Thermonuclear Explosions for Large-Scale Carbon Sequestration: A Call for Exploration

TL;DR

The paper proposes an unconventional, highly debated approach to gigaton-scale CO$_2$ sequestration by using deep underground thermonuclear detonations to pulverize weatherable rock and accelerate enhanced rock weathering. It combines ERW with explosive fragmentation, estimating that $60$ Gt of rock are needed to sequester $9$ Gt CO$_2$, and that a burial depth of about $1.34\ \mathrm{km}$ can contain the blast while producing millions of tons of fines for rapid weathering. The analysis provides detailed cost components, PSD modeling via the Swebrec framework, PSD-energy relationships, and byproduct monetization, arriving at a nominal sequestration cost of $0.68$/ton CO$_2$ at gigaton scales. It also addresses environmental, seismic, and political considerations and contrasts thermonuclear with conventional explosive implementations to assess feasibility and risks. Overall, the work offers a provocative, quantitative exploration of amplifying ERW with explosive fragmentation and highlights substantial practical and ethical hurdles to deployment.

Abstract

Climate change is a rapidly accelerating problem that requires fast and large-scale carbon sequestration to prevent catastrophe. This paper proposes a novel approach to use explosives for large-scale carbon sequestration. Combining the long-practiced method of explosive mining with newer enhanced rock weathering techniques, we propose a faster, greener, and profitable method of large-scale carbon sequestration. This method is applicable for all explosives, including thermonuclear, and can be done safely with minimal anthropological and ecological impact. We estimate a cost of $0.68/ton of CO2 sequestered.

Figures (5)

• Figure 1: Concept of the plan to use thermonuclear explosions for large-scale carbon sequestration in which (a) the hole is drilled into the Earth's surface (b) the explosive is detonated (c) the carbon-capturing rock powder is lifted out of the hole (d) the rock powder is transported and spread (e) and the byproducts are used as concrete aggregate.
• Figure 2: The double fragmentation-energy fan for Basalt samples collected by Faramarzi reported as Figure A6 in psd_energy_fan_advances. The bottom yellow line is the 20$^{th}$ percentile, the red middle line is the 50$^{th}$ percentile, and the top blue line is the 80$^{th}$ percentile. Note that here D is the original particle size before crushing, equivalent to $x_{\mathrm{max}}$, and the axes have been non-dimensionalized.
• Figure 3: Cumulative mass fraction vs. particle size at an $E_{\mathrm{cs}}$ of $20~\mathrm{kWh/t}$. The black dashed line annotated as $x_t$ indicates the transition from the Swebrec model to the fractal model with decreasing particle size. The blue curve represents the piecewise cumulative mass fraction, where the fractal model is applied for particle sizes smaller than $x_t$, instead of the Swebrec model (orange dashed curve).
• Figure 4: Specific comminution energy vs. distance from the explosion with points of interest of the melt zone radius, the upper limit of notable particle generation as the second dashed line, the crush zone radius, and the rupture zone radius.
• Figure 5: Specific energy vs. distance from the explosion with points of interest of the melt zone radius, the upper limit of notable particle generation as the second dashed line, the crush zone radius, and the rupture zone radius.