I am not talking about just ICE, but any thing that converts matter to energy.
Black hole. Matter goes in, energy (Hawking) comes out
By "matter" you mean "fuel", right?
I think that a matter/antimatter collider would be it.
There's only one "engine" that converts matter to energy, which is nuclear. Nuclear is currently very inefficient, capturing all of the various forms of energy released from a nuclear reaction (netruons, gamma, x-ray, etc.) isn't worth the effort.
I would guess that the most efficient engines currently made for converting stored energy in any form (chemical, electrical, etc.) to mechanical work would be either a high-end brushless electric motor (~90% IIRC) or maybe a purpose-built constant-speed turbine.
Matter/antimatter has a high specific energy density, but you still have to capture the energy and utilize it somehow for it to be classified as an engine... I would guess that a matter/antimatter reactor would look very similar to a current nuclear plant (water or other working fluid heated into steam and run through a turbine).
I thought that all engines did that. If e=mc^2 does not hold for chemical reactions, then what is the appropriate equation?
Yes i mean fuel, so the energy could be plant based or any other thing you could think of.
About 40% maximum efficiency?
Really? Huh, why's that?
Chemical reactions do not create or destroy mass; nuclear reactions are a different story.
Thanks for that explanation Mech_Engineer. However, I believe it is incorrect. I think that the making and breaking of chemical bonds involves the energy-mass equation e=mc^2 just as the making and breaking of nuclear bonds. the difference between the nuclear case and the chemical case is the amount of mass and energy involved.
Maybe that's true, but I think for all practical applications the mass change is considered to be negligible in a chemical reaction.
Yes, perhaps it is. In spite of what the article says, the amount of energy conversion for chemical bonds is exactly the same as for nuclear bonds, e=mc^2. In other words for 1 joule of energy, there will be the same amount of mass loss for either case. What differentiates the nuclear reaction from the chemical reaction is the mass and energy density.
There are some motor proteins in biology that convert the free energy from the hydrolysis of a fuel molecule (ATP) into motion. Many of these are very efficient, and one in particular called ATP synthase is thought to work at ~90% efficiency (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1692765/).
NB: In the body, ATP synthase actually catalyzes the reverse of the reaction described in the paper. It converts the energy from rotary motion into the formation of a chemical bond, creating ATP. In the laboratory, however, it is easier to study the motor moving in the opposite direction, hydrolyzing ATP to create rotary motion.
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