It seems too obvious to be a solution, but why did we give up on steam power? I believe nuclear power plants essentially work by generating steam, could this model be used in a car? Does steam not provide enough force to move the water and its container?
In: Engineering
It’s possible to run a car on steam. Some of the earliest cars were in fact steam powered. But steam has some disadvantages:
– If it’s an open system (the steam just gets exhausted to the air), that means that in addition to fuel, you have to haul around water, which is of course very heavy. And you have to make sure you don’t run out of water OR fuel.
– If it’s a closed system (the steam gets recycled), that means that you need to have a heat exchanger to condense the steam so that it can be recycled. This removes the “water as fuel” problem, but that heat exchanger is expensive and heavy, and so is the pump to get the water back to the engine, and the necessary tubing, and so on.
– Regardless of whether your system is closed or open, you need to heat the steam as a working fluid. That means that in addition to having a combustion chamber where the energy is being released from the fuel, you have to pass water through the chamber. This heat exchanger is, again, heavy and expensive.
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The reason internal combustion engines became the universal small engines is that instead of using water as the working fluid, they use air. That means they don’t have to carry around heavy water. Instead, they can just suck in air from the surroundings and use that – which you would need to do for a steam engine anyway!
Basically, the advantages of steam engines are that they can be more efficient than internal combustion engines, and they can effectively be scaled up to massive plants. This means they’re useful for large applications where weight doesn’t matter much, like power plants, ships, and to a lesser extent trains. (They’ve been obsolete in trains for a long time, but they survived in trains for decades after they disappeared as car engines.) For anything where weight is important, the significant weight penalty associated with having to circulate water is a huge problem.
Steam by itself is not power. There is no way to practically bottle up steam and use it like a battery. Instead, steam is usually used as an intermediary. Many power sources produce heat (nuclear, coal, etc). Heat by itself is not really easy to turn directly into electricity. So usually power plants heat water, which turns into steam and turns turbines, that mechanical movement then generates electricity.
To answer a little more directly, in order to use steam, you need to generate energy, use that energy to generate steam, then use steam to generate thrust. It is always going to be more efficient just to use fuel to generate thrust if possible.
They were quite popular in the early days of motoring. They were better for a time as well. Steam was a mature technology.
The problem is, they were a little less practical, requiring some time to heat up, and requiring water to be topped up regularly (although that’s not a major issue). But they’re also less efficient. There’s no real benefit to Steam.
Nuclear power stations use Steam turbines rather than traditional Steam engines, and this has indeed been used for cars, although not production vehicles. https://en.wikipedia.org/wiki/Inspiration_(car)
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