[cryptica]

When the article mentioned that the temperature was twice what they had expected, I wondered the exact same thing.

Could they cover the hole, pour water into it and use air pressure changes in the hole to generate electricity? There must be a way to make the hole air tight. I suspect that the rock near the bottom of the hole would already be air tight.

Also I never understood why steam engines release all the hot stream into the air? Doesn't that waste energy to let the hot steam out? Isn't it better to keep the heat trapped inside the system and generate electricity from the pressure only?

[technothrasher]

Isn't it better to keep the heat trapped inside the system and generate electricity from the pressure only?

Steam engines are old technology. They've been replaced by modern steam turbines, in which the steam is either cooled and recirculated, or used for other processes, or both.

Geothermal steam turbines typically use a heat exchanger and release the original steam, as geothermal steam tends to be very corrosive.

[jacquesm]

Steam is very corrosive in general.

[Turing_Machine]

> Also I never understood why steam engines release all the hot stream into the air?

They don't. All practical steam engines have condensers that recover most of the water and as much of the heat as current technology and the laws of thermodynamics allow.

[m4rtink]

In steam trains it is often injected to the chimney to increase draft, forcing more air through the firebox, improving combustion. This of course uses up a massive amount of water.

For this reason most steam engines in ships and elsewhere generally did have condensers & reused the steam as feedwater, as you describe.

[cryptica]

I was thinking that if the steam had to travel up 10km to the surface, that would give it more time to cool down. Maybe in cold countries, they could use outside air temperature to cool rising steam before it reaches the top of the hole.