Do car engines need to be so inefficient?

Car engines could be a lot better than they currently are. This is not some oil industry conspiracy, but a simple reflection that the design is pretty creaky. It has been around a long while. And, of course, cars are currently about as green as something that isn't very green at all.

It's remarkable that the internal combustion engine, the heart of travel industry still, is so impressively inefficient. Around 25% of the energy generated from the fuel is actually used to move the car.

Eventually I have no doubt we'll all be driving electric cars - we're just waiting for a shift in battery technology that seems pretty close on the horizon. (If I had the money, I'd be driving a Tesla right now.) But there are bound to be decades of gradual transition when we still need to make use of fossil fuels.

I've had pointed out this remarkable project to produce an engine that should increase efficiency of an internal combustion engine more than twofold. It's a turbine-like design, but a variant that reduces the complexity of technical problems with turbines, plus has only one moving part.

Will it work? To paraphrase Scotty on Star Trek, I'm a writer Jim, not an engineer. Clearly the claim in the video that this could 'reduce global CO2 emissions by up to 20 per cent in the next five years' is not viable. Given that a prototype doesn't exist yet, it's hardly going to change the world in five years. What's more, the website is somewhat vague about what fuel the engine uses, but I'm guessing LPG, in which case it's not just a matter of needing new cars with new engines, but also a distribution network for a fuel that isn't currently widely available. Even so, the prospect of an internal combustion engine that is so much more efficient than current designs is an impressive one.

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  1. Actually, diesel engines are reaching about 50 % efficiency. They are so efficient that around here, you have to burn extra fuel to generate heat so that the cabin is warm enough in winter and windows can be de-misted.

    1. Fair point, but diesel has never made much of a mark on the US market, and has its own problems with other pollutants.

    2. Well, in part that is an answer to your question "Do car engines need to be so inefficient?"

      When efficiency of combustion engines is increased by e.g. increasing the compression ratio, the result is higher NoX emissions.

      Those can then be reduced with other technologies (like urea injection) but that in turn increases the cost and makes the engines more complicated and more vulnerable to failure.


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