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Steven R. Hanna
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Steven R. Hanna and Franklin A. Gifford

Large (10 000 to 50 000 MW) power parks are being studied as one means of satisfying the nation's demand for energy. The dissipation of waste energy from these installations may result in significant meteorological effects. It is shown that the rate of atmospheric dissipation of the waste energy from these power parks is approximately equal to the atmospheric dissipation of energy by geophysical phenomena such as thunderstorms, volcanoes, and large bushfires. Cumulus clouds and whirlwinds often result from these energy releases. There is a possibility that natural vorticity will be concentrated by large power parks. A theory of multiple plume rise is used to estimate the enhancement of plume rise from multiple cooling towers.

Calculations of plume rise, ground level fog intensity, and drift deposition due to emissions from cooling towers at a hypothetical 40 000 MW nuclear power park are made. The plume rise from 50 towers is estimated to be more than 110% of that from a single tower if the tower spacing is less than about 300 m. At locations within 100 km of the cooling towers, excess fog will occur about one or two percent of the time. The vapor plume will be appreciably longer than those from present installations; for instance it should be clearly visible from earth satellites most of the time. Since there are no power parks of this magnitude yet in existence, there are no measurements to test these calculations. The conclusions are highly tentative and indicate that much more research is required on this subject.

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Steven R. Hanna, Michael J. Brown, Fernando E. Camelli, Stevens T. Chan, William J. Coirier, Olav R. Hansen, Alan H. Huber, Sura Kim, and R. Michael Reynolds

Computational fluid dynamics (CFD) model simulations of urban boundary layers have improved in speed and accuracy so that they are useful in assisting in planning emergency response activities related to releases of chemical or biological agents into the atmosphere in large cities such as New York, New York. In this paper, five CFD models [CFD-Urban, Finite Element Flow (FEFLO), Finite Element Model in 3D and Massively-Parallel version (FEM3MP), FLACS, and FLUENT–Environmental Protection Agency (FLUENT-EPA)] have been applied to the same 3D building data and geographic domain in Manhattan, using approximately the same wind input conditions. Wind flow observations are available from the Madison Square Garden 2005 (MSG05) field experiment. Plots of the CFD models' simulations and the observations of near-surface wind fields lead to the qualitative conclusion that the models generally agree with each other and with field observations over most parts of the computational domain, within typical atmospheric uncertainties of a factor of 2. The results are useful to emergency responders, suggesting, for example, that transport of a release at street level in a large city could extend for a few blocks in the upwind and crosswind directions. There are still key differences among the models for certain parts of the domain. Further examination of the differences among the models and the observations are necessary in order to understand the causal relationships.

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