Large scale carbon sequestration in deep sand dunes
The silicon of the quartz sand could be used to bind
atmospheric (and hydrospheric) excess CO2 into the from so silicon carbide aka moissanite.
Rather than just burying it as solid chunks is could make for a local underground network of tunnels and facilities
out of metamaterials out of standard nanomechanical structural and machine elements and standard microcomponents.
These could also be exported via the global microcomponent redistribution network.
But the sheer quantity might be too much thus possibly a goo place for gem gum-tech caches.
beside moissanite carbon feedstock, standard crystolecule magazines, microcomponent caches.
Facilities could be co-used for many things.
- Geologic (and less so biologic) research, particularly deep down at the water table and dune roots.
- Safe long term storage of building materials and data (often low seismicity & low uplift since in cratonic interiors)
- A major hub of the global microcomponent redistribution network.
- Sea to inland desalination and irrigation. For desertification halting and for desert greening. Latter: cost benefit ratio to weigh.
- connection to (or part of) to the lithospheric mesh (geothermal energy, … see link)
Environmental considerations (protecting presence of life)
- acting sterile, not bringing in any non native invasive microbial competitors
- not affecting the existing deep (but potentially still within the sand) water table
- leaving the sand as the singly connected contiguous matrix not blocking slow microbial migrations
- sticking mostly to the quite homogeneous sand phase, more concerns to be looked at when going below
- weighing cost vs benefit of (ab)use for desert irrigation endangering live that needs desert conditions to thrive.
Politcial considerations
To avoid conflicts obviously the local government / governance needs to
agree on any such enormous on geoengineering bordering projects and their details.
Many of places with deep silicate sand dune deserts may be located in politically labile regions.
Unfortunately not all governments represent the needs of their people well.
These and more factors or future companies attempting projects more or less related to the here described.