TL 4 Lava Use

[Sindri]

Lava* is cool. Low tech use of lava in forges and stuff is a common concept in fantasy. People have historically used lava produced materials like obsidian and profited from geothermal energy. Modern people have even cooked meat on lava. What could a TL 4 society realistically accomplish with lava? Of course lava isn't an identical substance so uses may vary based on it's composition.

*Or magma

[malloyd]

Originally Posted by Sindri

Lava* is cool. Low tech use of lava in forges and stuff is a common concept in fantasy. People have historically used lava produced materials like obsidian and profited from geothermal energy. Modern people have even cooked meat on lava. What could a TL 4 society realistically accomplish with lava?

Nothing really. Most lava is cooler than a typical medieval forge, glassblowing pot or pottery kiln. At the bottom end, it's actually cooler than a wood fire, and almost none of it exceeds the 1200 C minimum for crucible steels or blast furnaces (most of which actually get several hundred C hotter than lava ever does). If you can make glass, you can remelt most igneous rocks.

[Flyndaran]

Rock has very little capacity to hold thermal energy, so it will rapidly cool and solidify once it's removed from the heat source. Often a matter of mere seconds for man portable masses.

I saw a video of a lava "sculptor" that pulled out head+ sized amounts, and had to work ridiculously quickly before it "froze".

[Anthony]

If you have a source of lava, it's a geothermal heat source, and can be used in much the same way as any other geothermal heat source, which at TL 4 mostly means hot springs.

[Sindri]

Originally Posted by malloyd

Nothing really. Most lava is cooler than a typical medieval forge, glassblowing pot or pottery kiln. At the bottom end, it's actually cooler than a wood fire, and almost none of it exceeds the 1200 C minimum for crucible steels or blast furnaces (most of which actually get several hundred C hotter than lava ever does). If you can make glass, you can remelt most igneous rocks.

It is however a source of heat that doesn't require collecting a bunch of wood or charcoal or coal which could have advantages.

Originally Posted by Flyndaran

Rock has very little capacity to hold thermal energy, so it will rapidly cool and solidify once it's removed from the heat source. Often a matter of mere seconds for man portable masses.

I saw a video of a lava "sculptor" that pulled out head+ sized amounts, and had to work ridiculously quickly before it "froze".

For some things that's good. Obsidian forms because of rapid cooling.

Originally Posted by Anthony

If you have a source of lava, it's a geothermal heat source, and can be used in much the same way as any other geothermal heat source, which at TL 4 mostly means hot springs.

Could you usefully heat places using plumbing to transport the water from hot springs?

[Anthony]

Originally Posted by Sindri

Could you usefully heat places using plumbing to transport the water from hot springs?

Over short distances, sure.