Iceland's volcanoes might have an unexpected new purpose – an architect duo want to harness molten lava to shape the construction of houses and cities of the future

Neat idea but really lacking in details. How on earth do you guide lava before it cools into structures reliably and without ruining your settlement?

There are some obvious problems with the idea, such as the fact that it would exclusively build settlements that are directly in the path of active volcanoes. But the way they talk about it sounds more like a thought experiment or very early stage brainstorming:

"But the wider concept of the pavilion is not just about lava. It’s about addressing a risk and changing perspectives, hopefully inspiring conversations."

“One of the core concepts is that there is no private ownership of lava in Iceland,” says Skarphéðinsson. “If we create a city out of this material, then it would be owned by the people who live in it. And in this respect, we’re also thinking about places such as the Congo, where there are so many riches, so many minerals, but the people who live there don’t get any of the rewards. We want to put forward these questions that aren’t really being asked.”

Arnhildur Pálmadóttir seems to be a public advocate for sustainable building practices:

Her designs, [...] have a strong emphasis on using sustainably-sourced materials, reusing materials, reducing energy and resource use, climate-neutral solutions, and creating a more sustainable lifestyle

If it is in fact in the spitballing phase, I'd like to suggest diverting lava flows into large brick-shape moulds, then taking the new basalt bricks somewhere further away from the active volcano to build with.

The article is sparse on details, but says this of potential uses:

"The pair propose several possible ways to use lava, from channelling [sic] its flow into trenches to form foundations and extracting it from pockets of magma to 3D-print organically shaped building elements or bricks."

I'm not an expert in this field, but I see several problems with each of these uses.

The trench idea is problematic because the new building is next in an active volcanic field, which is inherently unpredictable. For example, the most recent Sundhnúkur eruptions forced the evacuation of the town of Grindavik due to the danger of future eruptions. The Icelandic government continues to pay housing expenses for the prior residents since the town is still deemed unsafe (i.e. BBC article 1 and BBC article 2).

Furthermore, the trench idea is flawed because these eruptions don't generally happen in places that people want to live. For example, the eruptions at Geldingadalir eruption were a long hike from a sparsely traveled highway. Here's a time lapse video of the hike.

The other idea (extracting lava to 3D-print building elements or bricks) is slightly less problematic because they're not building in a remote lava field. However, they'd still 1) need to design a printer capable of handling lava and 2) be working near a dangerous active lava field (see prior discussion of danger / unpredictability). I suppose they could use disposable 3D printers, but that doesn't seem very carbon friendly (one of the stated goals / benefits). Finally, they would still need to get this lava-resistant 3D printer to the lava, which doesn't seem like an easy task.

As I noted earlier, I'm not an expert. I'm also all for environmentally-friendly construction and Iceland attempting to minimize imports, and wish them the best of luck. However, these uses don't seem to make sense.

Instead, maybe transport some of the plentiful lava rocks to a geothermal station and use excess energy to re-melt the lava?

How very Dwarf Fortress of them.

We've known how to do this for years now - get a water bucket and a lava bucket and bam! Infinite cobblestone! The hardest part is to not let the water get to the source lava block or you get obsidian, which is much less useful.