in gas-turbine engines that propel aircraft in the air, and generate electricity on land, is pushing the operating temperatures of the engines to unprecedented levels. Replacing some of the current hot-section metallic components with ceramic-matrix composites (CMCs) is making that possible. A high-temperature ceramic coatings system, that includes environmental-barrier coatings (EBCs), are needed to protect CMCs. However, these coatings undergo degradation in the highly hostile environment of the gas-turbine engine consisting of a combination of high gas temperatures, pressures, and velocities. In addition, there is the ubiquitous presence of steam (a combustion by-product) and occasional ingestion of calcia-magnesia-aluminosilicates (CMASs) in the form of dust, sand, or ash from the environment. Steam can cause corrosion of EBCs, and the molten CMAS deposits can react with the EBCs resulting in their failure. This article provides a perspective on the understanding of these degradation mechanisms, and possible approaches, guided by that understanding, for mitigating the degradation. An outlook on the future challenges and opportunities is presented.

Padture, Nitin P. (ORCID:0000000166228559)↗
DOE OSTI2021

High temperature oxidation of corrosion resistant alloys from machine learning

Parabolic rate constants, k p , were collected from published reports and calculated from corrosion product data (sample mass gain or corrosion product thickness) and tabulated for 75 alloys exposed to temperatures between ~800 and 2000 K (~500–1700 °C; 900–3000°F). Data were collected for environments including lab air, ambient and supercritical carbon dioxide, supercritical water, and steam. Materials studied include low- and high-Cr ferritic and austenitic steels, nickel superalloys, and aluminide materials. A combination of Arrhenius analysis, simple linear regression, supervised and unsupervised machine learning methods were used to investigate the relations between composition and oxidation kinetics. The supervised machine learning techniques produced the lowest mean standard errors. The most significant elements controlling oxidation kinetics were Ni, Cr, Al, and Fe, with Mo and Co composition also found to be significant features. The activation energies produced from the machine learning analysis were in the correct distributions for the diffusion constants for the oxide scales expected to dominate in each class.

Materials Science↗
DOE OSTI2018

Atomic Origins of Water-Vapour-Promoted Alloy Oxidation

The presence of water vapor, intentional or unavoidable, is crucial to many materials applications, such as steam generator, turbine engine, fuel cell, catalyst, and corrosion 1-6. Phenomenologically, water vapor has been noticed to accelerate oxidation of metals/alloys 7,8, however, the atomistic mechanisms remain elusive. Herein, through direct in situ atomic-scale transmission electron microscopy observation and density functional theory calculation, we reveal that water vapor enhanced oxidation of Ni-Cr alloy is associated with proton dissolution promoted vacancy formation, migration and clustering. Protons derived from water dissociation occupy interstitial position in the oxide lattice, which consequently leads to the lowering of both vacancy formation energy and the cation diffusion barrier. The atomic scale observations reveal a water vapor derived proton mediated oxide growth mechanism, which provides insights for reckoning many technological processes concerning materials in moist environment at elevated temperatures.

Luo, Langli (ORCID:000000026311051X)↗
DOE OSTI2019

Computational design of CO-tolerant Pt 3 M anode electrocatalysts for proton-exchange membrane fuel cells

CO is a typical contaminant in hydrogen fuel produced via steam reforming. Development of a CO-tolerant Pt-based anode for the proton-exchange membrane fuel cells (PEMFC) is of great interest to avoid catalyst deactivation caused by strong CO adsorption on Pt. Pt–Ru, Pt–Mo, and Pt 3 Sn are three known Pt-based bimetallic CO-tolerant anode materials. The enhanced CO-tolerance of these alloys has been generally attributed to a bifunctional effect enabling oxidative CO removal at low applied potential and a ligand effect between the two metals which weakens CO bonding and reduces CO surface coverage. In this study, we use density functional theory to calculate surface adsorption states under reaction conditions for Pt-based alloys. Our calculations provide a molecular-level understanding of the enhanced CO-tolerance of Pt alloys induced by the second metal. We find that Mo and Sn dopants promote CO-tolerance by reducing CO surface coverage and enabling CO oxidative removal at low applied potential. In contrast, Ru is not able to promote CO electro-oxidation at the low applied potential of the operating conditions of a PEMFC anode. The CO-tolerance induced by Ru is attributed to the reduction of CO coverage on Pt sites. Based on these mechanisms, we carried out a computational screening of Pt 3 M electrocatalysts for CO-tolerant PEMFC anodes. A number of promising candidates have been identified for experimental examination.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Confinement effects on the solar thermal heating process of TiN nanoparticle solutions

We propose a theoretical approach to describe quantitatively the heating process in aqueous solutions of dispersed TiN nanoparticles under solar illumination. The temperature gradients of the solution with different concentrations of the TiN nanoparticles are calculated when confinement effects of the container on the solar absorption are taken into account. We find that the average penetration of solar radiation into the solution is significantly reduced upon increasing the nanoparticle concentration. At high concentrations, our numerical results show that photons are localized near the surface of the solution. Moreover, the heat energy balance equation at the vapor–liquid interface is used to describe the solar steam generation. The theoretical time dependence of temperature rise and vaporization weight losses is consistent with experiments. Our calculations give strong evidence that the substantially localized heating near the vapor–liquid interface is the main reason for the more efficient steam generation process by floating plasmonic membranes when compared to randomly dispersed nanoparticles. The validated theoretical model suggests that our approach can be applied towards new predictions and other experimental data descriptions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗