Most eco friendly and energy efficient way to hard boil eggs

A pressure cooker is a device everyone should own.

The way most people make hard boiled eggs, is a tragic waste of resources.
First, they boil a lot of water, as high as the height of an egg.
That takes a lot of energy, time, propane, or electricity.
If you could picture all the coal and fossil fuel emissions, air pollution, to do that, you'd try to use the least amount of energy as possible to do the job.

With a pressure cooker, all the heat is retained and put to work cooking the egg, not evaporating into the air like boiling a large pot of water.  I made a video above so you can see just how little water is needed. You only need a tiny amount of water with the pressure cooker. Enough to produce steam to engulf the eggs with the same heat from water vapor as you would get from water in boiling liquid form.

So it doesn't take long to bring a tiny amount of water, maybe 2-3 minutes to a boil.

Then you put in the eggs, put the lid on it, set a timer for 5 minutes.
When the pressure starts to build to to a noisy level, reduce to low heat, enough to keep the boil going.

After the 5 minutes timer sounds, turn off the stove. Set the timer for another 5 minutes, let the eggs continue to cook at near boiling temperatures with the retained heat.

When done, if you plan to eat the eggs right away, you can add some cold water to make it easy to peel the shell. Otherwise, just take the lid off and let it cool naturally. But this will cook the egg more, so if you want to keep the yolk at whatever level you decide, then add cold water.

So total time, this takes about 12 minutes. And uses the lowest possible amount of water and gas/propane.