- Storage of carbon dioxide;
- Storage of industrial chemicals;
- Storage of hydrocarbons;
- Storage of potable water by artificial recharge;
- Underground energy storage in the form of hydrogen and compressed air;
- Disposal of hazardous wastes;
- Disposal of radioactive wastes;
- Resource exploitation; and
- Development of underground infrastructure (e.g. road and rail tunnels).
For storage of resources and energy, the subsurface facilities need to provide containment or thermal insulation and allow for efficient retrieval, which requires good storage integrity, robustness of the system to repeated loading and unloading and confidence that the system will not fail in a way that affects the biosphere adversely.
For storage of hazardous wastes, the subsurface facility must provide sufficient containment integrity and there must be a plan to mitigate any unexpected migration of hazardous substances to the accessible environment.
A key part of ensuring efficient and safe usage of an underground facility is sealing any boreholes, shafts, tunnels or other excavated cavities that might otherwise provide pathways between the facility and sensitive environments at or near the surface.
The demonstration of operational and longer-term safety of subsurface storage and disposal facilities to regulators and other stakeholders requires a rigorous risk assessment / performance assessment based on sound evidence. Quintessa has a long track record of carrying out such assessments using soundly based structured methodologies, and documented to be accessible to all interested parties. Examples include:
- Natural gas storage in mined cavities and porous rock reservoirs;
- Hazardous wastes in mined facilities;
- Compressed carbon dioxide captured from power stations and industrial plants in underground depleted hydrocarbon reservoirs and aquifers; and
- Radioactive wastes in boreholes and excavated repositories.
Moreover, Quintessa’s decision support services provide assistance to the siting and licensing of underground facilities, and this is complemented by our geosciences expertise and experience, for example in assessing the integrity of borehole seals.