Carbon capture and storage (CCS) is vital to reduce CO ₂ emissions to the atmosphere, potentially providing 20% of the needed reductions in global emissions. Research and demonstration projects are important to increase scientific understanding of CCS, and making processes and results widely available helps to reduce public concerns, which may otherwise block this technology. The Otway Project has provided verification of the underlying science of CO ₂ storage in a depleted gas field, and shows that the support of all stakeholders can be earned and retained. Quantitative verification of long-term storage has been demonstrated. A direct measurement of storage efficiency has been made, confirming that CO ₂ storage in depleted gas fields can be safe and effective, and that these structures could store globally significant amounts of CO ₂ .