Why is it called an autoclave? Because it describes a device that automatically locks shut when the pressure rises (to avoid steam spraying out if you open it by accident). The word is French,
and comes from the Greek "auto" for automatic and the Latin "clvis," for key (as in lock and key).
Theory of operation
The basics. Why is an autoclave such an effective sterilizer? An autoclave is a large pressure cooker; it operates by using steam under pressure as the sterilizing agent. High pressures enable steam to reach high temperatures, thus increasing its heat content and killing power. Most of the heating power of steam comes from its latent heat of vaporization. This is the amount of heat required to convert boiling water to steam. This amount of heat is large compared to that required to make water hot. For example, it takes 80 calories to make 1 liter of water boil, but 540 calories
to convert that boiling water to steam. Therefore, steam at 100º C has almost seven times more heat than boiling water. Steam is able to penetrate objects with cooler temperatures because once the steam contacts a cooler surface, it immediately condenses to water, producing a concomitant 1,870 fold decrease in steam volume. This creates negative pressure at the point of condensation and draws more steam to the area. Condensations continues so long as the temperature of the condensing surface is less than that of steam; once temperatures equilibrate, a saturated steam
environment is formed.

There are two general types of steam sterilizers:
gravity displacement, in which the displaced air flows out the drain through a steam-activated exhaust valve; and
pre-vacuum, in which a vacuum is pulled to remove the air before steam is introduced into the chamber.
With both types, as the air is replaced with pressurized steam, the temperature in the chamber increases.
However, the latter is more efficient.
http://www.vliz.be/docs/Zeecijfers/autoclaveoperation.pdf

Investigating steam penetration using thermometric methods in dental handpieces with narrow internal lumens during sterilizing processes with non-vacuum or vacuum processes.

Superheated steam has a temperature exceeding the boiling point at a given air pressure and an energy conversion phase will not occur, the energy of the overheated steam will be spent in heating up the instruments and this will again be equivalent to dry heat sterilization conditions.
http://eprints.gla.ac.uk/145250/1/145250.pdf


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Note added at 57 mins (2019-01-14 16:06:50 GMT)
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3 ПРЕОБРАЗОВАНИЕ ЭНЕРГИИ
www.ene.ttu.ee/elektriajamid/oppeinfo/.../Energotehnika3-1....
Постоянное преобразование энергии, как показано на рис. 1.3.1 в разделе 1.3 ..... Papin, 1647–1712) обнаружил, что точка кипения воды зависит от давления. В 1680 г., используя это ... этот принцип используется и в автоклавах.

Использование навоза: от удобрения к энергии.
https://navozu.net/energiya-iz-udobrenij
Использование возобновляемых источников энергии - тема 21-го века, ... автоклавы, предназначены для сбора навоза и преобразования энергии, ...

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Note added at 11 hrs (2019-01-15 02:11:14 GMT)
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Наталья, я после смерти отца с 8 лет до 13 каждый день провела в больнице после школы у мамы на работе (за нами некому было смотреть, у нас не было родных). Я вас уверяю, что я не только знаю, как аутоклав работает, но в ранние годы я неоднократно помогла маме его загружать. Пожалуйста, не думайте, что я настолко д**рная, что не знаю, что аутоклав работает с помощью электричества.

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Note added at 11 hrs (2019-01-15 02:14:56 GMT)
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Автоклавы конечно, не вырабатывают электричество - и никто об этом не говорил. Но вы попутали электричество с энергией. Потому что в аутoклаве энергия преобразуется: аутоклав использует *пар под давлением*.

"High pressures enable steam to reach high temperatures, thus increasing its heat content and killing power. Most of the heating power of steam comes from its latent heat of vaporization. This is the *amount of heat required to convert boiling water to steam*. This amount of heat is large compared to that required to make water hot. For example, it takes 80 calories to make 1 liter of water boil, but 540 calories to convert that boiling water to steam."