H2POWER: Development of a methodology to calculate life cycle cost of small and medium-scale hydrogen systems
Abstract At this time, hydrogen-based power plants and large hydrogen production facilities are capital intensive and unable to compete financially against hydrocarbon-based energy production facilities. An option to overcome this problem and foster the introduction of hydrogen technology is to introduce small and medium-scale applications such as residential and community hydrogen refueling units. Such units could potentially be used to generate both electricity and heat for the home, as well as hydrogen fuel for the automobile. Cost modeling for the integration of these three forms of energy presents several methodological challenges. This is particularly true since the technology is still in the development phase and both the financial and the environmental cost must be calculated using mainly secondary sources. In order to address these issues and aid in the design of small and medium-scale hydrogen systems, this study presents a computer model to calculate financial and environmental costs of this technology using different hydrogen pathways. The model can design and compare hydrogen refueling units against hydrocarbon-based technologies, including the “gap” between financial and economic costs. Using the methodology, various penalties and incentives that can foster the introduction of hydrogen-based technologies can be added to the analysis to study their impact on financial cost.
An overview of automotive home and neighborhood refueling
Home refueling helped address the fuel availability issue for gasoline vehicles a century ago; it may still have important implications for alternative fuel vehicles today. The positive consumer response and lessons learned about home refueling for compressed natural gas vehicles, battery electric vehicles, and plug-in hybrid vehicles demonstrate its potential and warrant further research. This paper presents a historical review and comparison of home refueling methods for a wide range of motor vehicles; the home refueling experience of these vehicles and consumer preferences and response to these methods are discussed as well. A description of neighborhood refueling is also provided. Furthermore, the important questions, challenges, and opportunities of adopting a home and neighborhood refueling strategy for alternative fuel pathways are summarized. The paper intends to help us understand the potential of home and neighborhood refueling and the difference between home refueling for different alternative fuel pathways, and help facilitate further exploring of the implications.
Collagen dynamics in articular cartilage under osmotic pressure
Cartilage is a complex biological tissue consisting of collagen, proteoglycans and water. The structure and molecular mobility of the collagen component of cartilage were studied by 13C solid‐state NMR spectroscopy as a function of hydration. The hydration level of cartilage was adjusted between fully hydrated (∼80 wt% H2O) and highly dehydrated (∼30 wt% H2O) using the osmotic stress technique. Thus, the conditions of mechanical load could be simulated and the response of the tissue macromolecules to mechanical stress is reported. From the NMR measurements, the following results were obtained. (i) Measurements of motionally averaged dipolar 1H–13C couplings were carried out to study the segmental mobility in cartilage collagen at full hydration. Backbone segments undergo fast motions with amplitudes of ∼35° whereas the collagen side‐chains are somewhat more mobile with amplitudes between 40 and 50°. In spite of the high water content of cartilage, collagen remains essentially rigid. (ii) No chemical shift changes were observed in 13C cross‐polarization magic angle spinning spectra of cartilage tissue at varying hydration indicating that the collagen structure was not altered by application of high osmotic stress. (iii) The 1H–13C dipolar coupling values detected for collagen signals respond to dehydration. The dipolar coupling values gradually increase upon cartilage dehydration, reaching rigid limit values at ∼30 wt% H2O. This indicates that collagen is essentially dehydrated in cartilage tissue under very high mechanical load, which provides insights into the elastic properties of cartilage collagen, although the mechanical pressures applied here exceed the physiological limit. Copyright © 2006 John Wiley & Sons, Ltd.