Onboard CO2 mineralization turns ship emissions into stone: what it means for maritime decarbonization

A growing number of shipping companies are testing onboard CO2 mineralization systems that capture exhaust carbon and convert it into solid carbonate minerals. The process uses naturally abundant minerals like olivine or serpentine to react with CO2, forming stable rock that can be stored or potentially repurposed. Several pilot projects are now moving from lab trials to shipboard installations, with proponents claiming the technology could lock away CO2 permanently without the leakage risks of geological storage. The approach is particularly interesting for shipping because it avoids the need for large onboard amine scrubbers or cryogenic capture equipment. Instead, the mineralization reactors can be integrated into existing exhaust systems. Early data from small-scale tests suggests capture rates above 80% are achievable, though energy requirements for grinding and circulating the mineral feedstock remain a concern. The real question is whether the process can scale to handle the full exhaust volume of a large container ship without consuming too much auxiliary power. For carbon credit markets, onboard mineralization offers a verifiable, permanent removal pathway that could generate high-integrity credits. But the economics depend on mineral sourcing, reactor maintenance costs, and whether ports will accept the solid carbonate output for disposal or industrial use. If these logistics get solved, this technology could become a meaningful option for hard-to-abate maritime emissions.