An analytical investigation of a novel alternative fuel source, aluminum powder, for its reactive properties upon reaction with water. Extensive research has been performed over the years studying metal-water reactions for their heat generation and in-situ hydrogen production. Both theoretical and experimental studies have focused on determining the effect of parameters such as the type of metal, metal-to-water ratio, activation method, particle size, and temperature of the reaction. However, few have explored the implementation of such fuel in a power generation device. This work explores the use of aluminum-water reactions to power three different Siemens engines of varying power outputs: two industrial engines- RB211 (33 MW) and Trent 60 (66 MW) and one heavy duty gas turbine- SGT5-4000F (329 MW). The thermodynamics cycle is proposed, and analysis is performed to determine the required reactor size. Then, a life cycle carbon emission of aluminum-water fuel is analyzed and evaluated against that of natural gas – the fuel currently used in the three engines.
Keena Trowell, Sam Goroshin, David Frost, Jeffrey Bergthorson
Aluminum particles, spanning in size from 10 μm to 3 mm, were reacted with varying densities of water at 655 K. The density of the water is varied from 50 g L−1 to 450 g L−1 in order to understand the effect of density on both reaction rates and yields. Low-density supercritical water is associated with properties that make it an efficient oxidizer: low viscosity, high diffusion, and low relative permittivity. Despite this, it was found that the high-density (450 g L−1) supercritical water was the most efficient oxidizer both in terms of reaction rate and hydrogen yield. The 10 μm powder had a peak reaction rate of approximately 675 cmH23 min−1 gAl−1 in the high-density water, and a peak reaction rate below 250 cmH23 min−1 gAl−1 in the low- and vapour-density water. A decline in peak reaction rate with decreasing water density was also observed for the 120 μm powder and the 3 mm slugs. These findings imply that the increased collision frequency, a property of the high-density water, outpaces reduction in the reaction enhancing properties associated with low-density supercritical water. Hydrogen yield was minimally affected by decreasing the oxidizer density from 450 g L−1 to 200 g L−1, but did drop off significantly in the vapour-density (50 g L−1) water.
Yinon Yavor, Sam Goroshin, Jeffrey M. Bergthorson, David L. Frost
The in-situ production of hydrogen from a metal-water reaction resolves some of the main obstacles related to the use of hydrogen as an alternative fuel, namely storage and safety. In this study, experiments are conducted in a batch reactor with sixteen different commercially-available industrial metal powders, with water temperatures ranging from 80 to 200 _C. The hydrogen production rate, total yield, and reaction completeness are determined for each metal-powder fuel and reaction temperature. Aluminum powder produces the largest amount of hydrogen per unit mass throughout the temperature range, followed by the magnesium powder. Manganese powder, which produces the largest amount of hydrogen per unit volume at high temperatures, exhibits a sharp increase in yield between 120 and 150 _C, suggesting the existence of a critical energetic threshold. The aluminum and magnesium powders exhibit high reaction rates, and together with the manganese powder, appear to be the most attractive candidates to serve as fuels for in-situ hydrogen production.