Hydrogen energy offers great promise as an energy alternative. Hydrogen technologies can reduce and eliminate the release of carbon dioxide from fossil-fuel combustion, the main cause of global warming. One of the main challenges is hydrogen storage. Storing hydrogen in the solid-state hydride form holds a volumetric advantage over compressed and liquid hydrogen states. Solid hydrogen storage systems also have features of low-pressure operation, compactness, safety, tailorable delivery pressure, excellent absorption /desorption kinetics, modular design for easy scalability, and long cycle life.In this paper, solid hydrogen storage systems (such as portable power canisters, lightweight fiber wrapped vessels, and aluminum tubular vessels, developed by Texaco Ovonic Hydrogen Systems LLC) will be discussed. A system of four canisters each storing approximately 80 grams of reversible hydrogen is shown to run a 1 kW PEM fuel cell for more than 247 minutes at full power. Canisters show no plastic deformation after more than 500 charge/discharge cycles. The measured strain on canister surfaces indicates that DOT stress limits are not exceeded. The canisters are in the early commercialization stage for uninterrupted power supply (UPS) and auxiliary power unit (APU) applications.A lightweight fiber-wrapped vessel engineered with metal hydride and internal heat exchanger is being developed for onboard applications. At the system level, the vessel has a volumetric energy density of 50 grams of hydrogen per liter and a gravimetric density of 1.6 wt.%. The vessel is capable of storing 3 kg of hydrogen with a fast refueling capability. Ninety percent of the storable hydrogen can be refueled in 10 minutes at 1500 psig. The vessel can easily release the hydrogen at a rate of 350 slpm at 70 o C.Aluminum tubular vessels are being designed and tested for bulk storage and infrastructure applications including stationary power, hydrogen shipment and hydrogen service stations. The tubular vessel dimensions may be designed for specific applications. For example, a tubular vessel 6 inches in diameter and 62 inches in length can store up to 1 kg of hydrogen.
Recent efforts have been made to develop high-capacity complex hydride composites by combining alanates and amides. The hydrogen storage mechanisms in those composites are not unambiguously clarified because of chemical reactions during the sample preparation process. In this Article, we have studied the effects of sample preparation conditions on the phase stability of a mixture of 3Mg(NH2)2–2Li3AlH6 and identified that unlike high-energy ball-milling light mixing generates a physical mixture of the reactants without decomposition. Subsequently, the hydrogen storage properties, the desorption pathway, and the reversible reaction mechanism of the composite were investigated through a combination of kinetic measurements and phase and microstructure analyses. The results reveal that the first step of hydrogen release (initiated at 170 °C) involves decomposition of Li3AlH6 to LiH and Al. The second step of hydrogen release occurs as the temperature increases (to 230 °C) when Mg(NH2)2 reacts with LiH to form Li2Mg(NH)2. If desorption of the 3Mg(NH2)2–2Li3AlH6 mixture is limited to a temperature of 400 °C, then the reversible reaction takes place between Li2Mg(NH)2 (plus H2) and LiH and Mg(NH2)2. We find that the Al generated from the first hydrogen release step does not participate in the reversible hydrogen storage process and instead inhibits mass transfer that results in higher desorption temperatures (and low desorption rates) and lowers the overall reversible capacity (2.7 wt %) as compared with the neat reaction (i.e., ∼4.3 wt % without the presence of Al).
Our project focuses on evaluating the impact of pen-based computing devices and collaboration-facilitating software in the engineering, science, and technical communication classrooms. The faculty members engaged in the project are implementing pen-based devices (both HP tablet PCs and Wacom pen slates) in their courses. In order to take full advantage of the technology, these instructors are also using DyKnow Vision software to encourage students to work together, to reduce students' time spent copying notes and problems on the whiteboard, and to encourage more efficient methods of studying for exams. The assessment component of the project includes both formative and summative methods deployed throughout the 2006-07 academic year.
As digital ink technology continues to make an impact on the technical classroom, faculty members are exploring the different strategies for using this technology to improve student learning. The purpose of this panel is to demonstrate how faculty members are implementing this technology in engineering and science classrooms at three different institutions: Rose-Hulman Institute of Technology, University of Texas at Austin, and University of Vermont. The panel is designed to show both experienced pen computing users and those who are new to the field the different ways this versatile technology may be employed. In addition to the demonstrations, the presenters will discuss the pedagogical implications that result from the implementations. Faculty who are interested in both the pedagogy and assessment of pen-based computing in the classroom should find the session informative and useful.
is a Professor of Mechanical Engineering at Gonzaga University. Pat received his PhD in Metallurgical and Materials Engineering from the Colorado School of Mines. He has fifteen years of industrial experience in the casting and silicon wafer manufacturing industries. Pat is registered as a PE in the states of Ohio, Michigan and Washington.
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