The Power of Water

you let's start talking about getting energy from the tides one nice thing about tides is it's extremely dependable there are two high tides every day how many people have never thought about this why are there two G is it the Sun and Moon in different ways no it's actually really pretty clever you see the moon causes the tides so here's the earth and over here somewhere is the moon this is not drawn scale the distance between the center of the earth and the moon is 222 thousand miles approximately gravity affects things as 1 over the distance squared the earth is eight thousand miles across so that means this side of the earth is not 222 thousand miles from the moon but this side of the earth is only two hundred and eighteen thousand miles and this side of the earth over here is two hundred and twenty six thousand miles and you might think that oh these numbers are all so close but when you square them there is a noticeable difference there is a stronger pull on the side of the planet closest to the moon and there is a weaker pull on the side of the planet furthest away our planet is covered with water the layer water around the planet obviously not drawn to scale water can move and so this stronger pull causes the water to bulge out still not drawn to scale you might say well why is there two tides right say this is the top of the planet and I've got this person you know sitting up here on the side and plant it right there we go some arms we've got some legs and the planet rotates around in 24 hours and every time they go past this bulge where the moon is they have high tide then you see there's a bulge of water over here too and it's not because something is pulling this water away from the planet it's rather the planet itself is pulling away from the water this is the strongest force the force on the earth is next strongest and the pull on the furthest side is the weakest so this water bulges the earth pulls not quite as far as that water leaving this water in behind as the Earth turns you go from low tide the high tide the low tide the high tide every six hours of course the moon also goes around the earth and that takes a month 28 days by the time one days go on the moon has gone one 28th of its journey about an hour so the tide advances by an hour every day a high tide approximately twenty four twenty eighths not an hour that's why there's two high tides and two low tides every day since you can count on the tides can you get energy from them it really depends on how big of a tide the average tide around the planet is about one meter three feet that's pretty difficult to be able to get a lot of energy from but there are many places around the planet where the tide just because of the way the geography works currents work and so forth it's much larger and in some of those locations you could indeed capture the tidal energy the simplest way is to do it basically like a small scale hydro electric system if this is the say the bottom of the system and here's your shore and at high tide the water level is here and at low tide the water level is here all right low and high tide that you basically put in a wall with some convenient holes so the water can go through comes up the high tide it fills everything in and then when it drops down the low tide you close the holes the water level is no longer up here and you've got all this nice water trapped then if you have some type of turbine system you can run this water through the turbine and it will spin and you can make electricity of course once the water level are even because the tides rising and you're trapped water level is done then you're done making power for that cycle couple times a day for a few hours after the high tide you can generate electricity is this being done the largest place in the world that does this is run say France and that title system was built way back in 1968 and it makes 240 megawatts of electricity basically there's a bay and they've dammed it up you might say wow that's really great how come we haven't done that a lot more times across the planet since 1968 well you need the right spot you need a spot that has been for large tides and then you have to have a spot where they don't particularly mind if the entire Bay is blocked off yes there's a lock so you can get through with boats but it's a hassle compared to just going in and out there's also disadvantages of having the runoff tides are a wonderful way that Nature has to cleanse low tide high tide washes away the debt rias from the shore brings it out mixes it into the deeper ocean in a Bay Rivers runoff from the towns and streets and cities will collect and without having that flushing that constant flushing since we've now constrained the opening of this Bay a lot of stuff ends up being trapped inside the reservoir so from an environmental perspective loss of habitat change of things change of the water salinity and so forth tidal power on a large scale has to be careful and it's not applicable everywhere some places it works and you get free electricity a couple times a day there's another way to get some energy from thymes and that's basically to use the fact that the water is going to flow and make a current so just like you have Windows if I have here's my ocean bottom here's the ocean top and the water is all moving this way right I have some type of ocean current if I could construct some large device right with some type of rotor in it so as the water goes through here this nicely spins I can generate electricity I just have to fasten this onto the sea floor right I fastened this onto the sea floor the ocean current comes through and you could even make it reversible so maybe this is when the tides coming in when the tides going out you could have it turned the other direction and still generate electricity variety of these types of schemes are possible in places where you have a reliable ocean current just like a wind current basically these are windmills underwater that's how you can get energy from tides while we're on the topic of getting energy from the ocean we should discuss wave power many places the waves are extremely regular and there's always a rough sea why not harvest it I'm gonna take that constant energy which ultimately came from probably the wind somewhere blowing across the water and turn it into a system that will spin a turbine give us electricity there's one really interesting combination they sometimes call them sea snakes or ships with a broken back and the concept is that you have a ship or some type of floating object that can bend so if my waves look like that this type of ship like thing has segments all right didn't quite make it on the way but I think you get the concept here we've got segments of this ship and this this platform you like ship right has these these pieces that can bend they might so how does that make energy well you can see as the wave passes this piece will go up and down with respect to this piece right the first bead bent like this that is the wave goes and they're in a trough they're like this and this could actually take some type of piston like object it's in here and these Pistons would move back and forth as this bends and comes back ends and coming back the piston moves back and forth it can force air or it can actually move gears which would turn a type of rotor it could spin and make electricity this type of hinge contrivance suffers from a particular disability and I like to illustrate it with this example if you take a door with hinges and you stick something in the door jamb so the door can't be shot and then try to shut it anyway you're putting a lot of force on the hinges so a device like this that's designed to have resistance on that hinge because you're working against something literally doing the physics term of work you're moving a plunger you're spinning a turbine you're getting electricity energy out of this well it is going to put a severe stress on those types of joints in addition these are nice gentle waves but what happens when the waves are like this storm you might find your whole contrivance washed up on the beach or crashed onto the rocks oh don't worry we know storm is coming we're gonna bring it all in well add up that labor cost and tell me how that compares to the electricity you've been making during the rest of this and by the way you've made the electricity way out in the water or you still have to have some cables and somehow get this back to shore there is another type of wave power which does not have some of these distant damages and that's shore-based wave power and in short based wave power think about a rocky cliff and on this rocky cliff we're going to make a concrete structure and basically it will have a reversible turbine right so this would be our our turbine blades all right so maybe you have a variety of these turbine blades and these are air power all right so this is gonna be a air turbine and this concrete structure is sitting here right so the water well the water level let's say is gonna be around here and they're not calm day nothing happens but if I have waves right moving in when this wave gets here its whole going to swell this whole area and this whole area will now have the wave in it and all that air will be expelled through the turbine making it spin then as the trough of the wave comes and all this water leaves the air will rush back the other way and with the right type of gearing in your reversible rotor you can have this thing spinning with that comes in an advantage of this system is that it's on the coast so you don't have to take it away when there's a storm and you're making electricity where you can easily get wires to it and what we're doing is we're not actually using the force of the wave to bend or break anything we've made a seawall and we can do that pretty well and we're just letting the wave push air in and out of the device this type of wave generator does exist yeah it'd be in the right niche you've got to have a cliff a lot of waves and the desire to make Oh a few kilowatts or maybe tens of kilowatts of energy but it can be done that's how you can get energy from waves you you [Music]

Channel: Illinois EnergyProf

Views: 32,456

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Id: eHKCn51Srfw

Length: 15min 45sec (945 seconds)

Published: Tue May 14 2019