Journal of Energy Engineering

A specific analytical solution for flow through a horizontal crack of finite length drained by a series of vertical drains is presented. The solution is used to derive diagrams of uplift pressure on the base of a dam and to demonstrate the influence of drains on the distribution and magnitude of uplift forces. Our solution shows that there should be an almost linear drop in hydraulic head from the entrance to the crack at the heel of the dam to the line of drains, followed by a slight rise in head to the end of the crack. This is consistent with a previously suggested solution for porous media. The results show that drain holes are effective in substantially reducing uplift pressures in a crack and have the greatest influence when located between approximately one half and one fifth of the length of the crack from its upstream end.

A complete formulation of the spectral wave power equations, based upon linear wave theory, to be used with one‐dimensional and directional sea spectrum are presented. These equations are quite general and allow for the specification of device specific information, such as, the wave capture/conversion efficiency and vertical projected capture height. Previously published field data is used to emphasize that the wave power resource at a particular offshore site can be quite variable and may not provide adequate energy for continuous power generations. Two numerical examples are used to illustrate the sensitivity of wave power estimates for a hypothetical wave energy device. The first example shows that as the seastate at a particular offshore site increases, the useful power generated by a wave energy convertor does not necessarily increase. The second numerical example indicates the importance of the vertical capture height for both design and feasibility studies.

The energy efficiency of road, rail, and slurry pipeline transportation of mineral concentrates from a potential mine site in northwest Alaska to an ocean shipping terminal is analyzed. Energy consumption rates for construction, operation, and maintenance of each system over its expected life are the basis for the analysis. Several levels of annual concentrate production are assumed, and the energy (Btu) break‐even points between the alternative modes are calculated. The results of the analysis indicated that a slurry pipeline with an associated service road would require the least total energy at all levels of production. A rail system would be second, and truck transportation would be the highest energy consumer, especially at the higher production levels.