Andrew N. Rollinson

Urea as a hydrogen carrier: a perspective on its potential for safe, sustainable and long-term energy supply

Recently, there have been publications reporting the use of urea, as a source of hydrogen/fuel cell power. There have however been no reports that singularly assess the suitability of urea for this purpose. This article provides not only a perspective on the attributes of urea ((NH2)2CO) as a hydrogen carrier for fuel cells but also presents the findings of a review on the feasibility of utilising the enormous natural resource of urea that exists. Urea is a cheap and widely available commodity with well developed manufacturing infrastructure and a rapidly increasing volume of production. This offers rapid implementation of urea for application as a hydrogen carrier either directly or as a source of ammonia. Compared with other industrial chemicals previously considered, urea has the advantages of being non-toxic, stable, and therefore easy to transport and store. This report reveals that the natural resource of urea could be a solution to long-term future sustainable hydrogen supply and that the present status of scientific knowledge necessary to extract this natural resource is in the most part understood. It is considered realistic that these sustainable routes could be exploited if they are given sufficient focus of research attention.

Experiments on torrefied wood pellet: study by gasification and characterization for waste biomass to energy applications.

Samples of torrefied wood pellet produced by low-temperature microwave pyrolysis were tested through a series of experiments relevant to present and near future waste to energy conversion technologies. Operational performance was assessed using a modern small-scale downdraft gasifier. Owing to the pellets shape and surface hardness, excellent flow characteristics were observed. The torrefied pellet had a high energy density, and although a beneficial property, this highlighted the present inflexibility of downdraft gasifiers in respect of feedstock tolerance due to the inability to contain very high temperatures inside the reactor during operation. Analyses indicated that the torrefaction process had not significantly altered inherent kinetic properties to a great extent; however, both activation energy and pre-exponential factor were slightly higher than virgin biomass from which the pellet was derived. Thermogravimetric analysis-derived reaction kinetics (CO2 gasification), bomb calorimetry, proximate and ultimate analyses, and the Bond Work Index grindability test provided a more comprehensive characterization of the torrefied pellets suitability as a fuel for gasification and also other combustion applications. It exhibited significant improvements in grindability energy demand and particle size control compared to other non-treated and thermally treated biomass pellets, along with a high calorific value, and excellent resistance to water.

Gasification reactor engineering approach to understanding the formation of biochar properties

The correlation between thermochemical provenance and biochar functionality is poorly understood. To this end, operational reactor temperatures (spanning the reduction zone), pressure and product gas composition measurements were obtained from a downdraft gasifier and compared against elemental composition, surface morphology and polyaromatic hydrocarbon content (PAH) of the char produced. Pine feedstock moisture with values of 7% and 17% was the experimental variable. Moderately high steady-state temperatures were observed inside the reactor, with a ca 50°C difference in how the gasifier operated between the two feedstock types. Both chars exhibited surface properties comparable to activated carbon, but the relatively small differences in temperature caused significant variations in biochar surface area and morphology: micropore area 584 against 360 m2 g−1, and micropore volume 0.287 against 0.172 cm3 g−1. Differences in char extractable PAH content were also observed, with higher concentrations (187 µg g−1 ± 18 compared with 89 ± 19 µg g−1 Σ16EPA PAH) when the gasifier was operated with higher moisture content feedstock. It is recommended that greater detail on operational conditions during biochar production should be incorporated to future biochar characterization research as a consequence of these results.

Engineering and technology of industrial water power at Castleford Mills from the seventeenth century to the twentieth century

This article tells the story of engineering and technology at Castleford Water Mills from the seventeenth century to the twentieth century through the presentation of recently discovered design plans and deeds, supplemented by other historical research. One of Castlefords mills was operated by Dr Thomas Allinsons Natural Food Company and therefore retained stoneground milling when fashions for white flour prompted other mills to switch to roller systems. The millstones were powered by a high-efficiency breastshot wheel, believed to be the last of its type taken out of industrial service in Britain. Many of its features, and its subsequent longevity, can be attributed to the influential works of William Fairbairn and John Smeaton. Detailed colour designs show the construction specifications of this water-wheel and its civil housing, along with other engineering plans such as a previously unrecorded Henry Simon horizontal turbine. Links with John Smeaton and the entry in his catalogue of designs for Castleford Oil Mill are also explored, and a former flood mill is identified at the site.