The Ebb Tides

High Pressure Reservoir

     This page is dedicated to defining some of the less obvious details of a complete system.  The reservoir shown in this image is a high pressure reserve.  The image above looks like a maze of pipes for a reason.  Large high pressure vessles are very hard to design and build.  Whereas, pipe can be used in smaller diameters using thicknesses of metal that are easier to work with to achieve the same desired pressures.  Length, is then used to achieve any desired volume of fluid and or gas required to make the ebb tide pumping gap.

     A good example of how a smaller diameters of pipe can contain a higher pressures using the same thickness of metal is by comparing two isolated geometric models.  A metal box that initially contains one cubic foot of space is pressurized.  At 500 psi, it ruptures.  A pipe that has a circumfrence of 1 inch is pressurized to find the of psi at which the pipe will rupture.  Now, if the pipe is the same thickness as the metal box, the pipe will rupture at approximately 72,000 pounds per square inch.  The pressure is 144 times greater than the boxes internal pressure.  Which, is equal to the the number of square inches of the initial box.  At any one point the box is the same thickness but, the square area of the box has a total 72,000 pounds of force distributed over that area.  The fact that the surface area of the pipe's circumfrence is only one inch still has to experiance the same total 72,000 pounds of force for that thickness of metal to fail from fatigue.

     Here's how the reservior works.  At the end of every incoming or outgoing tide, there is an ebb tide.  During the ebb tide the water slows down, stops, then reverses directions.  When the tide reverses directions the pumps are no longer able to provide pressure, or produce any usable amount of water flow for power generation.  A nobel gas such as helium is used to fill all but 1/10th of the maze of pipe because, the gases can expand or be compressed whereas, water cannot and the result is that a volume of water stored under pressure will exit under the pressure of the stored gas.  Under pressure other gases such as oxygen, nitrogen, or as a better example carbon dioxide are absorbed by the water and the result gas escapes the system with the water as foam.  The first series of calculations are done to find volume of water to fill the pipe, and then to find the appropriate ratio of gas to water.  Now, the quantity of water required by the system over a period of time is defined by the duration of the ebb tide and the volume of water at an operational pressure used by the hydrogen generator.  The reservior should maintain a volume of gas that is 10 times greater than the volume of water required for the duration of the ebb tide.  During ebb tide the pressure of the water flowing through the lines should only drop 1/10th of the maximum line pressure at the very end of each ebb tide.  This results in a rather large high pressure container.  In this situation the total number cubic feet of water to be pumped and total number of pumps required during peak transition times to generate electricity and fill the reservior simultaneously can be found if the maximum desired output is known.  Rephrased, the total volume of water being pumped during the middle of the incoming tide, or the middle of the outgoing tide, is used to compensate for the total number of GPM reqired to generate hydrogen continuously throughout the ebb tide.  This changes the total volume of water that the pumps are required to produce and can change the number of pumps are required to produce the required volume of water at the necessary pressures to fill the reservior and generate hydrogen or electricity before, during, and throughout the tidal cycles.  Once, the total number of gallons of water required for power generation over the duration of ebb tide is known, then we can multiply the volume of water required for hydrogen production by 10 to find the total required volume of space in the reservior.  If the volume of the reservior is 10 times greater than the quantity of water required for hydrogen production during ebb tide, and the other 9/10ths of the tank filled with a nobel gas Helium then the maximum amount of change in pressure resulting from ebb tide will be only 1/10th of the maximum pressure in the reservior resulting from peak transistion times.  Since, all the calculations were derived from the day the smallest change caused by the tide in feet found on the tidal calendar, the single worst case senario was used as a starting point to establish our calculations for the tides forecasted over the course of several years.  Pressure release valves are then used to bypass exesses resulting from the majority of days that have a greater change in the high and low tides typically producing a greater change in the water level from day to day allowing the power plant to designed to produce a constant output throughout the course of years.

     Click on the following links for access to Tidal Calendars and Predictions which should be helpful in calculating minimum and maximum changes in the tide as the power plants worst case scenario.

Hood Canal Floating Bridge

Composite Plot from NOAA

Tide Predictions from NOAA

JTides Tide Prediction Software

The Flavored Coffee Guy