CARBON CAPTURE AND MINERALIZATION IN OFFSHORE BASALT RESERVOIRS

Continued fossil fuel burning is likely to increase CO₂ concentrations in the atmosphere to previously unknown levels, with potentially catastrophic impacts on the availability of food and water, human shelter and coastlines, and energy. In the United States alone, which emits about a sixth of current global CO₂, energy use is anticipated to grow by 1-2% per year throughout the century, and emissions will continue to outpace uptake unless limiting action is taken immediately. Several negative emission technologies (NETs) can also remove carbon dioxide directly from the atmosphere, including those aimed at removing CO₂ by enhancing natural forest uptake, using bio-energy in power production, and scrubbing CO₂ efficiently from air.

The concept of carbon capture and storage (CCS) aims to separate CO₂ from industrial emissions, or scrubbed from the air, and permanently store it underground. Developing acceptable sites on-land may be messy, with a tangle of issues surrounding underground property rights, overland access, and long-term risks and liabilities near populated areas. CO₂ injected into cooled volcanic rocks (basalt) under the ocean will react chemically with them to form solid minerals like calcium carbonate (e.g., limestone) mimicking the natural process of rock weathering. Subsea basalt may provide vast capacity for 100's of years of emissions, physical safeguards that will protect the oceans, and us, and can be located at safe distances from potential interference from heavily populated onshore areas and conventional land-based water supplies.

Two land-based proof-of-concept projects – one each in Iceland and Washington State – have demonstrated that CO₂ injected into underground basalt reservoirs rapidly converts into carbonates, far faster than originally expected, and promise a safe, permanent storage solution with reduced concerns about leakage and monitoring over time. Sub-seafloor injection of CO₂, an industry proven technology, offers a similar solution in oceanic basalt. An offshore demonstration project combining CCS with mineralization and integrated NET installations is considered. Sub-seafloor basalts are very common on Earth and this approach could potentially be implemented at large scale.