Quaze Millimetre-Wave Drilling: Melt Rock to Access Deep Geothermal Energy

In this video, Dr Ben Miles visits Quaze in Houston to explore a bold approach to energy: using millimetre-wave beams, powered by gyrotrons, to melt rock and create boreholes that vitrify the walls. The startup aims to reach deep geothermal energy by bypassing conventional drill bit limitations, employing a three-step process of melting, scraping, and clearing, on repurposed oil rigs. The team faces engineering hurdles around power delivery, beam alignment, vacuum conditions, and purged gas management, but they project a path toward thousands of metres of drilling at high temperatures, followed by geothermal energy extraction. The video also outlines the economic and scalability considerations shaping Quaze’s strategy and timeline through 2028.

Introduction

The video follows Dr Ben Miles as he travels to Houston, Texas, to examine Quaze, a startup attempting to redefine how we access deep geothermal energy. Instead of relying on conventional mechanical rock-cutting with drill bits, Quaze uses high-power millimetre-wave beams generated by a gyrotron to heat and vaporise rock from within the borehole. The company intends to leverage existing oilfield infrastructure and expertise, but redirect the focus from oil extraction to geothermal power generation. The narrative presents both the scientific curiosity and the engineering challenges involved in moving a radical drilling concept from idea to field deployment, with attention to the cost curves and the potential energy payoff if the technology scales.

Background: Why Deep Geothermal is Elusive

The discussion contextualises the deep geothermal opportunity and the barriers that have constrained it historically. The deepest human-made hole, the Kola Superdeep Borehole, reached about 12.3 kilometres over two decades but could not approach Earth’s core. The main bottleneck was power delivery to the drill bit: torque dissipates along long steel strings, and rock at high temperatures becomes ductile and fluid-like, compromising the cutting action. The result is a steep, escalating cost curve as depth increases, making conventional drilling for deep geothermal economically prohibitive in many cases. Yet, the energy resource beneath our feet remains vast, with deep geothermal potentially providing tens of gigawatts in the United States and hundreds of terawatts globally, if it can be accessed reliably and sustainably.

Technology Deep Dive: How Quaze Drills

Quaze’s core idea is to melt or vaporise rock using microwaves rather than grind and crush it with a mechanical bit. The process begins with a millimetre-wave beam emitted from a gyrotron housed in a dedicated cabinet. The beam is guided down the hole within waveguides, which act like optical mirrors for microwaves, reflecting the energy downward with minimal losses. As the drill advances, the beam can melt a borehole larger than the internal diameter of the waveguide, enabling efficient penetration. In the second phase, the system stops the beam and rotates the waveguide to scrape the newly formed borehole walls. This creates a smoother, glossy vitrified lining formed by the melted rock itself, potentially reducing the need for traditional steel casings and cement. The final phase involves pushing air through the borehole to clear debris and vaporised rock, which is then surface-collected for processing.

The Hardware Puzzle: Gyrotrons, Waveguides and Vacuum

The gyrotron is a nuclear-physics-inspired device that accelerates electrons in a magnetic field to generate millimetre-wave radiation. The video notes that the current setup outputs around 1 megawatt of continuous power to heat the rock, sufficient to vaporise rock at depth, with efficiency around 30–50% depending on configuration. To maintain beam integrity, the system uses an advanced beam relay consisting of precision mirrors with reflectivity greater than 99.8%. Active cooling is essential, as the mirrors must resist intense microwave heating. A critical design feature is maintaining a high vacuum to prevent energy losses from air molecules. As depth increases, new sections of the beamline are added, requiring dynamic alignment and a robust periscope-like relay to keep the beam on target.

Operational Concept: Three-Step Drilling Cycle

The team explains a three-step cycle: melt, scrape, and cleanse. First, the beam melts rock and forms a melt layer that expands the borehole walls. Second, the beam is turned off and the scraper removes melted material from the walls, esthetically smoothing the hole and establishing a vitrified lining. Third, compressed air clears out vaporised rock and debris, enabling another pass at deeper depths. This approach is argued to reduce reliance on high-torque surface machinery and to extend the life of conventional drill pipes by avoiding relentless mechanical wear.

Current Status and TRL Trajectory

As of the visit, Quaze is operating in the research and development stage, with a Technology Readiness Level around 6–7, meaning they have demonstrated a lab or field demonstrator and are working toward more robust, field-ready engineering. The company envisions a staged progression: from single-digit metres to tens, hundreds, and then thousands of metres, with increasing temperature and depth, culminating in a fully installed geothermal energy extraction system. 2025 marks the debut of a full-scale hybrid rig combining rotary drilling with millimetre-wave drilling. 2026 is targeted for the first thermal energy extraction, and 2028 for the first geothermal power plant, marking the transition from demonstration to commercialization.

Commercial Strategy and Risks

Quaze’s plan involves targeting shallower, high-temperature sites first, where the technology can prove its value and help refine the purge gas strategy and debris handling required for deeper wells. The shift toward shallower deployments is intended to buy time to solve challenges like long-distance purge gas transport, potential borehole sealing from cooling rock, and the risk of supercritical water interacting with vapourised rock along the ascent. The video acknowledges these risks and frames them as engineering hurdles to be addressed as the system scales. The ultimate payoff would be a new class of geothermal power plants that can operate continuously with high capacity factors, providing a significant portion of baseload energy if the technology can be cost-competitive at scale.

Conclusion

The video presents Quaze as a bold example of applying fusion-era heating concepts to near-term energy challenges. If the company can solve the engineering and economic challenges, drilling through rock to unlock deep, reliable geothermal energy could disrupt energy supply and transform how we think about carbon-free power. The team remains transparent about progress and setbacks, underscoring the iterative nature of engineering breakthroughs and the potential to redefine energy infrastructure through high-temperature, deep drilling.