Hydrogen from coal: Production and utilisation technologies

Error condition detected Although coal may be viewed as a dirty fuel due to its high greenhouse emissions when combusted, a strong case can be made for coal to be a major world source of clean H-2 energy. Apart from the fact that resources of coal will outlast oil and natural gas by centuries, there is a shift towards developing environmentally benign coal technologies, which can lead to high energy conversion efficiencies and low air pollution emissions as compared to conventional coal fired power generation plant. There are currently several world research and industrial development projects in the areas of Integrated Gasification Combined Cycles (IGCC) and Integrated Gasification Fuel Cell (IGFC) systems. In such systems, there is a need to integrate complex unit operations including gasifiers, gas separation and cleaning units, water gas shift reactors, turbines, heat exchangers, steam generators and fuel cells. IGFC systems tested in the USA, Europe and Japan employing gasifiers (Texaco, Lurgi and Eagle) and fuel cells have resulted in energy conversions at efficiency of 47.5% (HHV) which is much higher than the 30-35% efficiency of conventional coal fired power generation. Solid oxide fuel cells (SOFC) and molten carbonate fuel cells (MCFC) are the front runners in energy production from coal gases. These fuel cells can operate at high temperatures and are robust to gas poisoning impurities. IGCC and IGFC technologies are expensive and currently economically uncompetitive as compared to established and mature power generation technology. However, further efficiency and technology improvements coupled with world pressures on limitation of greenhouse gases and other gaseous pollutants could make IGCC/IGFC technically and economically viable for hydrogen production and utilisation in clean and environmentally benign energy systems. (c) 2005 Elsevier B.V. All rights reserved.

Determination of the orientational distribution and orientation factor for transfer between membrane-bound fluorophores using a confocal microscope

Orientational fluorophores have been a useful tool in physical chemistry, biochemistry, and more recently structural biology due to the polarized nature of the light they emit and that fact that energy can be transferred between them. We present a practical scheme in which measurements of the intensity of emitted fluorescence can be used to determine limits on the mean and distribution of orientation of the absorption transition moment of membrane-bound. uorophores. We demonstrate how information about the orientation of. uorophores can be used to calculate the orientation factor k(2) required for use in FRET spectroscopy. We illustrate the method using images of AlexaFluor probes bound to MscL mechanosensitive transmembrane channel proteins in spherical liposomes.

A qualitative cross-level investigation of safety climate perceptions

ver the last few decades occupational health and safety research has shifted its focus away from engineering and ergonomics as a means of improving workplace safety, and has given greater attention to examining the role played by organisational factors, such as safety climate. One factor constraining the advancement of our understanding of the safety climate construct is the tendency of researchers to remain steadfastly bound to the notion that safety climate is measured via a quantative measurement tool. Researchers in the area (e.g., Frone & Barling, 2004; Zohar, 2003) are now arguing for better triangulation of methodologies, in particular better qualitative research, to advance our knowledge and understanding. The present study extends the present body of safety climate literature in two ways; firstly, it addresses this methodological issue via the utilisation of a semi-structured interview methodology and secondly it examines the qualitative structure of safety climate perceptions across different levels (organisation, supervisor and co-worker) and different groups (managers vs. employees). Examination of the interview transcripts revealed qualitative differences and similarities between the different safety climate levels (organisational, supervisor and co-worker) and between manager and employee safety climate perceptions. Implications of these findings for safety climate theory and measurement are discussed.