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.
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