Selective harnessing of tides & earth's rotation

[newtonian]

Can we stabilize earth's rotation speed over billions of years by selectively harnessing tidal power in the direction required to speed earth's rotation, counteracting the slowing produce by tidal interaction with the moon [which also causes the moon to recede from earth slightly in its orbit.]?<br /><br />As saiph noted on another thread, this would involve transfering directional momentum from rotation to turbines which would average no specific direction.<br /> <br />Some of you may remember my old thread on this which was lost in the SDC crash.<br /><br />Please post specifically how the laws of motion apply to this scenario.

 

[nexium]

Energy obtained from tides may cost ten times energy from fosil fuel even charging fosil fuel with a reasonable percentage of the damage done by green house warming plus the next ice age. Maximising for speeding Earth's rotation will reduce the power production. My guess is millions of square miles would need to be empounded to cancel 1% of the effect of Earth's moon slowing Earth's rotation.<br /> Has anyone presented a detailed plan for getting energy from tides? Energy produced a few hours per day has little value, unless it can be timed to the peak demand period about sunset, Monday though Friday. Neil

 

[mcbethcg]

Other sources of renewable energy have the same problem. Solar only really works about 8 hours a day unless it's cloudy, wind power only works when its windy. <br /><br />The solution is to use as many different sources as possible, and if supply exceeds demand, store the energy.<br /><br />Large scale energy storage could probably take the form of an elevated water reservoir that is filled by by pumps and drained through a hydro electric plant.

 

[newtonian]

nexium - Tidal power has been tried. Here are a few excerpts from Awake, 10/8/91 concerning a pilot plant in the Bay of Fundy, Nova Scotia, Canada, that began operating in 1984:<br /><br />A full-fledged project was thus proposed that would generate 4,800 megawatts-6.5 million horsepower-of electrical energy. (By comparison, an entire nuclear plant in neighboring New Brunswick generated only 600 megawatts.) The cost of such a tidal power project, though, would be astronomical-estimated in 1981 at about $5,000,000,000 (Canadian)!....<br /><br />[concerning the operating pilot project]<br /><br />Called the Annapolis Tidal Power Project, it is located in a dam across the Annapolis River, which flows into Annapolis Basin, a tidal river basin that flows into the Bay of Fundy, near the town of Annapolis Royal, Nova Scotia. Completed at a cost of $55 million, the plant began generating electricity in 1984....<br /><br />the station generates some 30 million kilowatt-hours of power a year-enough to supply 8,000 homes. ...<br /><br />To meet these conditions, an experimental turbine was developed, 25 feet [7.6 m] in diameter. The magnetic poles of the generator, which produces electricity as the turbine revolves, are fixed to the rim of the turbine and turn with it. (Conventional turbines usually turn a shaft that drives the generator.) The result is a more compact turbine that operates efficiently when water velocity is relatively low.<br /><br />Would not the salt content of the water pose problems for this equipment? The corrosive effect of salt water has been a major problem, but engineers have dealt with it by putting a very small electric current in the water passage to offset corrosion....<br /><br />However, partially damming the Bay of Fundy for electrical power could cause serious problems. For one thing, the huge cost of construction is a worry. In addition, there is concern about environmental damage. The possible alteration of the tides of Fundy by several inches could resu

 

[bobvanx]

<blockquote><font class="small">In reply to:</font><hr /><p>Large scale energy storage could probably take the form of an elevated water reservoir that is filled by by pumps and drained through a hydro electric plant<p><hr /></p></p></blockquote>The losses in such a system are staggering. Until we find a really efficient method to pushing water uphill, that is.<br /><br />Do you now about the work being done with super-high-energy density flywheels? Spinning in hard vacuum on magnetic bearings, these things store immense amounts of energy. They are small, and the losses are also very small. They could be distributed throughout the grid, so that we can take advantage of off-peak hours in the transmission system.<br /><br />They'd be the ultimate load balancers.

 

[mcbethcg]

Its been done for many years. Its probably the only large-scale method of storing energy, with about a 73% efficiency.<br /><br />Heres one- its efficient enough to use to balance loads for fossil fuel plants.<br /><br />http://www.consumersenergy.com/welcome.htm?./ocompany/index.asp?ASID=17<br /><br />Flywheels are more efficient. Reservoirs are less expensive.

 

[paleo]

Newtonian, I lived a couple years on the Bay of Fundy in Nova Scotia. If you look at a map of Nova Scotia and look across the Bay from Annapolis you will see a town called 'Economy' and a point of land called 'Economy Point'. (in the Minas Basin). A couple decades back they were seriously thinking of puting a tidal power plant across the Bay of Fundy at his crossing. Not only was it not financially sound but the ecological damage would have been staggering.<br /><br /> i was doing some geology studies at a town called Parrsboro and the tidal project would have completely destroyed coastlines, salmon spawning grounds...altered water temperatures...salinity levels...and a dozen other negatives.

 

[mcbethcg]

Someday, the benefit of having the energy (at any price) will probably outweigh the down-sides.

 

[nexium]

$55 million divided by 8000 homes comes to about $7000 per home, which is more than most other ways to make electricity without fosil fuel, perhaps 8 random hours per day. I wonder if the $55 million included compensation for reduced fishing catches etc?<br /> I wonder what operating and repair costs have been over the 20 plus years since 1984? Five persons are needed to provide a trouble shooter 24/7 which is about $3 million in payroll for 20 years. If they need to decommision the facility in 2005, It may cost another $55 million to restore the ecology to the satisfaction of the enviromentalists. Worse, the pilot program was likely at one of the world's most favorable sites, so a thousand times 30 million kilowatt-hours per year = 30 gigawatt hours per year will likely be just as costly per kilowatt and per kilowatt-hour, inspite economies of scale, as mostly less favorable locations will be used.<br /> Another problem (partially offset by larger scale) is the turbine likely is not turning 16 hours per day. Frequent random output of zero is a big problem if a facility of any kind supplies more than 1% of the average power needs within about 100 kilometers of the facility. It should however be cost effective to design for full output during the daily peak demand period with rare exceptions.<br /> Is there any chance the 73% efficiency flywheels can be mass produced at lots lower cost? Isn't mantaining the hard vacuum moderately costly? Neil

 

[nexium]

Two humans could monitor 100 flywheels scattered over a large area, plus make other load control decisions. The 2nd human is needed in case the attention wanders, and computers would make default decisions unless told otherwise. The flywheels would generally increase RPM when there was surplus power no one wanted to buy for more than $20 per megawatt hour. The fly wheels would supply power to the grid when distribution lines were suppling more than optimum power to the part of the local grid supplied by the fly wheel and during peak demand period unless this would overheat a transformer or other distribution component. A fly wheel could supply some of the homes in event of a distribution line failure. The frequency, and duration of blackouts and brown outs would be reduced, even with reduced spending on distibution lines. Neil