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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Novel Application of Carbonate Fuel Cell for Capturing Carbon Dioxide from Flue Gas Streams

To address concerns about climate change resulting from emission of CO2 by coal-fueled power plants, FuelCell Energy, Inc. has developed the Combined Electric Power and Carbon-dioxide Separation (CEPACS) system concept. The CEPACS system utilizes Electrochemical Membrane (ECM) technology derived from the Company’s Direct FuelCell® products. The system separates the CO2 from the flue gas of other plants and produces electric power using a supplementary fuel. FCE is currently evaluating the use of ECM to cost effectively separate CO2 from the flue gas of Pulverized Coal (PC) power plants under a U.S. Department of Energy contract. The overarching objective of the project is to verify that the ECM can achieve at least 90% CO2 capture from the flue gas with no more than 35% increase in the cost of electricity. The project activities include: 1) laboratory scale operational and performance tests of a membrane assembly, 2) performance tests of the membrane to evaluate the effects of impurities present in the coal plant flue gas, in collaboration with Pacific Northwest National Laboratory, 3) techno-economic analysis for an ECM-based CO2 capture system applied to a 550 MW existing PC plant, in partnership with URS Corporation, and 4) bench scale (11.7 m2 area) testing of an ECM-based CO2 separation and purification system.

CO2 separation, Carbon capture, electrochemical me↗
DOE OSTI2015

High-Potential Electrocatalytic O2 Reduction with Nitroxyl / NOx Mediators: Implications for Fuel Cells and Aerobic Oxidation Catalysis

Efficient reduction of O2 to water is a central challenge in energy conversion and aerobic oxidation catalysis. In the present study, we investigate the electrochemical reduction of O2 with soluble organic nitroxyl and nitrogen oxide (NOx) mediators. When used alone, neither organic nitroxyls, such as TEMPO (2,2,6,6-tetramethyl-1-piperidinyl-N-oxyl), nor NOx species, such as sodium nitrite, are effective mediators of electrochemical O2 reduction. The combination of nitroxyl/NOx species, however, mediates sustained O2 reduction at electrochemical potentials of 0.19–0.33 V (vs. Fc/Fc+) in acetonitrile containing trifluoroacetic acid. Mechanistic analysis of the coupled redox reactions supports a process in which the nitrogen oxide catalyst drives aerobic oxidation of a nitroxyl mediator to an oxoammonium species, which then is reduced back to the nitroxyl at the cathode. The electrolysis potential is dictated by the oxoammonium/nitroxyl reduction potential. The high potentials observed with this ORR system benefit from the mechanism-based specificity for four-electron reduction of oxygen to water mediated by NOx species, together with kinetically efficient reduction of oxidized NOx species by TEMPO and other organic nitroxyls. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center, funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences.

Gerken, James B.↗
NASA NTRS2008

Unitized regenerative fuel cell system

A Unitized Regenerative Fuel Cell system uses heat pipes to convey waste heat from the fuel cell stack to the reactant storage tanks. The storage tanks act as heat sinks/sources and as passive radiators of the waste heat from the fuel cell stack. During charge up, i.e., the electrolytic process, gases are conveyed to the reactant storage tanks by way of tubes that include dryers. Reactant gases moving through the dryers give up energy to the cold tanks, causing water vapor in with the gases to condense and freeze on the internal surfaces of the dryer. During operation in its fuel cell mode, the heat pipes convey waste heat from the fuel cell stack to the respective reactant storage tanks, thereby heating them such that the reactant gases, as they pass though the respective dryers on their way to the fuel cell stacks retrieve the water previously removed.

Burke, Kenneth A.↗
DOE OSTI2012

Carbon based electrocatalysts for fuel cells

Novel proton exchange membrane fuel cells and direct methanol fuel cells with nanostructured components are configured with higher precious metal utilization rate at the electrodes, higher power density, and lower cost. To form a catalyst, platinum or platinum-ruthenium nanoparticles are deposited onto carbon-based materials, for example, single-walled, dual-walled, multi-walled and cup-stacked carbon nanotubes. The deposition process includes an ethylene glycol reduction method. Aligned arrays of these carbon nanomaterials are prepared by filtering the nanomaterials with ethanol. A membrane electrode assembly is formed by sandwiching the catalyst between a proton exchange membrane and a diffusion layer that form a first electrode. The second electrode may be formed using a conventional catalyst. The several layers of the MEA are hot pressed to form an integrated unit. Proton exchange membrane fuel cells and direct methanol fuel cells are developed by stacking the membrane electrode assemblies in a conventional manner.

Yan, Yushan↗
DOE OSTI2013

Recent Progress in Nanostructured Electrocatalysts for PEM Fuel Cells

Polymer electrolyte membrane (PEM) fuel cells are attracting much attention as promising clean power sources and an alternative to conventional internal combustion engines, secondary batteries, and other power sources. Much effort from government laboratories, industry, and academia has been devoted to developing PEM fuel cells, and great advances have been achieved. Although prototype cars powered by fuel cells have been delivered, successful commercialization requires fuel cell electrocatalysts, which are crucial components at the heart of fuel cells, meet exacting performance targets. In this review, we present a brief overview of the recent progress in fuel cell electrocatalysts, which involves catalyst supports, Pt and Pt-based electrocatalysts, and non-Pt electrocatalysts.

Zhang, Sheng↗
DOE OSTI2022

Spatially resolved performance and degradation in a perfluorinated anion exchange membrane fuel cell

Anion exchange membrane fuel cells may enable future operation with non-precious metal-based catalysts. These systems have a delicate sensitivity to operating conditions such as humidification levels and the presence of CO2 in the air oxidant stream. We present spatially resolved in-situ performance results that shed light on phenomena that are unique to anion exchange membrane fuel cells. For cell construction, a highly conductive perfluorinated anion exchange polymer was used as the membrane and the material in powder form as the ionomer. Experiments were conducted to investigate the effects of humidification, fuel/oxidant concentration, and carbonation effects on the performance and its distribution in the cell. The results indicated that (i) dry conditions at the cathode have a stronger effect than at the anode on overall cell performance, (ii) performance significantly suffered when humidification was below 90%, (iii) fuel and oxidant dilution effects lead mass-transport losses and were stronger than flow rate effects, (iv) CO2 in the cathode feed stream creates an equilibration disparity between the inlet and outlet sections and CO2 purging is affected by flooding conditions, and (v) after >500 h of operation, performance deteriorates predominantly at the inlet.

2+1D fuel cell model↗
NASA NTRS1986

Theoretical and Experimental Flow Cell Studies of a Hydrogen-Bromine Fuel Cell, Part 1

There is increasing interest in hydrogen-bromine fuel cells as both primary and regenerative energy storage systems. One promising design for a hydrogen-bromine fuel cell is a negative half cell having only a gas phase, which is separated by a cationic exchange membrane from a positive half cell having an aqueous electrolyte. The hydrogen gas and the aqueous bromide solution are stored external to the cell. In order to calculate the energy storage capacity and to predict and assess the performance of a single cell, the open circuit potential (OCV) must be estimated for different states of change, under various conditions. Theoretical expressions were derived to estimate the OCV of a hydrogen-bromine fuel cell. In these expressions temperature, hydrogen pressure, and bromine and hydrobromic acid concentrations were taken into consideration. Also included are the effects of the Nafion membrance separator and the various bromide complex species. Activity coefficients were taken into account in one of the expressions. The sensitivity of these parameters on the calculated OCV was studied.

Savinell, R. F.↗
DOE OSTI2013

Raising H2 and Fuel Cell Awareness in Ohio

The Ohio Fuel Cell Coalition was tasked with raising the awareness and understanding of Fuel Cells and the Hydrogen economy. This was done by increasing the understanding of hydrogen and fuel cell technologies among state and local governments using a target of more than 10% compared to 2004 baseline. We were also to target key populations by 20 percent compared to 2004 baseline. There are many barriers to an educated fuel cell population, including: a)Lack of Readily Available, Objective and Technical Accurate Information b)Mixed Messages c)Disconnect Between Hydrogen Information and Dissemination Networks d)Lack of Educated Trainers and Training Opportunities e)Regional Differences f)Difficulty of Measuring Success The approach we used for all the Community Leaders Forums were presentations by the Ohio Fuel Cell Coalition in conjunction with regional leaders. The presentations were followed by question and answers periods followed up by informal discussions on Fuel Cells and the Hydrogen Economy. This project held a total of 53 events with the following breakdown: From Aug 2009 through June 2010, the Ohio Fuel Cell Coalition held 19 community leaders forums and educated over 845 individuals, both from the State of Ohio and across the country: From July 2010 to June 2011 the OFCC held 23 community forum events and educated 915 individuals; From August 2011 to June 2012 there were 11 community forums educating 670 individuals. This report details each of those events, their date, location, purpose, and pertinent details to this report. In summary, as you see the Community Leader Forums have been very successful over the period of the grant with over 2,000 people being drawn to the forums. As always, we followed up the forums with a survey and the survey results were very positive in that the participants had a significant increase in knowledge and awareness of Fuel Cells and the Hydrogen Economy.

08 HYDROGEN↗