Stirling Engines - the power of the future?

this is a Stirling engine and which is more it's a Stirling engine now some of you might be thinking what's a Stirling engine well this is ah good you've stayed for more detail I like that because a lot of people think that if they have a label for something then they actually know what that thing is whereas in fact all they've really learned is a label for it now a Stirling engine is a type of engine that well there was a time shortly after its invention in 1816 by one Robert Stirling after him it's named the people thought well this is going to revolutionize the world and people thought that maybe the Industrial Revolution was going to be powered with these things instead it happened with steam engines but these things could possibly have powered the Industrial Revolution now imagine some of you are thinking what's powering it though III hear no I hear no engine running I hear a not the explosions of an internal combustion engine I don't see any steam or exhaust so what is powering this engine what is causing this flywheel to go round and round at such a staggeringly slow speed well what in short is behind the white piece of card right what we have here is a plastic tub filled with ice now some of you may think hang on it's ice powered that's brilliant all that so tremendously pull an engine that's powered by ice I mean just think you just sticker them in on an ice sheet in Antarctica and free energy well I mean it's not quite that simple and others of you who have done more physics at school might be thinking to yourselves hang on you can't power an engine using ice I mean it's the ice isn't actually in it it's just using the coldness of the ice to power the engine but how can you power something with coldness because coldness isn't a source of energy cold this is is a symptom of a lack of energy when I put my finger on something cold I'm losing heat to it heat is coming out of my finger into it it lacks energy cold is what we feel when we encounter something that doesn't have very much energy in it so how can you power an engine with a lack of energy well you've sort of can and then again you sort of come you see you could say that this is coal powered coal power because yet coal was shoveled onto the massive conveyor belt in the power station where it was created steam which turned the turbines which generated electricity which then came to my fridge freezer which then froze the ice and all that energy created a temperature gradient you see there are two steel plates here one at the bottom and one at the top and this engine runs off the difference in temperature between the two plates so if you cool down the bottom plate which is what we have actively done using the energy of that cold then you get an engine that runs but you can actually run one of these off heat and even better is a combination of heat and cold making one plate hot and the other one cold and it doesn't matter which one is the hot which are of the top or the bottom is the hot one and which theater cold it'll still work which is rather nice and rather useful so the Stirling engine ladies and gentlemen invented as I say in 1816 and by 1843 the iron foundries of Dundee were powered by these so this is a flywheel which is fairly heavy has with a mass as that goes round you can attach a fan belt to something that can then turn a crank shaft that can power machine that does good you go from from flywheel to good um and you could perhaps power locomotive only they didn't they used steam power in the end but in the early days a lot of people thought these would take over and they have a number of advantages over steam well one thing I'm I'm not being hit in the face by lots of steam another thing they're very very quiet which is rather nice and they don't involve a high pressure boiler that might explode and kill me now early steam engines did an awful lot of exploding and killing people and scolding others so it was a very appealing to have an engine which didn't do that but steam engines just created a bit more power particularly when they got big so if you wanted to power a really massive liner to go across the the Atlantic Ocean for instance Stirling engines maybe they weren't quite the way to go um they are for their power output a bit heavy now for efficiency they can be very good they can reach as much as 50 percent efficiency which is about the same as a diesel engine Wow you might think that's amazing only if you have a Stirling engine and that these of equal power the Stirling engine will weigh an awful lot more and so if you want to put one on anything that moves like a car or even more something that has to fly like an aircraft then maybe these aren't the engines for you although thanks to advances in modern materials in 1986 it was shown as possible to fly an aircraft powered by a Stirling engine where I was going really slowly now yes in all no in 1986 that's what probably happened is the temperature differences is evened out the cold of this ice now has percolated through and cooled the top plate but maybe if I warm the top plate just with my with my fingers that might be enough to get it going again god yes there you they go okay so it's now being powered by the heat of my hand and at the moment it's generating something like 1 watt of energy so yeah not very much not very impressive but this is just a toy demonstration version of a Stirling engine rather than that the full throttle thing anyway so yes 1986 a plane that weighed all of two and a quarter pounds that's about kilo flew for an amazing six minutes it didn't do any acrobatics it just managed to stay in the air and of course this is something far too small to carry a person so don't expect any fighter planes to be powered by Stirling engines in the near future but it is possible to power useful stuff with one of these particularly if you want something that's static and on constantly so if you want to for instance power the air in a church organ churches traditionally don't move around all that much and the airflow that you want through an organ is pretty constant so if you don't mind a very heavy engine if it's not going anywhere just sitting on the ground that's fine then the Stirling engine could be for you because they're very quiet which is good as well if you want to power a church organ and there are no emissions no there's no exhaust coming off it which again you might appreciate your congregation might appreciate that so how does it work well you can see in the bottom here there is a sealed chain with the steel plate at the bottom which at the moment is very cold and one at the top which is room temperature and between the two you can see this disc which is a thick insulation foam disc which is going up and down why is it going up and down well there are actually two cranks on the top of this and one of them this one here in the center is pulling that disc up and down and the other one is being driven by this piston so this is the power crank if you like this is what's actually driving the wheel round and this one is pulling this insulation disc up and down so what's this insulation just doing it's known as a displacer it displaces the air in the chamber well in this chamber there is air and when I'm going to stop this showing how incredibly au-pair it is I just stop it with my finger like that so when the disc is at the bottom like that it insulates the air in the chamber from the ice which means that the air can then heat up when this cranks round to the top this then insulates the air from the warmer plate and exposes it to the colder plate so it cools down so the air in this chamber is cooling down and then warming up and then cooling down and then warming up and cooling down and warming up now why is that significant well as air cools down it loses energy the molecules in it don't rush around so much and so they don't bang off the sides of the the sealed chamber nearly so often which means that they exert less pressure and if they're exerting less pressure then the atmospheric pressure in the room can push this piston down and this then turns the flywheel which has got a bit of momentum which then causes this to pull the disc up to the top no sorry to push it down to the bottom which means that it can then have the chill knocked off it now the moment I'm not actively heating the top but the room is reasonably warm and so that's enough to speed the the molecular movement the Brownian motion if you like of the the molecules in the air and they then exert a greater out of pressure and then the whole system is reset because the momentum carries the wheel round again and then it goes back down to the bottom the air does and it then group chills again and then the air pressure in the room pushes this down so at the moment the the air pressure in the room is pushing this down pushing this down pushing this down pushing this down so it's being driven by the air pressure in the room pushing this down over and over and over again notice I'm just pushing this down I'm not pulling it up and because it's not a flywheel on it oh I actually had it going wrong went wrong right there's another because it's got a flywheel on it the momentum brings it up again so I'm not pulling it up I'm just pushing it down if you had something hot down here that will be heating the bottom and the air with n big e be getting greater than atmospheric pressure and that would be pushing the piston up so it'd be driving the thing on the upstroke rather than the down stroke and it would go the other way around go the other way around because these two cracks are not actually at 180 degrees to each other there are more like about 90 degrees so there's only a 90 degree delay which means that it travels in one direction for cold and another direction for hot I think we should try this with something hot don't you um right so I'm back and now I'm going to fill this rather beautifully colored mag is some hot water right to the very brim like that and then I stick on my Stirling engine and we'll see how long that takes to get going now sometimes they can take a bit of encouragement to get going oh oh there we go and we're away and you can see that it's going a fair bit faster than it did with just the ice so the temperature gradient between this very hot water and the steel plate now at the top so now the top is the cold plate and the bottom is the is the hot plate the temperature gradient is clearly quite a bit more because it's going around quite a bit faster so the bigger the temperature gradient the more efficiently this thing works which means that they're not terribly good in very hot places so if you live near the equator and the the Sun slams down like a hammer out of the sky baking the land and heating all the air around it then these are not tremendously efficient because you can heat the bottom but the temperature difference between the bottom the top won't be so great because of all that Sun on the top whereas if you go into very far northern climes these work much more efficiently so if you are for instance a company like Google or Facebook and you're thinking of building an enormous array of servers in a building in northern Finland or something like that then you might want to stick it in a load of Stirling engine because all those servers are going to create a load of waste heat that you want to get rid of and that could heat one side of a Stirling engine which you could mount on the side or the roof of the building and then the the upper plate could be exposed to the icy air of the outside and you get a tremendous temperature difference from your waste heat that's just waste it's going to do nothing otherwise and you could then run loads of Stirling engines off that another use for the Stirling engine has been found by the Swedish Navy since 1996 they've been putting Stirling engines on their submarines yeah click submarine is is a sealed unit and you've got a problem with a buildup of heat on the inside and when you're underwater in your submarine you want to be stealthy because submarines all about stealth right so you don't want a little bubbles coming out so a type of engine that doesn't have any emissions is rather good and you also don't want to create a lot of noise because that's bad so a quiet Stirling engine that isn't going wrong because of explosions in an internal combustion engine or because of all that steam and so forth from a steam engine a Stirling engine can be rather efficient you've got the heat from the inside of a submarine and of course as the submarine moves through the cold waters of the Baltic you've got cooling on the outside of the submarine all the time as the cold water goes past which means that you can create again a wonderful temperature difference and you get loads of sort of free energy it doesn't it's not free in the sense of breaking laws of thermodynamics but it's using its using a temperature exists difference that exists anyway in practical senses so hey why not make use of it Stirling engines have been put to reasonably useful use it's early days yet but there's been a revival in interest in these things in the clean energy market so for instance there are there are setups in Spain where they've got a dish and the dish has reflective material on it it focuses on to the hot plate of a Stirling engine it's just a few feet away from it so you can set one of these up in your back garden doesn't have to be enormous and and focusing buildings onto a massive Tower that's a long way away it can be quite small and domestic and you can focus the Sun onto the hot plate of a Stirling engine and get a moderate amount of power out of it but it's they're simple and they're quiet and you just some degree to some degree let's not go overboard here but to some degree these could be the future now can we get this to go any faster well of course we're heating up the the bottom plate but what if we cool the top plate as well so let's add some ice some ice on the top maybe there'll be a detectable increase in the speed I don't know is that the new faster it is quieter which is interesting it's gone quiet oh and now it's going definitely faster and a little bit noisier yes so there you go heat on one side and ice on the other so imagine in some futuristic fantasy they set up using technology at the moment which makes our current technology look puny they set up enormous power stations although it's really picking speed now enormous power stations in Antarctica say now we have reason to believe there's quite a lot of volcanic activity in Antarctica but we don't know exactly where it is yet and we can't get to it but imagine that we can and and we dig down and very enormous chambers like this in the ground of Antarctica and these are heated by volcanic heat and the Pistons surge up and and push up into the icy air above cooling everything down and you get the flywheel going round you get power stations from from Antarctica and and that'll be okay again it's still not exactly free energy but it'll be potentially cheap and efficient at the moment all forms of alternative energy have problems but we're going through a stage of being a bit rubbish at it in order to get better at it and the Stirling engine might be a way that we improve our energy efficiency so for instance that server array in Finland I mentioned earlier and they won't be able to run the whole server off the power generated by the Stirling engines that's absurd because that would require them to be more than 100 percent efficient but even if you could say generate 30 percent of the energy you needed to run the array from the Stirling engines in the same building well I'll be pretty good I mean yeah I imagine that the electricity bill for Google and Facebook is quite large if you want something to start instantly then Stirling engines probably not for you a petrol engine be much better form and it started a couple of sparks into it in this part plug in the chamber and bang the petrol explodes and you're away but this is quite a lot faster to get a working than say a steam engine with steam engine you have to spend quite some while building up the steam pressure from nothing and if it's a very big steam engine that can take a while whereas these why don't they start mod ok not very quickly but but faster than the steam engine which is so in the future some of these might be used for what's known as combined heat and power so either you have waste heat which then generates electricity via Stirling engine or you deliberately create heat which can also heat something else like your home to a comfortable temperature and generate your electricity which is all rather nice and because they are simple and easy to maintain they can be used at a domestic level you don't have to make massive power stations out of them and maybe that's another thing which is good about them because a lot of other engines are very efficient when they're big whereas these tend to be more efficient when they're small up to about the 100 watt hundred kilowatt size so if it's true that the future is one in which we can have lots and lots of small power stations and people charging up batteries and then selling each other electricity on some complicated grid then these could play their part um so thank you Robert Stirling for inventing the Stirling engine and it's another first for Britain Lindy man by travelpod member

Channel: Lindybeige

Views: 1,832,444

Keywords: stirling, engine, engines, power, electricty, generation, generator, generating, how it works, mechanics, hot air, energy, ecological, environmentally friendly, cheap, emissions, exhaust, station

Id: vGlDsFAOWXc

Length: 19min 6sec (1146 seconds)

Published: Mon Nov 28 2016

Reddit Comments

[u/gonnaherpatitis]

Up voted for LindyBiege

[u/asoap]

I absolutely love sterling engines. They are a lot of fun to play with.

[u/thebestisyetocome]

I did a project on these in the 8th grade!! I wanted SO badly to order one online and build it for the project but my mom said it was too expensive :(

[u/Ari_Rahikkala]

Great video, but not the greatest pedagogy I've ever seen. I didn't notice anything he said in the video that was wrong (except maybe the 30% figure for powering servers on their own waste heat, which seems extremely optimistic even as an offhand guess). It's just that most of the video applies to just about any heat engine, of which there are many more types than just Stirling engines. For one, steam turbines pretty much power almost all of the electric grid, and they're heat engines too!

[u/Hands0L0]

The sterling engines i've worked with required quite a bit of heat to get the piston to move at room temperature.

High heat and moving parts lead to more failures.

Also, the minute you put a load on that engine it's gonna stop spinning.

If you were going to make a large scale version of it for low energy inputs...Lets see, the top plate would have to collect solar heat via phase changing materials - molten salts, and the bottom would have to have a cooling mechanism - running water? A river?

I'm sure there are other methods. Time to brainstorm

[u/aforsberg]

I really like things like this. I'm learning stuff I had never thought about, and this guy is making it entertaining. I could have read a Wikipedia article, but instead this dude taught me stuff, and I laughed too. I'm going to look into more from this guy.