Power plants – Pressure fluid source and motor – Utilizing natural energy or having a geographic feature
Reexamination Certificate
2002-02-26
2003-11-18
Look, Edward K. (Department: 3745)
Power plants
Pressure fluid source and motor
Utilizing natural energy or having a geographic feature
Reexamination Certificate
active
06647717
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a hydro/aero-power generation plant and method for generating hydro/aero-power, and more particularly, to a tower for generating power by spraying water into the top of the tower to produce a downdraft of air that turns a turbine arrangement within the bottom of the tower to generate power.
BACKGROUND OF THE INVENTION
The demand for power is increasing dramatically with expanding industrialization and the escalating use of high technology. The available natural resources, however, are continually being consumed and will eventually be used up. Other sources of power, such as nuclear plants, are in disfavor because of environmental concerns over the disposal of the resulting waste and possible accidents and wrong doings. Fossil fuel which is burned in thermal power stations involves air pollution, in general, and CO
2
which causes warming of the atmosphere, in particular. There is a danger that the environment will be destroyed long before the fossil fuel will be used up. The effect of warming up the atmosphere is already a measurable phenomenon causing an increasing concern. On the other hand, estimates of the benefit of using clean renewable energy vary between 2 and 9 U.S. cents per kWh. Thus, there is a demand for a source of energy utilizing a renewable natural resource without the environmental damages.
The most common sources of energy employing renewable natural resources are hydroelectric plants, windmills and the burning of biomass. Hydroelectric plants plus the burning of biomass account for about 20% of the power produced in the world. It is unlikely, however, that the use of hydroelectric plants will significantly increase since the remaining sources are not readily exploitable and are not large in extent compared to those which have already been exploited. similarly, energy produced by windmills is rather insubstantial on a world scale and has limited application. Several other renewable energy sources, such as Ocean Thermal Energy Conversion (OTEC), will not provide the necessary capacity or a low enough cost. The above mentioned renewable energy sources are not only limited in their capacity, but they are localized in certain small regions of the globe. Therefore, the need for an energy source using a renewable natural resource has largely gone unanswered.
One such source of energy utilizing a renewable resource exists in the geothermal, meteorological cycles of the earth. On a simplified global scale, the main cycle involves the sun heating the land, warming the air above and causing the air to rise. As the less dense warm air rises, a low pressure area is created which is filled by cooler, denser air from over the oceans. Thus, a natural convection occurs by the air flowing from the ocean to the land, rising above the land after being heated, and then falling over the ocean after being cooled. One of the most important geothermal cycles is the Hadley Cell named after its discoverer in 1735. Hot and humid air rises around the equator, then it expands and cools down. As a result of this action, rain is shed. The air then flows north and south around the globe. The air then descends mostly between 15° and 35° latitude, and turns back to the equator, while it collects moisture from the oceans, to replace the rising air. The descending air compresses adiabatically and warms up without regaining moisture, thus becoming hot and dry.
It is this descending air that produces the two belts of deserts around the globe. Clearly, hydro-electric power, wind energy and waves are also the result of the global geothermal cycles, however, the focus of the following is on utilizing another component of this cycle. The hot and dry air when cooled by a water spray will descend at an enhanced speed. This phenomenon occurs occasionally in nature and has been observed and recorded for a long time. In recent decades, it has been extensively studied because of its danger to aviation. It is sometimes called wind shear.
Some inventors have attempted to harness the geothermal energy in the atmosphere based on this simple and well-known principle that air can be cooled by spraying water into the air. Cool, moist air has a greater density than warm, dry air, and thus tends to fall toward the ground. For centuries, man has witnessed this phenomenon as a cloud burst on a hot summer day produces high winds and cools the area near the shower.
U.S. Pat. No. 3,894,393 to Carlson (the Carlson patent) suggested harnessing this power by initiating a downdraft of air within a duct by spraying water at a high elevation into the duct and extracting energy from the downdraft with a turbine near the outlet. There are several shortcomings in the Carlson patent, however, that appear to render the teachings impractical.
For example, the Carlson patent explains the physics and calculates the amount of water needed to be sprayed into the air at the top or at various elevations within the duct. According to the Carlson patent, the amount of water required is exactly equal to the amount that is evaporated to cool the air by &Dgr;T (column
5
, lines
35
-
40
), where it appears &Dgr;T is the average potential temperature difference, or cooling, between the inside and outside air (as it becomes clear from the equation on line
65
). The average potential cooling, however, is less than the maximum cooling over the full height of the duct which occurs at the bottom of the duct. If only the suggested amount of water is used, optimal power output will never be reached. Also, spraying the suggested mass using sea water would appear to cause huge amounts of salt precipitation that will be difficult to handle.
The present invention, unlike Carlson, teaches that the maximum cooling depends on the amount of water spray and the droplet sizes, so that a maximum net power will be obtained. For a simplified explanation, the air outside the duct is assumed to follow the dry adiabatic process where the air is warmed due to compression about 1° C. for every 100 meter drop in elevation. On the other hand, the air inside the duct theoretically can be immediately cooled by saturation. And then, upon being lowered and continuously wetted to saturation, the inside air is warmed about 0.5° C. for every 100 meter drop in elevation following the wet adiabatic process. As uniquely shown by this invention, the air, as it falls inside the duct, can be further cooled by evaporation of more water keeping the air temperature as close as possible to the wet adiabat. Thus, an amount of water sufficient only for the average potential cooling as defined by the Carlson patent reduces the effective cooling or the effective height of the duct thereby providing only a fraction of the maximum potential cooling taught by the present invention.
Additionally, the Carlson patent does not appear to realize that the cooling within the duct takes place gradually rather than immediately, thereby further reducing the effective cooling or effective height of the duct. Thus, the average actual cooling mentioned by Carlson as the yardstick to determine the necessary amount of water spray is less than the average potential cooling and, therefore, the amount of water to be sprayed as suggested by Carlson is significantly less than the amount needed to achieve maximum potential cooling.
Further, the Carlson patent does not appear to recognize that a mass of water larger than theoretically will evaporate must be sprayed, as taught by the present invention disclosed herein. As the water droplets diminish by evaporation, the concentration of solutes increases, which decreases the vapor pressure at the surface of the droplet. The evaporation rate then decreases due to the decrease in the difference between the vapor pressure at the surface of a droplet and the vapor pressure of the air. Thus, unlike Carlson, the present invention teaches that a substantial amount of excess water must be sprayed into the duct to ensure the proper vapor pressure drive and rate of vapor and heat transfer to evaporate water within the duct a
Burt Michael
Guetta Rami
Hitron Rony
Krivchenko Grigory
Poreh Michael
Gilman & Berner LLP
Hauptman Lowe
Kershteyn Igor
Look Edward K.
Sharav Sluices Ltd.
LandOfFree
Renewable resource hydro/aero-power generation plant and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Renewable resource hydro/aero-power generation plant and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Renewable resource hydro/aero-power generation plant and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3120832