The Quest For Wonder Special Features – Episode 1
After hard day’s questing for Wonder with his puppet pal Professor Brian Cox, puppet Robin is left with a few questions. So after each episode he’s taking time to video chat with one of our Cosmic Genome scientists.
The Quest For Wonder Episode 1 Subscriber Exclusive
Steam Power with Dr Helen Czerski
Robin - Hello Helen Czerski. So, right, first question, how can we get so much power for such a huge wheel out of something that to many people seems quite rubbish, really? You know, steam, not popular.
Helen - Steam is amazing, it isn't little and rubbish, that’s just sort of doing it down. The thing that’s amazing about steam is that it’s full of tiny molecules hammering and hammering and hammering and hammering like a big crowd that’s fighting to get out. And so, if you heat a load of water up and it produces a load of steam, what you've made is a space that is full of really hard hammering molecules and they're pushing on things, so it isn't that it’s weak and feeble just because you can’t see it, it’s that even though you can’t see it it’s still pushing and you can use that push to do stuff. So steam is great because it’s a reminder that even stuff you can’t see can be really powerful.
Robin - Now, steam looks really clean, it’s water, right, isn’t it, loose water, so why don't we still use it for everything?
Helen - So that push of the molecules you can use in a few different ways and a steam engine does it in one particular way, a steam engine is basically a giant kettle and…you have a big fire and then you have tubes running through it or a space above it with water in it and then you heat the water up and then you get the steam and the steam does the pushing. So there’s quite a lot of different stages in the way.
And so that was overtaken by the internal combustion engine which is what’s inside a car, and the clever thing about that is that it does the burning and the heat release and the heating up all in one cylinder, and the pushing. So instead of having a fire that heats water, that makes steam and the steam gets taken somewhere else and that does the pushing, what you have is all in one little cylinder, fire, bang, hot, push, and it all happens in one place, so it’s much much more efficient.
And you can go one further than that. So the internal combustion engine, the car, that’s all around us every day, and the only way you can make that even better, you can take the same principle further, is a rocket, where you don't even have the compression, you don't even have a piston that’s being pushed on, you're just pushing on the air on everything that’s behind, and a rocket is kind of like a car piston except that it’s got one end taken away and the push is directly on the rocket, it’s a really direct transfer of energy. So instead of pushing on a piston which pushes on a wheel, you push directly on a rocket and launch it right into space. So these hammering tiny molecules can do amazing things.
Robin - So, is that why there’s only steam powered trains and not steam powered space shuttles?
Helen - The limit on steam is efficiency. You can do it with steam, it’s just…you need a lot of water and a lot of fuel, so that’s a lot of two different things and you lose a bit in efficiency along the way. So there are limits to steam, it’s a beautiful technology - I love steam engines, I could watch steam engines forever - but there’s just too many things and so in the future, if you can take one of those things out and do the same job, but with less fuel, that’s what you’re going to do.
Robin - Is there a new type of better steam engine that I could build then, because I’ve got some plans, you know, like using hotter water, or bubbles or something, or heavy water?
Helen - We do still use steam engines in our power stations; so when a power station burns things, burns coal or oil or gas, whatever, it’s going to burn, even a nuclear power station will heat something up and turn it into steam and push on something else, so we are still using steam, but we don't use it every day in our cars and our homes, it’s all done somewhere else on a huge scale, so steam is still being used.
There are alternatives and what’s interesting about them is that they bypass this problem completely because what we really want is electricity and with power stations, we’re just burning stuff to push on things to make electricity, so if we can just make electricity directly without all those stages in the way - science is all about getting rid of those extra stages - if you can get straight to the electricity, you don't need that other stuff. So for example wind turbines do that; as the blades spin around, they push magnets past a coil of wire they make electricity, and you didn't need to push on anything. And it’s the same for wave power and solar energy is the same, sunlight hits a solar panel and it makes energy, it makes electricity directly without all that pushing. And some people have proposed that you could use bubbles to generate nuclear fusion and nuclear fusion is what happens at the centre of the sun, it’s where tiny atoms come together and then release energy because they've fused into something new and we’re starting to learn to do it with lasers and there are some people who think we could do it with bubbles, but its’ a bit impractical with bubbles because you have to squeeze the bubble really, really hard and really, really fast and the problem is, the bubble doesn't want to be squeezed and it takes an enormous amount of energy. So I think the lasers have a better chance of making nuclear fusion happen.
So there are lots of different ways of generating electricity, but really, we just want electricity, we’re just trying to make the stages from a pile of stuff, whether that pile is coal or oil or sunshine or waves, turning that into electricity. We just want to have as few stages as possible along the way.
Robin - Now, Brian says steam power was really important to British science, but he says that about everything, he’s always banging on about it you know, oh it’s really brilliant, isn't Britain brilliant. Anyway, why is it really that important?
Helen - It was very good because it meant that… humans didn't have to put in the effort; basically it frees humans up to do other things. You know, humans can lift buckets of water out of a mine and humans can carry big loads of goods across the world, but the problem is there’s only so many humans and you've got to feed them and they want to live in places and it’s all really inconvenient and what steam power did was it let us go, well, as long as we’ve got a big pile of coal, we’ve suddenly got all this energy, we can use it to do stuff, and that’s what civilisations need more than anything else, you need energy that lets you do things, it’s like a type of money you can spend, and steam was fantastically important because it’s relatively simple - you can buy a steam engine, here you go, here’s your steam engine, and then you can just use it to push things and pull on things and… as long as you keep feeding it coal, it keeps doing the work for you and it lets you do much bigger projects than you could otherwise.
Robin - While I was trying to look at that big wheel (it’s a mill engine!), Brian just kept going on about physics again. Anyway, everything abut physics as far as he’s concerned - so Boltzmann’s Constant this, Boltzmann’s Constant that, does physics really have anything to do with steam power?
Helen - Physics is the toolbox for how the world works and so it’s the thing that lets you take the stuff around you and make it do something, because its got all these useful rules like, if you push on something that something will go somewhere and it lets you work out how fast it’ll go there, and the reason physics is important - and we all know Brian goes on about it a lot - but the reason physics really is important is that it’s just a big box full of tools that lets you do things with the world and if you want to build a building, or build a smartphone or build a steam engine, you need to know the rules for how it all works and you need to be able to do the calculations so that you know its gonna work, and that’s what physics is, its just a toolbox. And it’s brilliant, you go out into the world and you can poke on things and push on things and pick things up and you can play with all those tools and check that they work for yourself, cause the really cool thing about physics is that the rules are the same everywhere, there the same here at my desk as they are on the surface of Venus, or in the middle of Antarctica, so its the same rules. Physicists are basically very lazy, instead of learning lots of different facts, they just learn about all the tools and then they just take the tools with them wherever they go ,they basically don't have to remember anything, its basically just laziness.
Robin - Fine, if steam power works on different scales, then what can I power with my kettle, little one, blue?
Helen - Your kettle is, let’s see, what could you do with a kettle. So what kettles are quite good at, if you can imagine - actually you see it with a boiling pan, if you have a pan of boiling water and you put the lid on the pan, and you see it, the steam builds up inside the pan, the water evaporates, the steam builds up and then it sort of lifts the lid once in a while so that’s about the amount of power that you can get out of a thing of boiling water about that big.
So what could you do with that, I reckon that you could, I reckon that you could run some small electronic devices with that, I reckon that you could probably make an LED flash, a little LED light, I reckon you could probably run something that requires a small battery. The problem with it is that you have to keep putting more water in, in order to keep running your watch or your car keys or whatever is it, so it would take a lot of water. In fact that’s amazing, the amazing thing about steam engines is, imagine you’ve got a big pile, like half a tonne of coal and you put that into your steam engine, how much water do you have to put in, like how much water can that coal turn into steam and its about five times as much. So if you put in 500 kilograms of coal, half a tonne, you have to put in two and a half tonnes of water as well for that coal to turn into water to do something else with, so one of the limitations of steam power is that you just have to keep putting water into it, you have to keep feeding it water to make the steam, so I’ve never tried it, it would be quite fun, what could you run? That’s a good experiment I reckon but I haven't done it, I shall go home and start playing with that.
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