Science

Why Digging 12 Miles Deep Is Almost Impossible | The Limit

Business Insider
Business Insider•May 2, 2026

Why It Matters

Deep‑drill geothermal could unlock near‑limitless clean power, dramatically expanding baseload renewable capacity and reducing reliance on fossil fuels.

Key Takeaways

  • •Deepest vertical borehole reached 12.2 km by Soviet Kola project.
  • •Heat and pressure limit conventional drilling beyond ~12 km depth.
  • •Quaz uses millimeter‑wave gyrotron to vaporize rock for 20 km drilling.
  • •Supercritical water at >500°C could boost geothermal output tenfold.
  • •Successful 1 km test aims to validate technology for commercial geothermal.

Summary

The video examines why digging beyond the current 12‑kilometre record – set by the Soviet Kola Superdeep Borehole after two decades of effort – remains a formidable engineering challenge. It outlines how temperature rises roughly 25 °C per kilometre and lithostatic pressures exceed 40,000 psi, overwhelming conventional drill bits and casing systems. Key insights include the limits of mechanical drilling, the promise of millimetre‑wave (gyrotron) technology that melts rock into a glassy liner, and the energy potential of supercritical water at 500 °C, which could generate up to ten times the power of traditional geothermal wells. The segment also highlights historical attempts such as the US Project Mohole and the Soviet Kola project, and cites Iceland’s success in tapping shallow magma for 30 % of its electricity. Notable moments feature a live demonstration by Quaz, where a gyrotron‑driven beam vaporises granite, producing glass‑like walls, and engineers explain how the resulting vitrified lining could act as a self‑forming casing. The company’s goal is a 1 km pilot in Texas by year‑end, a stepping stone toward a 10‑km, 20‑km target that would reach supercritical reservoirs. If the technology scales, deep‑earth geothermal could supply a steady, low‑carbon baseload, potentially covering 15 % of global electricity demand by 2050 and reshaping the energy landscape beyond regions with natural volcanic heat.

Original Description

The deepest hole humans have ever drilled into the Earth is just 12.3 kilometers, about 0.2% of the distance to the planet’s core. That effort, the Soviet-era Kola Superdeep Borehole, took more than 20 years to complete. And despite decades of technological progress since, we haven't gone any deeper. So what’s stopping us?
Business Insider visited drilling sites and spoke with engineers and industry experts to understand what it would take to go deeper than ever before, and whether reaching the Earth’s mantle is even possible.
00:00 - Intro
01:09 - The deepest hole
03:22 - Heat
05:55 - Millimeter wave
11:44 - Pressure
14:54 - Real-world testing
16:55 - What's down there?
18:34 - Earthquakes
20:36 - Economics
27:30 - The maximum depth
31:02 - Credits
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#digging #boreholedrilling #drillinggeology #thelimit
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Why Digging 12 Miles Deep Is Almost Impossible | The Limit | Business Insider

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