Issue No 3, December

Abstract

Hydrogen storage and transportation or distribution is closely linked together. Hydrogen can be distributed continuously in pipelines or batch wise by ships, trucks, railway or airplanes. All batch transportation requires a storage system but also pipelines can be used as pressure storage system. Hydrogen exhibits the highest heating value per weight of all chemical fuels. Furthermore, hydrogen is regenerative and environment friendly. There are two reasons why hydrogen is not the major fuel of toady’s energy consumption: First of all, hydrogen is just an energy carrier. And, although it is the most abundant element in the universe, it has to be produced, since on earth it only occurs in the form of water. This implies that we have to pay for this energy, which results in a difficult economic task, because since the industrialization we are used to consuming energy for free. The second difficulty with hydrogen as an energy carrier is the low critical temperature of 33K, i.e. hydrogen is a gas at room temperature. For mobile and in many cases also for stationary applications the volumetric and gravimetric density of hydrogen in a storage system is crucial. Hydrogen can be stored by six different methods and phenomena: high pressure gas cylinders (up to 800 bar), liquid hydrogen in cryogenic tanks (at 21 K), adsorbed hydrogen on materials with a large specific surface area (at T< 100 K), absorbed on interstitial sites in a host metal (at ambient pressure and temperature), chemically bond in covalent and ionic compounds (at ambient pressure), oxidation of reactive metals e.g. Li, Na, Mg, Al, Zn with water. These metals easily react with water to the corresponding hydroxide and liberate the hydrogen from the water. Finally, the metal hydroxides can be thermally reduced to the metals in a solar furnace. This paper reviews the hydrogen storage methods known and focuses on the basic limitations of each method and the current state of research.

Abstract

This paper deals with the development of membranes to be used in membrane reactors in which either natural gas or a coal gasification product is converted to CO₂ and H₂, while these two components are separated from each other simultaneously. In this way, a pure hydrogen stream is produced for combustion in a fuel cell or gas turbine for electricity production as well as a pure CO₂ stream for storage in e.g. an empty gas field. Two cases are described: one for the development of H₂ and one for CO₂ selective membranes. The H₂ selective membrane is a porous one, where the pore size has been tuned by Atomic Layer Deposition (ALD) to the kinetic diameter of hydrogen. The separation is thus based upon molecular sieving. The CO₂ selective membranes are also porous but here the transport mechanism is based upon affinity separation. Performances of both kinds of membranes are presented. They are promising, although both the membrane support and the synthesis of the separating layer need improvement.

Abstract

Growing demands for energy in the modern world require increased efficiency in the use of resources to generate power. This paper identifies the opportunity for technology development in this space, and the requirements for a solution to this issue. Solid oxide fuel cells (SOFCs) at megawatt scale offer a potential solution at high (60+ %) efficiency and benefit from a fuel flexibility not enjoyed by other types of fuel cell. This paper presents the Rolls-Royce Fuel Cell Systems Limited (RRFCS) technology to deliver a SOFC system at this scale and address the inherent challenges.

Abstract

This study investigates the physical-mechanical properties, the composition and the old manufacturing technologies of ancient bricks as well as their durability. The bricks, obtained from historical buildings in towns of Marche Region, are red or brown coloured and show detachments or swellings caused by exposition to polluted urban atmosphere rich in sulfur dioxide. This alteration, also deeply extended, can lower the mechanical strengths of the bricks and makes the assessment of their original properties more difficult. For this purpose, new brick specimens, made of original clay, were prepared and fired at temperature ranging from 200 ° to 1000 °C and than tested. The mechanical strength values of “re-made” bricks, correlated to firing temperatures, lead to the conclusion that, since the same clay was used, old red bricks were baked at about 600 °C and old brown ones at about 800 °C. The mineralogical phases were found depending on firing temperatures: gehlenite and wollastonite-like compounds. Bricks fired at lower temperatures contain a high amount of calcite which can be converted into sulfate by acid urban atmosphere. Phases formed with high temperatures can also be attacked by acid rain causing deep brick degradation.

Abstract

This article presents lifetime models for unplastered masonry (exterior part of a cavity wall) and for roofing tiles. How to quantify relative mass flows (per capita p.a.) of durable and recoverable ceramic ware by design, is demonstrated for Dutch dwellings. lt is shown that the power to prevent deterioration, and the fitness for recovery are governed by design. Sufficiently vitrified (solid) facing bricks and roofing tiles with a defectless isotropic structure appeared to be designed for quality control with respect to durability and recovery.

Abstract

The aim of this paper is to present a project which was undertaken to document, study and restitute the design process of two window grilles or transenne windows, made with glazed tiles. Below, first the location of these window grilles in a historic building and a description of their general characteristics is given. This is followed by a discussion on the geometry involved in their design process, with special emphasis on the geometric interlaces screening the window openings and the contribution of this geometry towards a restitution scheme. The final section of the paper gives the basic steps that were followed to delineate the interlace ornament as a Computer Aided Design project. For the final section, only one of the window grilles is selected in order to stay within the required limits of the paper.