Quantum cascade laser-based sensing for carbon sequestration leakage monitoring

Carbon capture and sequestration (CCS) may play a key role in our energy future. However, the widespread sequestration of CO₂ into storage reservoirs is inhibited by safety and leakage concerns. Effective leakage monitoring at the surface is recently made possible by the development of quantum cascade (QC) laser-based sensors, which are capable of tracking fluxes in CO₂ isotope concentrations. In this paper, we initially discuss the status of this technology, including recent results from distributed feedback QC lasers for use in sensing CO₂ isotopic ratios. These lasers show single-mode emission at 4.32 μm, overlapping strong absorption resonances of ¹²CO₂, ¹³CO₂, and ¹⁸OCO. We then consider the value of such devices for quantifying CO₂ leakage using a climate-economy integrated-assessment model that is modified to include CCS. The sensitivity of model outcomes to reservoir leakage is studied, showing that an average reservoir storage half-life on the order of 1000 years or longer can limit atmospheric temperature increases to 2° C or less over the next 150 years for economically optimal emissions scenarios. The present day economic value of CCS is established versus reservoir half-life, showing a significant return on investment (∼ 2 trillion U.S., or ∼ 4\% of gross world product) when the average reservoir half-life is 250 years, with a sharp drop in the value of CCS technology for half-life values below 250 years. Quantifying CO₂ leakage rates via QC laser-based sensing will contribute greatly toward accurately assessing CCS technology and its efficacy as part of CO₂ limitation strategies.