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So, I think energy from fat/sugar is more densely stored than energy from batteries, as covered by xkcd here - https://what-if.xkcd.com/128/. People are also working on lab-grown meat/muscle, often for environmental reasons as an alternative to farming animals. People have also demonstrated that you can use electrical impulses to muscles to get them to tense or contract.

My question is, in the future (of our universe) would it be possible to create cars that are powered with fat/sugar, and have an engine made of specially designed lab-grown muscle to pull the pistons? Theoretically that could have more range than an electric car right?

I imagine the main problems would be getting the muscles to convert the energy into sufficient horsepower to get the speeds required for modern cars. If the technology could not be used for cars, what other applications could there be for lab-grown biological muscle? (other than e.g implants)

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    $\begingroup$ Of course you can have engines powered by burning fat. Or vegetable oil, which has the advantage that you don't even need a new engine -- vegetable oil works fine in old-fashioned Diesel engines. (And the main application of vat-grown muscles is obviously food. Niam niam artificial stake.) The main problem with biofuels is not that they don't work; they work perfectly well: it is that you need to grow the fuels in the first place, and that takes up precious arable land. On the other hand, see ethanol in Brazil. $\endgroup$
    – AlexP
    Commented Dec 4, 2020 at 21:43
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    $\begingroup$ Yaba Daba do :o) $\endgroup$
    – Slarty
    Commented Dec 4, 2020 at 21:44
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    $\begingroup$ I think this is called a horse ;) $\endgroup$
    – DKNguyen
    Commented Dec 4, 2020 at 21:46
  • $\begingroup$ Animal muscles need a continuous supply of oxygen and nutrients, supplied by the bloodstream. It is not a simple task of exciting the muscle with an electrical pulse, you also need to provide every cell with a continuous supply of these nutrients and oxygen. That would be equivalent to having a tank of gas which is piped to the car engine. What you want is something like this onlinelibrary.wiley.com/doi/full/10.1002/advs.201901144 $\endgroup$
    – Justin Thyme the Second
    Commented Dec 4, 2020 at 21:58
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    $\begingroup$ Humanity does this every time it rides a bicycle. The mathematics explaining the capabilities of humans using bicycles, the efficiency of human muscles, and the conversion of food into energy are well known. There is no difference between what you're asking and a human on a bicycle other than scale and the lack of the controlling brain to need to reason. May you not be there when said brain decides it deserves to be paid. $\endgroup$
    – JBH
    Commented Dec 5, 2020 at 4:53

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It may be possible, but why would you want to?

An internal combustion motor burning that fat is about 25-30% efficient.

A human muscle burning that fat is about 22% (burning glucose to movement) * 70%(fat to glucose conversion) = ~ 15.5% efficient.

So a muscle-powered vehicle using fat as fuel will be less efficient than a simple internal combustion engined car.

Both the "muscle" car and the combustion engine will use the same fuel, emit the same pollutants, but the "muscle" car will require about twice the amount of fuel per distance.

Of course, most of us dispense with the Fat nonsense. That stuff is hard to pump around, and not a very good store of energy.
Fat: a whitish solid. 37.7 MJ/kg very hard to pump. goes rancid if stored.
Gasoline: a liquid. 45.5 MJ/kg pumps easy, stores moderately well.

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  • $\begingroup$ I am curious where you got your numbers for human muscle. $\endgroup$
    – John
    Commented Dec 4, 2020 at 22:59
  • $\begingroup$ @John I assume one of Stephen Vogel's books, but I do not know. $\endgroup$
    – DKNguyen
    Commented Dec 4, 2020 at 23:11
  • $\begingroup$ @john various, such as : openoregon.pressbooks.pub/bodyphysics/chapter/human-metabolism , en.wikipedia.org/wiki/Muscle and ncbi.nlm.nih.gov/pmc/articles/PMC3144848 . One would need to use the "fast" muscle types, of course, and they are not very efficient. But even with the more efficient types, muscles do not run on fat directly, but need to something to convert the fat to glucogen first. this process is not very efficient, either. $\endgroup$
    – PcMan
    Commented Dec 4, 2020 at 23:13
  • $\begingroup$ If you are using that then your numbers o off you are also comparing the efficiency of legs to wheels using those calculations. your own link shows muscle efficiency is closer to 50% $\endgroup$
    – John
    Commented Dec 4, 2020 at 23:42
  • $\begingroup$ Wow I did not realize fat was so close to gasoline in energy density. Batteries suck. $\endgroup$
    – DKNguyen
    Commented Dec 4, 2020 at 23:55

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