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The_Safe_For_Work t1_jdsuapx wrote

Steam doesn't just appear. It has to be made by burning something.

Nuclear power plants are still just a complicated way to make steam.

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schmidisl t1_jdsut8b wrote

Steam has to be made. When talking about fuels or propulsion, we use words like efficiency. This basically means: how much energy (for example heat or moving distance) can I get out of a fixed amount of a certain power source.

And steam is very inefficient. It takes a lot of energy (coal fire for example) to get the water boiling. For the same amount of money you pay for the coal, you could buy 4 times the amount of diesel fuel for a train (random numbers for clarification).

Edit: in modern days, steam engines kind of still exist. Nuclear and coal power plants are just another way of producing steam to turn generators to produce electricity. But making the steam requires a lot of non green fuel. And it's only capable of being used in huge power plants. Powering a car with steam would be a financial doomsday

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EspritFort t1_jdsv4q2 wrote

>Eli5: If we had steam powered trains back in the day, why didn’t steam become a common “clean” energy source? Why did it die out?

Steam is created by heating up water a lot. Steam engines burned coal for that.

You can heat up the water by other means too! Nearly every conventional contemporary power plant uses steam turbines to generate its output. Coal power plants burn coal to provide steam for their turbines, gas power burn gas to provide steam for their turbines, nuclear power plants use the heat generated from nuclear fission to provide steam for their turbines.
It's steam turbines all the way down. Either way, none of it is particularly clean. There's always something that gets set on fire or used up in the process.

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berael t1_jdsv7o9 wrote

You get steam by boiling water. How do you boil the water? That's the power source, not the steam.

The typical answer has been "burn coal to boil the water".

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feralraindrop t1_jdsvsq3 wrote

Old steam engines were powered by burning wood or coal to make the steam. Not a clean energy source at the time.

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Delphiantares t1_jdsy0n2 wrote

It didnt dieand it did become common. We are still using steam power. Nuclear power heats the water that turns into steam to spin a turbine under pressure. Coal /fossil fuel /natural gas same process to boil water into steam for a turbine. Steam is inefficient and dangerous due to the excess energy needed to keep it's temp.

We just realized there was a easier way to use steam in the form of electricity eventually. We still haven't really figured out how to turn one source of energy into one that our energy grid supports except in hydro, wind and solar without steam.

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tagged2high t1_jdszc0n wrote

Like others have said, steam for power generation is very much alive (and will continue to be so).

Besides not being "clean", it's cumbersome to generate steam power for use in many situations, especially in comparison with combustion engines, electricity delivery or storage, and other ways of producing energy.

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DarkAlman t1_jdszfkz wrote

Steam has to be generated by burning something to make heat. Early Steam trains burned wood or coal for that purpose.

Diesel electric trains (that we use today) are by comparison more powerful, pollute less, and have the advantage that you don't need to stop for water for the boilers.

Some form of electric train, or hydrogen powered trains have the potential of replacing diesel.

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X7123M3-256 t1_jdszyw0 wrote

Old fashioned reciprocating steam engines died out because they're very inefficient, heavy, and they burned coal so not at all clean either.

But we still use steam power. It's just that these days, we use steam turbines, which are much more efficient at extracting energy from fuel. It's still not clean energy unless the heat source is nuclear (or sometimes solar), but modern power plants burn a lot less fuel to produce a given amount of power than the old steam engines did.

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UnadvertisedAndroid t1_jdt3y60 wrote

Replying to The_Safe_For_Work (#2,378,906)

Old steam trains burned a lot of coal to make steam, which is dirty, smells bad, weighs too much to make it an efficient energy source for a moving object, and requires a ton of labor to keep the boiler fueled because of the limited space in a train making automated hoppers, like they have in coal power plants, just not feasible.

Oh, and diesel was a much more efficient fuel source and internal combustion a more efficient way of utilizing it. So, because of all that, steam trains died off.

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Mammoth-Mud-9609 t1_jdt4vfo wrote

Steam isn't a clean power in trains it uses coal and the coal smoke created was a major issue from the first day it was used and steadily became a bigger and bigger issue.

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Gyvon t1_jdtd0ri wrote

Steam power is still around. Coal power plants make power by burning coal to boil water into steam, which spins a turbine that generates electricity.

It's the same with natural gas and oil power plants. Even nuclear power plants use steam to generate power, only instead of burning fuel they use nuclear decay to heat the water.

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Mantzy81 t1_jdtmyjw wrote

Steam is made by boiling water. There are many ways to boil water. Steam trains were usually fuelled by coal, just like a coal-fired power station.

I think you need to know how a power station works first, and that's by a magnet spinning whilst surrounded by a copper coil. So what we really want is to spin the magnet. This is often done by steam. You can boil water with gas, coal, nuclear or geothermal (which is actually "clean"). Other options include using water to spin the magnet in hydroelectric plants.

So, sure, steam itself is clean. The process of making steam isn't always so.

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PerturbedHamster t1_jdtypzf wrote

Replying to UnadvertisedAndroid (#2,380,227)

I don't think it's the weight. Gas only has about 30% more energy per pound than coal. The big difference is that coal takes a long time to burn - you can't floor a coal-powered engine like you can a gasoline one.

Incidentally this is also one of many reasons while coal-fired electrical plants are going away. Power plants increase/decrease their output all the time to match demand. It's really easy to do this with natural gas, but really hard with coal.

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it_might_be_a_tuba t1_jdubmo1 wrote

New York still uses steam for heating and cooling buildings. They send steam through underground pipes to buildings, as an alternative to using electricity or gas directly.

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melatonin1212 OP t1_jduewlz wrote

Replying to PerturbedHamster (#2,384,623)

Does anyone know how the replica steam powered trains on the Disneyland Railroad work? Electricity heating up the water maybe? They claim they are actually powered by steam but obviously it’s a modified version. Nobody’s shoveling coal on that baby. And it’s a scaled down version of the real thing but seems fairly legit. They do a little announcement about how it’s actually steam powered when you get on

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csl512 t1_jdui3ma wrote

Steam isn't inherently clean. Your heat source largely determines how clean or not a method is. Heat engines are inherently inefficient, limited by Carnot's theorem which says the maximum efficiency depends on the temperature difference and the 'hot' side. 'Steam' locomotives were really coal locomotives. They also exhausted the steam, so they consumed both water and fuel.

Diesel engines use a liquid for fuel, so you don't need to shovel a solid coal into a firebox. The modern diesel-electric locomotive uses a diesel engine to turn a generator to make electricity to power motors. This takes advantage of the increased efficiency of a diesel internal combustion engine, and the fact that electric motors can be made more efficient and produce turning force (torque) at zero speed. (Internal combustion engines need to be rotating to produce the torque.) Electric locomotives receive electrical power, so they don't even need to carry their own fuel. If you don't need to accelerate the fuel around, that's even more efficient. Electricity can also be generated in ways that don't involve burning fuel, or with more efficient fuels. Plus for underground stuff you then don't have to worry about exhausting the combustion products or steam.

Really tangential to your original question, but combined cycle uses a gas turbine in tandem with a steam turbine for extra efficiency, so that's one way that electric trains are more efficient.

https://en.wikipedia.org/wiki/Disneyland_Railroad says they use diesel oil in the firebox to make the steam.

You might want to search for things like 'timeline of train technology'. One of the top results was https://www.railway-technology.com/features/featuretracks-in-time-200-years-of-locomotive-technology-4517022/ which looks pretty good.

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M8asonmiller t1_jdut3kw wrote

Steam wasn't the energy source, it was the working fluid. The energy source was coal, or later oil. Railroad companies recognized the utility of overhead electrification pretty much as soon as the technology was available, since you didn't need to carry around an entire steam engine and coal car, though nobody wanted to be the first to electrify their system. Diesel seemed like it would be a temporary stopgap in the transition to overhead electrification, but since it didn't need expensive railside infrastructure it basically became the default by the late 50s.

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