Carbon capture and storage (CCS) technology is an important tool in the fight against climate change. Carbon dioxide gas is captured following fossil fuel production or other industrial processes, then compressed and pumped underground under extremely high temperatures and pressures, and stored in depleted oil and gas wells or, in some cases, in underground salt caverns or saline aquifers. A key concern with CCUS technology is the ability to verify that the carbon dioxide remains in place and stored underground. If the carbon dioxide leaks from the disposal wellbores, this not only impairs the effectiveness of the sequestration process, but it can contaminate other underground water regions nearby. These wellbores are harsh environments to monitor, under intensely high pressures and chemically corrosive. Such environments are not friendly to the delicate conditions that most sensors need to operate effectively.  This grant will fund work by researchers Debbie Senesky at Stanford University and Pingfeng Wang at the University of Illinois at Urbana-Champaign to develop and deploy a novel, durable sensor system capable of operating in the harsh conditions of a CCS wellbore and thus able to monitor whether the sequestered carbon dioxide is staying put or seeping out. The project has the potential to significantly advance understanding of the effectiveness of CCS sequestration, and thus to help inform the future development of these technologies in the fight against greenhouse gas emissions. The project will train at least two graduate students and is expected to result in a number of academic publications and the development of new sensor technologies.